ELM法提取磷酸中La3+的相界面反应-传质机理研究

在以(D2EHPA+TOPO)/ROSO3H/液体石蜡/煤油为膜相,HCl为内相,磷酸中La3+为外相的乳化液膜(ELM)体系中研究了不同相比A/O、膜相D2EHPA(H2A2)、TOPO、ROSO3H浓度、料液相H3PO4、H2PO4和H+浓度和内相HCl浓度对总分配比DT的影响。实验结果表明:随A/O的增加,DT显著下降;随膜相H2A2、TOPO、ROSO3H浓度的增加,DT先增加后基本不变;但料液相H3PO4和H+浓度的增加使DT降低,DT随H2PO4浓度增加而升高;DT随內相HCl浓度的增加而升高。通过斜率法对ELM各组分H2A2、TOPO、ROSO3H、H2PO4、H3PO4、H+的logc-logDT的线性拟合直线的斜率确定了其参与的摩尔数,得到了该ELM体系的相界面反应-传质机理,并计算出萃取、反萃反应平衡常数k1、k2分别为107.7237、104.8025。

Study on the Phase Interfacial Reactions-Transport Mechanism in the Process of Leaching La3+ from Phosphoric Acid by Emulsion Liquid Membrane

An emulsion liquid membrane(ELM) system,in which(D2EHPA+TOPO)/ROSO3H/liquid paraffin/kerosene acts as membrane,HCl as stripping phase,and La3+ in H3PO4 as feed phase,was used to study the effects of the phase ratio(A/O =7,6,5,4,3,2),concentration of membrane compositions(H2A2,TOPO,ROSO3H),and concentration of feed phases(H2PO4,H3PO4,H+) on the total distribution ratio DT.The results show that the DT decreases with the increase of A/O ratio,and the high concentrations of H2A2,TOPO,ROSO3H in membrane,H2PO4 in feed solution and HCl in stripping phase are beneficial to the increase of DT,while increasing the concentrations of H3PO4,and H+ in feed phase will make DT decrease.The molar number of each components(H2A2,TOPO,ROSO3H,H2PO4,H3PO4,H+) taking part in feed-membrane-stripping phase reactions and the interfacial reaction-mass transport mechanism in this ELM system were determined by the slope of the logc-log DT curves,and the reaction equilibrium constant values k1 and k2 of 107.7237 and 104.8025 in feed-membrane leaching and membrane-stripping phase reactions were obtained,respectively by calculation.