预富集功能膜/光催化燃料电池（MPFC）高效废水深度处理方法研究

In recent years, China's still face serious wastewater pollution problems though the overall water quality has already slightly improved, for which reason, the new discharging limits of industrial and urban wastewater become more and more stringent recently. The advanced wastewater treatment reasonably become necessary but it was never really sincerely favored by the factories for its high operation cost. Therefore, advanced oxidation processes featured by energy recycling, saving energy, catches more and more concerns while photocatalytic fuel cell (PFC) wastewater treatment become one of the stars for it not only use clean solar energy, which is substantially free, during organic pollutant treatment but also recovery chemical energy from the waste pollutant compounds simultaneous. It was highly efficient and cheap fundamentally. But the real application of PFC for waste water treatment is unfortunately really hard because the wastewater is not an ideal "fuel", which contains relatively low concentration of organic pollutant and therefore its chemical energy density is relatively low , and also not good supporting electrolyte for it usually contain little salt after secondary wastewater treatment. In this application, we proposes a new method of conductive multi-membrane pre-concentration / photocatalytic fuel cell (MPFC) for wastewater treatment in which PFC treats pre-enriched solution, only a small percentage of original waste water, with high concentration of pollutant and high electrolyte concentration, and the property of solution is good for PFC electricity generation and organic degradation. More important, the two methods have synergistic effects. The cathodic product of H2O2 generated in situ in PFC during organic degradation will be recycled to membrane separation step in order to react with the pollutant of membrane fouling there, which is indeed a self-cleaning of membrane. And the electricity generated in PFC, which being applied to conductive and functional multi-layer membrane in order to enhance the separation of ion and small organic molecule via electrostatic repulsion and electro-adsorption. The fouling on membrane will also be degraded via electrochemical oxidation which is essentially another self-cleaning of membrane. These process help to maintain the permeate flux of membrane during long time running. The functional membrane with high efficiency pollutant separation, and adjustable filter, via electric controlling with different apply voltages to change its hydrophilic or hydrophobic property, will be firstly fabricated and studied. Also the high efficiency photocatalytic fuel cell with rotating dish structure for wastewater treatment will be developed and tested hereafter. The synergistic effect of above functional membrane pre-separation and photo-degradation process will be further studied, with the focus on the theoretical model development of fundamentally understanding of its structure-activity relationship of membranes and photocatalytic electrode, the generation electricity from PFC to enhance the separation performance of membrane pretreatment, and the pre-enrichment of pollutant enhancing PFC pollutant reaction rate. It is well believed that the treatment process of synergistic membranes pre-enrichment and PFC treatment is more close to real application of photocatalytic oxidation method for industrial wastewater, which will be indeed a new method corresponding to high efficiency, energy benefit, low cost, and environmental friendly.

近年来，我国水环境质量总体好转，但形势依然严峻，新标准日趋严格。废水深度处理普遍成本高，故以光催化燃料电池为代表的废水深度处理方法因其可利用清洁能源并同步回收污染物中化学能日益受关注，有望成为一种高效经济的废水处理新方法。本项目针对光催化燃料电池实际废水深度处理过程中有机物浓度低、传质效率差、电解质浓度低、电池内阻高的固有问题，提出了导/荷电复合自清洁功能膜预富集/光催化燃料电池废水深度处理（MPFC）的新方法，不但可同时提高膜通量和对污染物的截留、延长膜的再生周期，而且提高了PFC中污染物浓度与电导率以及处理效率。将在研究具有高效污染物分离特性的功能膜及其构效关系，以及高效光催化燃料电池转盘结构的基础上，进一步开展提高功能膜预分离和光降解的协同性以及理论模型的研究，并探讨其在难降解废水污染控制中的效能与规律，为发展一种可针对提标后废水的高效低耗的实用新方法及其相应理论打下坚实基础。

随着我国废水排放标准的提高，废水深度处理的成本也普遍升高。本课题聚焦光/电催化实际废水深度处理过程中有机物浓度低、传质效率差、电解质浓度低、电池内阻高的固有问题，提出了导/荷电复合自清洁功能膜预富集/光电催化燃料电池废水深度处理（MPFC）的新方法，通过导/荷电膜的功能设计，实现污染物的预富集浓缩，使70-90%的废水达标排放或回用，而光催化燃料电池用于处理预富集浓液。一方面，其产电用于导/荷电膜的强化，提高预富集效能，另一方面，光和电产生的H2O2用于污染物降解与膜自清洁，光电催化降解膜富集后的污染物也更加高效，从而达到深度废水高效处理与资源化的目的。经过五年的研究，研制了配位络合、静电喷涂纳滤荷电膜，电增强超滤导电膜、透过式电膜和酶膜等预富集功能膜，对无机盐、小分子有机物、磷等物质均有明显的富集与降解效果，并探究了导/荷电机制及其与膜通量、污染物的截留等污染物分离特性的构效关系；利用光催化燃料电池的电流-电压关系，在全槽维度优化了高电流输出的匹配机制；通过利用三相界面提高传质、光热耦合异质结等策略，阐明了聚酰亚胺聚合物、石墨烯二氧化钛等2e电子选择性的光/电催化剂产H2O2的机制，首次实现红外光催化产H2O2；非贵金属电催化H2O2的产率高达730 mmol∙g-1∙h-1，选择性为75.5%（见报告，待发表）。针对富集浓液中的硝酸盐污染物，探究了电催化降解硝酸盐氮的产物选择性调控、加氢策略，构建了硝酸盐到氮气的高选择性（可达93%）、高氢气利用率的电催化还原方法。通过集成导/荷电功能膜、光催化产物调控、高效电催化等的研究结果，建立了面向实际含盐（包括硝酸盐）难降解废水深度处理与资源化的工艺，并对垃圾渗滤液、印染废水、造纸废水和浓缩盐水四种实际废水进行了研究（其中两种达到中试规模），还搭建了PV光伏产电-光催化转盘教学示范与科普体验装置（共10套）。成果为发展一种可针对提标后废水性质选用预富集膜的组合及高效低耗的实用新方法及其相应理论打下坚实基础。