改性正渗透膜去除水中全氟化合物研究

Removal of Perfluorinated Compounds from Water by Modified Forward Osmosis Membrane

如何有效控制和去除水环境中的全氟类化合物(PFCs)是目前环境保护科学研究领域的热点问题之一。正渗透膜分离技术因其独特的优势,在去除水中全氟化合物领域表现出巨大潜力。研究了自主研制的氯化银表面改性正渗透膜对水中典型全氟类化合物(PFCs,即全氟辛酸(PFOA)和全氟辛烷磺酸(PFOS))的去除性能,分析了膜表面性能与PFCs去除效果的关系,探讨了水中共存物质对改性正渗透膜去除PFOS性能的影响。研究结果显示:改性膜的表面亲水性能和表面负电荷数量均得到提升,同时改性膜表面具有更高的水通量和PFCs截留率;一定范围内随着改性膜矿化度的增加,膜的水通量与对PFCs的截留率逐渐增大,但氯化银过量沉积会降低正渗透膜对PFCs的截留性能;矿化改性中交替浸泡4次制备出的正渗透膜具有最佳的全氟化合物去除效果,对PFOA和PFOS的去除率分别为96.2%和95.7%,同时也具有最大的水通量22.5 L/(m^(2)·h);正渗透膜与PFCs的相互作用方式主要为疏水作用和静电相互作用;改性正渗透膜主要通过降低与PFCs的疏水作用以及增强与PFCs的静电排斥作用,从而实现对PFCs的高效截留;水中不同物质共存会对正渗透膜与PFCs的之间疏水作用及静电排斥作用产生影响,从而影响膜对PFCs的截留性能。

Research on controlling and removing perfluorinated compounds(PFCs)in water has become a prominent topic in environmental protection science.Forward osmosis(FO)membrane separation technology demonstrates significant potential in removing PFCs from water due to its unique advantages.This study focuses on the removal performance of two typical PFCs,namely PFOA and PFOS,in water using a self-developed composite thin layer membrane called silver chloride surface mineralized polyamide(TFC)FO membrane.The relationship between membrane surface performance and PFCs removal efficiency is analyzed.The influence of coexisting substances in water on the removal performance is also examined.Results reveal that the modified membrane exhibits enhanced surface hydrophilicity and increased negative charge.Both hydrophilicity and negative charge on the membrane surface increase with a higher degree of mineralization.The modified membrane also demonstrates improved forward osmosis performance,characterized by higher water flux and greater PFCs rejection.These improvements are observed as the mineralization degree increases within a certain range.However,excessive deposition of silver chloride may decrease the membrane’s rejection of PFCs.The TFC FO membrane,prepared by alternately soaking for four times during mineralization modification,demonstrates the most effective removal of PFCs,with removal rates of 96.2%for PFOA and 95.7%for PFOS.Furthermore,it exhibits the highest water flux at 22.5 L/m^(2)·h.The interaction between the FO membrane and PFCs is primarily governed by hydrophobic and electrostatic forces.The modified FO membrane effectively rejects PFCs by reducing the hydrophobic effect and enhancing the electrostatic repulsion between the membrane and PFCs.Yet,the presence of different substances in water can influence the hydrophobic and electrostatic interaction between the FO membrane and PFCs,ultimately affecting the rejection performance of PFCs.