【作者】 唐首锋；

【导师】 李杰；

【作者基本信息】 大连理工大学 ， 环境工程， 2013， 博士

【摘要】 活性炭吸附法是治理低浓度、高毒性、难生化降解有机废水,以及突发性环境污染事故形成废水的有效方法。常规活性炭吸附只是将污染物从水相转移到固相,未达到彻底去除污染物的目的,而如果将未经处理的活性炭废弃,将导致环境二次污染,还会造成资源浪费,因此研发高效的活性炭再生方法一直为国内外学者所关注。介质阻挡放电(DBD)能够产生降解有机物的活性物质,如羟基自由基、活性氧、臭氧等,成为当今环境污染治理技术研发的热点。本文针对DBD等离子体处理活性炭机理、反应器结构设计与供电方法、运行方法等关键技术问题,以酚类物质为模型污染物,研究DBD降解活性炭吸附有机物和再生活性炭的效果及其影响因素、活性物质在活性炭颗粒间产生和传播过程,探讨DBD协同TiO2催化提高活性炭处理效果的可行性,提出DBD活性炭再生反应器放大方法,研制处理活性炭量为1kg和10kg的DBD放大反应器,考察放大反应器的运行性能。主要研究工作与结果如下：(1)采用双介质结构DBD反应器,研究了DBD降解活性炭吸附双酚A(BPA)及再生活性炭的可行性,考察了电气参数和载气参数对活性炭吸附BPA的降解及活性炭再生特性的影响。发现：增加放电电压、电源频率和空气流量均有利于BPA的降解；三次连续吸附/DBD再生后,活性炭再生率仍接近80%。与高频交流电源供电相比,采用双极性脉冲电源的BPA降解能量效率高10倍,三次连续再生的活性炭再生率分别高5%、6%和11%。(2)研究了DBD对活性炭上活性物质H2O2和·OH产生规律的影响,分析其传质机理,探索活性炭上苯酚的降解行为,探讨DBD降解活性炭吸附有机物及再生活性炭机理。结果发现：DBD作用下,活性炭上H2O2和-OH生成量随放电电压和空气流量的增加而增加,在活性炭含水率为10～20%范围内,H2O2和·OH生成量随含水率增大而增加；双极性脉冲电源能够有效促进活性物质生成,其H2O2和·OH生成量比高频交流电源的高出20%,并且H2O2和·OH的生成能量效率高出6倍。苯酚OH-官能团的邻位和对位易受攻击而发生邻、对位的取代和加成反应生成邻苯二酚、对苯二酚和苯醌这三种主要中间产物；随着放电电压、空气流量和活性炭含水率的增大,苯酚及其TOC去除率随之增大,三种主要中间产物的最大生成时间提前,最终生成浓度减小,苯酚及TOC去除率分别可达93%和50%。(3)开展了DBD协同TiO2催化降解活性炭上苯酚/再生活性炭的研究。采用浸渍干燥法制备了负载TiO2的活性炭(TiO2-GAC),运用X射线衍射仪、电子扫描电镜、傅立叶变换红外光谱、氮吸附等温线及Boehm滴定对负载TiO2前后、吸附苯酚前后、放电处理前后的活性炭进行表征,探索了TiO2催化对活性炭上苯酚降解、矿化、中间产物浓度变化、活性物质·OH和H2O2生成和活性炭再生特性的影响,探讨了DBD协同TiO2催化降解苯酚/再生活性炭的机理。发现负载TiO2后,其催化作用可使活性炭上产生更多的·OH和H2O2,有效促进活性炭上苯酚的降解、矿化及活性炭的再生：TiO2-GAC上·OH和H2O2的生成量分别提高了24%和28%,且苯酚降解率提高了19%,TOC去除率提高了9%,降解能量效率提高了27%,再生效率提高了14%。(4)提出了DBD再生活性炭放大反应器的设计方法和反应器气源的布气方法,研制了处理活性炭1kg和10kg级DBD放大反应器,进行了放大反应器的运行实验。应用1kg级DBD放大反应器再生1.2kg的废活性炭,通过优化电气参数、载气参数和活性炭参数考察了活性炭上苯酚的降解、矿化特性及活性炭再生效果：活性炭再生率和苯酚降解率分别达到了94%和70%；开展了10kg级DBD放大反应器与双极性脉冲电源的匹配研究,应用其再生13kg吸附真实工业废水的活性炭,两次再生循环后再生率分别为74%和66%,实验结果为下一步的工业应用研究奠定了基础。更多还原

【Abstract】 Activated carbon (AC) adsorption is an effective method in the treatment of the low concentration, high toxic and refractory wastewater, and wastewater from emergency environmental accident. The conventional use of AC adsorption alone is limited in that the contaminants are not degraded but instead transferred to the solid phase from liquid phase. To reuse the spent AC, an appropriate regeneration step is necessary to meet the environmental and economical requirements, which has motivated researchers to develop new methods for regeneration of spent activated carbon. The dielectric barrier discharge (DBD) plasma can generate varies of active species, such as hydroxyl radicals, ozone and active oxygen etc., which is a hotspot in environmental pollution control.Aiming at clarifying regeneration mechanism of AC by DBD plasma, design of the reactor, power supply for the reactor and operation of the reactor, we combined the granular activated carbon (GAC) adsorption and DBD, to decompose the phenolic pollutants adsorbed on GAC and regenerate GAC simultaneously. The main work was conducted in terms of the feasibility of pollutants degradation and GAC regeneration by DBD, active species generation and transference during DBD process, and DBD regeneration of GAC by the addition of a titanium dioxide catalyst. A methodology of scaling up the DBD plasma reactor was proposed, and the up-scaled reactors of1kg and10kg GAC were used to regenerate GAC. The detailed work and the summarized results are as follows:1. A DBD plasma reactor driven by bipolar pulsed power was used to regenerate the GAC adsorbed Bisphenol A (BPA), The effects of pulse voltage, pulse repetitive rate, treatment time and air flow rate were investigated. Experimental results indicated that increasing pulse voltage, pulse repetitive rate, and air flow rate could enhance the degradation of BPA. The energy efficiency of BPA degradation using bipolar pulse power was10times higher than that using high frequency power. After three cycles of adsorption/DBD regeneration, the regeneration efficiency (RE) remains close to80%, and the result of RE using bipolar pulse power was higher than that using high frequency power with5%,6%and11%, respectively.2. The generation of active species during bipolar pulse DBD process.·OH and H2O2were quantitative determined by chemical method at different operational parameters by bipolar pulse power and high frequency power. The results showed that the production of·OH and H2O2on GAC powered by bipolar pulse power was10-20%higher than those powered by high frequency power, and the energy efficiency of active species using bipolar pulse power was6times higher than that using high frequency power. The phenol degradation and mineralization and its main products generation on GAC characteristics were investigated, which was powered by bipolar pulse power. The experimental results indicated that increasing pulse voltage, air flow rate and water content of GAC could enhance the removal and TOC of phenol, and the generation time of three main byproducts was earlier, and their final production decreased, the phenol and TOC removal achieved93%and50%at optimized conditions, respectively.3. We have investigated a catalytic method to promote the regeneration of the saturated GAC by the addition of TiO2catalyst under the DBD. The TiO2-GAC hybrid was fabricated by an impregnation-desiccation method and characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, nitrogen adsorption isotherms and Boehm titration to investigate its adsorption and catalytic characteristics before and after the adsorption and DBD processes. In addition, the phenol degradation and GAC regeneration characteristics were investigated, TiO2-GAC exhibited remarkable catalytic activity, increasing the phenol degradation by19%, TOC removal by9%, energy efficiency by27%, and RE by14%relative to GAC in DBD treatment.4. A methodology of scaling up the DBD reactor for GAC regeneration was proposed, and the up-scaled reactors of1kg and10kg were developed. The1kg DBD reactor driven by bipolar pulse power was built to treat exhausted GAC. The feasibility of GAC regeneration using the up-scaled reactor was systematical assessed by monitoring the GAC regeneration RE and phenol degradation on GAC at different electrical, supply gas and GAC parameters. Under the optimized conditions RE and the phenol degradation reached94%and70%, respectively. After four adsorption-regeneration cycles, RE decreased from94%to55%. The10kg DBD reactor was used to regenerate GAC exhausted by real wastewater, and the results showed that after two cycles, RE decreased from74%to66%. The results have laid the groundwork for further industrial progress.更多还原