Extraction - Analytical Chemistry (ACS Publications)

Extraction Henry Freiser, University of Arizona, Tucson, Ariz.

S

continues to attract the high interest of chemists concerned with a broad variety of topics, from large scale separation and purification processes, to preparation of carrierfree trace levels of isotopes, from new analytical extraction procedures using familiar reagents to developing and testing new reagents, from designing and testing new extraction methods to physicochemical examination of import a n t systems to determine the underlying extraction mechanisms and to evaluate the role of molecular structural and experimental parameters that will help in the improvement of existing systems and in design of new extractants. Extraction processes have found increasing use in the study of the kinetic as well as thermodynamic aspects of chemical reactions, notably metal complex formation, in both aqueous and nonaqueous phases. Solvent extraction chemistry has provided a rational, useful guide t o the design of many new chromatographic procedures, particularly those involving “reversed-phase” techniques. The vitality and variety of the field, demonstrated in part by the record number of references included in this biennial review, was amply illustrated by the rich program of the International Conference on Solvent Extraction Chemistry at Gothenburg in 1966. The more than 80 papers presented are covered in this review M hich, in addition to including a few earlier references missed in the last review, covers the period from late 1965 to late 1967. The plan of this review is similar to the last one, with additional attention given to presenting as much information as possible in tabular form to facilitate communication of the essence of over 1100 publications. OLVENT EXTRACTIOS

REVIEWS AND BOOKS

General reviews (8, 19, 29, 233, 954) as well as those dealing with chelate systems (269, 777, 864, 1125), ion association systems (264, 397), amines (916)) phosphorus compounds (767), azo dyes (7f6),and molten salts (616) have appeared as well as those more restricted in scope:-Ion-association complexes of R e (321),of 110 (I&’), of P t metals (89), of F e and T1 (11%) and of Hf-Zr separation (942). The use of extraction in trace analysis (671),and h1IBK systems in metallurgical analysis (350), and extraction in aqueous reprocessing of reactor fuels (39) have also been reviewed. T h e proceedings of the 1965 International Conference on Solvent Extrac-

522 R

ANALYTICAL CHEMISTRY

8572I

tion of Metals which accented extraction of fission product and actinide metals have been published (636). DISTRIBUTION STUDIES

d considerable number of equilibrium distribution studies of various extraction systems have been reported. These studies can provide information about the nature of the extracting species, mechanism of extraction processes, and values of the component equilibrium constants of the reactions involved in the extraction. These studies are useful not only in providing a sound basis for developing and understanding extraction procedures but also in obtaining equilibrium d a t a for the aqueous solution chemistry of metal ions. Results reported for chelate and ion association systems are tabulated in Tables I ( a ) , I@), I(c), and I(d). KINETIC FACTORS IN EXTRACTION

Following the finding that the rate of extraction of metal dithizonates mm limited by the rate of chelate formation in the aqueous phase by Honaker,

ABBREVIATIONS

Alamine 336-S is tricaprylamine Aliquat 336-S is tricaprylmethylammonium chloride Amberlite LA-1 is S-dodecenyltrialkylmethylamine (secondary amine) Amberlite LA-2 is LY-lauryltrialkylmethylamine (secondary amine) Azoazoxy BN 1-(2-OH-l-naphthyla~o)-2-(2-0H-B-CH~-l-phenylazoxy) benzene BAMBP 4-sec-butyl-2-(amethylbenzy1)phenol BPHA AY-Benzoyl-S-phenylhydroxvlamine DBP Dibutylphosphoric acid DBBP Dibutyl butylphosphonate DEDTC Diethyl dithiocarbamate D I M P Diisoamyl methylphosphonate DOPA Ilioctylphosphoric acid Ferron 7-Iodoquinolin-8-01-5SOIH IBA Isobutylamine MIBK hIethyl isobutyl ketone PAN Pyridylazonaphthol PAR Pyridylazoresorcinol phen 1,lO-phenanthroline Primene, J l I - T .mixture of C18CZ2primary ammes Primene 81-R mixture of Clt-Cla primary amines TFA Trifluoroacetylacetone T B P Tributylphosphate TLA Trilaurylamine TOA Trioctylamine TTA Thenoyltrifluoroacetane

blcClellan, and Freiser (631) and, consequently, that chelate extraction kinetics could be used as a means of studying the rates and mechanism of metal chelation reactions (292), studies of the extraction rates of the Zn, Xi ( 7 4 9 , and Co (744) chelates of a series of substituted dithizones were carried out. Increases in the rates were observed with substituents having both positive and negative Hammett a values. Zinc was found to be much more affected by steric hindrance (provided by a n o-methyl group) than either Si or Co. This was in contrast to the kinetic behavior in 8-mercaptoquinoline extractions in which the Ki chelate of the 2methyl analog was seen to exhibit a greater rate decrease than Zn (708). The kinetic as well a the equilibrium behavior (466) of the S i (8-mercaptoquinolinate) indicated the possible presence of polymeric chelate structures. The rates of extraction of a number of other chelating systems (TTA, BPHA, P.4N) also seem to be controlled by chelate formation (1124). The effect of aqueous complexing agents such as acetate, thiocyanate, oxalate, mercaptoacetate, and others on the rate of extraction of zinc (196) and nickel (986) dithizonates was investigated. .Ilmost without exception, 1: 1 complexes in this group reacted more rapidly with dithizone than did the hydrated Zn or Xi ions, whereas the 2 : 1 complexes were much more inert. From these measurements, it was possible to determine the formation constants of the complexes as well as the specific reaction rate constants for the interaction of the 1: 1 complexes with dithizonate. Because the ZnOAc’ reacts 25 times as fast as Zn*+, and the ?;iOA4c+ is no faster than Ni2+, the difference in the rates of extraction of these two metal ions by dithiaone is significantly enhanced by acetate ions. Addition of thiocyanate was found to enhance conqiderably the rate of extraction of iron by TT.4 (283, 284). Similarly, fluoride accelerates the rate of extraction of the notoriously slow Cr(II1) (776). Further analytical applications of this line of investigation should be readily accessible. The rates of extraction of 8-quinolinol into CHCls (116) also seem to be governed by rate processes in the aqueous phase. The extraction rate of HC1 into T B P is proportional to [H+] X [Cl-] X [ T B P ] (731) and that of U02(N03) to [UOZ][SO,] [ T B P ]* (732) but whether

(Textcontinues on page 531 R )

System Chloride Bromide Dibutyldithiocarbamate llorpholine-S-dithiocarboxylic acid Phenylarsonic acid BPHA BPHA

BPHA A--Furoylphenylhydroxylamine Thiobenzoylphenylhydroxylamine Cupferron a-Benzoinoxime a-Furilmonoxime Resacetophenone oxime a-Furildioxime, nioxime, heptoxime Dithizone Dithizone Dithizone Dithizone Dithizone Dithizone Di-8-naphthylthiocarbazone

Diphenylcarbazone A7jlV’-Bis(2-OH-pheny1)formazan and 9 analogs 8-Quinolinol, 5,7-dichloro-, 5,7dibromo-, and 2-methyl- 8quinolinols 8-Quinolinol

Table I. Distribution Studies (a) SIMPLECOORDINATION SYSTEMS Metal ions Special information Extraction of SbC13 and AsC13 into aromatic Sb(III), AS(II1) hydrocarbons shows evidence of complex formation Of 48 elements, only those listed were extracted Ce, Sn, As, Sb, Se, Hg from H2S04-KBrinto CC14 (b) CHELATE SYSTEMS Extraction equil. improves with increasing diluent Cu, Ni polarity 34 metals Extraction study in CHCl3 Extraction study from HCl solution Pa Extraction and stability constants Fe(II1) Extraction and stability constant. V is reduced to V(V) V(W Hf, Zr Extraction equil. in concentrated acid Ti(1V) Extraction equil. CHCl3 spectra Extraction and stability constants. Better than Many metals BPHA Ti, Zr, Nb Nature of extracted species TiCup4, ZrCup4, Nb (0H)dCup Nb Extraction study in HC1 solutions Distribution in CHC13 and K a None Pd Ni, F e Extraction and chelation equilibrium Extraction equilibrium from HpSO4 .PKH*D~+ = Xone - 4.55 Cu, Pb, Cd, Ni, Zn Extraction equilibrium. Masking equil. of bis(carboxymethyl) dithiocarbamate. No masking of Zn Extraction equilibrium. Extracting species are Ga, Ge(I1) GaDz2CI, GeDzs Extraction and chelation equilibrium Ag species Te(1V) TeO(OH)+and extracted species is Te(II)Dzz Variable composition found for Au extract and to Au, P d lesser extent for Pd Pd Two species extract; Pd(HDz)2, blue and PdDz, pink (here H2Dx = dithizone) Hg, Zn, other metals Extraction and Hg, Zn chelation equil. Reagent more sensitive than dithizone Extraction and chelation equil. Cu 45 metals Heavy metals (bivalent) and some trivalent form CHC18 extractable complexes None Extraction and dissoc. equil. None

8-Quinolinol 8-Quinolinol 8-Quinolinol

Ti Ga Zn

8-Quinolinol

hlo(II1,

&Quinolinol &Quinolinol

In Ag

8-Quinolinol 8-Quinolinol and halogenated analogs 8-Quinolinol and its 5.7-dichloro and dibromo analogs

Nb Pb

5,7-Dichloro-8-quinolinol Dioctylaminoethanol and -butanone 5- (2-Pyridylazo)-2- (diethylamino )phenol 8-AIercaptoquinoline 3- or 5-Bromo-8-mercaptoquinoline

v, VI)

Ra, Ac, Pa, Am, Cm

Extraction equilibrium for C6&. Salting out order KCl > NaCl > K N 0 3 > NaCIOa Extraction and chelation equil. Extraction equilibrium Extraction equil. Complexes of dicarboxylates from oxalate-adipate, tartrate Extraction and chelation equil. No evidence of p\lo(IV) Extraction and chelation equil. Extraction and chelation equil. Aqueous species AgOx and AgOx*-, organic AgOx.HOx Extraction and NbO(tartrate)t complex equil. Extraction and chelation equil.

References (751, 752) (984) (1030) (108)

(701) (769, 770) (67)

(383) (783) (140)

(458) (778) (1063)

(104) (773) (11)

(408)

(626) (856) (855) (830)

(78) (1132) (379)

(807) (51) (471, 683)

Nd Nb. T a

Extraction equil. Extracted species are RaOx2.4HOx, Ac(OH)Oxp, H2[Pa(OH)60x]. BuNH2 improves Ra extraction at low [HOx] and p H Extraction and chelation equil. Extraction equil.

Pd(I1)

Extraction equilibrium

(374)

Many metals

Extraction order Hg > Sn > Cu > Mo > Fe Zn > V > Ni Co > Sb > BI > Pb > Mn. Re-extraction from CHC13 not m same order Extraction equilibria (Continued)

None

-

-

(825, 826) (235, 236)

(74, 474)

(75)

VOL. 40, NO. 5, APRIL 1968

523 R

Table 1. System 8-Mercaptoquinoline and its 3-, 5-, and 6-halo analogs Anilides of thiolactic acid

Metal ions Many metals iz.Io(V, VI)

Mercaptoacetic,. -propionic, -succinic Mo(V, VI) acids and their substituted anilides. Catechol and its 3 3 disulfonic acid Ti Catechol

(Continued) Special information Extraction and soly. in CHCl3, CCl4. Chelates of 6-halothioxines insol. in either Extraction by various substituted anilides (CH3, NOz, -OCzHb, C1) Extraction study. Anionic Mo chelates extract by associating with diphenylguanidinium and benzylthiouronium cations

(156)

(1130, 1131,1133)

Zn, Cd, Ni, Pd, Cu, Hg, Co, Pd Nd

CCl4 extraction

(996)

Extraction and chelation equil.

(772)

Ti Bi, Cu, Au, Hg, Ag

Acetylacetone Acetylacetone Acetylacetone Acetylacetone, TTA

Li Cu, Zn, Ga, In, Fe, Au, Sb Pa sc

TTA

Be

TTA

Alkaline earths

TTA

Nd, Sm, Gd, Sm

TTA

Pr, Ho, Lu

TTA

La, Eu, Lu, Am

TTA TTA TTA

Nb Hf, Zr Po

TTA

Pa

TTA TTA

Pu Eu, Pm, C, Am, Fm

3-Hydroxyflavone

V

1-Phenyl-3-methyl-4-benzoyl-5pyrazolone Thiothenoyltrifluoroacetone

Many metals

Selenoylacetone, selenoyltrifluoroacetone DBP, DOPA, dihexylphosphoric acid DBP DBP DBP DBP (R0)zPOOH

None

Extraction and dimerization equil.

Nb, T a Lanthanides Eu, Am Pu Sr

(R0)zPOOH C 4 4 ,

Hf

DBP

Ti(II1, IV)

(i-CsHii0)zPOOH

U

( C J L i 0),POOH DOPA DOPA

Lanthanides None Na, Cs, Sr, Ba, Eu

DOPA DOPA DOPA DOPA

Alkaline earths V In, Ga, T1, Sb, Bi Ga, T1, Bi

H202-HZS04 solutions Extraction equil. Extraction equil. various diluents Extraction equil. Extraction equil. Extraction improves with number of C, not with branching. Diluent aliph HC > C6H12> CCld > toluene. Some Na extracts at p H 3.5 Extraction equil. T B P is antagonist. Polymeric Hf species extract Species extract Ti(AHA)3and Ti(AHA)4 (HA = reagent) From 234 "01, TOA in 3.5: 1 ratio to reagent gives maximum enhancement Extraction and aqueous nitrate complex equil. Extraction and dimer. equil. Effect of TOA Extraction equil. Xature of species different in polar and nonpolar diluents Extraction equil. Be >> Ca > 3Ig > Sr > B a Extraction equil. Ext. species is VO(AHA)z Role of hydrohalic acids Extraction equil. (Continued)

ANALYTICAL CHEMISTRY

(706)

Extraction study of Ti-catechol-pyridine complexes in dichlorothane Extraction equilibrium in presence of oxalate Extraction equilibrium. Application to reversed phase chromatography Extraction equilibrium. Polar solvents better Extraction equilibria from hydrohalic and nitric acids Extraction equilibria Extraction and chelation equil. TTA to AA, K,, ratio of 105 Extraction equil. Sulfate and oxalate complex equil. Extraction equil. in AIIBK. Extraction order is hIg > Ca > Sr > Ba Extraction equil. log K,, increase linear with ion potential Extraction increases with atomic weight not ion potential Determination of aqueous chloride sulfate and oxalate complex equil. Alcohols improve extraction (butanol best) Extraction and aqueous complex equil. Extraction and aqueous complex ( C Z O ~ ~tar-, trate citrate, NTA, and EDTA) equil. Extraction and aqueous complex (Po43-, CCl3C0O-, OH-, SO42-) equil. Extraction and aqueous complex equil. Extraction and aqueous complex (thiocyanate, tartrate, C2Od2-, NTA, DCTA, EDTA) equil. Extraction equilibrium in CHCla a t pH 3-4, a 2: 1 chelate formation. With EtOH an ester complex extracts Extraction equil. Salts decrease extraction

Catechol Isooctyl thioglycollate

524 R

References (76)

Table 1. DOPA

Metal Ions Fe, Mo

DOPA DOPA

Tb, Eu Ce

DOPA DOPA

La, Eu, Lu, Am Pi-, Nd

DOPA

Sm, Nd

(C~HI~O)ZPOOH, DOPA

Hf

DOPA DOPA (R0)nPOOH

Zr Th

DOPA ( C I ~ H ~ ~ O ) P O ( O H ) ~ DOPA, octylphosphonic acid DOPA

U Tm, Eu, Am, Ca, U Am, Cf, Fm, Md

Dioctylpyrophosphoric acid

U, Th, Fe, A1

Dicaprylphosphoric acid Di-p-cresylphosphoric acid

U Zr

Di-p-chlorophenylphosphoricacid Bis(hexoxyethy1) hydrogen phosphate (RO)PO(OH)z Monooctylphosphinic acid

None Ca, U, Am, Eu, Tm

System

Dioctylmethylenebis(phosphoric acid) PAN, I-(thiazolylazo)-2-naphthol 6- (2-Thiazolylazo)-3- (dimethylamino )phenol 1-Thiazolylazo-2-naphthol Chlorophosphonazo DAL 2,7-Bis(o-sulfo-p-methylphenylazo)chromotropic acid dianilide Bis-salicylidene-ethylene- or ophenylenediamine 3-isopropylidene-X'4sonicotinoylhydrazine

u

Extraction equilibria in 502- solution Extraction equilibria in chloride solutions

Ag, Eu, Ho, Yb

Cu, Cd, Zn, Ni, Co

Extraction and chelation equilibria TAN for Eu (species RIAZHA) Extraction and chelation equilibria

Many metals Various metals Ba, Sr

Extraction study in CP, Hg Extraction equilibria Extraction into BuOH

Ni, U

Extraction and chelation equilibrium

cu

Both 1:1 and 2 : 1 complexes extracted into cyclohexanone (c)

References (459) (506 ) (1012)

(682, 881) (355, 366, 758) (86)

Extraction equilibria Extraction equilibria. Design of chromatographic separation Extraction equilibria in H3P04 solution. Rate of hydrolysis of reagent depends on preparation method Chloride and sulfate systems Extraction equilibrium. Species extracted is Zr(AHA)4(HA = reagent) Extraction and dimer. equilibria Extraction equilibria in various diluents

U Di-, tri-, and hexavalent metal ions Nb, T a

Nb forms 1 : 2, T a 1: 1 complex, both polymeric

> PAN

IONASSOCIATIONSYSTEMS

Triiodide Pol yiodides

Cs, Rb Na

Pol yiodides Polyiodides

Cs, Na, K Cs, Rb

18-

and I*(CNS)Dipicrylamine

cs

Dipicrylamine tetraphenylborate Phosphomolybdic acid

Zn, Co Alkali metals

Phenol Alkylated phenols

Cs, R b Cs, Rb

Cp-CI mercaptans Acetic, propionic, butyric acids

Co, Ni, T1, P d None

Butyric acid

Lanthanides, Sc, Th, U Di- and trivalent metals

Butyric acid

(Continued) Special information Extraction equil. AH', AS", AF". Extracted species FeAn.HA, MoO2A2.2HA Extraction equil. Role of diluent Extraction equil. Extracted species CeA4 or a t p H 1.7, Ce02A2 Extraction and aqueous chloride complex equil. Extraction equil. T B P separation factor better than DOPA Separation factor higher in C1- than in NOa-; both depressed by increasing acid and metal concentration Extraction equil. in clod- solution. Extracted species Hf(ClO4)h Extraction equilibria Extraction eauilibria Species at low HA/U is (UO*AZ),,; otherwise UOz(AHA)z

cs

Extraction equilibria C6H6NO2 Extraction equilibria C6H5No2 Dr;,> 1 at [Inlo 2 1M Extraction equilibria. Various solvents Complete separation of Cs and Rb possible in C6H6N02 CNS- and I- almost interchangeable Dc.at p H 10 increases with Ca > Sr > Ba Li pres ent Extraction of ammonia complexes into C6H6NO2 Extraction equilibrium C ~ H ~ X O ZSeparation . from Cs is Li > Na > H > K > Rb Cs extracts more than Rb. D is f ( [&I+] ) p-Substitute increases and o-substitute decreases extraction. Arom. nitro cmpds best solvents CBHIP,cc14,CHC18 as solvents Extraction, dimer. and mixed dimer. equilibria NaC104 salting out effectiveness increases with mol. wt. of RCOOH Role of pH in extraction

-

Alk. earths extract a t higher pH than lanthanides. Salts (NaC1 or NH4Cl) assist (Continued)

VOL. 40, NO. 5, APRIL 1968

525 R

Table I. Metal ions

(Continued)

Special information Extraction depends on order of addition. Extd. species colloidal Role of p H in extraction

System Valeric to lauric acids

Zr

Caproic acid Pivalic acid C1-Cg carboxylic acids Ci-Cg carboxylic acids

Fe cu Alkali metals La, Pr, Nd, Gd

C1-Cg carboxylic acids C1-Cg carboxylic acids

Mg, Mn, Al,Fe, Th, U Zr Extraction solvents decrease CBH~NOZ > CHCls > C6H6 > C7H16 > Et20 > MIBK > EtOAc. Equilibration takes over week Extraction equilibria Cu, Ni, Co Extraction equilibria. Organic species are Co, F e monomer-trimeric None Extraction equilibria in decane from 17"-33" C Na RCOOH/H20 system equilibria Extraction equilibria. Extracted species are Ni, Co dimers Extfact and aqueous thiourea complex equilibco ria In Extraction. equilibria. Extracted species is polymeric Ca, Mg, All Fe, Sr, U, Y, Ru, Ce, Nb, Zr Extraction equilibria, various diluents None Sr, Y Extraction and aqueous sulfate complex equilibria Zn Extraction equilibria U Extraction maximum at p H 5 Y, Ce cu Extraction equilibria. Extracted species is Cu(AHA)z Extraction and aqueous Sc hydrolysis equilibria sc Extraction and aqueous NH3 complex equilibria cu Thiocyanate system Ru Extraction equilibria. DNNS is hydrated in None heptane Extraction equilibria Be Extraction and aqueous complex equilibria Eu Extraction by alcohols increases with MgClz but HaBOs others show a maximum. DAMP best at low salt concentration M0 Extraction study of hetero- and isopolymolybdic acids M O hloOCl8 is monosolvated by BuzO, ~ - C ~ H I I O H , disolvated by Et20 and tetrasolvated by MIBK Pb, Bi, Po, &lo Chloride systems Extraction from LiCl decreases MIBK > T1 C6H1100CCH3> EtzO > i-Pr20 > Bu2O Se Chloride system. Both rate and extent of extraction increase with HCl Chloride system. Ketones are best, ethers Te poorest solvents. In TBP, extracted species is TeC14.3S Chloride system. NMR study of formation of Au third phase Chloride extraction equilibria. Nb more readily Nb, T a extracted Iodide system equilibria. K > Ka > NH1 Na, K, NH4 Chloride system. Maximum separation In from In, Sn Sn in 4M HCl Extraction equilibria. Role of salting out agents Hap03 Halide system equilibria. Li > Cs > Na K; Li, Na, K, Cs I > Br > C1 Chloride system In, Sn Extraction from concentrated hlgC12 (41% H3BOa complete) V Extraction from HC104 and H2S04 solutions Chloride system. Salting out study Fe Soly. of fluorides and nitrates Fe, Co, Mn Nitrate system in DzO. Extraction is greater U than from H 2 0 because hydration of U is decreased (Continued)

Octanoic acids Capric acid Caprylic acid Caprylic acid Caprylic acid Caprylic acid CI2-Clecarboxylic acids Palmitic acid Naphthenic acid Naphthenic acid Naphthenic acid Naphthenic acid Naphthenic acid Abietic acid 3,5-Dinitrobenzoic acid Versatic 9 Dodecvlbenzenesulfonic acid Dinonylnaphthalenesulfonic acid (DNNS) DNKS DNNS ROH, TBP, DAMP BuOH, EtzO, BuOAC Oxygenated solvents Oxygenated solvents Oxygenated solvents Oxygenated solvents Oxygenated solvents Diisopropylcarbinol, ether, ketone Oxygenated solvents BuOH Pentanol i-Pent anol i-Pentanol

N

Octanol Benzyl alcohol ROH (C13-Cl~)prim, sec. EtzO Et20 Et20

526 R

Extraction equilibria K > Cs > Na > Li Extraction decreased with decr. H-bonding of solvent

ANALYTICAL CHEMISTRY

Table I.

(i-C3H,)zO Mesityl oxide Linear aliphatic ethers

Metal ions Au, T1, Ga, Pt, Se, Mo, Os, I r Fe U Po, Bi

Aliphatic ketones MIBK

Se 30 metal ions

MIBK MIBK MIBK

Ga, I n Au Hi3

Cyclohexanone

Nb, Ta

C3-CB alcohols C4-Cs ketones

La, Pr, Nd

Acetophenone Butyl acetate Trioctylamine oxide

Hf Fe U

a-Pentylpyridme oxide a-Nonylpyridine oxide Neutral P compounds Tributylphosphine oxide &PO R = C,r-Cs Neutral P compounds Neutral P compounds

U

System (ClCH1CHy)zO

Special information Chloride system

None

Chloride system equilibria Nitrate system Nitrate system. Dibutylcarbitol and 4,4diethoxybutane separate Po and Bi well Chloride system Chloride system. Countercurrent distribution (120 tubes) equilibrium study Chloride system Chloride system. MIBK >> (ClCK2CH2)2O Chloride system. HgC12, HgC13- and HgC12are extracted as HC1 increases Fluoride system equilibria. NbF6- and TaF8extract Nitrate and thiocyanate systems. Role of salting agents. Cyclohexanone alone and with ROH gives best extraction Thiocyanate system Chloride system Extraction equilibria in HCl, "03, HzSO4. R 3 N 0 is better extractant than T B P or TOA Nitrate extraction equilibria R3NO better than TBP for many metals Nitrate extraction equilibria solutions Extraction equilibria in "03 Nitrate system. Extract species 1: 1 R3PO-Ln complex Iodide system. TOPO > DAMP > T B P Nitrate extraction equilibria affected more by inductive than steric factors Nitrate extraction equilibria. Extracted species Ce(N03h.3TOPO Extraction and aqueous hydrolysis equilibria Sulfate system Mutual soly. with HzO

None

Mutual soly. with H20

None

Nitrate extraction equilibria shows very little isotope effect of D20 Nitrate extraction equilibrium constant linearly related to Hammitt u value of R Nitrate extraction equilibria

Many metals None None La, Pr, Sm, Y Alkali metals Ce

TOPO

Ce

TOPO TOPO Bu~PO, i = 1-4 (C4Hg0 )&PO R = Cl-c3

Te

%Poi 2

(Continued)

U

= 1-4

&Poi i = 1 4

U

Trialkyl phosphates and phosphonates (C4H90)zCaHgPO BurPOi i = 1-4 DIMP

U, actinides

Ce subgroup

(iC5HIiO)CHaPO(OH), D I M P TBP TBP, DBP, ( C B H I ~ ) ~ P O TBP

Th, U, Zr, Ce, Zn None None None

TBP

None

TBP

None

TBP

None

TBP TBP

None HaBOa

TBP

Cu, Ag, Au, T1

TBP TBP

Co, Nil Mn Ga

TBP

V

Am U

Nitrate extraction equilibria Chloride extraction equilibria. UOZClzS3 and UCl& (S = solvent) are extracted species Nitrate extraction equilibria and design for countercurrent distrib. sepn. Separation factors increase with Li and A1 Nitrate extraction equilibria Spectral study of T B P dimer. formation Hvdrat ion ea uilibria Extraction thermodynamics in HzO-CBH~ or -CHC13 Extraction equilibrium for mixed Cl--C104-; only HC104 is extracted Perchlorate system. Third phase formation occurs with increased mol. wt. of hydrocarbon diluent Nitrate extraction equilibrium applied to detn. of of activ. coeff. of CaClz and RlgC12 Fluoride extraction equilibrium Extraction equilibria. Extracted species is &Bo3 *2TBP Halide (Cl, Br, I ) systems. Anionic species extracted Chloride system. Role of salting agents Chloride system. Extracted species include HGaC14, LiGaC14, GaC13 Chloride and thiocyanate systems (Continued)

(414) (46) (524, 625) (5291 (551, 632, 590, 956) (273, 440) (108, 680)

(342 1

VOL 40, NO. 5 , APRIL 1968

527 R

System TBP TBP TBP TBP DOPA, T B P TBP TBP TBP

Table I. (Continued) Special information Mo, w Chloride system Chloride system Fe Chloride and nitrate systems in presence of HClOa sc Ti Chloride extraction equilibria Pr, Nd Extraction equilibria. T B P separation factors greater than with DOPA U, Th, Ce Nitrate system. Salting with NH4+, La Pr, Nd Chloride and nitrate extraction equilibria Nitrate extraction equilibria. Greatest separaLa, Pr, Nd, Sm tion obtained when all T B P coord. to H + or Metal ions

~3

+

Lanthanides

TBP TBP TBP TBP TBP TBP TBP TBP TBP TBP TBP TBP TBP TBP TBP TBP TBP TBP TBP TBP TBP TBP TBP TBP

TBP

Nitrate system. Extraction increases with atomic no. and "03 conc. Sm, Am, E u Thiocyanate extraction equilibria Chloride system co Thiocyanate system Co, Ni, Cu, Pd co Extraction with salicylic acid (HZA). Extracted species Co(HA)z.BTBP TI Chlpride extraction and aqueous complex equilib- (186, 186, 667, 668, 1057) rium Chloride system Gal In, T1 Chloride extraction equilibria Te Solvated TeC14, HTeC15, and HzTeCla are extracted Sb Chloride system. Extract species is LizSbCls. 2TBP Th, Zr Sulfate system. Role of diluents Zr Nitrate system Hf Nitrate extraction equilibria. Effect of temperature related to change in activ. coeff. of Hf Mixed nitrate-perchlorate systems. Extracted Hf, Zr sDecies contain both anions Chloride extraction equilibrium. Extracted Nb species is HNbOC14.TBP Chloride and nitrate systems. Role of masking Nb agents Nb, Ta Chloride and thio cvanate svstems Extraction and aqueous complex equilibria in Pa H N 0 3 and HC104 Chloride system. Craig countercurrent study Pt metals Chloride and perchlorate extraction equil. Po U Extraction equil. study of T B P activity Nitrate system. Role of tartrate in sepn. Role u, Pu of diluent U Trichloracetate system U, T h Nitrate systems a t various temperatures U, T h Chloride system. Nature of extracted species Nitrate extraction equil. Quant. evaluation of U, T h saltinn out Nitrate system. Third phase due to salting Th, Pu effect of H N 0 3 Nitrate system. Extracted species NpOzN03 * NP TBP Extraction into C& or BuOH increases with C4H9SnC13 conc. (1076) Actinides Chloride and nitrate extraction equil. Nb, Pa, Tal Zr, Hf, Th Chloride system. Ta > Nb > Pa; Th > Hf > (667) Zr Nitrate system. Pu > N > Np (668) U, Np, Pu Y

TBP TBP TBP TBP, B u ~ P OT , OP0 Tetrabutylhypo- and pyrophosphates Tetrabutylhypo- and pyrophosphates Tetrabutyl pyrophosphate Trialkyl phosphates Tricapryl phosphate Monooctylanilino benzylphosphate [(C~Hia)zP(0)]zCHz [ (csHia)zP(o)]zCH2 (CsHi,0)2P(O)COCHa (C~H~~O)ZP(O)COC~HI~ (CeHn)zP(0)(CH2)nPO n = 1, 4, 5

528 R

0

ANALYTICAL CHEMISTRY

U Bi

TJ Zr, Nb None Zr, Nb, T a None

Nitrate extraction equil. Mineral acid extraction. Separates Bi from Sn, Sb,, As,, and Pb Chloride and sulfate systems Phosphoric and oxalic acid systems Extraction equil. from H N 0 3 and HClOd

(6601 (687)

Nitrate extraction equil. Extraction is greatest when n = 5, lowest a t n = 1 (Continued)

(336)

(9941 (433) (749) (659, 640)

Table I. System Dibutyl-N,N-diethyl carbamoylmethylene phosphonate (CH,)aXO, (Ca€Is)aXO X = N, P, As, Sb, S, Se, T e

(CeHs)aAsO (CsHii)SO Nitrobenzene Tetrabutylurea Hexamethylphosphoric triamide Polymethylphosphoric trimides R.nNH(3- n) n = 1-3 RnNH(4-&1 n = 1-4 Benzylamine, tribenzylamine, TOA

Metal ions Ce, Pm, Am Tc, Re

U, Bi, Th, Ce, Cr, V, Fe Zr Fe, In Actinides None Au, Zn, Sn, U None 63 metals

Pa None

Cyclohexylamine and N-methyl derivs. Pharmaceutical primary and secondary amines TOA

Kone

High mol. wt. amines

Cm, Am, Cf

Re

(Continued)

Special information Nitrate system. Extractions are about lOOX that with T B P Extraction equil. depends on basicity of 0, affected by R and X Sb > As > P Mineral acid extraction equil. Extracted species TOAsO.2IIC1, but TOAsO.HX, X = F, Br, NO3 Thiocyanate and chloride systems

References (938, 939) (534) (696)

Chloride system Chloride system. PhNOz solvates MeC14- species Nitrate system. TBU as good as simple amides Extraction equil. and solvent characteristics Hexa- and octa compds. form complexes Halide extraction equil. increases with anion radius but decreases with amine size Chloride system Chloride and sulfate systems R3N > RNHz for PalIV) and PaiS') Extraction equil. study of hydration Extraction and polymer equil. with various anions Extraction equil. HRe04 for TOA is better than for i-pentanol, TBP, or dioctylamine Nitrate systems. R4N gives better sepn. than RaNH Nitrate extraction and aqueous equil. Extraction and aqueous Zn hydrolytic equil. Thiocyanate system +

+

Amines Long chain amines High mol. wt. amines and quaternary salts Primary amines

Np, Pu Zn Zn

Primary naphthene amine Monolaurylamine

V Fe

Primene JlIT Amberlite LA-2, TOA

Th, Pa, U, RLI,Zr

Amberlite LA-1 Amberlite LA-2

Zn None

Amberlite LA-2

Mo

Amberlite LA-2 Diisononylamine Dinonylamine N-Octylaniline N-Decylaniline Laurylbenzylamine Trialkylamines Trialkylamines

V None Fe None U Ru None Lanthanides

C7-C9 trialkylamines

Co, Zn, Fe

Methyldioctylamine

Hg

TOA

None

TOA

None

TOA TOA TOA TOA TOA

None Many metal ions co co Fe

Pt, Pd

Chloride extraction equil. a t various temperatures. AH for NaCl and HC1 similar Extracted species are polyvanadates Phosphate system. Extracted species (RNHa)r Fe(P04)n. Sec- and tert- amines poorer than primary Sulfate extraction. equil. Combined LA-2 and TOA better for U, Zr, Ru than separately used Primary > secondary > tertiary amines Chloride system Sulfate system. Third phase forms when hexane is diluent Chloride, nitrate, and sulfate system. Optimum extraction from M H2SOd Chloride system Chloride extraction equil. Sulfate system. Extraction of Fe(OH)SOa Sulfate extraction equil. Sulfate systems. Role of diluent Thiocyanate system "03 extraction equil. Nit rate system. Extracted species (RsNH)3[Ln(NO3)8]enhanced by Li and Ca nitrates Chloride system. Ca2+ aids in extraction. Co extracts from 9-10M C1-; Zn and Fe from 3M C1Extraction study of Sodz-, SeOa2- and oxalate complexes Sulfate extraction equil.

(908, 1068)

(86, 176, 190, 191, 206, 226, 297, S12,524,1083)

Chloride extraction equil. Evidence of HClz- in org. phase Phosphate extraction equil. Chloride system Chloride extn. equil. Thiocyanate system. Role of diluents Chloride extraction equil. (Continued)

VOL 40,

NO. 5 , APRIL 1968

529 R

Table 1. Metal ions

System TOA

Fe

TOA4,dioctylamine TOA TOA

Reduced molybdophosphoric acid Cr(T1) Lanthanides

TOA

Nb

TOA TOA TOA RiNCl TOA TOA

Yb, Ta Nb, T a Pt metals

TOA

U

TOA, TLA TOA TOA

U U

Ru Ru

u, Mo

T0.4 TOA (CioHzi)4NOAc TOA, TL.4 Amberlite LA-1, LA-2 Triisononylamine TLA TLA

U U Pa Fe None None

TLA TL,4

h'one None

TL.4 TLA TLA TLA TLA TLA

Many metals Fe Zn Fe, Am Bi Sb(III), V)

TLA4

U

TLA TLA TLA Alamine 336 and 3369 Pyridine Quaternary heptylammonium ions Trioctylmethylammonium salts Quaternary butylammonium salt

Th, U Pa Pa Fe Many metals None Pb, Cd, Cu, Co, Zn, Fe Ti

Quaternary ammonium chlorides Quaternary ammonium chlorides Quaternary ammonium chlorides Quaternary ammonium nitrates (C8H17)4NBrcaprylic acid

co Zn Rh Actinides Pt, Ir, Pd

(CsHi7)aNCl

Pt groups

Aliquat 3365 Aliquat 3365

Li Lanthanides Actinides Pa, Ta, Nb Pt group

Aliquat 3365 Aliquat 3369 and other quaternary salts

(Continued]

Special information Thiocyanate system. Extracted species is Fe(SCN)j2Spectra of extract depends on nature of reductant and dilnent Extraction equil. Nitrate system. Role of EDTA masking. Use of Craig countercurrent distrib. Sulfate and oxalate extraction equil. Extracted species NbO(0H)BOa- and NbO(C204)*Chloride system Extraction of oxalate complexes Chloride extraction equil. Chloride system. Ru(V1) > Ru(II1) > Itu(1V) - varies with Extraction of [RuNO(NOZ)~(OH)] anion present Chloride system. Extracted species (R3NH)zuozcl4 Chloride system Sulfate system. A1 improves U extraction Sulfate system. h l o polymerizes in the organic phase Sulfate extraction equil. Acetate system. Cryoscopic detn. of polymer in CaHs phase HC1, HNOa, and H z S O systems ~

Thiocyanate extraction equil. Nitrate extraction equil. Mol. wt. detn. of amine salts (HNOa, HC104, HzSO~,HBr, HC1) Extraction equil. of mineral acids Trichloroacetic acid extraction equil. via 2-phase titration Extraction from various inorganic acids Chloride extraction equil. Chloride extraction equil. Chloride extraction equil. Iodide extraction equil. Evidence for Biz193Halide systems. Sepn. Sb(II1) from Sb(V ) best in 7 M HXOa or 0.64M HBr. methanol, ethanol, acetone acid Sb extraction Chloride-nitrate extraction equil. Polymer (877, 878) formation occurs Nitrate system H F and HC1 systems system Chloride system Azide system Extraction equil. of inorganic monoprotic acids Halide systems. For all but Fe, order is H I > HBr > HC1; reverse for Fe Extraction of citrate and tartrate complexes in pentanol and CHC13 Chloride systems Chloride extraction and aq. complex equil. Chloride systems Nitrate extraction equil. Bromide extraction equil. in RaNBr, RCOOH mixtures Chloride extraction equil. Binuclear species extracted Chloride and bromide extraction equil. Extraction from Al(N03)a-HNOa solns. Sepn. better than with RaNH + Extraction of citrate complexes Chloride system (Continued)

530R

ANALYTICAL CHEMISTRY

(745) (1138)

Table I. Metal ions

System Aliquat 3369

U

Aliquat 3369 Aliquat 3368

u, Pu

Aliquat 3368 Dime thylbenz ylalkylammonium chloride R z= ClZ-cl4 Dimethylbenzyl octadecylammonium chloride 2-Iminobenzimidazoline derivatives Pyridylazomonome thylamino-pcresol and its bromo derivatives Diphenylguanidine Diphenylguanidine, Toluidine Blue Diantipyr ylmethane Diantipyrylmethane Isobut yldiantipyrylmethane

4- (hlethylbenzylaminopheny1)antipyryl carbinol

Th, U Th, U V

Special information Extraction of U(1V) is best at 3-4M "03. Species is U(N03)e2Nitrate system Extraction equil. for anionic chelate of 1,2dihydroxyanthroquinone-3-sulfonate Extraction of anionic metal chelates Extraction optimum pH 4-6. Extracted species (R4N )sHV10028

Se

Chloride extraction equil. C2HaC12 is best diluent

Zn

Chloride systems. The l-benzyl-3-C14H~sderivative exts. Zn quantitatively Extraction equil. Extracted species is 1: 1 complex Extraction of thioglycollate complexes in various solvent mixtures Nitrate systems

Sb

Mo Ce None Fe, Mol Nb Many metals

Re

Cr (VI ) Triphenyltetrazolium C1, cetyldimethylphenylammonium chloride (CsHs)&bX (C&)4PbX Triphenylmethane dyes

(Continued)

w None B, Te, Se, As, Re Molybdophosphate

Crystal Violet

Ga

Crystal Violet

As

Thiocyanate extraction equil. Thiocyanate extraction equil. Thiocyanate system. Sn(I1) > Sn(1V) > Zn > Co > hlo > W > Ga > Fe > In > Ti > Hf Zr > T h > Hg > U > Sb > Bi > Sc > V > Cd > iMn Extraction of Reo,- decreases HaPo4 > H2S04 > HCl > HClOd because of anion competition Extraction and acid dissoc. equil. Extracted species is lLX +,HCrOaExtraction equil. study of polytungstate formation

-

Extraction of various anions into CHCl3 Extraction equil. of oxyanions, halides, CNS Extraction of dye-heteropoly anion complex in various solvents Chloride system. Mixed diluent CHCl,-acetyIacetone is best Chloride system. Spectral study shows dyeAsC13 complex

(d) MOLTEN SALTSYSTEMS Fused LiN03-KN03/Bi- and terphenyl distrib. of ZnC12, ZnBrt at 350" C Cs, Rb, Ba, Sr, Eu, Fused NaB0,jNaCl a t 830" C Nd, Ag Zn

these reflect slow homogeneous reactions or those taking place at the interface cannot be decided. Back extraction kinetics of a number of uranyl complexes have been examined. Fedorov (275) describes four steps for U02(N03)2: (a) replacement of organic solvation by water; (b) coordination of water to uranyl nitrate; (c) formation of the activated complex involving a partial rupture of the U-0-P bond (the slow step) which probably takes place in the interfacial layer (276); and (d) dissociation into UOZZ+, NOs-, and T B P . T h a t the slow step involves the partial rupture of the U-0-P bond is supported by the decrease in back-extraction of U observed in going from T B P to TOP0 (277, 278). I n another study, the rate of back extraction of U02(N03)2a2TBP was found to be a complex function of the organic phase concentration of uranium

(801, 804). The entropy of activation of these extractions was about 20 e.u. greater with chlorinated hydrocarbons as solvents than with mesitylene. The rate of extraction of metal diethyldithiocarbamates into CCld, which poorly wets the solids, is much slower than that into polar @containing solvents (68). A study of the kinetics of the extraction of cozs04 into didecylamine/C6Hs indicates that both neutral and anionic species can extract (633) depending on the nature of the complex in the aqueous phase (634) with some bias toward the extraction of U02(S04)22-. The rate of back-extraction of U02S04from Toil in butylbenzene by aqueous HF depends on the rate of mixing u p to 820 r.p.m., but then is a function of the concentrations of the reactants in a manner that indicates the extractable complex is formed in the organic phase (718). The rate of extraction of trivalent

(84

( f 103)

lanthanides in citrate or tartrate solutions by DOPA is decreased by Fe, All or Cr because of the formation of mixed metal citrate or tartrate complexes (197). Interfacial tension and bromide exchange rate measurements between (C,H,),NCl in C6H6and aqueous solutions indicate that the process is filmcontrolled (873). The change in interfacial tension during extraction of carboxylic acids into various organic solvents was found t o be linearly related to the logarithmic ratio of concentrations of the distributing species in each phase (298). The rate of extraction was shown to be quantitatively related to stirring intensity (slope of a log-log plot (rate us. intensity) was 3.2 or 0.9 above and below a critical range with a n intercept which depended both on the nature of the system and the direction of the extraction) ( S 4 f ) . VOL 40, NO. 5 , APRIL 1968

531 R

PROCESS OF EXTRACTION

The validity of the Kernst distribution law for very low metal concentrations in various chelate extraction systems has been examined (112). The results indicate the necessity of experimentally verifying this for individual systems employed in equilibrium studies, The use of extraction techniques for the determination of acid dissociation equilibria of extractants (1128),of stepwise metal complex formation equilibria (141, 2b2), of aqueous complex formation equilibria (966),and of the thermodynamic activity of water (386) have been described. A quantity V = (p DJ/(l D J , called the integral separation factor, where D is the distribution ratio and 0 = D 1 / D 2 has , been introduced to give a better indication of obtainable purity (370). The general role of solvents in extractions has been reviewed (332). Interpretation of extraction equilibria in terms of physicochemical parameters such a5 the effective electronegativity and Hammett sigma values and their application to the extraction processes for actinides by phosphorus extractants has been developed (831). T o standardize electrode potentials in nonaqueous systems (Le., by reference to the standard hydrogen electrode in water) the S e r n s t equations in aqueous and nonaqueous media can be related by the extraction constant (333). Further work has appeared relating the solubility parameter of the solvent to its effectiveness (1). I t was pointed out that simple additivity does not always apply in the calculation of solubility parameters of mixtures of low and high molecular weight liquids (299). Correlations of distribution constants of substituted oxines (688, 689), acylpyrazolones (946), and carboxylic acids (472) with solubility parameters of organic solvents have been established. Selectivity of 28 solvents for organic extractions (mixtures having aliphatic and aromatic components) have been found to increase with dielectric constant and dipole moment (106). The role of diluents in the extraction of monofunctional phenols by amines, esters, or DOPA has been studied (376). Micelle formation has been found to be influential in quaternary ammonium halide extractions (870). The critical micelle concentration is higher in the organic than in the aqueous phase (788), and the size of these micelles increases from Cl R b > K > S a > Li (128, 390, 468, 1123). Other I-’ compounds have been used in alkali metal extractions in which extraction capacity was found to parallel reagent basicity (834). Similarly, nonylphenol and naphthenic acid form amixed extractable complex with Cu (287). As might be expected from the ability of T B P or TOPO to form complexes, probably through H-bonding, with alkylphosphoric acids (539), TBP can exercise antagonistic effects in DOPA extractions, e.g., of Y and Sm (989), as can TO.$ for similar reasons in the DOPA extraction of C (218, 221), and TOPO and other adducting ligands in the dinonylnaphthalenesulfonic acid extraction of Zn (1068). Formation of mixed complexes in the aqueous phase such as Ce-Cr-citrate will decrease the extractability of Ce by DOPA in the presence of Cr (862). High Fe concentrations can suppreas extraction of traces of other metals from iJ1 HC1 into TUP (956). Mixed ligand complexes are more stable than might be expected on a statistical basis (591) when one ligand is strong and the other a e a k (722) or the mixed complex may be more extractable (617 ) . I n aqueous phase study of the Co-8-quinolinol-5-sulfonic acid-phenanthroline mixed complex indicated enhanced stability (861). -4number of tridentate Schiff’s bases

form chelates in which replacement of water of coordination by pyridine enhances extraction (610, 793). Zr and Hf form mixed chelates with %hydroxyquinoldoxime with carboxylic acids (optimum a t caproic) (840). A series of 2-substituted 8-quinolinols capable of acting as tridentate ligands may well be better extractants in the presence of pyridine or other adducts (977). Ion association systems involving charged chelates continue to be a n interesting source of new extraction systems (1127). Anionic Co nitrate complexes pair with tributylammonium ions (805), Am and E u complexes with H E D T A with Aliquat 336S62 (676), many metal chelates of 2-nitroso-lnaphthol-4-sulfonic acid with quinolinium ion (1020) form extractable species as does V-chelidamic acid chelate with pyridine (250). Various o-hydroxyazo dyes having sulfonic acid groups which have been employed as metallochromic indicators form anionic chelates t h a t couple with various “onium” ions to give characteristically colored extractable species. Thus, Calmagite has been coupled with B quaternary ammonium salt to selectively extract A I which can be colorimetrically determined at low concentration levels. (1088). Similarly Nb-azo dye complexes couple with diphenylguanidinium ion (33), as d o various metal arsenazo complexes (1021), P b rhodizonate (262), trihydroxy- and salicylfluorone complexes of Ti, Zr, Ge, Sn, J l o , W ( 9 3 4 , and many metallochromic indicator complexes (421) couple with quaternary ammonium ions. Some metallochromic indicator complexes can be extracted into butanol (1126). Mixed ligand complexes are formed by U(1V) and T h with N T A or E D T A with various ligands in the aqueous phase. For U(1V)-EDTA, Tiron > catechol > 8quinolinol-5-SO3H > phthalate (166). Positively charged intermediate chelate complexes can couple with suitable anions. Thus, Fe(II1) dithizone complex is extractable with (C6Hs)4B-; S n (IV)-8-quinolinol-caproate, Co (11)8-quinolinol-Methyl Orange are other systems (1134). Quaternary ammonium salts also significantly increase the stability of neutral metal chelates, e.g., Zn-PAN is stable to 0.6-0.8M HC1 in the presence of (C4Hg)JiBr (258). Metallochromic indicators having sulfonic acid groups can be transformed to chelating extractants by preparing the corresponding anilides (144) such as chlorophosphonazo dianilide. From studies of acid dissociation and metal chelate formation constants of some 8-mercaptoquinolines (464, 465, 467), the importance of using sulfur in place of oxygen can be seen in the higher ratio of metal ion to proton affinity displayed by mercaptides. Another feature making it possible to extract metali

from more acidic solutions with these reagents is their strong tendency to form zwitterions and thus lower their effective K D (distribution constant) values (464). I n the extraction of both S b and F e from HCl using p,p’-dichloroethyl ether, higher HCl concentration is required than with ethyl ether, an indication that the former is less basic (49). I n electrolysis of organic extracts of F e from HCl for ethyl and butyl ethers, there is no transfer of lvater of extraction into the anode region with FeCI4- showing that the coordination number of F e is four (679). In a study of the extraction of Fe, Sc, and lanthanides from HC1, and K b and Ta from HF using 17 reagents in the family RPO(OR’)* with various diluents, improvement due to the diluent was seen to vary inversely with HC1 or HF solubility in the organic phase (717). The extraction of Cd from H B r into pentanol is enhanced by nitrobenzene (394). Cse of iodineiodide mixtures in excess of 3: 1 gives improved polyiodide extractions into nitrobenzene of alkali metals in the order Cs > R b > K > K a > Li (11). Extraction of reduced molybdophosphoric acid was found to be quite similar to that of the unreduced species and is optimum in 0-containing solvents (495). The extraction of peroxychromic acid can be effected by the use of T B P or quaternary “onium” salts such as Alequat 336 S or (C6H5)4AisC1 (987). I n amine extraction systems, aqueous phase reactions predominate so that extraction follows an inverse order to the ease of hydration. Thus, for simple acids, extraction follows the order primary > secondary > tertiary’ amines and C104- > I- > B r - > C1- (252). Steric factors and tendency to aggregate modify basic strengths of amines in extraction processes (364). A Hammett relationship can be fitted to amine extraction equilibria (928). The extraction of U02C12by amines involves an ion association rather than coordination (859). Salting out agents for ion pair systems involving oxonium or pyridinium perrhenates follow a n order paralleling the extent of hydration of the salting out cation (522). In a spectral study of -paired with tetradecylammonium ion in C&, KO3- ion was shown to coordinate to the U first as a bidentate ligand (1056). il mixture of TOA and Amberlite LA-2 improves extraction of U(V1) from sulfate solutions (909). The uranium extracting ability of various neutral P compounds was shown to parallel the heat of dissociation of the P-0 bond (726). The extraction of HC1 or H N 0 3 by TUP involves a 1 : l acid-TBI’ complex (860). A general review of T13P syitems has appeared (635). The extraction of Ti and Zr from sulfate solutions by T B P is enhanced by the use of nonyl alcohol

(1111). Nitric acid extraction equilibria involving various neutral phosphates and phosphonates can be correlated Kith Hammett-Taft u constants and electronegativity of substituents (837, 936). A similar relationship applies to T h extraction by P compounds (1039). Various dye-anion pairs that are extractable require anions of proper radius (large), peripheral charge (small), and M-L (where the anion is lIL,,”-) bond strengths (high) (600). Distribution equilibria for various triphenylmethane dyes show that extraction is a function of the dye and 0-solvent concentrations (535). An interesting indirect method for T1 is based on the formation of a triphenylmethane dye by Tl(II1) oxidation of the leuco ba5e (638). Extraction constants were determined for C6H6 extraction of a pair formed by a nitrophenol and a triphenylmethane dye combined as monomer (617). Hexyldiantipyrylmethane is superior to diantipyrylmethane itself for many metal extractions (1113). Tiron B, unlike other masking agents, increases the P u extraction from HS03H N 0 2 solutions probably because the sulfonic acid groups are removed by HXO2 to give catechol, a component of the new complex (98). In UOZ2+extractions by T B P , formation of hydroxy complexes retards extraction (79). Separation factors for adjacent rare earths extracted by 2-ethylhexylphenylphosphonic acid show regularities (829). Trifluoroacetylacetone gives a higher Zr-Nb separation factor than benzoyltrifluoroacetone (923). Interaction of U02(SCS)2 with various 0-containing solvents decreases in the order: urea > (CHJ2S0 > antipyrine > tetrahydrofuran > H 2 0 (912). Extraction of Be and F e with DOPA and its deuterated analog gives complexes whose infrared spectra indicate that the H-bond of the dimer anion is symmetrical and only one P=O stretching frequency (1080). Co(III), Cr, and R h acetylacetonates can be partially resolved wing a discontinuous countercurrent extraction process with d-diisopentyltartrate and ethyl acetate. The l-enantiomer is preferentially extracted (125). The spectrum of anhydrous zinc 8quinolinolate in CHC1, shifts to the red with pyridines or butylamine, indicating a transmission of electronic effect between ligands through the metal ion (184). The p-diketone chelates of Gd form phen and dimethylformamide adducts which affect the nature of their phosphorescence (163). A liquid Zn-Ga alloy (“gallam”) can extract T1 from sulfate solutions (797). APPARATUS AND TECHNIQUES

Reinhardt and Rydberg (820) have developed a n apparatus for the continuous measurement of distribution VOL. 40, NO. 5, APRIL 1968

533 R

factors in extractions which permits the rapid and reliable determination of extraction equilibrium data. Pulsing techniques can significantly improve extraction efficiencies (844). Pulsed extraction columns have been used in the plant scale purification of P m by DOPA extraction ( 8 2 4 , for separating U from P u and fission products (229). Laboratory mixer-settlers and conditions derived from published equilibrium constants data provide a good description of the extraction of U0z(N03)z and "03 in the Purex process (958). Mixer-settlers have also been used in the purification of P u using TLA (602), in the separation and purification of K b and T a using H F and cyclohexanone (346), and in the separation of the Pt group metals using a quaternary ammonium chloride system (241). Peppard described a practicable application of the countercurrent distribution technique to improved laboratory scale separations without the use of anything more elaborate than 3-4 separatory funnels (76'7). Craig apparatus was used to separate the P t group metals from one another using an HBr-TBP/ C6Hs system (99). -4computer program facilitated the comparison of theoretical and observed results of this study. A discontinuous countercurrent distribution technique using the Craig apparatus in which the extractant concentration was altered a t several points in the train was developed along with a computer-programmed calculation of results (122, 123). A separation study of La, Pr, and Kd from HN03-Ca(N03)zsolutions carried out in a seven-stage countercurrent extractor as a feasibility evaluation indicated that 32 stages would be required t o yield 40% La a t 99.99% purity (762). Lanthanum was also purified from a rare earth mixture using DOP.4 in two batch multistage countercurrent extraction cascades (707). A general review of the use of solvent extraction in radiochemistry (100) as well as studies of the effect of radiation on the tertiary amine-chloride extraction separation of Am and Cm (586) and on the TBP-HN03 system separation of C , Th, and fission products (1029) have appeared. Solvent extraction has been used to concentrate 51Cr by recoil enrichment (43.2). A review of the general principles of substoichiometry (842, 843) as well as a comparison to other concentrationdependent distribution techniques for radioisotopes (565) has appeared. The substoichiometric principle was verified in the extraction of Cd dithizonate (572). A continuous automated substoichiometric extraction method for the determination of Hg was developed (1.94). Equations were developed to describe equilibrium conditions necessary for the application of substoichiometry and

534 R

ANALYTICAL CHEMISTRY

were employed in the rare earth-EDTATTA system (1.95). The use of extraction in both flame emission and absorption spectroscopy has been reviewed (1129). The sensitivity of flame photometric determination of Mn is increased by using TTA/ MIBK extract (456). Extraction by pyrrolidine dithiocarbamate in MIBK is good preparation for atomic absorption procedures for many metal ions (698). 8-Quinolinol in ethyl acetate can also be used in this fashion (486). An atomic absorption method for P t employs a prior extraction by dimethyldithiocarbamate in MIBK (1000). Phosphorus or silicon can be determined indirectly by an atomic absorption determination of Mo following the extraction of the heteropolyacid (487). Direct photometric determinations of extracted metals in organic solvents have been developed based on the addition of a chromophoric agent to the organic phase. Thus, Sm and E u extracted into T B P can be spectrophotometrically determined following the addition of phen or TTA (645),U extracted into TOA by carminic acid addition (1027), V extracted with benzoinoxime ( 6 0 4 , or Mn extracted with D E D T C (687) by 8-quinolinol addition, Fe extracted with DOPA by thiocyanate addition (172), and T h extracted by DOPA can be determined using arsenazo 111 reagent (171). In the photometric determination of Hg in dithizone, interference from Cu was eliminated by measuring absorbances a t isobestic points for the copper dithizonatedithizone system (9). The feasibility of conducting a polarographic determination of metal ions in the organic extract has been established in the case of U,extracted from H K 0 3 by TOPO (93), of Pb, Cu, T1, and Cd, extracted by 8-quinolinol (457), of In and Pd, extracted by acetylacetone (4, and of P or Si indirectly by polarographic determination of Mo after extraction as the heteropoly acid (50). Sensitivity of polarographic methods can be greatly increased by coating the mercury electrode with an extractant. Thus, Z r 0 2 + sensitivity was increased 104-fold when 3 x 10-aM diisopropyl methylphosphonate in the solution formed a monolayer on the mercury (952). The application of solvent extraction chemistry to develop suitable organic phase components of ion-selective electrodes presents an exciting prospect for greater understanding of extraction processes as well as for new and improved electrodes. Current progress in this field, which is now a popular symposium topic, can be gauged by the reports of Ca-selective electrodes using DOPA (827),of polyvinyl chloride membranes impregnated with T B P and TTA

(911), and anion-selective electrodes using N-lauryltrialkylamine (963), as well as by review articles (819). Highly selective membranes for ion transport have been made by incorporating alkylphosphoric acids in polymeric films. In this manner, U has been separated with complete selectivity (107, 108). A wide variety of extraction systems have been adapted to the development of both normal and reversed phase chromatographic separation procedures (406, 981). Representative systems include use of amines and quaternary ammonium salts (31, 1.90-152, 228, 288, 40.2, 655, 656, 941, 980, 1065, 1078), dinonylnaphthalenesulfonic acid (1077, 1078), M I B K (295)) T B P (982), TOPO (980), DOPA (214, 366, 594, 684, 685), [ (C8H&PO]zCHz (750),polyiodides (17, 434), 8-quinolinol (1028), dithizone (105), D E D T C (895), and isooctyl thioglycollate (294). A related technique, of combining ion exchange and solvent extraction has been developed by Korkisch (519-522) and others (580, 581, 915). Conversely, GLC can be used to evaluate selective extraction solvents by allowing one substance to be used as the stationary phase while passing a mixture of solvents through the column. From the position of the two peaks, the ratio of D values can be calculated (584, 585). Extraction of Be by TFA is used for preparing Be samples for GLC determination (877). Also, TLA and other extractants may be purified by using activated clays (194). Extractive titrations (those with extractive end points) have been developed for determination of impurities in gallium arsenide (309), in GeOz or GeCh (307, 508))and for microgram levels of P b (441) using dithizone. Extractive titrations can be used to determine the carrier in a mixture of radioisotopes and combined with radiometric titration in double isotope dilution methods (547). Convenient cuvettes for extractive titrations have been developed (809,441). Separations using reagents capable of extracting m8ny metals may sometimes be improved by adding a large quantity of the next most extractable element before extraction provided that this element does not interfere with the determination of the element under test (1112). Back-extraction of metals can be carried out using other metal ions, e.g., using C d 2 + to displace Sn from SnDEDTC, in order t o avoid too acidic a solution (436). Sickel salts can be rid of trace levels of Fe and Cu by extraction with nickel complexes, e.g., Ni soaps (318). Selective extraction has been accomplished by foaming solutions containing cetyltrimethylammonium bromide and Na phenate because of competitive attraction existing between an ionic (Text continues on page 542 R )

Table II. Element extracted Ac Ag

Separated from Ra Soils and rocks Pure Se and Te Soils and rocks

Se hletals

As(II1)

Impurities Pu-A1 alloy PI Si Sb(III), Se(IV), Te(IV), Au(III), Fe(II1) Ores In

High purity P b Geologic materials Cyanide waste solutions

Extraction Procedures

Solvent system (before mixing) Aqueous phase Organic phase TTA-TBP/CCL Cu dithizonate/hexane 0.5M &SO4 Complexon 111, citric acid, NHdOH, 1,5-di-p-Naphthylthiocarbazone/ pH 8-9 CHC13 Triisooctylthiophosphate in CaH6 Dil. H N 0 3 Trioctylbenzylammonium hyCyanide droxide/decyl alcohol NaCN, 0.1M NaOH, Crystal Violet C6Hs 8-Quinolinol in C& pH 9.55 TT A/xylene (NH4)zS~08, Ag+, heat 90' C, 10 minutes, cool, NH4OAc-HOAc (BuO)zBuPO/CC14 4-6M NOaTBP/hydrocarbon 6.5M Nos-, 0.1M H f CHC13 Ascorbic acid, KaDEDTC AgDEDTC H C1 C6H6 or toluene 9-10M HCl HC1, SnCl2, K I NH4 molybdate, hydrazine NaDEDTC, p H 8.5-9.5 0.25M H2S04, ascorbic acid 1OM HC1 LiCl, pH 4.0 3N HBr HCl, KMnO4, 3M HCI Cyanide

Bk(1V)

p H 1.1 with HCl, hexamethylphosphoric triamide M HC1 CU C1-, 6M HzSO4, Butylrhodamine C 0.5-0.6N HCl, Crystal Violet Pb, Cu concentrates 0.02M HCl, Methylene Blue Ore concentrates Organic borates, boro- Acid silicate glass 0.5.y H2S04, 5 % H F stand for 30 mmutes. Add Methylene Blue H2SO4, N H 9 , Malachite Green NaOH, Si, GeOz HF, Methyl Violet Steel Complexon 111, dil. HC1, acetylRocks acetone EDTA, p H 1-1.5 Fe, Co, Zn EDTA, 4M HzS04 Impurities Acid (1) NaDEDTC Pig iron, steel (2) dithizone Many metals pH 8-10, tartrate, cyanide, Complexon 111 Dil. HNOa Many metals l0M H2S04, 1,3-bis(8-mercaptotheophyllin-7-y1)propane 0.1-0.6M HC104, thiourea Cast iron, Sb Dil. HzS04, Na citrate, thiourea, K I 0.05M HBr, HNOl Zn, Sn(IV), In, P b Various metals 0.5-3.5M "03 or 0.25-0.5M

Br

c1, I

Ca

Alkali halides Pure iron Be compounds Up to lo7 X [Zn]

B

Be

Bi

Cd

Zn, Co, Cr, All Mn, Fe, Mg

(1) H2S04 KhhOa extract (2) to organic phase add: lO-3.6M each Hg(NO&-KI, Hg(SCN), diphenylcarbazone NHaOH p H 12.5, glyoxalbis(2-hydroxyanil)

0-5M "01, Diphenyldithiophosphoric acid Dilute HOAc

CCla i-Pentanol TBP Substoichiometric Zn(DEDTC)z in CHC13 Substoichiometric amount Cu( D E D T C h in CHCl, TTA/xylene EtzO, then isopentanol MIBK

Reference

(492) (288)

(509) (92) (90)

(8141 (670, 671) (979)

Trioctylmethylammonium hydroxide/decyl alcohol CHzClg Rhodamine B in CHCls C6Hi Toluene CHCla 2-Ethyl-1,3-hexanediol in CHC13 CHzClCHzCI

(422, 456, 691, 1044)

CsH6 CzHC13 CCl4 TFA/CHC13 or C& 2-Ethylhexoic acid/kerosine CCl4 3,5-Diphenyl-l-pyrazolyldithiocarbamate/CHCla BPHA/CHCla CHC13

(150) (187) (52)

TBP Pentyl acetate Amberlite LA-1 or TOA/xylene TTA/xylene

(677)

CCla

(748)

(40, 1022) (677) (9911

8-Quinolinol/BuOH BuOH Azoazoxy BN/CC14-TBP 0,O'-diethyldithiophosphoric acid/ CCl4 CHCla

(11 6 )

0,lM TFA, 0.4M IBA in CHC13

(878)

(Continued)

(949) (460) (545) (159)

VOL 40, NO. 5 , APRIL 1968

535 R

Table II.

Element extracted Ce

Separated from Cast iron Metallic Ni Steels

Cl(VI1)

C1-, C103-, CrZOp-, CrOh*-, NO,-, NOzF-

Cm co

Pu-AI alloy Ni and ferronickel Reactor coolant water Ni Ni, many other cations

(Continued)

Solvent system (before mixing) -4queous phase Organic phase 1: 1 "01 Et20 8M "03, NaBr03 TBP 0.3M HzS04, Methylene Blue, 2M CeHe KOH pH 4.5-7.0, Brilliant Green C6He Crystal Violet 6.5M NOa-, 0.1M H + pH 3.0-3.7, NaDEDTC pH 5.0-5.5, NaDEDTC

CeH6 or C&Cl TBP/hydrocarbon CC14 CeHs

NHd tartrate, ",OH, K methylxanthate NaN02, borax, a-furilmonooxime 0.1M NaOAc, pyridine Dil. HOAc HOAc, NaNOz, citric acid, NazHP04

CIIc13

pH 4-5, citrate, 1-YO-2-naphthol p H 3-4, citrate, H2OZk 2-NO-1naphthol HOAc-NaOAc, NH4F, 2-nitroso-lIron, steel naphthol Na4PI07, thiourea, PAN, HZOz p H Mo metal, Ti hard 4.5-5.0 materials 9M HCl O.1M HCl ([Cl-] = - 2.6M) Ni Irradiated target, M n 9 M HCl NHSCN, sz08'-, and Po43-, p H Mn ores 6-7 KSCN, benzyldimethyltetradecylMany metals ammonium chloride (Zephiramine) Diphenylcarbazone, pH 1.5 Many metals pH 2.4-2.8, 8-aminoquinoline pH > 12 Rb, K, Na pH 4, 1.5M N a + 0.07M H I 0.01M Ca(0H)Z Neutral solution, CI-(NCS)~(CeHs"z)z pH 10, NaDEDTC LiCl Ammoniacal tartrate, NaDEDTC Pb, Cd, Zn, Sb, As, Bi, T1, Mn, Te, Ni, Co, Fe 0.3-0.7M HCl, NaDEDTC Al-alloys, steels pH 8-9, EDTA, citrate Biological materials, pure A1 Complexon 111, NaDEDTC Ammonium alum High purity Zn (Ni, p H 4, NHd citrate Co, Fe, some Bi, T1) Dilute HCl, KHlPO4 Cast iron, steels 0.01M HCl Ores VH5 Al, Sn HF, p H 4.5 Nb, T a Dilute HOAc Ascorbic acid, 0.1M HCl High purity Fe

Cr cs

cu

Pure Ga Many metals

Ga, As AI Pure iron

536 R

ANALYTICAL CHEMISTRY

Tartrate, p H 1.6-2.0 pH 6.6, 3,5dimethylpyrazole, KSCN Dilute acid, n-pent,yl-2-pyridylketoxime NHzOH, Na citrate, p H 4-6, neocuproine NHzOH, pH 3-3.5, neocuproine NH4 citrate, pH 6 , bathocuproine NH20H. HCl

CHCla Acetylacetone/C& 0.1M TFA, 0.4M IBA in CHC13 TTA in xylene CaH6 CHCla Pentyl acetate CHClj Amberlite LA-a/xylene ( CsHl~)4NCl/toluene TOA in CCHB 3: 1 Et20-pentanol CHC13 i-Pentanol 1: 1 Benzylalcohol CHC18 BAMBP in kerosine DOPA/BAMBP 1: 5 in kerosine CeHsNOz Ca dipicrylaminate in C6H5N02 CsH5NOz CCl4 CCl4 i-Pentanol Morpholinium morpholine-N. dithiocarbamate/CHCIJ &Pentanol Zn(DEDTC) in ccl4 Dithizone in CClr Dithizone/CCl4 Dithizone/CHCla 8-Quinolinol/EtO Ac 0.1M TFA, 0.4M IBA in CHCh 6-R.lethvl~icolinicacid thioamide/n-pentino1 PAN/pentyl alcohol CHCh i-Pentanol or CHCla CHCla Pen tanol CHCla 2,3,8,9-Dibenzo-4,7-dimethyl-5,6dihvdro-1, 10-vhenanthroline/isopeityl alcohd (Cmtinued)

Element extracted

Separated from Most metals

56 cations La203

Eu FFe

Mn, Ni, Co, Zn, All Mol W, V, Ti, Th 54Mn

Cu, Bi High purity tin Pure reagents PbMOO4, P U Fe(II1) in hematite Fe(II1) Sea water, A1 alloy Metallic All transistor-grade Si

Ga

Table II. (Confinued) Solvent system Aqueous phase p H 4.7, NHzOH, ascorbic acid, 2,3bis [2-(6-methylpyridyl)]qumoxaline EDTA, p H 4-6 neocuprohe Urotropine, TTA, phenanthroline p H 5-5.5 Acid solution, triphenylsilanol Dilute H2S04 p H 1, N-cinnamoyl-N-phenylhydroxylamine Dipyridyl, dilute acid Acid solution, 3-OH flavone in dimethyl sulfoxide p H 4, Morin 8M HCl, 2.7M HNOj >8M HCl Concentration NaCl, 0.1M HCI, [(CH3)i"PO Dilute acid, KSCN, Zephiramine Dipyridyl Irradiate buffered (pH 4.0-5.5) solution containing phenanthroline and NaC104 for 1 hour Phenanthroline, ",OH, tartrate, NaClO4 Ar atmosphere, phenanthroline, NaC104, p H 4-5, citrate pH 2.0-2.1,- bathophenanthroline ",OH, bathophenanthroline, or 2,4,6-tripyridyI-sym-triazine After pre-extraction with cupferron and DEDTC, p H 5.5 Resorscylaldehyde formyl hydrazone, saturated NaClO4

(before mixing) Organic phase Pentanol CHCla COHE CHCla 2-Mercaptopyridine/CHCls i-Pentanol Acetylacetone/CHCla C6Ha i-Pentanol

CHzCl2 CHCla 1: 1 C6H,-cresol CHCla CzH4C12or C ~ H ~ N O Z CHC1, CHCla Propylene carbonate

(794 (976)

Substoichiometric amount of 8quinolinol/CHCla i-Pentanol

(1108)

Et20 EtzO-CsHa Et20 BuOIl

(77) (6121 (6251

c Clc CHCls

(1046)

(400)

Ni; In,' As .

W ores Nb Alloys Many metals

Ge

Se

Many metals

I100 ppm C1, 2 ppm Br

I(VI1) (CsHs)zI In

+

Cu, Co, Zn, Fe Ca, Mg, Al, Cd, Mn, Zn

La

Ga Ce(IV), Y

HCI, PAN HCl, Rhodamine B 5 M HBr p H 6, 2-(3',4'-dihydroxypheny1azo)4-phenyl-5-benzoylthiaaole H C1 F!uoride, tartrate, p H 8.9, 8quinolinol in iMezCo pH 4, Complexon 111, KSCN pH 3, EDTA, 4,4'-bis(dimethy1amino)thiobenzophenone 0.2-0.3M H2SOaKCI, bis(Pmethy1benz ylaminopheny1)antipyrmylcarbinol 0.2-0.3M HzSO4, KBr, 4-dimethylaminophenylan tipyrinylcarbinol Saturate HgL, H2SOk,methylene blue 0.05M HN03, 10-a.6M each Hg(NOs)rKI Crystal Violet p H 2 10, dipicrylamine Zn KCN, pH 5.2 p H 3, 4-(2-pyridylazo)-l-naphthol 5-(2-pyridylazo)-2-ethylamino-pcresol, p H 3.16 5-(2-pyridylazo )-4-ethoxy-2-(methylamino)toluene, pH 5.87 KI-HtSOI Borate, Na salicylate, Alizarine SI 8-quinolinol

(4% 449,997)

(800)

1,5-Di-~-naphthylthiocarbazone in CHC13 i-Pentanol

(1016)

C&a C& CHC1, Diphenylcarbazone/CsH, CaHs CHCla 1-(2-Pyridylazo)-4-naphtholin CHCla CHCls GPentanol i-Pentanol Amberlite LA-l/xylene BuOH

(Continued) -

VOL. 40,

NO. 5, APRIL 1968

8

537 R

Element extracted

Separated from Zr, Fe, Hf, Cd

Li hlg

Be Pd, Al, Cu, Pd, Cd, Zn

RIn (11)

hleteorites Zr, Hf, Nb, Th, Fe, sc, co, c u High purity metals

Mn (VI1) Mo(V)

W, V, Re, other metals

Mo(V) and (VI)

W, Co, Ti, Ni, Cr, Fe, V, Al W hletallic Nb Stainless steels Copper ores Fe(II1)

hIo(V1) hIo(V1)

V Fe and other impurities Mo(V1) Nuclear fuels V Steel

N as NHa

Zr-Nb alloys hlo, W Zr Most metals Pure iron, Ti, T a Alloy steel

Nb

hlany metals M O

hlany metals

U alloys Steel Steel Pure iron Rocks W or WO3, various metals Meteorites

Ni

Pure Cd or Zn Fission products Phenol wastes Iso- and terephthalates Dinitrophenols

NP (VI 1 Phenolate Phthalate Picrate Picrate Alkylbenzentesulfonate

C1-, Br-, S 0 2 -

Table ll. (Continued) Solvent system Aqeueous phase DCTA, pH 1.8-2.2 Chlorophosphonazo dianilide Ai KOH and K F "4015, KCN ("4)2CzO4, equal volume butyl Cellosolve pH 11.5, piperidine p H 8-8.5, NH4DEDTC Neutral, pyridine pH 7.8-9.2, tartrate, F-, CNAmmoniacal-tartrate-cyanide 0.lM HzS04, (CIOHZI)ZNH Substoichiometric Ph4AsCl H2S04, NaSCN, Crystal Violet Phenanthroline, NaCl, HCl, SnClz pH 1.6-4 2.4N HCl, citric acid HF, HCI, toluene-3,4-dithiol Dilute HCl, mercaptoacetic acid Dilute HCl p H 2.2, catechol-3,5-disulfonic acid, diphenylguanidinium chloride NzHd.2HC1, 7M HC1 9'11 HCl 6M HCl, 4'11 LiCl 4 . 8 ~~ c i - 3 . 6HzSO4 ~ pH 1-7, (C6Hs)aSbCl To Kjeldahl distillate add phenol and NaOCl, saturated NaCl p H 10-10.5 Ammoniacal citrate 6-7.5'21 HzSO4 7111 HC1, 10% BuOH 2M H2SOlrLumogallion Tartrate, ascorbic acid, Complexon 111, Sulfochlorophenol C, 1.5M HCl, diphenylguanidinium chloride 6M HCl, Sulfochlorophenol C, diphenylguanidinium chloride Pyrogallol, Bu4NBr H2S04, tartaric acid 1 0 s HzS04, 0.7U fluoride 0.047, Butylrhodamine S 3 . 7 5 HzS04 ~ KSCN, HCl, SnC12 Ascorbic acid, KSCN, HCl KCNS, (CsHs)&Cl Thioglycollic acid, NH4SCN Tartrate, KSCN, SnC12,HCl Dilute HOAc NaOH, Na Dimethylglyoximate

p H 8-8.5, NHiDEDTC NH4 tartrate, NH40H, K methylxanthate pH 7-8, pyridine p H 10, citrate, NH3 CeNH4 nitrate CuS04, S H 2 0 H , NazHP04

(before mixing) Organic phase BuOH 0.1M Dipivaloylmethane in EtzO S-Quinolinol/CHC13 Eriochrome Black T/pentanol CHC13 TTA/CeHs Substoichiometric TTA/ethyl acetate PAN/CHCla CsHe CHCla CsHe Benzyl alcohol Thiolactic acid p-phenetididel i-pentanol-CeH6 Toluenedithiol/butyl acetate

cc14

1-Pen tanol a-Benzoinoxime/CHCl3 1: 1 i-pentanol-CHCla

Pentyl acetate 307, i-Pentyl acetate/C6H6 1:4 TBP-CCld Pentyl acetate CHzClt BuOH

8-&uinolinol/CHCl~ 8-&uinolinol/CIIC13 BPHA/CHC13 TTA/xylene BuOH BuOH BuOH EtOAc MIBK CeHe iV-Benzylaniline/CHCl3 Et20 TBP/CHC13 9 :2 CHC13-acetone TOPO/CeH1z MIBK O.1M TFA, 0.4M IBA in CHC13 E h O or CHCla CHC13 CHCli Acetylacetone/CHClt CHC13 MIBK Amberlite XLA-3 Neocuproine/MIBK

0.2-0.3M NaOAc, dipyridyl, Fe(II), C&sNOz pH 2.5 CHCL or C2H&lZ 0.08M HzSO,, hlathylene Blue Crystal Violet CaHs (Continued)

538 R

ANALYTICAL CHEMISTRY

Reference

Table

Element extracted Separated from a- and 8-NaphDisulfonate anions thalene sulfonate Diphenylborinate Quinine

os

II.

(Continued)

Solvent system (before mixing) Organic phase Aqueous phase 0.1 % Rhodamine G

5 yo phenol, diphenylcarbazone Tic14 in HCl, Na salicylate, pH 3 2M HCl, 2-mercaptobenzimidazole pH 4, 2-mercaptobenzthiazole, Most metals NiEDTA 4-6M HCl, o-(pbenzoy1thioureido)Many metals benzoic acid M HCl Mans metals M HCI, SnClZ,dichlorpbenzylTi(IV), Ni, Cu, triphenylphosphonium chloride W ( W , As, Sb, Hg, Sn, Pb, Ag, In(IV), Rh(1V) Dilute HNOa, NH4 molybdate Steel

As, W, steels

C6Hn CHCla BuOH-CaHs CHCla Ethyl acetate 2-Octanone C H C l / l O ~ oacetylacetone

i-Pentanol, EhO, butyl acetate, pentyl acetate Butyl acetate

pH < 1, NH4 molybdate and heat (both depend on % P) cool Propyl acetate 0.05M molybdate, 0.01M &quinolinol, 1M HCl. Heat to 70" C for 1 hr, add 12M HCl (a) 1:1 BuOH-cyclohexanol (b) add Crystal Violet Dioctylamine/l :1 CHCl&CsH1lOH NH4 molybdate, HCOONaHCOOH.. HzS04, ~.SnC~04,NaF Fe, "08, acetone C~zHzs"z/CHCla i-Pentanol 2.5M HzS04, benzenearsonic acid ~

A~Pz0.r'Pa

Pod8Ti, Zr, Th, U, other metals Group IVa & Va Daughter nuclides

Pb Fe, steel Pd

Ag metal

Pt P t group, Fe, Co, Ni P t group, most other metals (not Cu) P t group metals, many others Pt, TI, Cd, Sb, Bi, Pb, Ni, Zr, Fe, U, Ce

Catalysts P t group, most other metals Co, Ni, Cu, Fe, Ag, Pt. Ir. Rh Many metals I

Aliquat 336 S/xylene

Dilute HOAc

0.1M TFA, 0.4M IBA in CHCl, TTA in pentan-%one

PH 4

cch Dithizone/CC14 MIBK CHCla 1: 1-BuOH-ethyl acetate CaH6 CHCla Glyoxime (C2H~O2N2)/CHCl~

Hg(NOa)z,pH 4-6, isonitrosoacetyl- cc14 acetone 0.1M acetic acid, masking agents Isonitrosoacetophenone/C6H6 Picolinealdehyde 2-quinolylhydraCHCla zone, pH 8 Dilute H2S04,pH 1.5-2.3 Pyridine-2-aldehyde-2-quinolylhydrazone/CHCla Dilute HzS04, KCl, PAR i-BuOH

i

Fe, Co, Ni, many other metals

Pt, Os, Ir, Ru, other

Po

HC1 HzSOrHCl NaDEDTC Ascorbic acid, NHI citrate, KCN, pH 8.5-9.5 Na tartrate, Na dimethyl dithiocarbamate Thiourea, 8-mercaptoquinoline M HCl, thioglycollic acid 4-6M HCl, i-pentyl ester of 8mercaptohydrocinnamic acid 2M HzS04, pmercapto-8-phenylpropiophenone pH 1, HCl-EDTA

metals Au, Ru, Ir, Os, Cu, Pt Rh, Ir, other metals Rh, Ir, other metals Bi

pH 3, EDTA, 4,4'-bis(dimethy1amino)thiobenzophenone 9M H2S04,2-[2-(4,5-dimethylimidazol-2-ylazo)phenyl] -8hydroxy-4,5,7-trimethyIqumazoline, heat 10 min a t 90" C. Add CzHsOH pH 2.5-2.7, N-methy1anabasine-o'azo-a-naphthol pH = 2 (NOa- absent) phenoxanthiin, (CH&3O KI Concentrated HCl, 1,4-thioxane 7 M HCl

i-Pentanol CHCls

CHCls CHgClp TBP CHzClz TBP/xylene (Continued)

VOL 40, NO. 5, APRIL 1968

539 R

Table II. (Continued) Element extracted Pt

Re

Separated from

Ir, Rh Ag, Mn, Cu, Ni, Pb, Cr, La, Bi, Th, UWI) Ag, Cu,'Ni, Pb, Al, La Many metals Mo, V Tc(VI1)

Mo, W, V, Se, As hlany metals Mo, Cu, W hlo, W hlolybdenites M O

Rh Ir

Ru

Ir Zn-Mg alloys

U

SzSOS2- or St-

SCN Sb

Sb(II1) Sc

Se(1V)

Iron and steels Lead Impurities in Sb, e.g., Al, Bi, In, Cd, Ca, Co, As, Cu, Mn, Mg, Ni, Pb, Ag, Te, Cr, Zn So1ders Steels

Solvent system Aaueous Dhase pH 3-12, Na 8-mercaptoquinolinate 5M HCl and 2M AlCla p H 3-4, chloride, Fe phen32+ KI

M "0s

(before mixing) Organic *Dhase CHC13 Mesityl oxide CBHSNOZ TBP TTA/CeHe

M HNO,, arsenazo I11

(C6HsCHz)aN-BuOH

(661)

HCl 1.5M HzS04, NzH4*HzSOi 5M NaOH, 0.03M N z H ~ , 7 min Alkaline medium p H 0.7, bis(4dimethylaminophenyl)antiDvrvlcarbino1 pH >*f,~ C ~ H s ) r h C 1 pH 9, (CeHdsSeC1 pH 8-9, Methylene Blue Tartrate p H 7 , Ethyl Violet HC104 pH 5.1, PAN heat to boil for I hour 21.f HCl, thioglycollic acid SnBr2, HBr, 42% HClOd HzS04,NazSO4, NaIO4

MIBK Pentanol MIBK

(1091) (1093) (799)

Quinoline or pyridine C6H&HC13

(1004, 240)

pH 4.8-5.0, 4,7-diphenyl-l,l@phenanthroline NaC104, p-MeZNC6H4NHzand Fe(II1) pH 7.0, Hg(NO&, KBr, diphenylcarbazone Dilute H2S04,Methylene Blue &Sod, Ti(III), NaI Concentrate HC1 12M HC1

6M HCl, Malachite Green 6M HCI, Na hexametaphosphate, Brilliant Green 6M HCl, Na hexametaphosphate, Steels "*OH Rhodamine B Br water, 0.5M "08, Methyl P b metal, oxides and Violet battery powders Thiourea, HCI, pyridylazomonoCu, Pb, Sn, As, Bi, ethylamino-p-cresol Cd Salicylaldehyde acetylhydrazone, TI, Ag, Pb, Hg, Be, saturated NaClO4 Cd, Ca, La, Ce, Cr, Mn, Co, Ni, In, As Salicylaldehyde semicarbazone Al, many metals 0.1M HCl, NaDEDTC Se(V1) 2M HCl, Bismuthiol I1 (K salt of 5-sH-3-C&-1,3,4thiadiazole-2-thione) p H 0-2, 1,4-diphenylthiocarbazide Te HzS04, ascorbic acid High purity S Sludges, sinter cakes 7.5M HCl, diisopropyl ketone HCOOH, Complexon 111, 3,3'-diHC1 aminobenzidme. Stand 45 minutes in dark, NH40H HNOa-HzS04,NH4 molybdate High purity Cu, brasses 2.5M &Sod, NH4 molybdate, HF, High purity metals, steels Fe4"( )z (SO4)z,SuClz 3M HCl, NH4 molybdate, Crystal Violet

CHCla CHzClz CHC13 C6H6 TTA/ (CH&CO-xylene CHCla 1:1 BuOH-ethyl acetate i-Pentanol CClr (develop color in extract with l-NO-2-na~hthol) n-hexanol

CHCla (747)

CsH6 CHzCIz C6H6 i-Propyl ether &p'-dichlorodiethyl ether

Toluene Toluene Diisopropyl ether

CHCla i-Pen tanol i-Pen tanol TBP CCld or CHC13 CHCla C6Hs CHCla Toluene Pentanol i-Pentanol 2 :3-Cyc1ohexanol:pentanol (Continued)

540 R

ANALYTICAL CHEMISTRY

Reference

Table II. Element extracted Sn

Separated from Ores Metals and alloys

Ta Si02, SiHC1, High purity Nb Mo, Al, Nb, Re Steel, Nb, various alloys PIany metals Nb Fission products Nuclear fuels

(Continued)

Solvent system (before mixing) Aqueous phase Organic phase CHC18 pH 5.5 tartrate, NaDEDTC CCl4 0.2M chloride, pH 1, 5,7-dibromo-8-quinolinol CsH, 4.5M H2S04, NaI, HnSO3 P y r o g a l l ~ l - ( C ~ H , ~ in ) ~ethyl N I acepH 4.5-5.0, (NH4)GOr tate Butylrhodamine C/C& Dilute HzSOI HF, (NH4)2C204, Rhodamine 6G CEHB (CsHs)rAsCl/CHCls H2S04, I&C2O4, NaF, HC1 0.2M HF, hIethyl Violet CEH~ H2S04, HF, Malachite Green CsHe

'

Tc(VI1) Te

Many metals Pb, Ti, In, Co, Ni, Cr, Zn, Mn, Al, Mg, Cd, Sb, Si Iron, steel Se Th Many metals

Minerals Ti(1V)

Ca Be, Al, Mn, Cu, do, Ni, Cr, Fe, V(VI), Mo(VI), Pb, Ag, W, Nb, Zr,T a

Steel and alloys Zr

T1 Al, Ga, In P b metal oxides

Pb, Zn, U ores V(V), Fe(II1)

Zr Th, Zr Rocks Parent T i Pure iron Brine

0.3111 HC1, Ethyl Violet HF, HCl 0.1-3.5M HzSO4, H202 DTPA, NaOH (C3H7)rNOII pH 5.9, Methyl Violet pH 8.5-8.8, NaDEDTC 3M HCl, Bismuthiol I1 6dB HCl 4M HCl, 2-mercaptobenzothiazole Dilute HCl, tetramethylthiuram disulfide

Butyl acetate Amberlite LA-2/CeHG Cyclohexanone CHCls CsHaCl MIBK CHCla Thiocarbanilide/CHC13 CHCla CHCls

6M HCl 0.6111 HC1, saturated K I Ascorbic acid, Butylrhodamine B pH 5.2 NaOAc-HOAc 0.1M HCl DCTA, arsenazo DAL [dianilide of 3,6-bis(2-arsonophenylazo)4,5-dihydroxy-2,7-naphthalenesulfonic acid] 6M "03, methyldiantipyrinylmethane 1-5M HN03, 1-lOM HzSO,, or 1-10M HCl, with HzC204

MIBK or methyl ethyl ketone MIBK CeHe 8-Quinolinol/i-CsHi10H-CHCls 1: 19 DOPA/cyclohexane BuOH

Hz02, p H 5, PAN pH 2-3, diphenylguanidine, Xylenol Orange Pyrocatechol, picolinic acid pH 1-2 M HCl, diantipyrylmethane, SnC12 11M HzS04 8-Quhoh01, p H 5.5 1.5-8M HCl M HC1 N HBr Br water, 0.5M "0s 0.1-6.OM HCl, 4,4'-bisdimethylaminodiphenyl-3-(9-cyanoethylcarbazy1)methane HsPOI, FeCls, HzOZ, Crystal Violet pH 6-7

BuOH BuOH

pH 5-7, >&I fluoride 5M HC1 0.05M H2S04or 0.1kf Hap01 Sulfosalicylic acid, NaF

Fe(III), U(V1)

4M HC1

Steels and ores

HzSOd HCl

p H 1.4

CHCls DOPA/CsHe

CzH4C1z CHCls TBP/CHC13-CsHirOH CsHe MIBK MIBK Ethyl acetate Butyl acetate CsHs Toluene or CHCls Toluene N-Cinnamoyl-N-phenylhydroxylamine/CHCla DOPA-TOPO/kerosine TOA/xylene 8-Quinolinol/BuOH-C~Hs 5,7-Diiodo-8-quinolinol in heptanol BPHA/CHCls BPHA/C& BPHA/CHCla N-Furoyl-N-phenylhydroxylamine/ CHCla A'-Cinnamoyl-N-p henylhydroxylamine/CHClt N-Furo ylphenylhydroxylamine/ CHC1, 9: 1-Salicylaldehyde-BuOH (Continued)

VOL 40, NO. 5,

APRIL 1968

541 R

Table II.

Separated from Steel Steel

(Confinued) Solvent system Aqueous phase 1.2M HCl, a-benzoinoxime pH 1, HaP04, Schiff base of salicylaldehyde and anthranilic acid 0.1M H2S04, KaF, Ferron

Al, Ba, Be, Cd, Ce(III), Cr, Co, Cu, Pb, Mn, Mg, Hg, Nil Th, U(VI), Fe(III), V(1V) V(IV), Al, Ba, Cd, pH 1, Ferron Ce, Co, Cr, Mg, Mn, Ni, Th, U, Zn. Cu. Fe HCl, 1% p-methoxybenzothioSteel; U dmpds. hydroxamic acid pH 5, PAR, quinine pH 35-4.5, pyrocatechol. pachyh4any metals carpine p H 1.8-2.4, 8-aminoquinoline 1:1 benzyl alcohol Ni, Mn, Co, Cr, AI, p H 5, diphenylguanidine, pyroNb gallol or catechol HF, HCl, Ti(III), toluene-3,4Metallic Nb dithiol M HCl, K toluene dithioate, 80-90' Silicates, natural waters C for 20 minutes. Cool v Dilute HCl, ascorbic acid, K benzohydroxamate Xenotime pH 9.5, 5,7-dichloro-8-quinolinol Fission products 0.3M HC1 DCTA, pH 1.8-2.2, ChloroZr, Fe, Hf, Cd phosphonazo dianilide Citric acid Copper pH 8.5-9.0 Diethanoldithiocarbamate, pH 8-9 Many metals Acetate buffer pH 5.6, Na2S208 Cu, Pb, Co Alkaline medium Soils Dilute HOAc KCN, chloral hydrate, saturated Many metal ions thiourea, 10% NaOH, heat to

(before mixing) Organic phase CHC13 C6H6

Reference (604) (95)

BuOH

(554)

BuOH

(553)

CHC13 CHCls CHC13 CHCla i-Pentanol

cc14 Butyl acetate 1 : 1-i-Butanol-CHCla

CHaCl DOPA/xylene BuOH Dithizone/CHCla Substoichiometric dithizone/CHCla Substoichiometric dithizone/CCld Dithizone/CC14 Dithizone 0.1M TFA and 0.4M BA in CHCl, o-RIercaptothenalaniline in CHC13

looo c

GeC14 Ba, Cu, Be, Sn Fe, Pb, AI, Mg, Ca Al alloys metallic Ni and Cu

Co, Mg, Ni, Mn, Cd, Al, Fe Zr

Nb Nb (NHu),uz07 Nb High alloy steels

surfactant and one associated into micelles (409). Masking with EDTA of La-Ce or Tm-Yb in the Alamine 336HNO, system is greater with the heavier element and results in separation factors of 8.5 and 3.4, respectively (88). Cyclohexanone can be recovered after use in Ta-Kb separation by kerosine and re-extracted by H ~ S O ~ - ( N H ~ ) Z(547). SO~

542 R

ANALYTICAL CHEMISTRY

p H 8, 8-(p-tosylamino)quinoline 0.25-0.4.44 NaOH, tartrate 3M HCOONa 2-3M HC1, diantipyrylmethane

CHC13 Azoazoxy NB/CC14-TBP Pyridine CHC1,

NH4SCN-Rhodamine B pH 5-6, NH4SCN, hexamethyl phosphoric acid triamide Fluoride, tartrate, pH 8.9, 8quinolinol in Me2C0 0.025-0.05M HsS04 0.1M HnSOa, HzOz 4.5hf "03 0.04M H3POir 0.008M HzCz04 HC1, citric acid, ascorbic acid, thiourea, Picramine R, diphenylguanidinium C1 p H 1.1, diphenylguanidine, Xylenol Orange

Et20 CHzC12 CHCla BPHA/CHCl, Trifluoroacetylacetone/c6H6 TTA/CsHc Monoctyl anilinobenzyl phosphate BuOH BuOH

A number of computer programs for use with extraction calculations and process simulation (42) have appeared. These include computer solution to extraction cascade calculations for composition of all streams in multicomponent countercurrent distribution (879) and simulation of TBP-I! extraction train (215). Such simulation leads to

equations which help in the prediction of the number of stages needed for binary separation (164). A tabulation relating D us. position in both simple and countercurrent extraction has become available (36). Chalmers has extended his application of solvent extraction to systematic qualitative analysis (174).

Table 111.

Multielement Separations

High purity Sn

Elements extracted Extraction systems Pb, Cd, In, Bi, Cu, Sb MIBK-HI, dithizone, 8-quinolinol neocuproine Fe, Ga Et20-HCl, TTA, DEDTC In, Hg, Cu, Pb, Bi, (i-CaH7),O-HBr, dithizone, 01Cd, Zn, Co, Ni furildioxime, 1-NO-2-naphthol Dithizone

Tin-containing materials High purity W and WOS Zinc

Sb, Bi, Fe Co, Cu, Pb, Ni, Zn Al, Cd, Pd, Cu, Fe, Si

Mater ia1 Ferrous and nonferrous alloys Zone refined Mg Indium

High purity salts of Li, Rb, Cs High purity LiNO3, RbNO3, CsN03 Pure reagents A1 salts Various materials Natural PbS Silicate rocks Granite and diabase rocks Ce02 Environmental and bioassay samples Underground thermonuclear explosion products

Alkylphosphoric acids Dithizone/CHC13 8-Quinolinol, IIEIlTC, dithizone, phen, Molv Blue Fe, Co, Ni PAN 20 elements NaDEDTC, 8-quinolinol Al, Bi, Ga, In, Cd, Cu, C7-c~fatty acids As, Sn, Pb, Sb, Ag, Cr, Fe, T i RIixture of heavy Ilithizone (reverse method) metals Ca, Xlg, Fe, Ni 8-Quinolinol/llIBK Bi, Cd, Co, Cu, Fe, NHI pyrrolidinecarbodithioate Ilg, hln, Ni, Pb, Sb, in MIBK Zn T1, In, Ga, Sb, Sn HBr-Et20 Rare earths TBP/nitrate Co, Pa, Fe, Ag, Zn, (CizHz,)3NHCl, TBP, T T A Hg, s c La, Pr, Kd DOPA 37 elements DOP$ T O 4 Actinides, lanthanides

LITERATURE CITED

(1) Abramson. A. A.. Zh. Prikl. Khim. ‘ 38, 2597 (1965). ‘

(2) Adamiec, I., Chem. Anal. (Warsaw) 11, 1175 (1966). (3) Affsprung, H. E., Anal. Chim. Acta 37, 81 (1967). (4) Afghan, B. K., Talanta 14, 715 (1967). ( 5 ) Agazzi, E. J., ANAL.CHEM.39, 233 (19671. \ - - -

I

(6) Aggett, J., Chem. Znd. (London) 1966, 27. (7) Aggett, J., J. Znorg. ,Vucl. Chem. 29, 1113 (1967). (8) Ajtai, &I., Magy. Tud. Akad., Kem. Tud. Oszt., Kozlemeny. 24, 20.5 (1965). (9) Akaiwa, H., Kawamoto, IVauk SSSR, Inst. Geokhim. i Analit. Khim. 1966,28. 135) Zolotov, Yu. A., Seryakova, I. V., Sukhanovskays, A. I., Karyakin, A. V., Antipova-Karataeva, I. I., Uribov, L. A., Petrov, A. V., Kutsenko, Yu. I., Sovrem. dfetody Analiza, AIetody Issled. Khim. Sostava 2' Stroeniya Veshchestv, A k a d iyauk SSSIZ, Inst. Geokhim. i Analit. Khim. 1965,238. (1136) Zommer, S., Lipiec, T., Acta Pol. Pharm. 23, 567 (1966). (1137) Zvyagintsev, 0. E., Frolov, Yu. G., Sergievskii, V. V., Huang, C., Zh. Neorgan. Khim. 11, 661 (1966). (1138) Zvyagintsev, 0. ,E., Sinitsyn, N. M., Pichkov, V. N., Ibsd., p 198.

VOL. 40, NO. 5 , APRIL 1968

553 R