Table I. Optimal pH Ranges for Greater t h a n 95% Precipitation
w
Precipitation reagent, 0.05M
m
:, :x.0
Element
a
Aluminum Cobalt Copper Iron Lead Manganese Nickel Vanadium Zinc
..
0
,-
&E. U 0 U
PVO
6-9 6-9 4-9 4-9 7-9 7-9 4-9 4-5 5-9
111
112
PV0;oxine
PVOIoxine
6-9 7-9 4-9 4-9 7-9 7-9 4-9 4-5 6-9
8-9 7-9 4-9 4-9 7-9 8-9 4-9 4-5 6-9
Nuclear Science Center and the University of Rhode Island Computer Laboratory for their assistance in obtaining and analyzing the experimental data. Figure 11. Percent retention of sodium by 0.05, 0.02, and 0.01M
LITERATURE CITED
PVO after the sample was washed with a potassium solution
tion of total [&-I concentration, PVO/oxine ratio, pH, and time of contact are needed to better understand the mechanism of the precipitate formation. SUMMARY PVO and mixtures of PVO and oxine have been used to precipitate copper, aluminum, vanadium, manganese, lead, cobalt, iron, and nickel from solution. By varying the pH and the reagent concentration, these trace metals may be rapidly removed from salt solutions. ACKNOWLEDGMENT The authors acknowledge Dr. B. M. Vittimberga and Dr. Vijayaraghavan for their helpful comments and suggestions concerning our production of PVO using their original organic synthesis procedure. We also thank the Rhode Island
(1) J. J.Fox, J. Chern. Soc.,97, lll9(1910). (2)H. M. Haendler and T. G. Thompson, J. Mar. Res., 2, 12 (1939). (3)H. R. Fleck and A. M. Ward, Analyst (London), 58, 388 (1933). (4)H. R. Fleck, Ana/yst(London),62, 378 (1937). (5) H. Goto, SOC.Rep. Tohoku,26, 391 (1937). (6)R. L. Mitchell and R. 0.Scott, J. SOC.Chem. lnd., London, 62, 4 (1943). (7)D. M. Smith, Ana/yst(London), 71, 368 (1946). (8)R. L. Mitchell and R. 0.Scott, Analyst(London),66,330(1947). (9)R. L. Mitchell and R. 0.Scott, Spectrochim. Acta, 3, 368 (1947). (10)G.E. Heggen and L. W. Strock, Anal. Chem., 25, 859 (1953). (1 1) J. P. Riley and G. Topping, Anal. Chim. Acta, 44,234 (1969). (12)R. A. A. Muzzareili, Anal. Chim. Acta, 54, 133 (1971). (13)Vijayaraghavan, Ph.D. Thesis, University of Rhode Island, Kingston, R.I., 1968. (14)J. D. Stary, "Solvent Extraction of Metal Chelates", Macmillan, New York, N.Y., 1964.
RECEIVEDfor review April 21, 1975. Accepted July 14, 1975. Work supported in part by the Department of Health, Education, and Welfare, Public Health Service, National Institutes of Health, Grant No. 1 R01 HD 06675.
Kinetics of the Formation of 12-Molybdophosphate in Perchloric, Sulfuric, and Nitric Acid Solutions P. M. Beckwith,' Alexander Scheeline,* and S. R. Crouch3 Department of Chemistry,'MichiganState University, East Lansing, Mich. 48824
The klnetlcs of formation of the 12-molybdophosphateanion (12-MPA) from Mo(V1) and phosphate have been Investlgated In strong acid solutions by stopped-flow methods. Mechanisms are proposed for the reaction in HC104, " 0 3 , and H2S04 solutions whlch involve an lnltlai reaction between a Mo(VI) species and phosphate followed by several polymerlzatlon steps. The rate laws obtalned from the proposed mechanisms are In agreement wlth experimentally determined rate laws. The proposed mechanisms along wlth rate constants and activatlon energles give insight about the 1
Present address, BASF Wyandotte Corp., Wyandotte, Mich.
48192.
Present address, Department of Chemistry, University of Wisconsin, Madison, Wis. 53706. Author to whom requests for reprints should be sent. 1930
influence of the ac.- anion on the formation L. 2. !PA. The results obtalned can be used to choose reagent concentratlons for phosphate analyses uslng 12-MPA procedures.
The reaction of Mo(V1) and phosphate in strong acid solutions (pH
