【作者】 屈广周；

【导师】 李杰；

【作者基本信息】 大连理工大学 ， 环境工程， 2010， 博士

【摘要】 活性炭(AC)吸附与介质阻挡放电(DBD)等离子体技术分别作为传统与新兴水处理技术,一直受到各国学者的关注。随着人们对这两种技术的深入研究发现：AC吸附只是将污染物质从一相转移到另一相,本质上并没有达到彻底去除污染物的目的,且AC需要再生,而目前的AC再生方法又存在许多不足;DBD等离子体技术虽然能够有效的降解水体中的有机污染物,但是存在能耗高的问题,从而限制了其工业化的应用。针对两种技术存在的问题,扩展DBD等离子体技术在废水处理中的广泛应用,本论文将AC吸附与DBD等离子体技术相结合,用于水中难降解有机污染物的去除,同时实现了两个过程：一是DBD等离子体对AC上吸附的有机物的降解；二是DBD等离子体对AC的再生。主要开展的工作及研究结果如下：1.设计了一种AC填充DBD等离子体反应器。通过对影响反应器放电特性的因素(如介质材料、介质厚度、电极间距以及AC等)的考察和优化,获得较佳的反应器结构参数。考察了DBD等离子体对新AC的形貌、微晶结构和吸附能力的影响,结果表明：DBD等离子体对AC表面具有刻蚀作用,但不会显著影响AC的微晶结构,不同载气下产生的等离子体对AC吸附性能的影响是不同的。2.研究了DBD等离子体对吸附在AC上五氯酚(PCP)的降解作用,考察了放电电压、电源频率、载气种类和AC处理量等参数对AC上PCP降解效果的影响。结果表明：增加放电电压和电源频率可以提高PCP的降解率；O2作为载气的处理效果好于N2和空气作为载气的处理效果；气体流量和AC的处理量存在着一个最优值；增加AC的含水率,有利于AC上PCP的降解。在考察AC上PCP降解规律的同时,对DBD等离子体再生AC的可行性进行了研究,结果显示：DBD等离子体可以用于“废AC”的再生,并且具有较高的再生效率。3.采用热重(TG)、能量色散X射线光谱(EDX)、X射线光电能谱(XPS)傅立叶变换红外光谱(FT-IR)、气相色谱-质谱联用(GC/MS)等分析了DBD等离子体对AC上PCP的降解产物,并探讨了降解途径,从而推断其降解机理为DBD产生的高能电子和·OH、O3等活性物种使PCP脱氯脱羟基,生成氯代酚(如TetraCP、TriCP、DiCP等)和氯代苯(如四氯苯、三氯苯等)等中间产物,并在·OH、O3等活性物种的进一步作用下使苯环开环最终降解成酸、醛或酮等小分子的有机物以及H2O和CO2等。4.考察了AC吸附/DBD等离子体再生循环次数对吸附偶氮染料酸性橙Ⅱ(A07)AC再生的影响。通过测定不同吸附/再生循环后AC对AO7的吸附量和吸附速率分析此方法的再生效率,结果显示：DBD等离子体可以有效地恢复AC的吸附能力,经过多次连续吸附/再生循环后,AC仍保持较高的吸附性能。通过分析DBD等离子体再生对活性炭表面物理和化学特性及对AO7吸附能力的影响发现：AC孔隙结构和表面化学含氧官能团的变化以及AC上的残留物导致了该方法的再生效率随着再生次数的增加而下降。能耗分析显示：DBD等离子体再生AC技术是一种经济可行的再生工艺,具有广泛的工业化应用前景。更多还原

【Abstract】 As traditional and emerging water treatment methods, respectively, activated carbon (AC) adsorption and dielectric barrier discharge (DBD) plasma technologies attract the extensive attention of scholars from different countries. Further studies on these two technologies find that AC adsorption simply transfers pollutants from one phase to another phase and does not remove the pollutants in essence, and the spent AC also needs to be regenerated for reuse. However, current AC regeneration methods exist many disadvantages. Although DBD plasma can degrade pollutants in wastewater effectively, high energy consumption limits its industrial applications. To solve these problems, and extend industrial applications of DBD plasma technology in wastewater treatment, an integrated AC adsorption and DBD plasma process is adopted for the treatment of refractory organic pollutants in this paper. Two procedures simultaneously are achieved:One is that the pollutants adsorbed on AC are degraded; the other is that AC is regenerated by DBD plasma. The following works are carried out and main results are summarized as follows:1. An AC packed DBD reactor for the pollutants treatment is designed. Through investigating the controlling factors (such as dielectric materials, dielectric thickness, gas gap between two electrodes and AC) that effect discharge characteristics of reactor, the optimal structure parameters of reactor are obtained. The effects of DBD plasma on morphology, microcrystalline structure and N2 adsorption capacity of virgin AC are also investigated in this optimal reactor. The result shows that plasma has etching behavior to AC surface, but has no significant effect to crystal structure of AC. N2 adsorption capacity of AC after plasma treatment under various gas atmospheres is different.2. By investigating the effects of condition factors (such as discharge voltage, power frequency, gas kinds and gas flow rate) on degradation efficiency, the decomposition of pentachlorophenol (PCP) on AC by DBD plasma is studied. The results indicate that with increasing of discharge and power frequency degradation efficiency of PCP on AC increases. The treatment effect of O2 as the carrier gas is better than that of N2 and air as carrier gas. While gas flow rate and treatment amount of AC has an optimal value, respectively. The higher is water content of AC, the better is degradation efficiency of PCP. In the investigation of PCP degradation process, AC regeneration feasibility by DBD plasma is also studied. The results indicate that DBD plasma can be used for the regeneration of AC, and can achieve high regeneration efficiency.3. Identification of intermediates is accomplished by some analysis tools, such as thermal gravimetric (TG), energy-dispersive X-ray spectrometer (EDX), Fourier transform-infrared spectroscopy (FT-IR) and gas chromatography/mass selective (GC/MS), and the degradation mechanism of PCP is speculated. The PCP is dechlorinated and dehydroxylated to chlorinated phenols (such as TetraCP, TriCP, DiCP) and chlorinated benzene (such as 4-chlorophenyl, 3-chlorobenzene) by DBD generated high energy electrons and active species at first, and then the dechlorinated or dehydroxylated products are further degraded into organic small molecules (such as acid, aldehyde or ketone), H2O and CO2 by·OH and O3.4. Another investigation is performed for the regeneration of AC exhausted with acid orange II (AO7). The efficiency of this procedure is analyzed by determining the rate and amount of AO7 adsorbed in successive adsorption/DBD plasma regeneration cycles. Although the regeneration efficiency decreases with the adsorption/regeneration cycle numbers increases, the adsorption rate and capacity of AC can maintain relatively high levels. Effects of this regeneration on the structural properties,.surface chemistry and the AO7 adsorption capacities of AC samples are examined. It is found that the decreases of AC adsorption capacity are resulted from the change of pore size distribution and surface chemistry, and residue on AC. Energy consumption analysis indicates that AC regeneration by DBD plasma is a viable regeneration technology, and has extensive industry application prospects.更多还原