三辛胺萃取草酸的机理

EXTRACTION MECHANISM OF OXALIC ACID BY TOA

选择草酸稀溶液为萃取对象 ,采用三辛胺 (TOA)为络合剂 ,正辛醇为稀释剂 ,开展了TOA萃取草酸的机理研究 .以红外谱图为分析手段 ,通过测定络合剂及被萃溶质的浓度对萃合物组成的影响 ,得到其萃合物以 1∶1和 1∶2 (酸 :碱 )两种形式存在于有机相中 ;并通过萃取平衡实验 ,获得了TOA萃取草酸的平衡特性 ,进一步验证了萃合物组成 .以此为基础建立了草酸与TOA两种萃合比情况下的数学模型 ,拟合求得了K11及K12 ,其中 1∶2萃合物的化学萃取平衡常数远远小于

Water-oxalic acid-TOA (octanol) is used as the experimental system, and TOA, octanol as complexing agent, diluent respectively. The extraction mechanism of oxalic acid by TOA and the influence of the concentration of TOA (S0) and solute on extraction equilibrium are studied. The structure of complex in organic phase is measured by infrared spectroscopy, and it is obtained that there are two types of complexates in organic phase, 1:1 and 1:2 (acid:TOA). The distribution coefficient increases with S0. Loading of complexing agent shows an increasing tendency with S0 and the equilibrium concentration of acid in aqueous phase (x). The saturated loading is achieved at higher x and increases with S0. The mathematical model with two type complexes is proposed. The model parameters, K11 and K12 are obtained by fitting the experimental data of extraction equilibrium, and K11 is much larger than K12.