基于聚电解质修饰二维纳米材料层层自组装纳滤膜的高盐印染废水资源化基础研究

Among dyeing wastewater treatment techniques, the conventional biological and chemical processes are unable to remove dye and inorganic salts at the same time, which results in the accumulation of salts in the treated water, and the dye removal efficiency and water recovery rate are affected by the increasing concentration of salts. In this study, to realize the wastewater reclamation and reuse, nanofiltration(NF) integrated electrodialysis (ED) process were proposed to treat high saline azo dye wastewater, NF is used to selectively remove azo dye whereas ED fractionate and concentrate salts from NF effluent, and the synergistic effect of NF-ED will be evaluated. Meanwhile, to enhance the salt/azo dye separation factor, polyelectrolyte functionalized MoS2 (or WS2) layer-by-layer NF membranes are going to be developed. The laminar channels in between the MoS2 (or WS2) sheets are tailored by the configuration of polyelectrolytes under different preparation conditions. The correlation of physicochemical properties and configuration of multilayers with transport of ions and water as well as the performance of separation will be investigated, besides, the membrane fouling propensity and membrane antifouling mechanisms will be studied. The fulfillment of this study is expected to pave the way for two-dimensional nanomaterial application in nanofiltration membrane fabrication, meanwhile, provide a theoretical foundation for NF-ED process in wastewater recycling and reuse.

目前的生物法和化学法等印染废水末端处理工艺不能脱除有机污染物同时高效脱盐，造成出水无机盐积累，限制了污染物去除效率及水回用率提高。本项目拟采用高盐度偶氮染料废水为研究对象，一方面构建纳滤-电渗析耦合工艺，通过纳滤膜选择筛分脱除偶氮染料分子，电渗析膜选择透过分离富集NaCl，研究耦合工艺协同作用机制，以实现染料废水深度处理并资源化的目的。另一方面，为强化纳滤膜对盐/染料分离因子，本项目拟开发聚电解质膜包覆MoS2（或WS2）层层自组装纳滤膜，根据聚电解质构象可控性调节MoS2（或WS2）层间孔道尺寸，探究分离层物化性质及构象改变对膜传质特征及分离性能影响机制，探索膜分离层污染机理及抗污染机制，获得高选择性、抗污染、高化学稳定性的纳滤膜。该课题的成功实施，有望促进二维材料在纳滤膜制备中的应用，为纳滤-电渗析耦合工艺用于废水资源化综合利用提供理论依据。

目前的生物法和化学法等印染废水末端处理工艺不能脱除有机污染物同时高效脱盐，造成出水无机盐积累，限制了污染物去除效率及水回用率提高。纳滤技术是筛分染料和典型无机盐助染剂NaCl行之有效的工艺。该研究将二维纳米片WS2引入层层自组装(LbL)纳滤膜分离层，结合各种表征手段探究分离层物化性质对传质特征及分离性能的影响机制。WS2的引入增强了LbL膜的亲水性和表面负电性，并与聚丙烯酸中羧基形成配位键，在改善层层自组装纳滤膜在高盐溶液中稳定性的同时，增强了染料/NaCl分离效率。WS2纳米片的堆叠及其光滑无含氧基团的表面促进了水分子在多层的聚电解质中的传输。2 wt% WS2掺杂LbL膜展现出最高纯水通量，并在分离刚果红/NaCl和活性黑5/NaCl的二元溶液时，分离系数高达7238和9036。此外，掺入WS2的膜在高盐溶液中可稳定运行，并对典型有机污染物显示出更好的抗污染性能。. 金属有机框架（MOFs）是一类具有微孔结构、大比表面积及功能性的新兴的晶体纳米材料，该研究将MOFs衍生磁性纳米笼型材料mNCs作为吸附剂去除废水中的典型的染料及抗生素，从吸附动力学、等温线、热力学角度分析吸附剂对有机污染物的吸附行为及作用机制；实验结果表明吸附过程均可采用准二级动力学方程及Langmuir模型进行描述。对亚甲基蓝和盐酸四环素的吸附过程是自发且吸热的。此外，循环使用5次后，吸附剂吸附容量仍> 80 %；.MOFs衍生纳米笼经十八胺修饰后制备的ODA-h-ZIFs引入聚哌嗪酰胺分离层中制备薄层纳米复合膜（TFN膜），探究ODA-h-ZIFs掺杂量对于TFN膜PA分离层交联度变化规律及对截盐性能的影响规律。ODA-h-ZIFs的掺杂虽降低了PA层交联度，但特殊的笼型结构及大的比表面积为水分子提供了额外的传输路径，又由于其负电性，赋予TFN膜更高水通量的同时，也助力TFN膜克服了传统TFC膜水通量与截留率之间的“trade-off”效应。.