Solvent stable nanoporous poly (ethylene-co-vinyl alcohol) barrier membranes for liquid-liquid extraction of lithium from a salt lake brine
Solvent stable nanoporous poly (ethylene-co-vinyl alcohol) barrier membranes for liquid-liquid extraction of lithium from a salt lake brine
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DOI：
10.1016/j.memsci.2016.08.027
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发表时间：
2016-12
影响因子：
9.5
通讯作者：
Xing Lixin;Jianfeng Song;Zhansheng Li;Jindun Liu;Tao Huang;Pengjia Dou;Ying Chen;Xuemei Li;T. He
中科院分区：
文献类型：
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作者：
Xing Lixin;Jianfeng Song;Zhansheng Li;Jindun Liu;Tao Huang;Pengjia Dou;Ying Chen;Xuemei Li;T. He
采用离子渗透、溶剂稳定的屏障膜可避免膜萃取过程中有机萃取物的损失。溶剂稳定材料的研制一直是液液膜萃取的关键问题。以嵌段共聚物聚乙烯-共乙烯醇（EVAL）为原料，采用浸渍沉淀法制备了一种新型的抗溶剂膜，作为膜提锂的屏障。研究了EVAL浓度对铸膜液粘度和膜性能的影响。通过扫描电镜（SEM）、吸水性、纯水通量、机械强度和Li+扩散通量对膜进行了表征。在低于聚合物结晶温度的温度下进行膜相分离，以保证合适的膜结构。在0.1 mol/L的Li+进料浓度下，由30 wt% EVAL制备的膜的Li+通量为2.7×10−8mol cm−2s−1。采用磷酸三丁酯(TBP)/煤油萃取剂，膜萃取中锂通量与进料锂浓度呈线性关系。此外，长期稳定性试验表明，EVAL材料在1037 h左右具有稳定的锂萃取通量。这些结果表明EVAL材料是一种很有前途的液液萃取锂稳定屏障膜。
Loss of organic extraction in membrane extraction process could be avoided by using an ion permeable, solvent stable barrier membrane. Development of solvent stable materials has been a key issue for liquid-liquid membrane extraction. A new type of solvent resistant membrane, prepared from block copolymer poly (ethylene-co-vinyl alcohol) (EVAL) via immersion precipitation, is introduced as the barrier in membrane extraction of lithium from a real salt lake brine. The influence of EVAL concentration on the casting solution viscosity and the membrane properties was investigated. The membranes were characterized by scanning electron microscopy (SEM), water uptake, pure water flux, mechanical strength, and Li+diffusion flux. Membrane phase separation was conducted at a temperature below the crystallization temperature of the polymer to ensure suitable membrane structure. The membrane prepared from 30 wt% EVAL content showed a Li+flux of 2.7×10−8mol cm−2s−1at a Li+feed concentration of 0.1 mol/L in a diffusion test. Using a tributylphosphate (TBP)/kerosene extractant, the lithium flux in a membrane extraction showed a linear relationship with the feed lithium concentration. In addition, long term stability tests showed a stable lithium extraction flux for about 1037 h. These results indicate that EVAL material is a promising stabilizing barrier membrane in liquid-liquid extraction of lithium.