Degradation Of Antibiotic Sulfanilamide In Aqueous Solution Via A Heterogeneous Fenton-like Reaction Catalyzed By Iron Oxides

Sulfonamides are one of the most antibiotics produced in China. They are widely used in production. Most of the antibiotic sulfanilamide energy to the environment in the form of a prototype or metabolites after they are used. It can be detected in aqueous solution.Residual drugs can cause the destruction of the ecological environment. It can not only result in drug-resistant pathogens but also harm the human health mostly by the means of the enriched food chains. Thersfore, it is of great significance to develop an effective degradation of the antibiotic sulfanilamide.Advanced oxidation technology in environmental pollution control is the hot research topic in wastewater treatment. Fenton technology is widely applied. It is suitable for treating the difficult degradable organic pollutants. At present, degradation of the antibiotic sulfanilamide in aqueous solution via a heterogeneous Fenton-like reaction catalyzed by iron oxides is also rarely reported. In this experiment, the degradation of the antibiotic sulfanilamide by a Fenton and a heterogeneous Fenton-like reaction catalyzed by iron oxides was investigated. The influences of initial sulfanilamide concentration, the amount of catalyst, H2O2 dosage, and initial p H value were assessed. The best parameters of degradation kinetic was determined and the degradation products of sulfanilamide were analyzed. The main research contents and the reesults were as follows.1. The degradation of antibiotic sulfanilamide by Fenton reaction was investigated. The influences of initial sulfanilamide concentration, the amount of Fe2+, H2O2 dosage, and initial p H value were assessed in the Fenton reaction. The results showed that at the optimal reaction conditions with initial sulfanilamide concentration of 2 mg·L-1, Fe2+dosage of 10 m L·L-1, H2O2 dosage of 2.5 ml·L-1, and the initial reaction p H of 3.0, the degradation rate of sulfanilamide could reach 95.4% at reaction time of 7 h.2. The degradation of antibiotic sulfanilamide by a heterogeneous Fenton-like reaction was investigated using different nano-sized iron oxides(hematite, maghemite, magnetite,ferrihydrite) as catalyst and hydrogen peroxide as oxidation agent. The influences of initial sulfanilamide concentration, the amount of catalyst, H2O2 dosage, and initial p H value were assessed in the Fenton-like reaction catalyzed by natural iron oxides. The results showed that at the optimal reaction conditions with initial sulfanilamide concentration of 2mg·L-1 the catalyst amount of 1 g·L-1, H2O2 dosage of 30 ml·L-1, and the initial reaction pH of 3.6 the degradation rate of sulfanilamide could reach 99.27% at reaction time of 72 h.Effect of some inorganic ions on a heterogeneous Fenton-like reaction was studied as actual. Experimental results showed that Cl- had great influence on decreasing oxidation velocity of a a heterogeneous Fenton-like reaction, and the same tendencies were observed for H2PO4-, Cu2+ and Mn2+ also lowered the reaction efficiency. SO42-, NO3-, Mg2+ and Na+had no effect on degradation rate of antibiotic sulfanilamide.3.The aqueous reaction of potassium ferrate with sulfanilamide was inwestigated for evaluating the effects of ferrate dosage and p H value on the removal of sulfanilamide. The results showed that an the initial reaction p H of 9.18 and the molar ratio of potassium ferrate and sulfanilamide for 40:1 the degradation rate of sulfanilamide could reach 97.8%at reaction time of 120 min. The ferrate dosage and the initial reaction p H had a significant effect of the degradation of sulfanilamide.4.The degradation products of sulfanilamide by the Fenton-like reaction were analyzed by LC-MS, which suggested that the degradation of sulfanilamide was mainly catalytic oxidation reaction, the degradation product was 4-Nitrobenzenesulfonamide, and the group of –NH2 in the molecular structure of sulfanilamide was oxidized to the –NO2. The proposed pathway of sulfanilamide degradation was hydroxylation of sulfanilamide, an?OH radical attacks on –NH2 to form of –NH2.