Kinetics of microwave-enhanced oxidation of phenol by hydrogen peroxide

Aqueous solutions of phenol were oxidized by hydrogen peroxide assisted by microwave (MW) irradiation. A simple kinetic model for the overall degradation of phenol in the presence of excess H₂O₂ is proposed in which the degradation rate of phenol is expressed as a linear function of the concentrations of phenol and H₂O₂. A detailed parametric study showed that the degradation rate of phenol increased with increasing [H₂O₂] until saturation was observed. Phenol degradation followed apparent zero-order kinetics under MW radiation or H₂O₂ oxidation. However, after 90 min of irradiation, the observed kinetics shifted to pseudo first order. The overall reaction rates were significantly enhanced in the combined MW/H₂O₂ system, mainly because microwave could accelerate H₂O₂ to generate hydroxyl radical (^·OH) and other reactive oxygen intermediates. The observed synergetic effects of the MW/H₂O₂ process resulted in an increased in the net reaction rate by a factor of 5.75. When hydrogen peroxide is present in a large stoichiometric excess, the time required to achieve complete mineralization is reduced significantly.     

提高柠檬酸钠净化甲苯废气效率的实验研究

以柠檬酸钠溶液为吸收剂,添加三种不同的添加剂在填料塔中进行了吸收法净化含甲苯有机废气的实验研究。在相同的工艺条件下,分别研究了添加柠檬酸,无机盐助剂、聚乙二醇(PEG200)以及三者的组成对柠檬酸钠吸收剂去除甲苯效果的影响。实验结果表明,当5%柠檬酸钠吸收剂分别添加柠檬酸时pH=6,无机盐0.05%硅酸钠、0.1%磷酸钠和0.1%碳酸钠,0.5%聚乙二醇时,对甲苯净化效率及吸收容量都有显著提高。当三种添加剂组合时效果更佳。     

电袋复合除尘器在燃煤锅炉大型机组上的应用

近年来,电袋复合除尘技术在燃煤锅炉烟气除尘行业的应用取得了快速发展,并实现了600MW、1000MW大型机组的突破。电袋复合除尘器已成为继电除尘器、袋式除尘器之后的新一代高效除尘设备。应用实践表明,电袋复合除尘器对煤种变化的适应性强,可长期保持低排放,并具有运行阻力低、占地面积小等优点。介绍了世界上首台1000MW机组电袋复合除尘器的开发和应用情况。     

臭氧对化工园区废水厂二级出水的选择性氧化

以化工园区废水厂二级出水作为实验废水,采用臭氧氧化工艺对其进行处理,采用分子量分级、亲疏水性分离和傅里叶红外等手段对臭氧氧化前后水质进行了系统分析。结果表明,在进水COD为126 mg/L,臭氧氧化60 min的条件下,COD和UV254的去除率分别为37.9%和55%;臭氧氧化对水中疏水性物质去除效率高于亲水性物质,部分疏水性物质氧化成亲水性小分子有机物。臭氧氧化可以改变废水中有机物的分子结构,使水中分子量小于1×103 kDa的有机物比例从56.3%提高至71.2%,分子量大于1×105 kDa的有机物比例由原来的24.2%下降至9.6%。红外光谱分析表明,臭氧氧化具有一定的选择性,可显著去除水中含不饱和键、酚类、醇类等有机物,但对饱和烷烃基本无降解效果。