Study On The Performance And Mechanism Of Homogeneous And Heterogeneous Ce-Fe-based Fenton Degradation Of Catechol

Fenton oxidation technology has been widely used in wastewater treatment engineering containing refractory organic matter due to its advantages such as high treatment efficiency,low operation cost and simple operation and management.However,the classical Fenton system also has some obvious disadvantages,such as:?1?The reaction can only be carried out under acidic conditions;?2?The rate of the whole Fenton reaction is limited by the conversion rate from Fe³⁺to Fe²⁺;?3?Low utilization of H₂O₂.Based on this,this study intends to add the rare earth element cerium to construct a homogeneous and heterogeneous composite Fenton system.Catechol was used as the target pollutant to systematically study the degradation performance of compound Fenton system on the target substance,andgC-MS,XPS,FTIR,XRD were used as measurement and characterization means to reveal the degradation mechanism.It provides theoretical basis and data support for the construction and operation parameter optimization of efficient Fenton oxidation system.The main research conclusions are as follows:?1?The results showed that the application range of pH in homogeneous composite Fenton system with cerium was expanded from acid to neutral,and the degradation efficiency of organic matter was also improved.For the H₂O₂/Fe²⁺/Ce³⁺system,under the optimal conditions of pH=7,Fe²⁺/Ce³⁺?molar ratio?=4:2,and the initial dosage of H₂O₂ is 20 mmol/L,the removal efficiency of catechol,COD and TOC reaches 84%,82%and 72%,respectively.For the H₂O₂/Fe³⁺/Ce³⁺system,under the optimal oxidation conditions of pH=7,Fe³⁺/Ce³⁺?molar ratio?=1:2,and the initial dosage of H2O2=30 mmol/L,the removal efficiency of catechol,COD and TOC reached 97.2%,97.5%and 94.2%,respectively.?2?The analysis of the precipitate produced by homogeneous composite Fenton system showed that the structure of catechins was destroyed during the oxidation process,and Fe²⁺/Fe³⁺and Ce³⁺/Ce⁴⁺existed in the system at the same time,which proved that two catalytic reduction systems would be formed when cerium ions were added to the Fenton system.The free radical quenching experiment showed that the main active species of the reaction was still·OH,and under the condition of pH=7,HO₂·/O₂·^-was used as the intermediate activegroup to promote the efficient circulation of the two systems through chain reaction,so as to improve the utilization rate of H₂O₂,generate more·OH,and improve the degradation performance.?3?In the heterogeneous Fenton system,the prepared CeFeO₃ catalyst material significantly improved the removal rate of pyrocatechol compared with Fe₂O₃ material.The removal efficiency of catechol,COD and TOC was 80%,78.9% and 74%,respectively,under the optimal reaction conditions of pH=7,the initial dosage of catalyst was 1 g/l,and the dosage of H₂O₂ was 30 mmol/L.The removal efficiency of catechol,COD and TOC of Fe₂O₃ catalyst materials under the optimal conditions of pH=3,initial dosage of 4 g/l and H₂O₂ dosage of 40 mmol/L was 15.2%,15%and 20%,respectively.?4?The addition of cerium ion can obviously increase the all phase and heterogeneous Fenton reaction of oxidation degradation of performance,but homogeneous system with the advantages of mass transfer performance,so the addition of cerium ions on the homogeneous Fenton reaction is superior to the improvement of the performance of the oxide heterogeneous Fenton reaction,but CeFeO₃ catalyst material performance is superior to the classic Fenton system,and heterogeneous Fenton reaction after the easy separation materials and solutions.The homogeneous and heterogeneous Fenton reactions after the addition of cerium ions have high degradation performance under neutral conditions,which provides advantages for practical applications.