Construction Of Clay-based Photocatalyst Composites And Evaluation Of Their Catalytic Performance For Removal Of Organic Pollutants In Water

In recent years,with the development of industry,environmental pollution and energy shortage have aroused great concern.Therefore,it has become a hot topic for researchers to make rational use of solar energy to treat sewage.Montmorillonite as a new green material,has a large specific surface area,high cation exchange capacity and other characteristics,widely used in adsorption,photocatalytic,etc.In this paper,the new photocatalyst AgCl-Mt and AgBr-Ag₃PO₄-Mt were designed by using montmorillonite as the carrier and by loading AgCl,AgBr,Ag₃PO₄.The catalytic activity of the catalysts was evaluated by using dye acid red 18?AR18?and methyl orange?MO?as the target pollutants,respectively under ultraviolet lamp and visible light.Through the comparison experiment,the factors that influence the catalytic efficiency of the catalyst were discussed,and the reaction mechanism of the catalytic degradation of pollutants was investigated by the inhibiting experiment.The morphology of the catalyst was characterized by means of SEM,XRD.The main content and research results are as follows:?1?Through a pot of the precursor prepared by[Ag?NH3?2]+-exchanged Mt,then using HCl gas and[Ag?NH3?2]+-exchanged Mt powder reaction,synthesized catalyst AgCl-Mt.The structure of the catalyst was analyzed by means of various characterization methods.The characteristic diffraction peaks of AgCl and Mt were also found in the XRD spectrum,and the SEM and TEM inmages were also clearly see the AgCl cubic lattice structure and Mt layer structure,AgCl on Mt surface and edge distribution layer combining closely,suggests that the AgCl-Mt successful compound.In the UV-vis spectrum,it can been see that the photoresponse range of the composite catalyst increases,indicating that the catalyst has the potential to degrade the target pollutant.This possibility is also verified in subsequent experiments.Under the irradiation of ultraviolet lamp,the catalyst AgCl-Mt couled degrade 50 mg/L dye AR18 completely at about 8 min.Under same experimental conditions,change the concentration of AR18 or AgCl-Mt,or change the pH of AR18 to explore the influence of the catalytic system.By inhibiting experiment and coumarin tracking experiment,it is concluded that in this catalytic system,the main active suvstances oxygen ions?· O2-?and holes?h+?,and the possible reaction mechanism was reasonable speculation.Although the catalytic efficiency of the catalyst decreased in the cydic experiment,the activity of the catalyst was recovered by calcination.It is shown that AgCl-Mt is a catalyst with good catalytic activity.?2?AgBr-Ag₃PO₄-Mt was prepared by precipitation deposition,and the uniform dispersion of AgBr and Ag₃PO₄ was ensured by ultrasonic and stirring in the preparation process.The catalyst was characterized by a serious of description methods.By spectrum of UV-vis,the catalyst AgBr-Ag₃PO₄-Mt has a larger light response range than the Mt,and AgBr-Ag₃PO₄-Mt can degrade target pollutants in the visible light range.The initial concentration of the dye,the initial pH of the dye and the concentration of catalyst has an effect on the catalytic efficiency.Add the corresponding inhibitor,we know that the main active substance of the catalytic system is ·O2-,h+.The reaction mechanism has also discussed.Through cyclic experiments,it is shown that AgBr-Ag₃PO₄-Mt is a stable and reusable catalyst.