Abstract:

The novel extraction gel membrane (EGM) prepared from polydimethylsiloxane-tetraethyl orthosilicatedi(2-ethylhexyl) phosphoric acid (PDMS-TEOS-D2EHPA) was applied in extraction of Ni ion. The basic physical and chemical properties of EGM were analyzed. The influences of the concentrations and flow rates of the two aqueous phases, aqueous phase temperature, module packing density, the feed circulation mode on the operation stability and Ni(Ⅱ) mass transfer flux of the EGM were explored. The results from 9 h experiments show that the highest extraction efficiency and the stability of EGM at the aqueous phase temperature of 22℃ were achieved in the condition of feed phase flow rate of 1900 ml·min^-1, stripping flow rate of 93 ml·min^-1, module packing density of 14% and the feed phase circulating through shell side, respectively. Finally, the operation stability of the EGM process were investigated and compared to conventional supported liquid membrane (SLM) process based on data from 60 h continuous running experiments. The results show that the conventional SLM suffered 100% flux loss within only 35 h, while the flux attenuation of EGM was merely 27.1% at the end of 60 h. Simultaneously, a 6.8 times promotion in initial flux compared to the traditional SLM was obtained. The results show dual advantages in improving both mass transfer efficiency and long-term operation stability of the EGM.

Key words: extraction, gels, membranes, stability, mass transfer flux

摘要：

利用交联反应在PVDF超滤膜表面创新性的构建含有萃取剂磷酸二异辛酯的聚二甲基硅氧烷-正硅酸乙酯体系萃取凝胶膜（EGM）；并对其基本物理化学性质进行了表征。研究了EGM过程中料液相循环方式、料液相及反萃相浓度与流量、水相温度、组件装填密度等工艺条件对镍离子传质性能及EGM运行稳定性的影响规律。9 h实验结果表明在室温水相温度为22℃条件下，当工艺运行条件为料液相流量1900 ml·min^-1、反萃相流量93 ml·min^-1、组件装填密度14%、料液相循环于壳程时，EGM对镍离子的萃取性能及稳定性达到最佳值。在此基础上，对该系统进行了60 h稳定性实验，并与传统支撑液膜进行了对比。结果显示传统支撑液膜持续运行35 h后通量降为0，衰减率为100%；而EGM持续运行60 h后通量衰减率仅为27.1%；同时EGM初始传质通量相比于传统支撑液膜提高了6.8倍，体现了EGM过程在传质通量大幅提升和长期运行稳定性显著增进方面具有双重优势。

关键词: 萃取, 凝胶, 膜, 稳定性, 传质通量