基于表面复合改性提高阴离子交换膜抗污染性能及机理研究

Improving the antifouling performance of anion exchange membrane (AEM) by surface modification is of great significance to promote the wide application of electrodialysis desalination technology in industrial wastewater and increase the water reuse rate. But at present, there are still some problems in the modified AEM, such as the instability of modified layer, the nonuniformity of the properties and the poor antifouling properties. Based on the study on the fouling property and its formation mechanism of representative organic compounds, such as phenol, quinoline, anthraquinones and the homologues in industrial wastewater, to cause the AEM fouling in electrodialysis, the surface composite modifications of AEM are investigated to improve its antifouling properties of the organic compounds with long carbon chains, benzene rings, heterocyclic or polycyclic, etc. in this project. The influence of different modified components, modification methods, process conditions and their composite modification on the physical and chemical properties and antifouling performance of modified AEMs were systematically studied, to obtain the optimized surface composite modification method of AEM to improve the uniformity, stability and antifouling properties of the modified layer. The interaction of electrostatic, affinity and steric hindrance between the model pollutants and the original AEM or modified AEM, and the adsorption and migration behavior of pollutants at the base membrane/ modified layer - solution interface are study by contrast, to reveal the antifouling mechanism of the modified AEMs to the representative organic compounds. The antifouling performance of the surface composite modified AEMs can be verified by the electrodialysis system of actual industrial wastewater. The surface modification of anion exchange membrane is further optimized to obtain the composite modified AEM with good antifouling performance and stable coating layer, which can provide a basis for the industrial preparation of new antifouling anion exchange membrane.

通过表面改性提高阴离子交换膜的抗污染性能，对促进电渗析脱盐技术广泛应用和提高水回用率意义重大，但目前改性阴膜还存在修饰层不稳定、性质不均匀和抗污染性能不理想等问题。本课题拟基于工业废水中代表性有机物如苯酚、喹啉、蒽醌及同系物等造成电渗析膜污染性质与形成机理研究，探讨通过膜表面复合改性，抑制带长碳链、苯环、杂环或多环有机物对电渗析阴膜的污染。系统研究修饰组分、改性方法、工艺条件及复合修饰等对改性阴膜性质及抗污染性能的影响，探讨提高修饰层稳定性及抗污染性能的阴膜表面复合改性方法；对比研究模型污染物与原始阴膜或改性阴膜间的静电作用、亲和作用和空间位阻等及污染物在基膜/修饰层-溶液界面的吸附迁移行为，揭示改性阴膜对代表性有机物的抗污染机制；通过实际工业废水电渗析验证改性阴膜的抗污染性能及表面改性优化，获得具有抗污染性能良好且修饰层稳定的复合改性阴膜，为新型抗污染阴离子交换膜的工业制备提供依据。

电渗析技术用于工业废水脱盐，由于易发生膜污染而造成脱盐效率下降和影响系统运行稳定性，是电渗析脱盐技术广泛应用的主要限制因素。探讨工业废水电渗析脱盐的膜污染机理及防治技术，对促进工业废水电渗析技术的广泛应用具有重要意义。本项目拟基于电渗析膜污染性质与形成机理研究，探讨通过离子交换膜表面重构和复合改性提高膜抗污染性能展开深入系统研究，为研制新型抗污染膜提供依据。主要研究内容和成果如下：.研究典型带不同长碳链和亲水基团有机物的电渗析膜污染性质和形成机理，表明电渗析膜污染形成与废水中有机物浓度、pH、电流密度等密切相关，且带强极性基团有机物可被电迁移到膜表面附近，当其浓度超过其临界胶束浓度时在膜表面形成污染层，可导致膜脱盐性能恶化及限制离子跨膜迁移；研究发现膜污染程度与膜结构性质密切相关，模型污染物SDS造成阴膜污染污染程度为：均相膜、半均相膜、异相膜的脱盐性能分别下降42.3%、15.3%、9.2%，且基膜结构越致密造成膜污染越严重；对比不同分子结构有机物的膜污染特性，发现十二烷基硫酸钠（SDS）和十二烷基苯磺酸钠（SDBS）都在膜表面上形成致密的污染层，进一步证明带有苯环、长碳链和强极性基团的表面活性剂类物质在膜表面易形成污染层而造成严重的膜污染，且带苯环、杂环类有机物造成阴离子交换膜的污染程度更大。.系统研究带不同功能基团（如-SO3-、-COO-、-OH和-NH2）修饰组分、改性方法（如电沉积、低温等离子体诱导聚合、层层组装、复合修饰、聚多酚-聚多胺共沉积和层层界面结合）和工艺条件（如修饰组分浓度与配比、电流密度、pH、修饰时间、修饰层数）对改性膜抗污染性能的影响，制备出多种抗污染性能良好的复合改性膜；基于改性膜抗污染机制及失效原理研究，获得提高改性膜抗污染稳定性的方法。本项目相关研究成果可为新型抗污染膜研制和膜污染综合防治提供理论依据，并促进电膜脱盐技术在工业废水处理中的广泛应用。