Preparation Of Heterogeneous Fenton Catalyst With Bentonite As Carrier And Its Application In Dye Wastewater Treatment

So far,azo dyes have been widely used in textile industry all over the world.Some dye pollutants are released from textile wastewater to nature,which will undoubtedly have harmful effects on ecosystems and humans due to their toxicity and carcinogenicity.Among the existing physical,chemical and biological dye treatment technologies,advanced oxidation processes（such as Fenton process）have become promising dye treatment methods worldwide.Fenton process has been continuously improved because of its narrow p H adaptation range and defects associated with the formation of a large number of iron sludge during the reaction process.In order to overcome the defects of homogeneous Fenton process,recent studies have focused on heterogeneous Fenton process,in which solid phase catalyst is used as the source of active components in Fenton process,and the defects of homogeneous Fenton process are largely avoided.In heterogeneous Fenton process,clay as carrier catalyst has been widely studied because of its unique dye adsorption performance,low cost and easy access.In this study,two new heterogeneous Fenton catalysts were prepared by simple impregnation method with bentonite as carrier,Fe₂O₃with Ce O₂ and Fe₂O₃ with La₂O₃ as active components（Fe-Al-Ce/B and Fe-Al-La/B）.Fenton activity tests of organic dyes（methyl orange and rhodamine B）in water were performed on two composites under dark conditions,respectively.The test showed that after the dye was adsorbed for 30 min and hydrogen peroxide was added for 90 min,The Fe-Al-Ce/B composite material Fenton catalytic degradation of methyl orange（MO）solution has a decolorization rate of 96.95%;After dye adsorption for 40 min and hydrogen peroxide addition for 40 min,the decolorization rate of Rhodamine B（Rh B）solution catalyzed by Fenton oxidation of Fe-Al-La/B composite reached 99.68%.The mechanism of removal of organic dyes by Fe-Al-Ce/B and Fe-Al-La/B heterogeneous Fenton catalysts was studied.First,the high adsorption capacity of two heterogeneous catalysts can be attributed to their high surface area;secondly,in the heterogeneous Fenton reaction,the main active substances are·OH and·O₂^-,when hydrogen peroxide is added to the reaction system,after a series of reaction cycles,the two free radicals are completely present in the organic dye solution.Organic dye molecules are constantly attacked and degraded by them.Finally,organic dye molecules are degraded to carbon dioxide,water and other by-products.