MnO_(x)/Al_(2)O_(3)催化臭氧氧化处理含氰废水

Treatment of Cyanide Wastewater by MnO_(x)/Al_(2)O_(3)-catalyzed Ozone Oxidation

本研究采用浸渍法,以Mn(NO3)2为前驱体、γ-Al_(2)O_(3)为载体,制备负载型金属氧化物催化剂MnO_(x)/Al_(2)O_(3),用于处理氰化废水中的氰离子。其间考察了臭氧投加量、催化剂制备工艺参数、催化剂投加量、溶液pH等因素对废水中氰化物去除效率的影响。试验表明,从制备催化剂的最佳工艺参数来看,Mn目标负载量为8%,焙烧温度为500℃,焙烧时间为4 h。在优化的试验条件下,氰化物浓度可以从5.4 mg/L降到0.2 mg/L以下。反应机理研究表明,MnO_(x)/Al_(2)O_(3)催化臭氧氧化处理氰化废水遵循羟基自由基机理。反应动力学分析表明,该反应符合一级反应动力学模型,表观反应速率常数为0.031 6 min^(-1)。

In this study,loaded metal oxide catalyst MnO_(x)/Al_(2)O_(3)is prepared by impregnation method using Mn(NO3)2as the precursor and γ-Al_(2)O_(3)as the carrier,so as to treat cyanide ion in cyanide wastewater.In the meanwhile,the effects of ozone dosage,catalyst preparation process parameters,catalyst dosage,solution pH and other factors on cyanide removal efficiency in wastewater are investigated.The test shows that according to the best process parameters for preparing the catalyst,the target loading of Mn is 8%,the calcination temperature is 500℃,and the calcination time is 4 h.Under the optimized test conditions,the cyanide concentration can be reduced from 5.4 mg/L to below 0.2 mg/L.The study of reaction mechanism shows that MnO_(x)/Al_(2)O_(3)-catalyzed ozone oxidation treatment of cyanide wastewater follows the hydroxyl radical mechanism.The reaction kinetics analysis shows that the reaction conforms to the first-order reaction kinetics model,and the apparent reaction rate constant is 0.031 6 min^(-1).