正渗透杂化膜脱除水中重金属的性能

Performance of Forward Osmosis Hybrid Membrane to Remove Heavy Metals From Water

以水滑石为添加剂,采用共混法制备水滑石与聚砜支撑层,利用界面聚合技术制备得到聚酰胺/聚砜-水滑石层板(PA/PSF-LDH)杂化膜.以新型PA/PSF-LDH正渗透杂化膜与NaCl汲取液构建正渗透体系,以3种重金属离子Cr(Ⅵ)、Pb2+与Cd2+水溶液为目标物,考查原料液pH值、原料液质量浓度及流速、汲取液浓度及流速对正渗透金属离子水通量和截留率的影响.结果表明:在pH=2~5,金属离子质量浓度为20 mg·L^(-1),汲取液浓度为1.0 mol·L^(-1),原料液与汲取液流速分别189.15和359.27 mL·min-1的条件下,该体系水通量较商品化HTI膜提高2.0~3.0倍,达到15~63 L·m^(-2)·h^(-1);体系对3种金属离子的截留率均大于94.5%.随溶液pH值的升高,Cr(Ⅵ)、Pb^(2+)与Cd^(2+)的水通量与截留率的变化规律与3种金属离子的空间位阻与静电效应有关.

With layered double hydroxide(LDH)nano sheets as additive,LDH nano sheets support layer were prepared by blending method.Polyamide/polysulfone hydrotalcite laminate(PA/PSF-LDH)hybrid membrane was prepared by inter facial polymerization technology.A new PA/PSF-LDH and 1.0 mol·L^(-1) NaCl solution were used to construct a forward osmosis system.Three kinds of heavy metal ions Cr(Ⅵ),Pb2+and Cd2+aqueous solutions were used as targets.The effects of solution pH,feed concentration and flow rate,extract concentration and flow rate on ion separation performance and water flux were investigated.The results showed that the water flux of the system was 2.0~3.0 times higher than that of HTI membrane under the conditions of pH 2.0~5.0,the mass concentration of metal ions 20 mg·L^(-1),the concentration of extract solution 1.0 mol·L^(-1)NaCl,flow rates of feed solution and extract solution 189.15 and 359.27 mL·min-1,respectively,reaching 15~63 L·m^(-2)·h^(-1);the rejection rate of the system to three kinds of metal ions>94.5%.With the increase of solution pH,the water flux and rejection rate of Cr(Ⅵ),Pb^(2+)and Cd^(2+)are related to thesteric hindrance and electrostatic effect.