环烷酸类载体液膜体系对金属离子传输机理的研究

本文先在大块液膜体系中以环已烷甲酸为载体,通过正交设计,系统地研究了各种因素对希土离子输送作用的影响规律。比较了相同条件下RE~(3+)(希土)同Na~+,NH_4~+、Ca~(2+)和Fe~(3+)等离子的输送作用。发现在适当条件下,无皂化的羧酸载体对RE~(3+)离子具有良好的输送效果,同时证实,羧酸输送RE~(3+)离子是通过三个H~+离子与一个RE~(3+)离子的交换,而当载体皂化时,皂化的载体直接与接收相H~+离子发生交换,从而降低了羧酸对RE~(3+)离子的输送和分离效果。 在大块液膜研究的基础上,建立了一个以无皂化的环烷酸为载体的乳状液膜体系,从模拟离子矿的硫酸铵浸出液中萃取希土,通过正交试验确定了最优的液膜萃取条件,希土萃取率达96％以上,富集度30～40倍。

TRANSPORT MECHANISMS OF SOME CATIONS ACROSS LIQUID MEMBRANE BY NAPHTHENIC ACID

The naphthenic acids are useful extractants. Their extraction for metal ions have been widely studied in liquid-liquid extract system. In thispaper, naphthenic acids were used as carrier for the transport of rare earth ions in liquid membrane systems. Effects of various factors on the transport of rare earth ions in liquid membrane were investigated systematically by orthogonal test, an emulsion membrane system with non-saponified carrier was constituted and the optimized condition for extracting rare earth were investigated by orthogonal test.(1)transport of rare earth in bulk membraneIn this part, cydohexyl carboxylic acid was used as carrier, the transport of sare earth ions were compared with that of Na⁺ NH₄⁺, Ca²⁺ and Fe³⁺ ions at the same condition in bulk membrane.In general, the carboxylic acids as extractants in liquid-liquid extraction system should be saponified in order to obtain a good extraction for metal ions. However, it was found in present investigation that, by the non-saponified carboxylic acid as carrier, a good transport of rare earth ions can be achieved under suitable condition. And it was verified that the carboxylic acids transport rare earth ions through the transfer of three hydric ions to one rare earth ion, RE3+. In the case of using saponified carboxylic acid as carrier, a direct exchange between the saponified carriers and the hydrogen ions in receiving phase takes place, resulting in a poor transport and poor separation of rare earth from other cations(saponifying ions). So, when use carboxylic acid as carrier, the saponifying of carrier is inoperative or inappropriate in liquid membrane systems.The differences between liquid membrane transport and liquid-liquid extraction processes are drscussed in this part.(2)emulsion membrane extraction of rare earth with non-saponified naphthenic acid as carrierAccording to the bulk membrane investigation, an emulsion membrane system with the non-saponified merchant naphthenic acid as carrier was established and the optimized condition for extracting rare earth from ammonium sulfate solutions was determined by orthogonal test. The extraction percentage for rare earth is about 96% and concentration of rare earth ions is raised about 30-40 time.