旋转微气泡反应器强化臭氧降解水中对硝基苯酚

Enhanced ozone degradation of the p-nitrophenol wastewater by rotating-microbubble reactor

臭氧氧化技术在水处理系统中具有良好的应用前景,但实际应用中受到臭氧传质及氧化选择性的限制。故本研究以对硝基苯酚废水为研究对象,采用一种新型旋转微气泡反应器,通过多孔陶瓷填料的旋转将臭氧气泡尺寸破碎至微米级别,实现对废水降解过程的强化,同时本研究还进一步考察了操作条件对臭氧传质过程和臭氧分解产生羟基自由基过程的影响规律。实验结果表明,提高反应器转速和气体流量可以加快臭氧传质和羟基自由基产率,同时提高溶液pH也可以提高羟基自由基产率进而提高对硝基苯酚的去除率。与其他操作变量相比,反应器转速的影响最为明显,说明改善臭氧气泡流体力学行为能有效地提高对硝基苯酚的去除效果,体现反应器强化臭氧体系的可行性。此外,二甲亚砜的加入抑制了对硝基苯酚的去除,说明臭氧的间接氧化方式是降解对硝基苯酚的一种重要途径。本研究结果为旋转微气泡反应器在臭氧氧化降解过程中开发及应用提供合理指导。

Ozone oxidation technology has a good application prospect in water treatment systems,but its practical application is limited by ozone mass transfer and oxidation selectivity.In this paper,enhancement of wastewater degradation with p-nitrophenol by adopting a novel rotating-microbubble reactor to break the ozone bubbles to micro size was studied.Meanwhile,the effect of various operating conditions on ozone mass transfer and the production of hydroxyl radicals from ozone decomposition was further investigated.Results showed that improving reactor speed and gas flow could accelerate the mass transfer of ozone and the yield of hydroxyl free radicals,while increasing the pH in water could also provide hydroxyl free radical yield and thus improve the removal rate of p-nitrophenol.Compared with other operational variables,the influence of rotating speed of reactor was most obvious,indicating that improving the hydrodynamic behavior of ozone bubbles could effectively improve the removal effect of p-nitrophenol.The result revealed the feasibility of the reactor to strengthen the ozone system.In addition,the addition of dimethyl sulfoxide inhibited the removal of p-nitrophenol,indicating that the indirect oxidation of ozone was an important way to degrade p-nitrophenol.The results of present study provide a reasonable guidance for the development and application of the rotating-microbubble reactor in the process of ozone oxidative degradation.