Study On Preparation Of Catalyst And Treatment Of Wastewater Containing Benzoic Acid By Novel Fenton-FBR

Fenton process is one of the advanced oxidation processes which are now widely used.Homogeneous Fenton process is a mature Fenton process, but there are a few kinds ofdisadvantages such as narrow pH range, iron mud from reactions by ferrous addition neededcosts, that limit its industrial application. To deal with these disadvantages, the heterogeneousFenton process was develpoed. A novel Fenton-Fluidized Bed Reactor （FBR） studied in thispaper is one of the heterogeneous Fenton processes. This paper selected benzoic acid as thefeatures pollutant for preparation and application of catalyst in Fenton-FBR by componentialanalysis of leachate after physical-chemical treatment and biochemical treatment.Treatment of benzoic acid by homogeneous Fenton process has been studied firstly, inorder to determine the treatment extent of benzoic acid （BA） and the best reaction conditions.The influencing extent of H₂O₂, Fe²⁺and pH were studied by orthogonal design experiment.The results shows: initial pH＞H₂O₂concentration＞Fe²⁺dosage. The best condition is initialpH3, H₂O₂initial concentration13.1mM/L, Fe²⁺dosage0.52mM/L, which derived fromsingle factor experiments. In this condition, BA concentration could be removed79.1%, CODremoval rate57.9%after reacting1hour.Five novel Fenton-FBR catalysts had been prepared by two loading methods throughchanging the valence of loading iron and drying temperature. These catalysts are Fe（II）-ceramicite, Fe （III）-ceramicite,40-ceramicite,60-ceramicite,80-ceramicite. The twoloading methods are direct evaporation method and cycle infusion method which got byresearching.60-ceramicite was designed as the Fenton-FBR catalyst to treat benzoic acid byexperiments in this paper. Iron oxide loaded on60-ceramicite was speculated as goethite orferrihydrite by SEM. The surface iron content is21.426mg/g, density of2.2016g/cm3.The best reacting condition of60-ceramicite in Fenton-FBR was initial pH4, catalystloaded rate80-120g/L, dosage of H₂O₂9.8mM/L, initial Fe²⁺concentration0.33mM/L.In thiscondition, BA concentration can be removed72%,CODCrcan be removed71%. The catalystcould remove60%BA after reacting four times in Fenton-FBR, CODCrremoval ratedecreased from68.2%at first to54.8%at the fourth. Using60-ceramicite catalyzing H₂O₂ reacting heterogeneous Fenton in actual wastewater can reduce a certain amount of Fe²⁺dosage and the costs of follow-up treatment of iron sludge.