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Abstract: Selectively extracting tungsten to purify sodium molybdate solution was studied using primary amine N1923, including various conditions, such as equilibrium pH values, concentrations of extractant in organic phase and metals in feed solution, contact time of extraction and stripping, types of acidic solutions added, temperature of extraction and the dosage of stripping agent. Graphical method using McCabe-Thiele diagram and counter-current extraction simulation (CCES) were used to determine the required stages of deep removal of tungsten. The results show that appropriate concentrations of tungsten and molybdenum in feed solution have great influence on the difficult degree of the separation between the two metals. Organic phase including 0.051M of N1923 modified by LK-N21X diluted in kerosene can extract 92.7% of tungsten in sulfuric acid solution at equilibrium pH value of 7.07 for 10min in one-stage extraction at 15.5°C, and the separation factor reaches 329 under those optimum conditions. A two-stage CCES removes 99.83% of tungsten and obtains the purified sodium molybdate solution where W/Mo (mass ratio) reaches 2.9×10−5. Stripping can be accomplished by NaOH solution completely and quickly. Furthermore, the extraction and stripping reactions of tungsten and molybdenum in equilibrium were proposed. [Copyright &y& Elsevier]

In this report the extraction of V(V) and Cr(VI) from a synthetic feed solution and real leaching solution of the chromium-bearing vanadium slag (V–Cr slag) using primary amine LK-N21 was studied. Detailed fundamental research work was conducted to investigate the primary amine extracting V(V) and Cr(VI). The mechanism and the difference between the two metals of extraction were studied and the experimental results were compared with previously published data. The optimum technological parameters for the separation of two metals were determined including: pH value in feed solution, phase ratio, mixing time, as well as others. The results showed that primary amine LK-N21 can extract V(V) selectively by hydrogen bonding association. Cr(VI) competed V(V) to combine with the primary amine, and the concentration of Cr(VI) decided the percentage extraction of V(V) and Cr(VI). Primary amine LK-N21 extracted more than 90% of V(V) which resulted in over 90% of Cr(VI) left in the leaching solution of the V–Cr slag in the optimal conditions. Based on the results of experiments, V(V) and Cr(VI) can be separated with a high degree of selectivity. [ABSTRACT FROM AUTHOR]

Abstract: After leaching of the waste printed circuit boards with HNO3, the leach liquor bearing 5.13kg/m3 Cu, 0.63kg/m3 Fe (III), 0.36kg/m3 Zn, 1.31kg/m3 Ni and 34.59kg/m3 nitrate was obtained. Development of a solvent extraction flow chart for the separation and recovery of Cu, Ni and Fe (III) using LK-C2 as the extractant from nitrate solution was investigated. Extraction of the metals depends on the equilibrium pH in the aqueous phase and the increases with rise in equilibrium pH. Based on the difference in their extraction behavior as a function of equilibrium pH in the aqueous phase, it was possible to separate and recover copper, nickel and iron. Copper is extracted using 15% LK-C2 in kerosene at two stages at initial pH of 2.60 and the extraction percentage is 99.98%. Copper is stripped by 2.00mol/L H2SO4 at three stages and the stripping percentage is 97.51%. Fe and Ni are extracted using 20% LK-C2 in kerosene at two stages at initial pH of 3.00 and 10.00, and the extraction percentages are 96.14 and 99.35%, respectively. Fe is stripped by 2.00mol/L HCl at two stages and the stripping rate is 99.18%. Ni is stripped by 3.00mol/L H2SO4 at three stages and the stripping percentage is 98.32%. [Copyright &y& Elsevier]

Abstract: Three-liquid-phase systems containing polyethylene glycol with different molecular weight were explored to investigate the partitioning behavior of simulated wastewater-containing isomers of p-Nitrophenol (p-NP) and o-Nitrophenol (o-NP). The distribution behaviors of p-NP and o-NP with different parameters in three-liquid-phase system were investigated. The results showed a great effect of the solution pH, extractant type on the partition coefficient of the two isomers. In the three-liquid-phase systems, the satisfying separation results were obtained with hexane as extractant. At pH=4.00, about 85% o-NP and 90% p-NP partitioned into the top organic phase and middle polymer-rich phase, respectively. The separation factor decreased sharply with the increase of the solution pH from 6.5 to 8.5. After once back extraction with 10wt.% sodium hydroxide, high recovery percentage of o-NP was obtained from the top phase. The removal efficiency of phenolic compounds in the polymer-rich phase could reach 95% when the middle phase was extracted with butyl acetate (BA) twice. p-NP could be recovered when the BA phase was back extracted with 10wt.% sodium hydroxide aqueous solution. [Copyright &y& Elsevier]