硫代磷酸/伯胺N_(1923)协同萃取锌和镉的机理

Mechanism of Extracting Zinc and Cadmium with Thiophosphoric Acid-Primary Amine N1923

有机硫代磷酸/伯胺N_(1923)协同萃取锌、镉的萃取率随pH的变化较为反常,可能因伯胺N_(1923)与硫酸作用进而聚力反向胶束。实验表明,如以(N_(1923))_n·H_2SO_4表示反向胶束的实验式,N_(1923)与H_2SO_4比值n多为3左右,可能与空间效应相关。萃取机理为: M^(2+)_(a)^(2+)+2BHA_(o)+(2/n)SO_4^(2-)_(a)=MA_(2(o))+(2/n)(B_n·H_2SO_4)_(o)+2(1-2/n)H^+_(a),n=3,4,5。

In the extraction of zinc and cadmium with di-(2-ethlhexyl)-dithiophosphoric acid(D2EHDTPA)-primary amine N1923 or di-(2-ethlhexyl)-monothiophosphoric acid(D2EHMTPA)-primary amine N1923, the dependence of the percentage extraction on pH was comparatively abnormal, which was probably caused by primary amine N1923 reacting with H2SO4 and aggregating into reversed micelle. If the empirical formula of the N1923-H2SO4 adduct is expressed by (N1923)n·H2SO74, the ratio n between N1923 and H2SO4 was about 3 in most cases of our research, which might be related to stereoscopic effects. The extraction mechanism was proved as follows: M2+(a)+2BHA(o) + (2/n)SO42-(a) = MA2(o)+ (2/n)(Bn-H2SO4)(o) + 2(1-2/n)H+(a), n=3,4, 5.