Preparation Of Flexible Titanium Dioxide-based Composite Fiber Membrane And Its Photocatalytic Degradation Of Tetracycline Wastewater

At present,there are many antibiotics pollution in the ecological environment,which are of great concern,potential harm and high risk.Antibiotic resistance genes can persist and migrate in the environment,and induce drug-resistant strains,which do more harm to the environment and human health than antibiotic residues.Photocatalytic technology is advanced and efficient for the treatment of antibiotics.It can degrade antibiotic macromolecules into non-toxic inorganic substances,CO₂ and H₂O.Catalysts play a very important role in the process of photocatalysis.Among many catalysts,semiconductor catalysts are stable and efficient.For example,titanium dioxide(TiO₂)has a wide range of sources,low price,good stability and high treatment efficiency,so it is widely used in photocatalytic treatment.However,TiO₂ is difficult to use visible light.The electron-hole pair generated by the light source has a high probability of annihilation,and it is in powder form.In practical application,it has the problem of huge energy consumption and difficult recovery,and may cause secondary environmental pollution.Aiming at the problems of TiO₂ in practical applications,this paper uses the combination of electrospinning technology,hydrothermal method and other technologies to modify TiO₂,explores the degradation effect of composite catalyst membrane materials on tetracycline(TC)under visible light,and puts forward the related mechanism.(1)TiO₂ was modified by doping Ag₂S.Firstly,TiO₂ precursor fiber membrane was prepared by electrospinning,and then Ag₂S/TiO₂ composite membrane was synthesized by hydrothermal method in one step.A series of characterizations were carried out,and the photocatalytic degradation of TC by composite membrane with different content of Ag₂S was studied under visible light.The composite membrane has good flexibility and recyclability.The degradation rate of TC of Ag0.1 composite film under visible light is70.54%,which is 1.59 times of that of TiO₂.The catalytic performance of the composite film was obviously improved under visible light.(2)In order to further explore other methods of TiO₂ modification,graphene quantum dots(GQDs)were combined with TiO₂.Firstly,GQDs solution was prepared by hydrothermal method,and then GQDs/TiO₂ composite films were prepared by hydrothermal together with TiO₂ precursor fiber films.The morphology,structure and optical properties of the composite films were characterized,and the degradation effect of the composite films with different content of GQDs on TC under visible light was studied.The results showed that the photodegradation efficiency of GT5 to TC was 71.40%in 240min,which was 1.68 times higher than that of TiO₂.The unique upconversion performance of GQDs improves the utilization of visible light,effectively inhibits the recombination of photogenerated electron hole pairs,and greatly improves the photocatalytic performance of TC under visible light.In this paper,two kinds of flexible TiO₂ based composite fiber membranes were synthesized by using electrospinning and hydrothermal methods as the main preparation techniques,and two different materials were used to modify TiO₂.They were used for the degradation of TC under visible light,which provided a reference for the future research and had practical and social significance.