Establishment of transport channels with carriers for water in reverse osmosis membrane by incorporating hydrotalcite into the polyamide layer

Abstract

Thin film nanocomposite (TFN) reverse osmosis (RO) membranes were prepared by incorporating hydrotalcite (HT) in polyamide layer during interfacial polymerization process using two methods: (1) dispersing HT in aqueous solution directly; (2) preparing layered double oxide (LDO) via calcination of HT and then dispersing the obtained LDO in aqueous solution to reconstruct HT. The results demonstrated that TFN RO membranes exhibited higher water flux compared with the pristine RO membrane, which could be mainly attributed to water channels constructed by HT as well as the enhancement of hydrophilicity and the increase of relative surface area. In addition, TFN RO membranes prepared using LDO showed higher water flux than those prepared using HT, which is contributed to the uniform distribution of water channels in polyamide layer resulting from the process of calcination and reconstruction reaction. Compared with pristine RO membrane, water flux of TFN RO membranes prepared with 0.075 wt% HT and those prepared with 0.050 wt% LDO was enhanced by 19.1% and 22.8% without sacrificing the salt rejection.