Preparation Of Supported Heterogeneous Fenton Catalyst And Its Performance In Humic Substances Degradation

In recent years,the effective treatment of polluted source water has become a hot topic of research with the continuous development of water quality analysis technology.Contaminated water bodies often contain more humic acids,especially black and odor water bodies.The formation of chromaticity in natural water bodies is partly caused by humic acids.Humic acids are important reductive organics with unpleasant color and taste and they can affect the migration and fate of heavy metals in water.Besides aquatic humic acids are the main precursor of mutagenic mutagens produced by chlorination of drinking water and they are also one of the important factors that cause the problem of drinking water.Therefore,it is of great significance to seek efficient and economical humic acid treatment process.In this study,attapulgite（ATP）which is produced in Jiangsu Xuyi was used as the carrier and a heterogeneous Fenton catalyst was prepared by loading iron and iron oxides with oxidation reduction method.Besides preparation performance of the catalysts were optimized and the morphology was characterized,meanwhile the catalytic performance of the heterogeneous catalyst for the degradation of sodium humic acid wastewater by single factor catalyst was optimized and the kinetics was also studied.The main research contents are as follows:In this study,the supported heterogeneous catalysts were synthesized by using the cheap and easily available attapulgite as raw material,after organic modification,the iron and iron oxides were loaded on it by oxidation reduction method,meanwhile three kinds of catalyst samples were analyzed by means of XRD,FT-IR and SEM.The analysis results showed that the structure of the ATP has not changed obviously before and after the modification,but the specific surface area is obviously increased.In addition,a new absorption peak appeared on the FT-IR atlas of attapulgite indicating that the attapulgite has been successfully modified.The XRD and SEM measurements showed that the iron and iron oxides were successfully loaded on the surface of the modified attapulgite.Attapulgite clay was organically modified to prepare five supported type heterogeneous catalysts by using five kinds of silane coupling agent.Under the same conditions,the catalytic degradation of sodium humate wastewater was carried out and it was found that the attapulgite modified by KH-792 had high catalytic performance after comparison.It was discussed that the effects of reaction temperature,initial pH value,the initial HA-Na concentration,catalyst dosage and H₂O₂ concentration on the degradation of HA-Na using heterogeneous catalyst by the single factor experiments and the catalytic performance was optimized.The results showed that the degradation rate of HA-Na was 40%after the reaction of 60 min under the optimum reaction conditions.Besides,the catalyst still maintained high catalytic performance after ten cycles.In this study,the kinetic was also studied and the degradation process accorded with the first order kinetic.Heterogeneous catalysts which were prepared from attapulgite clay modified by anionic surfactant sodium oleate,cationic surfactant eighteen alkyl three methyl ammonium chloride were used to degrade humic acid sodium wastewater.It were discussed that the effects of reaction temperature,initial pH value,the initial HA-Na concentration,catalyst dosage and H₂O₂ concentration on the degradation of HA-Na using heterogeneous catalysts by the single factor experiments and the catalytic performance of the two catalysts were optimized.The results showed that the degradation rates of two kinds of catalysts for sodium humate wastewater were 85%and 97%after the reaction of 60 min under the optimum reaction conditions.Besides,the catalyst still maintained high catalytic performance after ten cycles.In this study,the kinetics were also studied and the degradation process of the two catalysts all accorded with the first order kinetics.Meanwhile,the process and mechanism of the degradation of sodium humate wastewater were briefly discussed.The iron leaching amount and production of·OH radicals of three kinds of catalysts were discussed,it was found that the iron ion leaching amount of three kinds of catalysts were small enough to be ignored,illustrated that the degradation process of HA-Na by three kinds of catalysts were heterogeneous Fenton system and had better stability.The production of·OH radicals of three kinds of catalysts were also studied.It was found that production of·OH radicals in the three catalysts was Fe/OATP-KH792<Fe/OATP-SO<Fe/OATP-OATC.Through comparative experiments,it is found that the heterogeneous catalyst modified by organic cationic surfactant（Fe/OATP-OATC）had the best catalytic performance.Through the calculation of activation energy and full band scanning of the catalyst,the catalytic advantage of the catalyst was further illustrated,and the catalytic mechanism was discussed.