| Fluoroquinolone is a widely used synthetic antibiotic.It has attracted much attention in recent years because it is continuously detected in the water environment and has potential risks to the ecosystem.Therefore,it is significant to explore the efficient removal of fluoroquinolones in water.In this paper,moxifloxacin was used as the research object.The g-C3N4@TiO2@MoS2 visible light composite was prepared based on heterojunction complex and in situ growth technique.The efficacy and mechanism of removal of moxifloxacin in water by g-C3N4@TiO2@MoS2 were investigated.We hope that it could offer us ideas and solutions for moxifloxacin removal from aquatic water environmentIn this paper,g-C3N4@TiO2@MoS2 was prepared by introducing two layered narrow band gap materials of g-C3N4 and MoS2 into TiO2 nanomaterials.The physical and chemical properties of the materials were characterized by X-ray diffraction,Transmission electron microscopy,UV-visible diffuse-reflectance spectrum,Fourier transform infrared spectroscopy,X-ray photoelectron spectroscopy and Raman spectroscopy.The composite was found to be anatase with a band gap of 2.71 eV and a specific surface area of 145.58 m2/g,which indicating that g-C3N4@TiO2@MoS2 has both visible light catalysis and good adsorption properties.The adsorption process of g-C3N4@TiO2@MoS2 composite for the removal of moxifloxacin was studied.The adsorption kinetics,adsorption isotherm and adsorption thermodynamics were analyzed.The fitting results showed that the composite adsorption of moxifloxacin combined with physical adsorption and chemical adsorption,in line with the second-order kinetic equation.The equilibrium adsorption capacity qe increases with the increase of moxifloxacin concentration,and decreases with the increase of dosage,reaching a maximum of 19.96 mg/g.We also investigated the effects of pH,humic acid,anion and cation on the adsorption efficiency of the composite.It was found that the adsorption efficiency was greatly affected by pH.Compared with the neutral conditions,the removal rates under acidic and alkaline conditions were significantly decreased.Mainly because pH affects the dissociation of moxifloxacin and the surface charge of the material.It was also found that when the concentration of humic acid increased from 0.605 mg/L to 4.840 mg/L,the overall removal rate of moxifloxacin by g-C3N4@TiO2@MoS2 decreased first and then increased.The efficacy,reaction kinetics,influencing factors and photocatalytic mechanism of g-C3N4@TiO2@MoS2 visible photocatalytic degradation of moxifloxacin were also studied.The results showed that the photocatalytic degradation of moxifloxacin followed the pseudo first-order kinetic reaction.Moxifloxacin was completely degraded after 100 min of photocatalytic reaction,but the mineralization rate was only 42.4%.pH and anion have a great influence on the reaction process,mainly affecting the dissociation of moxifloxacin and the surface charge and free radical formation of the material.The photocatalytic degradation reaction product of moxifloxacin was analyzed by LC-MS.Combining the charge distribution and the electrostatic potential extreme value of moxifloxacin based on density functional theory.It is concluded that visible light catalyzes the degradation pathway of moxifloxacin.The study of free radical mechanism shows that·O2-and·OH plays a major role in the visible light catalysis process.The luminescent bacteria toxicity test found that the visible light catalytic degradation of g-C3N4@TiO2@MoS2 material can reduce the biological toxicity of the reaction system. |
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