镍钴双金属氧化物催化过硫酸氢钾效能和机理

Efficiency and Mechanism of Catalyzed Peroxymonosulfate by Co-NiO_x

为了探究双金属催化剂对PMS(过硫酸氢钾)强氧化活性的活化效果,以酸性橙7(AO7)为目标污染物,采用溶胶-凝胶法(sol-gel method)制备Co-NiO_x(镍钴双金属氧化物)催化剂,考察了镍钴催化剂的活性以及催化PMS降解AO7的影响因素;并对其反应机理进行了探究。结果表明,Co-NiO_x催化PMS氧化AO7的效果明显优于单金属催化,以及单独氧化。随着催化剂投量的增加,AO7降解率明显增大;AO7的降解率随着PMS初始浓度的增加而增大,且150μmol/L为最佳投量。当AO7初始浓度从32μmol/L逐渐升至96μmol/L,在反应20 min时AO7降解率由92.5%降至67.07%;初始pH在4左右时AO7有最大降解率95.02%。添加乙醇(EA)和叔丁醇(TBA)的自由基抑制剂试验结果表明,氧化体系中起主要氧化作用的是SO_4^-·(硫酸根自由基)。XPS结果显示,Co-NiO_x催化剂中Co、Ni主要以Co^(2+)、Ni^(2+)的形式存在,O主要以表面羟基氧、吸附氧和水的形式存在。研究表明,Co-NiO_x催化剂具有良好的催化性能,能够有效活化PMS产生SO_4^-·和·OH,进而实现对水体污染物的降解。

Bimetallic Co-NiOx oxide is prepared using the sol-gel method to activate the strong oxidation activity of peroxymonosulfate(PMS)for the removal of Acid Orange7(AO7).The activity of Co-NiOx catalyst and the influence factors in the degradation process and mechanism are investigated.The effects of initial concentration of Co-NiOx,PMS,AO7and initial pH on the degradation of AO7are tested.The results show that Co-NiOx/PMS system has better performance than Co/PMS,Ni/PMS and alone PMS system on the oxidation of AO7.The degradation rate of AO7improves apparently with increasing initial concentration of Co-NiOx,while a same change in the degradation rate is observed with increasing dosage of PMS.And the optimum dosage is150μmol/L.In addition,as initial concentration of AO7increases from32μmol/L to96μmol/L,the degradation rate of AO7decreases from92.5%to67.07%at20min.Besides,the degradation rate maximizes to95.02%when initial pH is about4.The reaction of the Co-NiOx catalyst-activated PMS is conducted with the addition of ethylalcohol(EA)and tertbutylalcohol(TBA),which shows that the oxygen species in the system are identified as sulfate radicals.The results of XPS show that Co-NiOx catalyst consists of CoO and NiO,and oxygen exists in the forms of surface hydroxyl oxygen,adsorbed oxygen and water.The research indicates that Co-NiOx catalyst has excellent catalytic performance,which can effectively activate PMS to generate powerful radicals such as SO-4·and·OH.And then realize the degradation of pollutants in wastewater.