金属纳米线/碳纳米管电极强化脉冲电晕放电降解有机物体系构建及机理研究

Recently, plasma discharge was wildly used in wastewater treatment. The high instantaneous voltage and strong instantaneous current was benefit to degrade the pollutants. However, there were also several problems such as the safety and energy utilization efficiency. Corona discharge is the stable discharge style, how to reduce the discharge inception voltage of corona discharge and enhance the treatment efficiency, to achieve the safety treatment is also need to discuss. We plan to prepare metal (Au、Ag、Pt et al.) nanowires/carbon nanotubes electrodes, and set up an enhanced corona discharge system. One of the typical Persistent Organic Pollutants (POPs), Polychlorodiphenyls (PCBs), was selected as the aim pollutant. The carbon nanotubes was used as based adsorption material and metal nanowires produced tip weak discharge to enhance corona discharge and achieve the treatment of pollutants with safety, high efficiency and low energy consumption. It is mainly to prepare the electrode and improve the enhanced performances, and study the effect on the discharge inception voltage; then, study the degradation of PCBs in the enhanced system and confirm the safety validity; finally, investigate the enhanced mechanism and search the main reaction step. It is helpful to supply an efficient treatment method and equipment for industrial POPs pollutants degradation.

目前，等离子体技术被广泛应用于水处理，其瞬时电压高、瞬时电流强，有利于污染物降解，但也存在安全隐患以及能量利用率不高等问题。电晕放电是最稳定的放电形式，如何降低起晕电压，提高电晕放电处理效率，实现安全处理仍需探讨。本申请通过制备金属（Au、Ag、Pt等）纳米线/碳纳米管电极，构建金属纳米线/碳纳米管电极强化电晕放电体系，以持久性有机污染物（POPs）中典型的多氯联苯（PCBs）作为目标污染物，利用碳纳米管作为吸附支撑材料以及金属纳米线尖端微放电特性，强化脉冲电晕放电，实现有机物安全、高效、低耗处理。重点开展电极材料制备及强化性能调控，考察电极对起晕电压的影响；开展强化体系对多氯联苯降解规律研究，明确强化体系的安全有效性；探明金属纳米线/碳纳米管/电晕放电体系强化机制，明确主要反应步骤，为难降解POPs污染物工业化处理提供有效的处理方法和处理装置。

近年来，等离子体催化技术一直被认为是一种高效降解有机污染物的高级氧化技术，但液相放电技术存在电压高，电极损耗较大等问题。通过改变微观纳米结构的电极材料产生纳米效应，促进电晕放电的产生，能提高电晕放电过程中污染物降解。由于纳米线相比于纳米颗粒更具有尖端微放电效果，本项目致力于开发新型的金属纳米线/碳纳米管/海绵电极，主要研发了Ag、CuO@Cu、CuO@Cu/Ag、ZnCo2O4、CoFe2O4/碳纳米管/海绵电极和TiO2负载型催化电极，通过电极形貌调控、结构分析、性能表征，评价金属纳米线电极和TiO2负载型催化电极具有较好的催化效果和较高的稳定性。其次，采用板-板式气液放电反应器实现电晕放电，以苯酚作为目标污染物进行电极性能分析，研究发现纳米线/海绵电极能降低电晕放电起晕电压，提高电晕输入能量，促进臭氧产生，通过5次重复实验反应60 min仍能达到100%去除效果。考察电源影响因素、电极材料、多氯联苯在金属纳米线/碳纳米管/脉冲电晕等离子体强化体系中的降解规律，实验发现复合纳米线CuO@Cu/Ag、ZnCo2O4、CoFe2O4/碳纳米管/海绵电极均能提高污染物降解效果，同样发现CuO@Cu/Ag/碳纳米管/海绵电极能促进2,4,5-三氯联苯降解，去除率达到65%。最后，通过加入羟基自由基、超氧自由基、活性电子捕获剂，考察活性物质对污染物降解的贡献率，主要以羟基自由基反应为主。本研究构建了金属纳米线/碳纳米管强化脉冲电晕放电降解水中POPs污染物新体系，通过海绵基底的强吸附性，水溶液被吸附在电极表面和内部，在复合电极表面和内部进行电晕放电，大大提高了传统电晕放电的范围，达到预期处理效果，可进行污染物有效处理。