【摘要】 针对煤化工废水的生化出水,开发了以纳米MgO为催化剂的催化臭氧氧化系统,分析了纳米MgO催化臭氧氧化处理废水的机理。采用均匀沉淀法制备纳米MgO臭氧催化剂(平均粒径为17. 1 nm),并从臭氧传质以及叔丁醇和磷酸盐对催化剂催化活性影响等方面开展了相关研究。试验结果表明,纳米MgO的加入不但可以降低尾气中的臭氧浓度、提高臭氧转移率,而且能够加速水中臭氧分解、降低水中臭氧饱和浓度至1. 1 mg/L,从而强化水中污染物对臭氧的利用。当pH值接近催化剂表面零电荷点时,催化臭氧氧化处理废水的效能最高,系统对COD的去除率为75. 1%,且催化臭氧氧化系统内引入叔丁醇和磷酸盐能够明显降低COD去除率,说明催化过程遵循·OH机理,即MgO表面的羟基基团是其发挥催化作用的活性位点,臭氧与催化剂表面羟基反应生成的·OH与废水中的污染物快速反应,从而提升对废水的处理效果,这为煤化工废水的高效深度处理提供了一种切实可行的方法。更多还原

【Abstract】 The catalytic ozonation system with nano-MgO as catalyst was developed to treat biologically pretreated coal gasification wastewater,and the mechanism of catalytic ozonation was explored. Nano-MgO(mean particle size of 17. 1 nm) was prepared by homogeneous precipitation method,and the effects of mass transfer by ozone,tert-butanol(TBA) and phosphate on activity of the catalyst were explored. The addition of nano-MgO not only reduced the exhaust ozone concentration and increased ozone transfer rate,but also accelerated the ozone decomposition,decreased the dissolved ozone concentration to 1. 1 mg/L and improved the ozone utilization efficiency. When the pH value was closed to the zero charge point on the surface of the catalyst,the efficiency of catalytic ozonation process was the highest,achieving 75. 1% of COD removal,and the introduction of TBA and phosphate in the system significantly reduced the COD removal efficiency. It was revealed that the catalytic ozonation followed the ·OH mechanism. The hydroxyl group on MgO surface was the active site. Ozone reacted with the hydroxyl groups on catalyst surface to generate · OH,which degraded pollutants rapidly to improve wastewater treatment efficiency. This provided an efficient method for advanced treatment of coal gasification wastewater.更多还原