Degradation Of Tetracycline Antibiotics By Modified TiO 2

Poly-vinyl alcohol (PVA)-iodine complex doped mesoporous TiO2 catalysts were prepared by hydrothermal method, using tetrabutyl titanate as precursor, potassium iodate and iodine as iodine sources. The as-prepared catalysts were characterized by UV-Vis, XRD, BET, TG-DTA, XPS and FE-SEM. The photocatalytic activity of catalysts was evaluated through photocatalytic decolorization of tetracycline aqueous solution under the simulated sunlight. The results showed that when KI and I2 molar ratio was 2, the calcination temperature was 200℃, PVA-I modified mesoporous TiO2 was anatase TiO2 and the specific surface area, pore diameter, pore volume and band gap was 221.49 m2·g-2,41.96,0.2324 cm3·g-1 and 1.39 eV, respectively. After 4 times repeating, efficiency of tetracycline by the mesoporous TiO2 was more than 90%.The photocatalytic degradation of tetracycline were studied PVA-I modified mesoporous TiO2 as catalysts and 400W halogen lamp as light source. The influences of initial concentration, pH, and coexisting ions on the photocatalytic removal efficiency of the tetracycline were discussed. The results The results showed that degradation eflficientcy for 0.1g·L-1 tetracycline may reach 96.7% under simulated sunlight reacted 60 min catalyst dosage of 1g·L-1, pH=4, The low concentration of NO3-、SO42- and PO43- have a significant effect on degradation of tetracycline. Two probable degradation pathways were speculated according to photocatalytic degradation, the first was substituted tetracycline removal; the second was tetracycline polycyclic break.Photolysis, absorption and photocatalytic degradation of tetracycline, oxytetracycline hydrochloride, chlortetracycline hydrochloride and tetracycline hydrochloride were studied by simulated sunlight irradiation and PVA-I modified mesoporous TiO2 catalysts. The toxicity of four solution during degradation was determined. The results showed that the order of photolysis was in turn etracycline, chlortetracycline hydrochloride, tetracycline hydrochloride, oxytetracycline hydrochloride; the order of adsorption by catalysts was in turn chlortetracycline hydrochloride, tetracycline, tetracycline hydrochloride, oxytetracycline hydrochloride; the order of photocatalytic degradation was in turn tetracycline, tetracycline hydrochloride, oxytetracycline hydrochloride, chlortetracycline hydrochloride. Photocatalytic degradation of tetracycline antibiotics was a detoxification process.The early stage of the reaction, the toxicity of solution was slightly increased, toxicity of solution decreased with the growth of degradation time. Photocatalytic degradation reaction kinetics of four kinds of antibiotics were followed the first order kinetics model.