The Mechanisms Of Antibiotic Sulfamethoxazole Degradation By Solar Photoelectro-Fenton Process

In recent years,a large volume of antibiotics and their derivatives have been discharged into environment through various waysdue to their widespread use or even abuse. It has been paid much attention on the potential harm to human health andecological security due to the occurrence of drug resistant bacteria in the environment. Because of theirs good antibacterial effect,sulfonamide antibiotics occupy a larger market share, which environmental pollution has aroused widespread concern and gradually become a research hotspot in recent years. Because these antibiotics are often non-biodegradable, conventional water treatment (biological treatment) is difficult to remove these pollutants;it is particularly necessary to develop new processesfor treating this kind of pollutants. Advanced electrochemical oxidation process can produce high activity of hydroxyl radical, can non-selectively oxidize organic pollutants, it is the ideal choice for the treatment of antibiotic wastewater. But the cost of this technology is relatively high, which may hinder its practical application. This thesis will propose to use the actual sunlight as energy and driving force, whichis a kind of green energy, using photovoltaic battery assisted solar photoelectro-Fenton process for treating sulfonamide antibiotics in the water, to achieve complete mineralization, whichis seldom reported about using this method for treatment of organic pollutants in water. In this paper, sulfamethoxazole (SMX) was chosen as the research object, and four different specific surface area of activated carbon fiber (Activated carbon fiber, ACF) as cathode, simulated solar light (Xenon lamp) and sunlight were used as irradiation source. The degradation of SMX by different oxidation processes was investigated as follows:1At first, the adsorption of SMX by the ACFs was studied, the results showed that the surface area of ACF affect the adsorption capacity, the larger specific surface area, the strongeradsorption capacity. Based on the multiple adsorption experiments by four specific surface area of ACF-1000, ACF-1300, ACF-1500and ACF-1800, the adsorption capacity follows the order of ACF1000<ACF1300<ACF1500<A CF1800. At the same time, the regeneration behavior by different oxidation process of ACF was also studied.2.The degradation of SMX by the photoelectro-Fenton under Xenon lamp condition (Xe-PEF) process was investigated using RuO2/Ti as the anode and ACF as cathode. The results show that the Xe-PEF process can mineralize SMX largely, at the optimal conditions of pH=3,0.36A, Fe2+1.0mM, O2flow rate of60mL/min, the removal rate of TOC reached73.3%, which is far higher than the anodic oxidation (AO)12.6%, the electro-generated H2O2(AO-H2O2)18.6%, Xe-AO-H2O237.4%, electro-Fenton (EF)39.5%. At the meanwhile in the sunlight conditions, solar photoelectro-Fenton (SPEF) can also mineralized SMX well,which solar photovoltaic battery was used as energy. At the optimal conditions of pH=3, A0.36, Fe2+1.0mM, O2flow rate of60mL/min, the removal rate of TOC reached63.6%. UV-Vis results show that Xe-PEF and SPEF can completely destroy SMX molecules, organic nitrogen in its molecule was transformed into ammonia nitrogen ion after SMX was degraded.3. The effect of different ultraviolet wavelength(UVA, UVB, UVC) irradiationon the PEF process on the mineralization also studied. In the UVA-PEF process, the TOC removal rateis45%, in UVB-PEF process TOC removal rate is52.5%, and the removal rate of TOC was56.4%in UVC-PEF process. The effect of initial SMX concentration, pH, current intensity, Fe2+concentration, gas atmosphere on Xe-PEF and SPEF degradation process were also investigated.4. At lasta boron doped diamond (BDD) film electrodewas used as catalytic anode for enhancing photoelectro-Fenton (Xe-BDD-PEF) degradation of SMX process. With BDD as anode and ACF as cathode, the results show that the Xe-BDD-PEF process can mineralized SMX completely, at the optimal conditions of pH=3, A0.36, Fe2+1.0mM, O2flow rate of60mL/min, the removal rate of TOC reached89.9%.In conclusion, the results show that the PEF is an efficient treatment for degradation of organic pollutants, and the SPEF using photovoltaic battery involves high efficiency, low energy consumption and easy equipment. Through the use of a catalytic anode such as BDD electrodes may achieve complete mineralization of the organic pollutant.