锰镁氢氧化物碳基复合材料催化臭氧化降解亚甲基蓝

Manganese-magnesium hydroxide carbon based composites forcatalyticozonation degradation of methylene blue

染料废水具有色度和有机污染物含量高、难生化降解等特点,常规水处理技术难以达到理想的处理效果。分别以碳纳米管、氧化石墨烯和石墨烯为载体,利用共沉淀法制备了锰镁碳复合催化剂,用以催化臭氧化处理亚甲基蓝废水。采用SEM、XRD和FTIR等技术对催化剂的结构进行表征,同时对比研究了催化剂投加量、臭氧浓度和pH等因素对催化效果的影响。结果表明,锰镁碳复合催化剂催化臭氧化过程均符合准一级反应动力学模型,不同催化剂对亚甲基蓝的降解速率不同,其中LDH/CNT对亚甲基蓝的催化降解效率最高。在pH=8,催化剂投加量为0.6 g/L,O_(3)浓度为6.7 mg/L的条件下,LDH/CNT脱色率可达97.45%,COD去除率为74.85%,且催化剂活性稳定。结构表征表明,碳纳米管和氧化石墨烯具有丰富的含氧官能团,提升了催化剂的催化能力,而锰镁氢氧化物与石墨烯的结合能力较差,导致锰镁石墨烯的催化能力相对较弱。叔丁醇抑制试验表明,该催化过程遵循·OH机理,·OH对亚甲基蓝的降解起主要作用。

The dye wastewater has high content of chroma and organic pollutants and is difficult to biochemical degradation,so it is difficult to achieve an ideal treatment effect with conventional water treatment technology.In this paper,manganese magnesium carbon composite catalysts were prepared by co-precipitation method using carbon nanotubes,graphene oxide and graphene as carriers for catalytic ozonation of methylene blue wastewater.The structure of catalysts was characterized by SEM,XRD and FTIR,and the influences of catalyst dosage,ozone concentration and pH on the catalytic effect were compared.The results show that the ozonation process catalyzed by the manganese magnesium carbon composite catalyst conforms to the quasi first order reaction kinetics model,and the degradation rates of methylene blue vary with the species of the catalysts.Among them,the catalytic degradation efficiency of methylene blue is the highest with the manganese-magnesium carbon nanotube(LDH/CNT).At pH=8,when the dosage of catalyst is 0.6 g/L and the concentration of O_(3) is 6.7 mg/L,the decolorization rate of LDH/CNT can reach 97.45%,the COD removal rate is 74.85%,and the catalyst activity is stable.Structural characterization showed that carbon nanotubes and graphene oxide possess abundant oxygen-containing functional groups,which enhances the catalytic ability of catalysts.However,the poor binding ability of manganese-magnesium hydroxides with graphene leads to the relatively weak catalytic ability of manganese-magnesium graphene.The tert-butyl alcohol inhibition test revealed that this catalytic process follows the·OH mechanism,and the·OH plays a major role for the degradation of methylene blue.