Preparation Of Modified MoS₂ Photocatalysts And Study On Its Photocatlytic Degradation On Tetracycline

With the rapid development of China's economy and medical industry,people and livestock have began to use antibiotics extensively.Antibiotics will be discharged into the water body and remain in the soil environment,which brings a serious threat to human health.More and more attention has been paid to the treatment of antibiotic wastewater,while the traditional process of removing antibiotic wastewater is not ideal.The semiconductor photocatalytic oxidation technology can take advantage of the solar energy to remove the organic pollutants in the wastewater,so it has become the most promising technology for sewage treatment in recent years.In this paper,C-MoS₂ with the addition of surfactant cetyltrimethyl ammonium bromide?CTAB?,transition metal ion iron?Fe?,cobalt?Co?,nickel?Ni?doped MoS₂ and MoS₂/BiOBr heterojunction composite photocatalysts were prepared by hydrothermal method.The morphology,crystal structure,composition and properties of the prepared samples were investigated by means of XRD,SEM,FT-IR,UV-Vis and XPS.Using tetracycline wastewater as the target pollutant,the photocatalytic catalytic degradation of tetracycline was studied under visible light to investigate the catalytic performance of prepared photocatalysts.The main research in this paper is as follows:?1?The flower-like spherical MoS₂ was prepared by hydrothermal method and the folding rose C-MoS₂ was prepared with the addition of surfactant CTAB.The results showed that the addition of CTAB did not change the crystal structure of MoS₂,but had an important effect on the morphology and size of MoS₂.The results of SEM analysis showed that the size of C-MoS₂ was obviously smaller than the pure MoS₂,the size of C-MoS₂ was more uniform,and the wrinkle morphology also made the reactive sites more exposed.The photocatalytic degradation experiment showed that the degradation efficiency of C-MoS₂ to tetracycline was close to 50%,which was higher than that of pure MoS₂?33%?.The main reason for the improvement of photocatalytic performance is that the introduction of CTAB makes the size of MoS₂ smaller and the morphology uniform,which provides more reactive sites.?2?Fe-MoS₂,Co-MoS₂ and Ni-MoS₂ photocatalysts were prepared by hydrothermal method.Compared with the pure MoS₂,the catalytic activity of the Fe-MoS₂,Co-MoS₂ and Ni-MoS₂ photocatalysts was obviously improved,and the photocatalytic activity of 3%Ni-MoS₂ was the best,the degradation rate to tetracycline was 67.1%,which was higher than5%Fe-MoS₂?62.9%?and 3%Co-MoS₂?60.3%?.In addition,the photocatalytic mechanism of Fe-MoS₂,Co-MoS₂ and Ni-MoS₂ was discussed.The reason for the enhancement of photocatalytic activity is that the doping of transition metal ions reduces the band gap of the material,improves the absorption of light,and thus effectively promotes the separation of photoelectrons and holes.?3?MoS₂/BiOBr heterojunction composite photocatalyst was successfully prepared by hydrothermal method.SEM analysis showed that lamellar MoS₂ interspersed in the gap of BiOBr microspheres and formed heterojunction structure.The photocatalytic degradation experiment showed that 5%MoS₂/BiOBr exhibited the highest photocatalytic activity,and the degradation rate of tetracycline was close to 80%within 90 min.The enhancement of the photocatalytic performance of MoS₂/BiOBr is attributed to the formation of heterojunction structure between MoS₂ and BiOBr,which improves the responsiveness in the visible light region,and thus improves the separation efficiency of the photoinduced charge.