Adsorption And Degradation Of Tetracycline Hydrochloride Wastewater By Low Temperature Plasma And Catalyst

With the continuous improvement of residents medical level,the pollution problem caused by the frequent use of various drugs has become increasingly prominent.Among them,antibiotics are widely detected in the water environment,which poses a huge threat to human physical and mental health and the aquatic ecological environment.Therefore,the removal of antibiotics in wastewater is of great significance.Novel oxidation technologies for the treatment of antibiotic pollutants in wastewater by utilizing a large number of reactive oxidizing substances generated during the dielectric barrier discharge（DBD）plasma discharge process have received extensive attention.However,this technology is limited by factors such as low energy utilization and insufficient salinity,resulting in limited removal of antibiotic pollutants in wastewater.Therefore,in this study,granular activated carbon（GAC）was used as a carrier to prepare TiO₂/GAC by a sol-gel method,and it was combined with DBD plasma technology to fully utilize the ultraviolet light generated during the reaction process.At the same time,it promotes the conversion of O₃and H₂O₂to hydroxyl radicals（·OH）.The influence factors and degradation mechanism of the composite oxidation technology on the degradation process of tetracycline hydrochloride simulated antibiotic wastewater were studied.The main research conclusions are as follows:（1）The effects of different factors on the degradation of tetracycline hydrochloride by DBD system were explored.The experimental results show that the degradation rate of tetracycline hydrochloride increases with the increase of input power,but when the initial concentration of the solution,the discharge distance and the initial conductivity of the solution increase,the degradation rate gradually decreases.When increasing,the degradation rate of tetracycline hydrochloride first increased and then decreased.Under the optimal conditions,the DBD system was treated for 30 min,the degradation rate of tetracycline hydrochloride was 83.1%,and the COD removal rate was 30.1%,and inorganic salts and acidic substances were generated during the treatment.（2）Orthogonal optimization experiment was carried out on the preparation conditions of TiO₂/GAC,and the best preparation conditions were obtained as follows:calcination time 180 min,calcination temperature 450℃,initial p H of solution hydrolysis was 3,dosage of tetrabutyl titanate was 10 m L.After activation of GAC,the specific surface area,total pore volume and total amount of surface acid groups were greatly improved.The loading of TiO₂led to a decrease in the above parameters,but it was still better than that of unactivated GAC.（3）The results show that there is a synergy between the DBD system and GAC and TiO₂/GAC,but the synergy strength will weaken with the progress of the reaction.Among them,the synergistic effect of TiO₂/GAC is better than that of GAC,and the maximum synergistic strengths between DBD plasma technology and activated GAC and TiO₂/GAC are 21.45 and 54.18,respectively.When TiO₂/GAC was used as the catalyst,under the optimal conditions,the degradation rate of tetracycline hydrochloride was 97.7%and the COD removal rate was 71.5%at 30 min.The optimal conditions were optimized using the response surface method.The optimized experimental conditions were as follows:the initial concentration of the solution was100 mg/L,the circulating flow was 85.47 m L/min,the input power was 95.17 W,the discharge distance was 6 mm,the initial p H of the solution was 8.67,and the initial solution was 8.67.The conductivity is 58μs·cm^-1,and the dosage of TiO₂/GAC is4.38g.（4）The degradation effect of DBD plasma and TiO₂/GAC was repeated by 7.4%after five repeated experiments.The degradation of tetracycline hydrochloride by this synergistic system was the result of the joint action of various active oxidizing substances.Among them,O₃can not only directly react with the target substance,but also can be converted into·OH for indirect oxidation,while H₂O₂can only be indirectly converted into·OH to oxidize the target substance.Combined with the analysis results of intermediate products,it is indicated that under the action of active oxidizing substances mainly composed of·OH,tetracycline hydrochloride undergoes reactions such as hydroxylation,ring opening and demethylation,and finally is mineralized into inorganic small molecules.