Extraction of Cr(VI) in Aqueous Solution with L35-Ammonium Sulfate Aqueous Two-phase System
WANG Hao-cong CHEN Fang-fang WANG Hai-yang LI Meng-han HUANG Hui-ming ZHANG Yong-qiang
College of Environmental and Chemical Engineering, Yanshan University College of Environmental and Chemical Engineering, Yanshan University College of Environmental and Chemical Engineering, Yanshan University College of Environmental and Chemical Engineering, Yanshan University College of Environmental and Chemical Engineering, Yanshan University College of Environmental and Chemical Engineering, Yanshan University
Abstract：Cr(VI) in simulated waste water was extracted with L35-(NH4)2SO4-H2O aqueous two-phase system, the effects of initial concentration of Cr(VI), pH value of aqueous phase, amount of charge modifier (1812), extraction time, phase-separating time, amount of L35 and ammonium sulfate, and extraction temperature on the extraction rate of Cr(VI) were studied. The results show that the extraction rate and distribution coefficient of Cr(VI) are mainly affected by pH value of aqueous phase, and increase obviously after addition of charge modifier, and decrease gradually with increasing of extracting temperature. The extraction rate of Cr(VI) increases gradually and then is close to steady value with increasing of concentrations of L35 and ammonium sulfate. The equilibrium times of extraction and phase-separating are all short. Under the optimum conditions, the extraction rate of Cr(VI) reaches 92% and the distribution coefficient of Cr(VI) is above 15 in single stage extraction. The theoretical calculation and experimental results are basically consistent, and the concentration of Cr(VI) decreases from 2 g/L to below 0.5 mg/L, which meets the national discharge standards of waste water. The extraction mechanism analysis indicates that two modes can be deduced, one is in the form of solubility mode into L35 micellar interior by its relatively hydrophobic property, and another in the form of electrostatic attraction into L35 micellar interior by FT-IR and DLS. The stripping rate of Cr(VI) achieves above 99.5%(w) by single stage stripping with NaOH aqueous solution.
2015, Vol. 15 
