【作者】 逯秀；

【导师】 郑经堂；

【作者基本信息】 中国石油大学 ， 化学工程与技术， 2011， 硕士

【摘要】 高压脉冲放电非平衡等离子体技术是集羟基自由基（·OH）、过氧化氢（H₂O₂）、臭氧（O₃）等活性物质的作用于一体的高级氧化技术,因其能耗少、处理效率高、反应迅速且无选择性、无二次污染等优势,使该技术呈现出良好的应用前景和很大的市场潜力。从目前的研究现状看,吸附/催化剂的合理选择是限制该技术优势充分发挥的主要障碍之一。本论文对课题组原有的非平衡等离子体放电反应器进行了改进,以甲基橙为模拟污染物,考察了反应器各种工艺参数对甲基橙降解率的影响,确定了最佳工艺参数,初步探讨了非平衡等离子体对有机污染物的降解机理。采用浸渍改性法制备了双氧水改性和硝酸铁改性两种改性活性炭纤维,向非平衡等离子体反应中加入改性活性炭纤维,考察ACF的吸附催化性能,探讨改性ACF与非平衡等离子体的协同作用。向液相中高压针电极和气相中地电极施加脉冲高压后,液相中H₂O分子在高能电子的撞击下产生·OH、H₂O₂等活性物质,气相中O₂分子在放电电极上受到高能电子的碰撞、激发,发生分解反应产生O₃,部分O₃可由气相传质到液相。向放电反应中加入H₂O₂、Fe²⁺后,甲基橙的降解速率和降解效率均得到了有效提高,但存在二次污染问题。甲基橙在气液两相同时放电反应中会生成羧酸和苯胺类等小分子物质,这些小分子物质最终可被·OH矿化为H₂O和CO₂。非平衡等离子体与改性ACF联合处理甲基橙表现出很好的协同作用,协同作用的产生主要归因于改性ACF的吸附和催化作用,ACF是污染物分子的一个浓集中心,在其表面及其周围毗邻区域通过吸附创造了高浓度的环境,而ACF表面则是污染物分子的转化分解中心。双氧水改性ACF表面的酸性官能团能与放电反应产生的活性自由基反应,催化诱导O₃分解产生·OH ,从而提高甲基橙的降解率。ACF经硝酸铁改性后,表面活性点增加,二次热处理后ACF表面的Fe₂O₃在放电反应中生成Fe²⁺、O₂等物质,Fe²⁺通过光助芬顿反应、O₂通过自由基反应可进一步参与生成·OH、O₃等活性物质,有助于催化降解甲基橙。更多还原

【Abstract】 Non-equilibrium plasma water treatment is an advanced oxidation technology, which integrates the effectiveness of many active species including hydroxyl radical, hydrogen peroxide, ozone, etc., and bears preferable future application and large market potential because of its advantages of low energy consumption, high treatment efficiency, rapid and non-selective reactivity, and free of secondary pollution, etc.. The current difficulties for widely application of this technology exist mainly in selection of appropriate adsorbents and catalysts. In this work, the original electrical discharge reactor was improved for degrading methyl orange as the model pollutant in water. The infiuence of technological parameters on degradation efficiency was investigated and the best technical parameters were confirmed. The degradation mechanism of organic pollutants by non-equilibrium plasma was discussed. Two kinds of modified activated carbon fiber were prepared by dipping method. One was ACF modified by H₂O₂, and the other was ACF modified by Fe（NO₃）₃. The modified ACF were added for degrading methyl orange combined with non-equilibrium plasma. The adsorption of pollutants and the catalytic effect of ACF were evaluated. And the synergistic mechanism of modified activated carbon fiber with non-equilibrium plasma was discussed.With pulsed voltage supplied between the high voltage needle electrode in the aqueous phase and the ground electrode in gas phase, activate species of hydroxyl radical and hydrogen peroxide were produced in liquid phase and ozone in gas phase, some of which dissolved into the liquid phase. Both the efficiency and the degradation rate of methyl orange were obviously improved with the addition of H₂O₂, Fe²⁺ to the reactor, while it may lead to secondary pollution. Methyl orange was easy to break down into small-molecules, such as carboxylic acid and aniline in the gas-liguid discharge reaction. The small-molecules could be mineralized into carbon dioxide and water by·OH eventually.The combined treatment by pulse discharge with modified ACF showed good synergistic effect due to the adsorption and catalysis of modified ACF. A high concentration of pollutants on ACF surfaces was achieved by adsorption, and the surfaces performed as conversion and decompose centers of pollutants. The surface acidic functional groups of H₂O₂ modified ACF could reacts with the activate species in the discharge reaction, which could generate·OH and increase degradation efficiency. The active surface area of Fe（NO₃）₃ modified ACF increased. After heat treatment Fe（NO₃）₃ was converted to Fe₂O₃, which could generate Fe²⁺ and O₂ in the discharge reaction. The methyl orange can be degraded by·OH and O₃, which were generated from Fe²⁺ and O₂ by fenton reaction and free-radical reaction.更多还原