Dual-layer polybenzimidazole/polyethersulfone (PBI/PES) nanofiltration (NF) hollow fiber membranes for heavy metals removal from wastewater
Dual-layer polybenzimidazole/polyethersulfone (PBI/PES) nanofiltration (NF) hollow fiber membranes for heavy metals removal from wastewater
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DOI：
10.1016/j.memsci.2014.01.001
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发表时间：
2014-04
影响因子：
9.5
通讯作者：
Wen-Ping Zhu;Shi‐Peng Sun;Jie Gao;Fengjiang Fu;T. Chung
中科院分区：
文献类型：
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作者：
Wen-Ping Zhu;Shi‐Peng Sun;Jie Gao;Fengjiang Fu;T. Chung
为有效去除模拟废水中的重金属离子(Cd~(2+)、Cr2 O~(2+)、−~(2+)和Pb2+)，设计并表征了一种高效双层纳滤膜。以聚苯并咪唑(PBI)和聚醚砜(PES)/聚乙烯吡咯烷酮(PVP)为原料，采用干喷湿相转化法制备了聚苯并咪唑(PBI)和聚醚砜(PES)/聚乙烯吡咯烷酮(PVP)共混膜。PBI因其优异的耐化学性和独特的电荷特性而被选为外选择层，而PES/PVP共混物则因其合理的成本、优异的可纺性、亲水性、良好的力学性能和易于形成多孔膜而被选为支撑层。此外，PVP与PBI和PES都是相容的。新开发的双层纳滤膜对各种盐类具有较好的截留率。膜对镁离子和镉离子的截留率分别达到98%和95%。通过改变溶液的pH值，对Cr2O72-−和Pb2+的截留率分别达到98%和93%以上。实验结果表明，高截留率是由于以下因素：(1)平均有效孔径为0.32 nm、截留分子量(MWCO)为249 Da的窄孔径分布膜；(2)由于两性PBI的电荷性质而增强了Donnan排斥效应；(3)由于PBI的亲水性，其表面对重金属的吸附能力较低。
We have designed and characterized a high performance dual-layer nanofiltration (NF) hollow fiber membrane for effective removal of heavy metal ions (Cd 2+, Cr 2 O 7 2− and Pb 2+) from model wastewater. The membrane was fabricated by the simultaneous co-extrusion of polybenzimidazole (PBI) and polyethersulfone (PES)/polyvinylpyrrolidone (PVP) dopes through a triple-orifice spinneret using a dry-jet wet phase inversion process. PBI was chosen as the outer selective layer because of its superior chemical resistance and unique charge characteristics, while a PES/PVP blend was employed as the support layer because its reasonable cost, superior spinnerablity, hydrophilic nature, good mechanical properties and easy formation of porous membranes. In addition, PVP is miscible with both PBI and PES. The newly developed dual-layer NF membrane has superior rejections to various salts. The rejections of the membrane to Mg 2+ and Cd 2+ achieve 98% and 95%, respectively. By changing the pH of the solution, the rejections to Cr 2 O 7 2− and Pb 2+ can reach more than 98% and 93%, correspondingly. Experimental results indicate that the high rejections are owing to the following factors:(1) a narrow pore size distribution membrane with a mean effective pore radius of 0.32 nm and a molecular weight cut off (MWCO) of 249 Da;(2) an enhanced Donnan exclusion effect due to the amphoteric PBI charge property;(3) low adsorptions of heavy metals on the PBI surface due to its hydrophilic nature.