Photocatalytic Performance Of Composite Photocatalyst For Degradation Of Tetracycline Under Visible Light Irradiation

With the development of the livestock and poultry breeding industry,and the excessive use of antibiotics,livestock and poultry breeding wastewater has become the main source of antibiotic pollution.Photocatalytic technology can degrade organic pollutants while making full use of solar energy,which is one of the effective ways to solve the problems of environmental pollution.Therefore,based on the current situation of increasing antibiotic pollution in livestock and poultry wastewater,we took the tetracycline(TC)as a typical representative of antibiotics,synthesized an efficient TiO2@g-C3N4(TCN)photocatalyst at first,then immobilized it by electrospinning technology to achieve efficiently degradation of tetracycline in livestock and poultry breeding wastewater while facilitating recycling of the catalyst.First,an in-situ synthesis method was used to prepare photocatalyst TCN with a special core-shell structure(shell thickness was about 5-10 nm).The quantum effects of g-C3N4 shell and the formation of tight and uniform heterojunction,effectively improved the charge transfer performance.The TCN photocatalyst exhibited excellent photocatalytic performance and the degradation efficiency of tetracycline was up to 96.5%in 4 h under visible-light irradiation.Moreover,TCN had good stability.Second,a PVDF-TCN electrospun fiber was fabricated by using electrospinning technology to achieve the immobilization of the catalyst.The PVDF-TCN fiber was composed of nanofibers and the diameter was about 300-400 nm.The results of WCA and FTIR demonstrated that the electrospun fiber was extremely hydrophilic which could effectively mitigate the fiber pollution.The PVDF-TCN-0.2g fiber exhibited excellent photocatalytic performance and the degradation efficiency of tetracycline was as high as 97%in 300 min under visible-light irradiation.The reaction kinetics conformed to the quasi-first order kinetic model.In addition,the PVDF-TCN-0.2g electrospun fiber exhibited good stability after cycles experiments.Last,in order to effectively improve the catalyst dispersibility and reduce th e catalyst entrapment,the surfactant sodium dodecylbenzenesulfonate(SDBS)was introduced to prepare the SDBS-PVDF-TCN electrospun fiber,which composed of bonded scaffold nanofibers and two-dimensional(2D)nanonets.1%SDBS-PVDFTCN-0.1g electrospun fiber exhibited excellent photocatalytic performance and the degradation efficiency of tetracycline was up to 95.8%in 300 min under visible-light irradiation,and it had good stability.In this study,the TiO2@g-C3N4 photocatalyst was immobilized by using electrospinning technology to make it not only had excellent photocatalytic performance for degradation of tetracycline in livestock and poultry breeding wastewater,but also facilitated recycling of the catalyst.Therefore,we believed this study provided a new strategy in catalyst immobilization and wastewater treatment.