Ind. Eng. Chem. Process Des. Dev. 1085, 24, 244-250
244
dehydration, is endothermic with a reaction enthalpy of 90 cal/g, while the second, corresponding to the formation of paraffinic and aromatic hydrocarbons from olefins, is exothermic with a reaction enthalpy of -400 cal/g. Therefore, if the reaction is carried out in an adiabatic fixed bed reactor, it would be interesting to partially recycle the gaseous products to eliminate the reaction heat and at the same time limit the possible decrease of the yield that ethanol dilution would produce, with an increase in the pressure. This is in agreement with the observations made on studying the influence of both variables. Registry No. EtOH, 64-17-5.
Literature Cited Argauer, R. J.; Landolt, G. R. U.S. Patent 3702886, 1972. Bolis, V.; Vedrine, J. C.; Van den Berg, J. P.; Wolthuizen, J. P.; Derouane, E. G. J . Chem. Soc., Farahy Trans. 1 1979, 75, 11. Calvin, M. Chem. Eng. News 1978, 56(12), 30. Chang, C. D.; Lang, W. H.; Smkh, R. L. J. Catal. 1979, 56, 189. Cheremlsinoff, N. P. “Gasohoi for Energy Production”; Ann Arbor Science Publishers: MI, 1979. Dejaifve. P.; Vedrine, J. C . ; Bolis, V.; Derouane, E. G. J. Catal. 1980, 63, 331. Derouane, E. G.; Nagy, J. B.; Dejaifve, P.; Van Hoof, J. H. C.; Spekman, B. P.; Vedrine, J. C.; Naccache, C. J. &&I. 1978, 53, 40. Hernandez, P. J. Ph.D. Thesis, Facultad de Ciencias Ouimicas, Universidad Complutense: Madrid, 1983. Kokotailo, G. T.; Lawton, S. L.; Olson, D. H. Nature (London)1978, 272, 437. Kothari, S. P.; Patel. P. S. EnergyprOg. 1982, 2 , 3. Mltchell, T. E.;Schroer, B. 1.; Ziemke, M. C.; Peters, J. F. CHEMT€CH 1983, 13. 4. Poulsen, P. B. Ing. Quim. 1982, 764, 25. Rollman, L. D.; Waish, D. E. J. Catal. 1979, 56, 139. Venuto, P. B.; Hamilton, L. A. Ind. Eng. Chem. Process Des. D e v . 1987, 6 , 190. Weisz, P. B.; b a g , W. 0.; Rodewakl, P. 0. Science 1979. 206. 57. Whitcraft, D. R.; Veryklos, X. E.; Mutharasan, R. Ind. Eng. Chem. Process Des. Dev. 1983, 22, 452. ~
-1001
,
,
0.05 0.1
,
,
,
0.5
1.0
5.0
WHSV-’
(h)
Figure 8. Thermochemistry of the ethanol to gasoline process at 400 OC.
dration rate and therefore the sign of the slope should be opposite to that of a kinetic constant. The kinetic model already set out predicted, with the same precision, the experimental kinetic data corresponding to catalysts with different Si/A1 ratios and different ethanol dilutions (Hernandez, 1983), so quantitatively confirming the already mentioned observations. Figure 8 shows the values of the energy exchanged in fixed bed ethanol conversion at 400 “Cvs. the space time. It can be seen that the process displays two clearly different steps: the first, which corresponds to ethanol
Received for review September 30, 1983 Accepted February 21, 1984
Modekg of Simple Multistage and Countercurrent Multistage Copper Extraction by Hydroxyoximes Jan Szymanowski’ and Piotr Jeszka Technical University of Poznafi, Institute of Chemical Technology and Instltute of Environmental Engineering, Poznafi, Poland
Extraction isotherms were determined at 18-20 O C for 2-hydroxy-5-nonylbenzldehyde oxime and 2-hydroxy-5nonylbenzophenone oxime, and appropriate equatlons modeling the surfaces of the extraction isotherms were derived and then used to discuss simple multistage and countercurrent multistage extraction processes. The extraction rate was also determhd. The superkrlty of an isdated “pure” fraction of 2-hydroxy-5-nonylbenzaldehyde oxime over an isolated “pure” fraction of 2-hydroxy-5-nonylbenzophenone oxime was proven. With the use of 2-hydroxy-5-nonylbenzaldehydeoxime, copper extraction can be carried out with smaller scale extraction equipment or with greater flow of the aqueous phase. Under comparable conditions a smaller number of extraction stages is needed when 2-hydroxy-5-nonylbenzklehyde oxime is used.
Introduction In previous papers of Stepniak-Biniakiewicz and Szymanowski (1979,1981a, 1981b), Goszczyfiski et al. (1981), and Szymanowski and Atamdczuk (1982), copper and nickel extraction from acidic diluted aqueous solutions was studied. Theoretical and empirical models were derived and the influence of oxime structure upon its extraction properties was discussed. However, all the obtained data concerned extraction from diluted model solutions, and 0196-4305/85/ 1124-0244$01.50/0
industrial applications were not discussed. The aim of this work is to compare the extraction properties of “pure” isolated fractions of 2-hydroxy-5nonylbenzaldehyde oxime and 2-hydroxy-5-nonylbenzophenone oxime from concentrated copper solutions and to discuss some technological problems concerning the number of extraction stages and the flows of the aqueous and organic phases in simple multistage and countercurrent multistage processes. 0 1985 American Chemical Society
Ind. Eng. Chem. Process Des. Dev., Vol. 24, NT 2, 1985 245
Experimental Section Materials. 2-Hydroxy-5-nonylbenzaldehydeoxime (I) and 2-hydroxy-5-nonylbenzophenone oxime (11)were obtained from commercial nonylphenol. Intermediate 2hydroxy-Bnonylbenzophenonewas obtained by the condensation of nonylphenol with benzotrichloride carried out in an aqueous alkaline solution (Szymanowski and Blaszczak, 1982). Intermediate 2-hydroxy-5-nonylbenzaldehyde was obtained in the reaction of nonylphenol with formaldehyde carried out in an acidic methanolic solution (Stepin the presence of p-nitroso-N,N-dimethylaniline niak-Biniakiewicz et al., 1983). These reagents were separated from the post-reaction mixture by distillation and fractional distillation under reduced pressure. The oximes were obtained by the standard method in the reaction of the intermediate ketone and aldehyde with hydroxylamine hydrochloride. The purity of the intermediate ketone and aldehyde and the oximes were checked by gas chromatography using filled and capillary columns (Szymanowski and Blaszczak, 1982;Rusiiiska-Roszak, 1981). The products were analyzed as trimethylsilyl derivatives. Thin-layer chromatography and UV spectra were also used. The ratio of E to Z isomers in the 2-hydroxy-Bnonylbenzophenone oxime was 5.9;in 2-hydroxy-5-nonylbenzaldehyde oxime the Z isomer was not found. Escaid 100 was used as a diluent. Other chemicals were the same as in the previous work of Stepniak-Biniakiewiczand Szymanowski (1981b). Copper Extraction. Extraction isotherms were determined at 18-20 "C for different oxime concentrations and different initial concentrations of sulfuric acid in an aqueous phase. The oxime concentrations were equal to 5,10,15,and 20%, while the amount of sulfuric acid added to the aqueous phase varied from 0 to 50 g dm-3 for 2hydroxy-5-nonylbenzophenone oxime and from 0 to 200 g dm-3 for 2-hydroxy-5-nonylbenzaldehyde oxime. The equilibrium copper concentrations in the aqueous phase varied from about 0 to 30 g dm-3. The ionic strength of the aqueous phase was not adjusted. Kinetic data were obtained by means of the single-drop method (Whewell et al., 1975). The concentrations of copper and hydroxyoximes were equal to 0.0787 and 0.242 mol dms, respectively. The amount of added sulfuric acid changed from 0 to 200 g dm-3. Taking into account the previous works of Forrest and Hughes (1975a,b), Hughes et al. (1975),and Robinson (1971),the equilibrium copper concentration in the organic phase (c*,~) was correlated with the equilibrium copper concentration in the aqueous phase (c* ), with the amount of sulfuric acid added to the aqueous.fayer (C"H~FO,) and with the initial oxime concentration in the organic phase (cooxime).Two types of relations were considered = + b l c * a q + b2C0HzS04 + b3Cooxime + b4C*aqCoH2S04 + b5C*aqCooxime + b6CoH2SO~Cooxime + b7C*aqCoH~SO~Cooxime+
C*org
bE(C*aq)'
=
In
c*aq
+ b6C*aqCoHzS01 + b7C*aqCooxime +
bgC"H&O>n
c*aq
b10CoH$304Cooxime b12C*aqCooxime
In
+ b9c"o-e
In
c*aq
+ bllC*aqCoHzSO, In
+
c*aq
+
+ ~ 1 3 ~ * a q C o H ~ S O ~ C o o x+ ime + b15CoH$304CooximeC*aq In c*aq
c*aq
+ + b17(ln c*aq)2 + b18(C0H&04)2 + b19(Cooxime) 2
~ l 4 ~ " H Z S O 4 ~ " o x i In m e c*aq b16(C*aq)2
+ b9(CoHzS04)2 + b10(Cooxime)2 (1)
+ bz In C*aq + ~ ~ C " H ~ S +O , b4CooXime +
bo + b&*aq
where copper and sulfuric acid concentrations are given in g dm-3 and the oxime concentration in wt %. Simultaneously, appropriate relations correlating the equilibrium sulfuric acid concentration (c*H.+o,) with both its initial concentration in the aqueous layer and with the equilibrium copper concentration in the organic phase were derived = + h C * o r g + b2C0HzS04 + b3Cooxime +
'*Hzs04
b5C*orgCooxime
b8(c*org)2
C*HzSO,
b4C*orgCoHzS04
+
+ b6CoH~SO~Cooxime+ b7C*orgCoH~S0~Cooxime+
+ b9(CoH$30,)2 + b10(Cooxime)2 (3)
=
bo + blC*org + bz In C*org + b3CoHzS04 + b4C"oxime + b5C*org In c*org + b6C*orgCoH2S04 + b7C*orgCooxime + ~EC'H~SO In~ C*org + bgc'oxime In C*org + b 1 0 C o H ~ 0 4 C o o x i m e+ bllC*orgCoH2S04 In c*org + b12C*orgCo oxime In *erg+ b13C*orgC "HzSOlCo oxime + b 1 4 C o H ~ S 0 4 ~ o o x i mIn e c*org + b15CoHzS04CooximeC*org In c*org + b16(C*org)2 + b17(ln C*orgI2 + blE(CoHzS04)2 + b19(Cooxime) 2
(4)
Results
C*org
Figure 1. Surface of the extraction isotherm for 2-hydroxy-5nonylbenzaldehyde oxime (codme= 10%1.
(2)
The obtained relations are statistically significant at a probability level of 1.oooO. The correlation coefficients are equal to 0.967- 0,999.Equations 2 and 4,the more complex models, show higher accuracy. The regression coefficients of the derived basic models and their statistical characteristics are given in Tables I and 11. More simple models valid for selected regions of the considered parameters, i.e., constant oxime concentrations, low or high copper concentrations, low or high sulfuric acid concentrations, can be found in Jeszka's doctoral thesis (1982). The exemplary surfaces of the extraction isotherm for an oxime concentration of 10% are given in Figures 1 and 2. Similar surfaces were obtained for other considered concentrations of the oximes. In each case considered the extraction properties of 2-hydroxy-5-nonylbenzophenone oxime decrease very sharply with the increase of sulfuric acid concentration. The equilibrium copper concentrations in the organic phase are relatively low, especially in the region of low copper concentration in the aqueous phase (below 10 g dm-3) and of high concentrations of sulfuric acid (above 20 g dme3). 2-Hydroxy-5-nonylbenzaldehyde oxime shows much better extraction properties than 2hydroxy-5-nonylbenzophenoneoxime; higher concentrations of copper in the organic phase are obtained for I. In
246
Ind. Eng. Chem. Process Des. Dev., Vol. 24, No. 2, 1985
r)
Figure 2. Surface of the extraction isotherm for 2-hydroxy-5nonylbenzophenone oxime (cOxime = 10%).
Figure 4. Copper extraction by 2-hydroxy-5-nonylbenzophenone oxime in a simple multistage process (cocuz+= 5 g dm-3, cooxime= 15%; (0) C O H ~ S O ~ = 0 g dm-3; (A)c ~ H =~10~g dm-3; o ~ volume ratio of the aqueous to the organic phase: curve 1,l.O; curve 2, 2.0; curve 2, 5.0).
of e x t r a c t i o n stages
Number
0
1
2
3
4
5
6
7
humber of e x t r a c t i o n stages
Figure 3. Copper extraction by 2-hydroxy-5-nonylbenzaldehyde oxime in a simple multistage process (c0cu2+= 5 g dm-3, coH2so4= 0 g dm-3; (0) c0,,,,, = 15%; (A)cooxime= 5%; volume ratio of the aqueous to organic phase: curve 1, 1.0; curve 2, 2.0; curve 3, 5.0).
the region of low copper concentrations, in the aqueous layer the extraction isotherms for I are incomparably steeper than for 11. Thus, a much higher extraction percentage can be obtained when I is used as the extractant. This superiority of I is only partly the result of the lower molecular mass of I in comprison to 11. (MI= 263, MI, = 339, for the same weight concentrations of the oximes a higher mole concentration is obtained for I.) Therefore, some sample results showing the amount of copper transferred in the equilibrium to the organic phase by one mole of the oximes are given in Table III. They show that under comparable extraction conditions the amounts of copper extracted by I and I1 vary, respectively, in the range of 0.06-0.47 mol of Cu2+/molof oxime I and 0.00.40mol of Cu2+/molof oxime 11. In each case a much higher extraction capacity is obtained for 2-hydroxy-5-nonylbenzaldehyde oxime. This result is in good agreement with previous results of Szymanowski and Atamaiiczuk (1982) concerning copper extraction from diluted sulfate solutions and the acidity of the phenolic group. The obtained models were applied to calculate the copper concentrations in the organic and aqueous layers and the number of theoretical stages in simple multistage and countercurrent multistage processes. Different extraction conditions, Le., different copper, oxime, and sulfuric acid concentrations and different ratios of the aqueous to the organic phase, were considered. In a simple multistage extraction process the decrease of copper concentration in the aqueous phase depends generally upon all the considered parameters. The number of theoretical extraction stages needed to extract the same percentage of copper increases with the increase of the
Figure 5. Comparison of copper extraction by 2-hydroxy-5-nonylbenzaldehyde oxime (0) and 2-hydroxy-5-nonylbenzophenone oxime (A)in a simple multistage process (cooxime = 15%, c o ~ ~=o0 4g dm-3; volume ratio: curve 1, 1.0; curve 2, 2.0; curve 3, 5.0).
0
1
2
3
4
5
6
7
Number o f extraction stages
Figure 6. Comparison of copper extraction by 2-hydroxy-5-nonyland 2-hydroxy-5-nonylbenzophenone oxime benzaldehyde oxime (0) (A)in a simple multistage process (cooxime = 15%, coH2so4= 10 g dm-3; volume ratio: curve 1, 1.0; curve 2, 2.0;curve 3, 5.0).
volume of the aqueous phase and with the increase of sulfuric acid concentration. The influence of these parameters is much stronger for I1 than for I. Figure 3 shows the data obtained for copper extraction by 2-hydroxy-5-nonylbenzaldehydeoxime when sulfuric acid was not added to the initial copper solution. When 10 g dm-3 of sulfuric acid was also added to the aqueous phase no significant effect was observed; the curves obtained for different volume ratios of the aqueous to the organic phase shifted only negligibly. However, when 2-hydroxy-5-nonylbenzophenone oxime was used the addition of 10 g dm-3 of sulfuric acid influenced copper extraction significantly and a smaller extraction percentage was observed for each stage (Figure 4). A comparison of the considered oximes (Figures 5 and 6) shows the greater superiority of 2-hydroxy-5-nonylbenzaldehyde oxime, es-
Ind. Eng. Chem. Process Des. Dev., Vol. 24, No. 2, 1985 247 Table I. Regression Coefficients of the Derived Models for Copper Extraction by 2-Hydroxy-5-nonylbenzaldehydeOxime regression equation type coeff" 1 2 3 4 bo -0.6569 0.06867 1.069 19.46 bI 0.16752 0 0.99582 -34.929 b2 -0.031123 0 1.0579 45.153 b3 0.88605 -0.036692 0 1.2053 0.89008 0 0 b4 0 b5 0.010271 0 -0.081478 8.0732 -0.0022841 0 0 -0.072652 0 0 2.4123 b7 0 b0 -0.0039728 0 0.086062 0 b9 0.00010203 0.097306 -0.00046965 -5.2719 bl0 -0.015669 -0.0034634 0.026569 -0.011056 0.000072615 0.023661 bll bl2 0 -0.56776 b13 -0.00087860 -0.0018218 b14 0.0021903 0.013389 bl.5 0.00019494 0 b16 -0.00047444 0 b11 0 11.613 bl8 0.00012722 -0.00041070 -0.014843 0.037740 bl9 correlation coeff probability no. of exptl points
0.9674
0.9863 1.0000 184
1.ow
184
0.9987 1.0000 184
0.9990 1.0000 184
'The meaning of the bi coefficients depends upon the equation type and is reflected in the general equation.
I
1
s
e; g0.5
a02
Q05
at
0.2
Copper c o n c e n t r a t i o n in r a f f i n a t e , g.dm-3
0.5
Figure 7. Critical volume ratio of the aqueous to organic phase in a multistage countercurrent process (c0H#or = 0 g dm-3, co,dme = 10%; (0)oxime I; (A)oxime 11; curve 1,cocuz+ = 5 g dm-3; curve 2, cocuz+= 10 g dm-3; curve 3, coCu2+ = 25 g dm-3).
pecially when the aqueous solution contains sulfuric acid. Lower numbers of theoretical stages are obtained when 2-hydroxy-5-nonylbenzaldehyde oxime is used as the extractant (Table IV). When the same numbers of extraction stages are used, similar extraction results for copper may be obtained for both considered oximes, but different ratios of the aqueous to the organic phase must be used. The data presented in Table V show the values of this ratio obtained for some typical conditions under which copper extraction is possible in 3 or 5 theoretical extraction stages. Much higher values for the volume ratio of the aqueous to the organic phase, usudy 2-4 times, were obtained for 2-hydroxy-5-nonylbenzophenoneoxime. Thus, when we use 2-hydroxy-5-nonylbenaldehydeoxime, copper extraction can be carried out with smaller scale equipment or larger flows for the aqueous phase. In a multistage countercurrent extraction process the critical volume ratio of the aqueous to the organic phase, corresponding to an infinitely great number of theoretical extraction stages, must be considered. This critical ratio was calculated from the interception point of the extraction isotherm and the operation line. Appropriate models for the extraction isotherm surfaces were used.
is
0.02
Copper 0.05 c o n c e r t r a t0.i 1o ? r r a f f i na2 a t e , g dtK3
0.5
Figure 8. Critical volume ratio of the aqueous to organic phase in a countercurrent multistage process (coohe = lo%, cocuz+ = 5 g dmT3; (0) oxime I; (A)oxime 11; curve 1, ~ ' ~ =8 00g dm-3; ~ curve 2, coHflO4 = 10 g dm-3; curve 3, ~ ~ H =~20s god m ~ 3.
I:
- 1
20
- 2
I
0.02
1
1
Q05 0.1 a2 Copper c o n c e n t r a t i o n in raffinate. g dmd
1
0.5
Figure 9. Critical volume ratio of the aqueous to organic phase in a countercurrent multistage process (cooxime= lo%, cocuz+ = 5 g dm-3, C'H~SO~.= 0 g dm-3; (0) oxime I; (A)oxime 11; curve 1, cocuz+o%= 0 g dm- , curve 2, C ' ~ , , Z + = ~ ~ 0.5 g dm-3).
The influence of the considered parameters upon the value of the critical ratio is shown in Figures 7-9. They show that the critical volume ratio of the aqueous to or-
Ind. Eng.
248
Chem. Process Des. Dev., Vol.
24, No. 2, 1985
Table 11. Regression Coefficients of the Derived Models for Copper Extraction by 2-Hydroxy-5-nonylbenozphenoneOxime regression equation type coeffO 1 2 3 4 -0.8809 0.099641 -0.10795 0.61670
-0.1405 -0.056086 0.37601 -0.096701 0.43729 0 0 0.037089 -0.011014
0 0.0029563 -0.0041377
0 -0.0012323 0.0015508 -0.016966
-1.231 1.4679 0.98340 0.15339 -0.0075421 0.024225 0.0016236 0 -0.035253
0
0.3642 0 0.50090 0.96106 0.17711 1.3030 0.023005 0 0 -0.062656
0
-0.0056288
-0.0090373
0
0
-0.019136 0.015821 0.00059473 0 0 -0.22925
-0.0088034 -0.0011954 0.0029713 0.00026341 0.0018678 0 0.0018272 -0.013555
correlation coeff probability no. of exptl points a
0 0 -0.0072376
0.9799 1.0000 151
0.9630 1.0000 151
0.9992 1.0000 151
0.9993 1.0000 151
The meaning of the bi coefficients depends upon the equation type and is reflected in the general equation.
Table 111. Comparison of the Extraction Properties of 2-Hydroxy-5-nonylbenzaldehydeOxime and 2-Hydroxy-6-nonylbenzophenoneOxime c*,~:', AC*~=, c*,;, mol of mol of mol of co,Cme, c * . ~ , coH2so, Cu2+/mol Cu2+/mol Cu2+/mol % P dm-3 e dm$ of oxime of oxime of oxime
0.5
5
30
0 10 20
0.39 0.25 0.22
0.21 0.03 0.01
50
0.06
0
0.47 0.43 0.41 0.36 0.33 0.21 0.10 0.46 0.45 0.42
0.00 0.40
10 20 50 15
15
0
0.5
20 50 0 20 50
30
I
0.10 0.22 0.21 0.06 0.07 0.11 0.20 0.26 0.20 0.19 0.10 0.11 0.26 0.36
0.32 0.21 0.10 0.13 0.02
0.00 0.35 0.19 0.06
1
Figure 10. Extraction rates for 2-hydroxy-5-nonylbenzaldehyde oxime and 2-hydroxy-5-nonylbenzophenone oxime.
ganic phase decreases significantly with the increase of copper concentration in the initial aqueous solution or with the decrease of the initial oxime concentration in the organic phase. The decrease of the critical volume ratio is also caused by an increased concentration of sulfuric acid;
Table IV. Number of Extraction Stages i n a Simple Multistage Process (Copper Concentration i n the Raffinate = 0.05 g dm-3) no. of ..^1 extr v VI C'oximer COH~SO, c0cu2+, ratio, stages in % I I1 edm-' admg dm3/dm3 5
0
5
5
5
5
5
5
10
15
0
5
15
0
10
15
0
25
15
10
5
15
10
10
15
10
25
0.7 1.0 2.0 1.0 2.0 1.0 2.0 2.0 5.0 2.0 5.0 0.5 1.0 2.0 5.0 2.0 5.0 0.5 1.0
2 2 3 2 3 3 6 2 3 2 6 2 3 2 3
3 6 2 3
3 4 8 6 10 10 >14 3 6 6 13 8 >14 5 9 9 >14 >14 >14
the influence of this parameter is especially strong when I1 is used as the extractant. The copper concentration in the raffiiate and the copper content in the recycled organic phase have only a small influence. When the organic phase contains 0.5 g of Cu2+dm-3 the values of the critical ratio decrease by about 0.1, 0.05, 0.02, and 0.01 for copper concentrations in initial aqueous solutions of 5, 10,25, and 50 g dm-3, respectively. Much higher values of the critical volume ratio, usually 2-4 times, were obtained for 2-hydroxy-5-nonylbenzaldehyde oxime. Therefore under conditions typical for I copper extraction by means of I1 is impossible or an unrealistic number of extraction stages is needed (Table VI). However, when we use a lower ratio of the aqueous to organic phase, extraction is possible by means of I1 in 2-3 theoretical stages. Using I as the extractant, extraction proceeds more quickly (Figure 10). For both oximes, the extraction rate
Ind. Eng. Chem. Process Des. Dev., Vol. 24, No. 2, 1985
249
Table V. Volume Ratio of the Aqueous to Organic Phase in a Simple Multistage Process (Copper Concentration in the Raffinate 0.05 g dm-’) I, vol ratio for 11, vol ratio for n = 3, n = 5, n = 3, n = 5, Cooxime, % g dm-3 cocUz+,g dm-3 m3/m3 m3/m3 m3/m3 m3/m3 5 0 5 2.0 4.0 0.7 1.3 10 1.0 1.5 0.45 0.65 0.3 0.55 10 5 1.7 2.5 0.15 10 0.7 1.3 0.1 5 3.2 7.0 10 0 0.85 1.5 2.0 3.5 10 0.9 0.65 0.22 3.1 6.5 5 0.55 10 1.4 3.1 10 0.50 0.20 5.0 8.5 4.2 2.0 5 15 0 2.8 4.0 10 1.0 1.7 5.0 3.2 5 1.3 10 2.0 2.0 3.2 10 0.5 0.85 Table VI. Number of Extraction Stages in a Countercurrent Process (Copper Concentration in the Raffinate = 0.5 g dm”, c O c U * + O m = Copper Concentration in the Initial Oxime Solution) no. of vol ratio, extr stages in Cooxime, % c o ~ z s g~ dm+’ ,, c0cu*+,g dm-3 coCU2+org, g dm-3 dm3/dm3 I I1 0 0.99 3 no 5 0 5 0.29 1 2 5 0 5 0.5 3 no 0.88 0.17 1 2 0.90 5 10 5 0 3 no 1 4 0.19 0.5 0.79 3 no 5 10 no 5 20 0 0.81 3 0.17 no 1 no 5 20 0.70 0.5 3 2.74 no 15 0 0 3 2 0.89 1 2.63 0.5 3 no 15 0 5 1 2 0.78 1.36 15 0 10 0 3 no 1 2 0.46 1.31 3 no 15 0 10 0.5 0.40 1 2 1.28 0 3 no 15 10 10 0.42 1 5 1.20 0 15 20 10 3 no 0.30 1 >14 ‘no = extraction was impossible.
decreases with the increase of sulfuric acid concentration, but more strongly when I1 is used. Thus,with the increase of the amount of sulfuric acid added to the aqueous phase the extraction rate, under experimental conditions, decreases from about 200 X g of Cu2+m-2 s-l to about 50 X g of Cu2+m-2 s-l for I and from 70 X 10” g of g of Cu2+m-2 s-l for 11. Cu2+m-2 s-l to 4 x 10-~ The obtained results prove the superiority of “pure” isolated fraction of 2-hydroxy-5-nonylbenaldehydeoxime, which is observed to have a better location of the extraction isotherms and a higher extraction rate. Due to this, using 2-hydroxy-5-nonylbenzaldehydeoxime copper extraction can be carried out with smaller scale extraction equipment or with a greater flow of the aqueous phase. Under comparable extraction conditions a smaller number of extraction stages is needed when 2-hydroxy-5-nonylbenzaldehyde is used. However, the extraction strength is not the only factor which influences the design and development of the industrial process. susceptibility to stripping is another important factor. As our results show, due to the smaller influence of sulfuric acid concentration upon copper extraction by 2-hydroxy-5-nonylbenaldehydeoxime, higher levels of sulfuric acid must be used to strip copper from organic solutions. These high concentrations are not
practical on a commercial scale. As a result, the extraction properties of I are modified in the industrial products with an nonylphenol or aliphatic alcohol to decrease its extraction strength and to increase its susceptibility to stripping. The kinetic behavior of I1 is also modified by the addition of some accelerating compounds. Thus, the properties of the commercial products, which are more complex mixtures containing specially added components, are different from those determined for isolated pure active substances. Therefore, the results given and discussed here cannot be automatically adapted for copper extraction processes carried out by means of commercial extractants. Acknowledgment Acknowledgment is kindly given to Mr. John Thomas for his assistance in the proof-reading of this paper for publication. Registry No.
I, 50849-47-3;11,37339-32-5; copper, 7440-50-8.
Literature Cited Forrest, C.; Hughes, M. A. Hydrometallurgy 1975a, 1 , 25. Forrest, C.; Hughes, M. A. Hy&omefalwgy 1975b, 1 , 139. Goszczyiiski, S.; Szymanowski, J.; Borowiak-Resterna, J. J . Chem. Tech. Blofechnol. 1981, 3 1 , 333. Hughes, M. A*.; Anderson, S.; Forrest, C. Int. J . Miner. Process. 1975, 2 , 267. Jeszka. P. Ph.D. Thesis Technical University of Poznafi, Poznaii, 1982.
250
Ind. Eng. Chem. Process Des. Dev. 1985, 24, 250-255
Robinson, C. G.; Paynter, J. C. Proc. ISEG' 77, SOC.Chem. Ing., London 1971, f 7 , 1416.
RusiAska-Roszak. D. Ph.D. Thesis, Technical University of PoznaA, PoznaA, 1981
Stgpikk-Bioiakiewicz, D.; Szymanowski, J. J. Chem. Techno/. Biotechnol.
Szymanowski, J.; AtamaAczuk, B. H Y & O ~ ~ ~ I I " ~ ~1982, Y 9 , 29. Szymanowski, J.; Blasrczak, J. Chem. Stosow. 1982, 26, 99. Whewell, __.. R. J.; Hughes, M. A.: Hanson. C. J . Inorg. Nucl. Chem. 1975, 37, 2303.
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Received for reuiew April 7, 1983 Accepted April 19, 1984
1983, 27, 249.
Use of Gasoline To Extract Ethanol from Aqueous Solution for Producing Gasohol Fu-Ming Lee' and Robert H. Pshl Phillips Research Center, Phllips Petroleum Company, Bartlesville. Oklahoma 74004
The purpose of this study was to explore the technical feasibility of using gasoline to extract ethanol from aqueous solution for producing gasohol directly. Gasohol is a mixture of 10 vol % ethanol, derived from agricultural products, and 90 vol % unleaded gasoline. Our experimental results from both a simulated &stage countercurrent extraction scheme and a bench-scale continuous extraction column show that gasohol can be produced by extracting ethanol from a 90 wt % ethanol aqueous solution. The extractions were conducted at temperatures from ambient up to 108 O F , and four difterent unleaded gasoline bases were successfully used as the solvents. These results were qualitatively predicted from our theoretical calculations based on the phase diagrams using two different types of gasolines as the extractive sotvents. Various amounts of water will be extracted along with ethanol, depending upon the aromatics content in the gasoline. I n a continuous extraction column, the gasohol extracted by highly aromatic gasoline (33 vol % aromatics) could contain up to 0.7 wt % water. Even a minor amount of water in gasohol will create a phase separation in colder cllmates. Both molecular sieve adsorption and chemical treatment can effectively remove the minor amount of water from the product gasohol. However, the economics of these treatments need to be investigated.
Introduction Gasohol is a mixture of 10 vol % ethanol, derived from agricultural products, and 90 vol % unleaded gasoline. It is one of the more controversial topics of the current energy debate, because some people argue that too much energy is required to process grain into anhydrous ethanol (Chambers et al., 1979; Scheller and Mohr, 1977). For example, the distillation steps alone may consume a little more energy than the fuel value of the product ethanol. Researchers at various institutes are currently working on new technologies to minimize the energy required to separate ethanol from water solutions. One of the novel techniques is to use cellulose or cornstarch to absorb some of the water, so that the energy used in recovering anhydrous ethanol from fermentation broths can be cut to about 10% of the ethanol fuel value (Ladisch and Dyck, 1979; Hartline, 1979). Other new methods include gas chromatography, membrane technology, supercritical extraction using C02 as the solvent, and adsorption using zeolites (molecular sieves). Although there is little doubt that these less conventional separation techniques may prove more energy efficient in the long run, improved conventional distillation, extractive distillation, or liquid-liquid extraction is still the technology of choice for the immediate future. Regarding the liquid-liquid extraction method, we felt that it might be possible to use gasoline to extract ethanol from an ethanol-water mixture. The expectation was that the extract stream would contain 10 vol % or more ethanol and could be used as gasohol. Although some researchers were quite critical of this idea, Leeper and Wanket (1982) o i 9 6 - 4 3 0 5 m i i i i24-0250$01 .5am
at Purdue University recently published their proposed scheme for separation of ethanol from water by extraction with gasoline and presented experimental data on the extraction step. The first part of our investigation was to explore the technical feasibility of the process concept of using gasoline as the selective solvent for ethanol extraction. The second part was to study the process variables of a continuous extractive process for producing gasohol in a bench-scale packed column. In this study, however, no attempt was made to evaluate the economics of this extraction process. Theoretical Calculations As a guide for our experimental work, graphical calculations were carried out on the ethanol-water-gasoline diagrams for a countercurrent multistage extraction process. The phase diagrams of two different gasolines were given by Nakaguchi and Keller (1979). The simplified composition analyses of the gasolines are given in Table I. If we use gasoline F (containing 38 vol % aromatics) at 68 O F , an extract with 8.7 wt % ethanol can theoretically be produced from 80 wt % ethanol-water mixture with higher than 99% ethanol recovery. The solvent to feed ratio was determined to be 8.8. The raffinate contained 98.5 wt % water, 1.5 wt % ethanol, and essentially no gasoline. The number of theoretical stages could not be determined since only a part of the tie (equilibrium) lines were shown in the phase diagram. By use of the available information from the phase diagram, the graphical design procedures were carried out and are presented in Figures 1 and 2. 0 1985 American Chemical Society
