Study On Fe-based Fenton Oxidative Degradation Characteristics And Heat Release Law Of Waster

In order to reduce the harmful substances produced by fossil fuels in the heating process,wastewater heat utilization technology has been extensively studied.Among them,the heat extraction is restricted by the temperature of sewage,which is a technical difficulty in the process of sewage heat utilization.To solve this problem,the paper proposes a solution to oxidize and degrade sewage by using iron-based active species to catalyze H2O2 to produce hydroxyl radicals(·OH),and use the heat generated by the catalytic oxidation process to increase the temperature of the sewage.The degradation and heat release characteristics of four typical Fe-based Fenton treatment OPD(o-phenylenediamine,OPD)wastewater were studied,including Fe2+/H2O2 homogeneous Fenton,Fe3+/H2O2 homogeneous Fenton-like,Fe2O3@MSCe/H2O2 heterogeneous Fenton and Fe3O4@MSCe/H2O2 heterogeneous Fenton.The main research work of the full text is as follows:(1)A new idea of using the reaction heat generated in the process of iron-based Fenton degradation of sewage to effectively increase the temperature of sewage is proposed.The degradation exothermic experiment and reaction path analysis of OPD wastewater oxidation by O3 and Fe2+/H2O2 homogeneous Fenton reagents were carried out.Studies have shown that the Fe2+/H2O2 homogeneous Fenton reagent exhibits better degradation and exothermic performance.The process of O3 degradation of OPD wasteWater is a single oxidation exothernic process.Fe2+/H2O2 Homogeneous Fenton degradation of OPD wastewater has a variety of exothermic processes,such as the catalytic reaction of ·OH and HO2·radicals,the degradation reaction of free radical oxidation of OPD and the free self-quenching reaction.The superposition of multiple reaction heats is the main reason for the effective increase of sewage temperature during the re2+/H2O2 homogeneous Fenton degradation process.When the degradation rate of Fe2+/H2O2 homogeneous Fenton degradation OPD wastewater is 93%,the temperature rise of the solution can reach above 11℃.It shows that the idea of using the heat generated by the Fe2+/H2O2 homogeneous Fenton degradation process to increase the temperature of the sewage is feasible in theory and practice.(2)Research on the exothermic performance,pH adaptability and reaction mechanism of Fe3+/H2O2 homogeneous Fenton-like degradation.The experimental results show that the Fe3+/H2O2 homogeneous Fenton has good degradation exothermic performance and pH adaptability.When pH=7.8,the degradation rate of OPD wastewater is 93.5%,and the solution temperature rise value is 7.2℃;in the range of pH=8.0～11.3,the degradation rate of Fe3+/H2O2 homogeneous Fenton system for OPD wastewater treatment was significantly higher thar that of Fe2+/H2O2 homogeneous Fenton in the same pH range.The internal mechanism of the heterogeneous reaction revealed,that under alkaline conditions,the Fe3+/H2O2 homogeneous Fenton-like system has not only the homogeneous reaction of Fe3+ catalyzed H2O2 production·OH and HO2·radical oxidation OPD,but also Fe(OH)3 colloidal particles catalyzed H2O2 production-OH.(3)The Fe2O3@MSCe composite material was prepared and the research on the exothermic performance and reaction mechanism of Fe2O3@MSCe/H2O2 heterogeneous Fenton degradation was carried out.The characterization results show that Fe2O3@MSCe has a large specific surface area,a variety of functional groups,and a strong chemical adsorption capacity.The experimental results show that Fe2O3@MSCe/H2O2 has good degradation and exothermic performance.When the initial pH of the solution is 7.8～8.9,the degradation rate of sewage is 88.2%～80.5%,and the temperature rise of the solution is 7.1～6.9℃.The process of Fe2O3@MSCe/H2O2 heterogeneous Fenton degradation of OPD wastewater follows a cooperative degradation mechanism.(4)Prepared Fe3O4@MSCe composite material and carried out the research on the exothermic performance and reaction mechanism of Fe3O4@MSCe/H2O2 heterogeneous Fenton degradation.The experimental results show that in the range of pH=7.8～11.2,the degradation rate of OPD wastewater is 90.9%～89.1%,and the solution temperature rise is 7.3～6.9℃,which is compared with Fe2O3＠MSCe/H2O2,Fe3O4@MSCe/H2O2 produces more excellent degradation exothermic characteristics.The internal switching of electrons between Fe(Ⅱ)and Fe(Ⅲ)in Fe3O4 crystals is the main factor that accelerates the electron transfer between Fe3O4 crystals and H2O2 molecules and enhances the Fe3O4@MSCe/H2O2 heterogeneous Fenton-like catalytic activity(5)Research on the macroscopic laws and microscopic mechanisms affecting the degradation and heat release performance of iron-based Fenton.Four typical Fenton systems of Fe2+/H2O2 homogeneous Fenton,Fe3+/H2O2 homogeneous Fenton-like,Fe2O3@MSCe/H2O2 heterogeneous Fenton-like and Fe3O4@MSCe/H2O2 bivalent heterogeneous Fenton-like system are studied.The influence of reaction conditions on the degradation exothermic performance,and the microscopic mechanism of the influence of ·OH radical reaction path on degradation exothermic performance.The study found that in the process of iron-based Fenton degradation of OPD wastewater,the concentration of H2O2 is the main factor that affects the temperature increase of the wastewater,and the concentration of iron-based catalyst and the initial reaction temperature are the macroscopic laws that afect the reaction rate.The study revealed that the heat release in the process of iron-based Fenton degradation of OPD wastewater mainly depends on the total reaction amount in the system,and the amount of degradation mainly depends on the microscopic mechanism of the reaction amount of·OH radicals with OPD molecules.