酸性萃取剂负载Cr (Ⅲ)的碱反萃取研究

Experiment on Back-extraction of Cr(Ⅲ) in Acidic Extractant by Alkali

摘要: 针对酸性萃取剂负载的Cr(Ⅲ)高酸难反萃、反萃不完全的问题，根据不同酸度条件下Cr(Ⅲ)与OH^-络合形态的差别，进行了碱作为反萃取剂从负载Cr(Ⅲ)的酸性萃取剂中回收铬实验研究.结果表明，碱反萃取P204负载有机相时的优化条件为0.5 mol/L氢氧化钠、相比为1、常温、反萃取反应为10 min，经四级逆流反萃取，反萃取率达到98.3 %；碱反萃取P507负载有机相时的优化条件为2 mol/L氢氧化钠、相比为1、常温、反萃取反应为20 min，经四级逆流反萃取，反萃取率达到98.8 %.

Abstract: Back-extraction of chromium from acidic extractant is difficult, whose recovery is generally low. This paper studies the back -extraction of Cr (Ⅲ) in acidic extractant by alkali based on the different complexing speciation of Cr (Ⅲ) and OH^- in various acidic solution. The optimized conditions for P204 and P507 extractants are as follows: O/A is 1, sodium hydroxide concentrations are 0.5 mol/L and 2 mol/L, separately; back-extraction times are 10 and 20 min, and the recoveries reach 98.3 % and 98.8% after 4 steps back -extraction at room temperature.