解离型PPCPs在壳聚糖荷电纳滤膜中的去除机制

Pharmaceutical and personal care products (PPCPs) are widespread in the surface water,groundwater and the secondary effluent of wastewater treatment plant. These emerging trace contaminants have become the potential menace to current drinking-water sources. This project aims to develop positively charged nanofiltration membrane technology for the removal of ionized PPCPs. The hemiacetal structure of glycosidic bonds of chitosan molecule make it possess good adsorbability, film forming and permeability, so a quaternary ammonium salt grafting modification of chitosan was conducted to the active groups with lone pair electrons. The water-insoluble quaternary ammonium salt chitosan positively charged nanofiltration membrane was prepared using coating-crosslinking- in situ phase inversion method, and it will be used to separate the trace ionized PPCPs from bodies of water. The membrane microstructures were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM). The separation properties and stable performance were measured by streaming potential, the pore size distribution, water flux, rejection, water uptake and mechanical strength. Additional，the positively charged nanofiltration membrane was used to further study the screening and electrostatic separation mechanism for removal of ionic PPCPs based on the influencing factors of PPCPs molecular structure, charged characteristic and its dissolubility, which will be provide new ideas and theoretical supports for advanced treatments of these emerging trace contaminants-PPCPs.

药物和个人护理用品 (PPCPs) 这类普遍存在于地表（下）水及污水处理厂二级出水的新型痕量污染物，已成为当前饮用水源水安全的潜在威胁。本项目旨在发展荷正电纳滤膜技术用于解离型PPCPs的分离去除。壳聚糖分子中糖苷键的半缩醛结构使其具有良好的吸附性、成膜性和通透性，拟对其具有的活性孤对电子基团进行季铵化接枝改性，采用涂覆-交联-原位相转化法制备非水溶性的季铵化壳聚糖荷正电纳滤膜，并将其用于分离环境水体中的痕量-微量解离型PPCPs。通过扫描电镜、透射电镜和原子力显微镜手段对膜微观结构形态进行观测，通过对膜流动电位，孔径分布、水通量，溶胀度，力学强度和截留率等参数测定研究膜的分离性能和稳定性能，在考察PPCPs分子结构、荷电性、水中溶解性有机物等影响因素的基础上，阐明壳聚糖荷正电纳滤膜对解离型PPCPs的筛分和静电分离机制，为PPCPs这类新型痕量污染物的深度处理提供新的思路和理论支撑。

药物和个人护理用品（PPCPs）这类普遍存在于地表（下）水及污水处理厂二级出水的新型微量污染物，已成为当前饮用水源水安全的潜在威胁。本项目旨在发展荷正电纳滤膜技术用于解离型PPCPs的分离去除。研究以壳聚糖(CTS) 接枝共聚物2-羟丙基-3-三甲基氯化铵壳聚糖(HTCC)为活性层，建立了HTCC/CA/TiO2杂化膜、HTCC/PES荷正电复合纳滤膜及HTCC-Ag/PES抗菌膜的制备方法；同时建立了水中常见的几种荷正电PPCPs的SPE-HPLC分析方法，评价了方法的准确性和精密度，并将其应用于痕量微量解离型PPCPs的分析；探讨了壳聚糖荷电纳滤膜对解离型PPCPs的分离机制，基于位阻效应和静电排斥理论，深入研究了荷正电纳滤膜分离去除水中特征阳离子型PPCPs的机制。. 结果表明，以2,3-环氧丙基三甲基氯化铵(GTMAC)对壳聚糖(CTS)进行季铵化改性，获得不同取代度的2-羟丙基-3-三甲基氯化铵壳聚糖(HTCC)，并以HTCC和醋酸纤维素(CA)共混作为有机基体，通过溶液共混法制备出有机-无机HTCC/CA/TiO2杂化膜；以CTS的接枝共聚物HTCC为表面活性层，聚醚砜超滤膜(PES)为支撑层，环氧氯丙烷(ECH)为交联剂，采用涂敷交联法和涂敷交联协同光化学还原法分别制备出荷正电的HTCC/PES复合纳滤膜和HTCC-Ag/PES抗菌膜。以上方法已申请专利3项。同时，本研究建立了固相萃取-高效液相色谱法（SPE-HPLC）检测水体中的卡马西平、布洛芬、马来酸氨氯地平和阿替洛尔4种药物及个人护理用品（PPCPs）的分析方法，探讨了HTCC取代度、PPCPs荷电性、离子强度和水体pH对HTCC/PES荷正电纳滤膜去除阿替洛尔、氨氯地平、布洛芬和卡马西平的影响。证明了HTCC/PES荷正电纳滤膜去除荷正电性PPCPs阿替洛尔和氨氯地平主要依赖静电排斥作用；Ca2+对于膜表面双电层的削弱作用比Na+更为强烈；离子强度和水体pH对于HTCC/PES荷正电纳滤膜去除荷正电性PPCPs阿替洛尔和氨氯地平的影响趋势基本相似，对于荷负电性PPCPs布洛芬的去除影响较为复杂，而对于中性药品卡马西平并无明显影响。