Study On The Preparation And Properties Of Sodium Alginate Based Heterogeneous Fenton-like Catalyst

With the application of antibiotics in agriculture,animal husbandry,pharmaceutical synthesis and other fields extensively,the pollution of antibiotics in water is becoming more and more serious.Traditional water treatment technology is difficult to remove antibiotic wastewater completely,so it is necessary to develop an effective and feasible technology to treat it.In recent years,the Fenton oxidation process has become a research hotspot of water treatment technology,with the advantages of high efficiency,simple operation,and economy,showing great potential in the treatment of antibiotic wastewater.However,the traditional Fenton oxidation technology has a narrow p H response range,solid sludge generation,serious iron leaching,and other shortcomings,so developing a stable and efficient catalyst is the key to this technology.In this study,sodium alginate（SA）as the matrix,graphene oxide（GO）and graphite phase carbon nitride（g-C₃N₄）as additives,and multivalent metal cations as crosslinking agents were used to prepare sodium alginate-based heterogeneous Fenton-like catalyst.Moreover,the catalyst and H₂O₂ together formed a heterogeneous Fenton-like reaction system.The degradation performance and possible reaction mechanism of the catalyst for tetracycline hydrochloride（TC）were explored.Firstly,the Fe-Cu-AG catalyst was prepared by using ferrous sulfate and copper sulfate as cross-linking agents and the SA/GO mixed solution for physical cross-linking.The effect experiment of the preparation conditions on the performance of the catalyst showed that the optimal preparation conditions of Fe-Cu-AG catalyst were Fe²⁺/Cu²⁺molar ratio of 1:2,SA concentration of 41 g/L,GO dispersion concentration of 8 mg/m L,and cross-linking agent concentration of 0.2 mol/L.The characterization results of SEM,EDS,TEM,FT-IR,and XPS showed that the Fe-Cu-AG catalyst surface was mainly composed of C,O,Fe,and Cu elements,with a clear three-dimensional network structure.Moreover,the introduction of GO increased the thermal stability and specific surface area of the Fe-Cu-AG catalyst.Through the study of the effect of reaction conditions on the catalyst performance degradation,it was found that the Fe-Cu-AG catalyst for the degradation of TC reached 92.90%after reaction for60 min with the following reaction conditions:TC concentration 20 mg/L,the initial p H 3.5,temperature 25℃,catalyst dosage 8 g/L,H₂O₂ dosage 9 mmo/L.Meanwhile,the TOC and COD removal rates were 43.07%and 71.43%,respectively,indicating that the Fe-Cu-AG/H₂O₂ reaction system can mineralize TC effectively.Reuse experiments and the dissolution of metal ions proved that the Fe-Cu-AG catalyst had good stability.According to the classic free radical capture experiment,EPR,and LC-MS analysis methods,possible reaction mechanisms and degradation pathways were proposed.Secondly,the Fe-Ce-Ca-ACN catalyst was prepared by using the solution of ferric nitrate,cerium nitrate,and calcium chloride as the cross-linking agent and the SA/g-C₃N₄ mixed solution for physical cross-linking.The effect experiment of the preparation conditions on the performance of the catalyst showed that the optimal preparation conditions of the Fe-Ce-Ca-ACN catalyst were g-C₃N₄ dispersion concentration 1.0 mg/m L,SA concentration25 g/L,Fe³⁺/Ce³⁺/Ca²⁺molar ratio 1:1:1,and cross-linking agent concentration 0.1 mol/L.Characterization analysis of SEM,EDS,TEM,BET,FT-IR,and XPS indicated that the surface of Fe-Ce-Ca-ACN catalyst was mainly composed of C,N,O,Fe,Ce,and Ca elements with a three-dimensional network structure.Due to the successful introduction of g-C₃N₄ into SA,the specific surface area of the catalyst was improved.When the initial concentration of TC was 20 mg/L,initial p H was 4.5,the reaction temperature was 20℃,H₂O₂ dosage was 5mmol/L,and catalyst dosage was 5 g/L,the removal efficiency of TC by Fe-Ce-Ca-ACN achieved 84.58%after reaction for 30 min.Furthermore,the TOC and COD removal efficiencies were 40.45%and 68.91%,respectively.The above results indicated that Fe-Ce-Ca-ACN/H₂O₂ reaction system made TC mineralization effectively.Reuse experiment and the dissolution of metal ions proved that Fe-Ce-Ca-ACN catalyst had good stability.According to the classic free radical capture experiment,EPR,and LC-MS analysis methods,possible reaction mechanisms and degradation pathways were proposed.