| Antibiotics pollution to aqueous system and ecology environment was evoked widely attention by international community. Conventional water treatment technology was not effective in remove antibiotic contamination, photocatalytic technology was supposed to be a most effective way to remove antibiotics in aqueous system.TiO2 was excellent photocatalyst with high performance, but could not utilize visible light energy (43% in the sun,400-750nm) under the sun. An addition of light source add cost, prepare visible light responsible catalyst to remove antibiotics in aqueous system is a trend in this area.TiO2 was modified and C/TiO2-SiO2 visible light responsible catalyst was prepared. TC·HCl was choose as target contaminant. The visible light responsibility of C/TiO2-SiO2 was tested by C/TiO2-SiO2 photocatalytic degradation of TC·HCl under visible light. Degradation rate analysis of catalyst in different prepare condition was studied and the best prepare condition of C/TiO2-SiO2 was optimized. C/TiO2-SiO2 was characterized; the mechanism of C/TiO2-SiO2 show visible light responsibility was studied.The optimization experiment of photocatalytic degradation of TC·HCl was designed by Response surface method (RSM) and Central composite design (CCD). Environment factor during experiments of TiO2 photocatalytic degradation of TC·HCl and C/TiO2-SiO2 photocatalytic degradation of TC·HCl under visible light was optimized; the kinetics process during degradation was analyzed.TiO2 photocatalytic degradation of Tetracycline hydrochloride (TO·HCl), Aureomycin hydrochloride (CTC·HCl), Oxytetracycline hydrochloride (OTC·HCl), Ofloxacin (OF), Sulfamethoxazole (SMZ) under UV was analyzed, active radicals during degradation process was analyzed. The role of active radicals during C/TiO2-SiO2 photocatalytic degradation of TC·HCl under visible light was analyzed, kinetics process was analyzed, C/TiO2-SiO2 photocatalytic performance was analyzed.Results were as follows:(1) C/TiO2-SiO2 has visible light response, C/TiO2-SiO2 degradation of TC·HCl under visible light was able to reach a nearly 100 percent removal in 110 minutes. C/TiO2-SiO2 degradation of TC·HCl under visible light followed pseudo-first-order kinetics according to the Langmuir-Hinshelwood model. When the preparation condition of C/TiO2-SiO2 was as:actived carbon in 2.5 percent by quality, TiO2 ratio SiO2 in 7:3, cooling temperature 573K.Catalyst C/TiO2-SiO2 has a best rate constants 0.0751 and shortest the half-life 8.51 minute in degradation of TC·HCl.The partical size of C/TiO2-SiO2 is 10～100μm, minimum diameter is 20nm, BET surface area is 5.90m2/g. C doped and SiO2 loaded extends TiO2 in response to the visible light region, improve the stability of TiO2. C/TiO2-SiO2 was able to remove TC·HCl under visible light in the photocatalytic degradation process effectively and with an considerable visible light response activity.(2) The optimized degradation condition for 20mg/L TC·HCl is:2.09g/L for TiO2 concentration,5.55 for initial pH, and 20.95 minutes for degradation time. The actual removal efficiency was 93.1%. The optimized degradation condition for 1mg/L TC·HCl is: 2.1g/L in C/TiO2-SiO2 concentration,7.9 in initial pH, and 26 minutes in degradation time. The actual removal efficiency was 96.9%.(3) The contributions of active radicals during TiO2 photocatalytic degradation of different kinds of antibiotics vary respectively. During the photocatalytic degradation of TC·HCl under UV,56.79% of degradation rate is contribute by the hVB+.Photocatalytic degradation of CTC·HCl and OTC·HCl, other reactive oxygen species (ROSs) plays important contribution which is 44.08% and 52.11% respectively. Photocatalytic degradation of OF and SMZ, ROSs only pay a very minor role, during the degradation of OF, the degradation rate of OF with 85.19% was contribute by the hVB+. The degradation rate of SMZ with 80.66% was contribute by the HO·radicals. C/TiO2-SiO2 degradation of TC·HCl under visible light,69.5% of degradation rate was contribute by the HO·radicals. |
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