Preparation Of Composite Catalyst Bimetal Of Pd/C₃N₄ And Its Catalytic Properties For The Reduction Of Nitrate In Water

With the rapid growth of population and the rapid development of the field of economy,the discharge of domestic sewage and industrial wastewater leads to the increasingly serious nitrate pollution in groundwater.However,nitrates are relatively stable in nature and are generally difficult to remove from water.Therefore,people urgently need to develop an efficient and convenient nitrate removal technology.Catalytic reduction method is a new water denitrification technology,which has the advantages of fast reaction rate,reaction selectivity,simple operation and low energy consumption.It is considered as the most potential method to remove nitrate from water.In this paper,the reduction method used for the reduction of nitrate is mainly the photocatalytic reduction method,we did the research on catalytic performance of the g-C3N4,the AgPd/g-C3N4 and the CuPd/g-C3N4 photocatalytic reduction of nitrate.And hope that more experience and methods can be provided for the removal of nitrate through the experimental expolration.Firstly,in order to reduce the amount of precious metals,we introduced the transition metal Cu into Pd NPs to form CuPd alloy structure.CuPd alloy nanoparticles were prepared by high temperature liquid phase method with OAm as solvent and reducing agent.CuPd NPs were uniformly loaded on the g-C3N4 carrier by means of ultrasonic method and osmotic method.After that,the preparation method of CuPd nanowires was changed,CuPd alloy catalyst was prepared by one-pot method.And then CuPd/g-C3N4 composite catalyst was formed by osmosis loading onto the carrier g-C3N4.The catalytic activity of CuPd/g-C3N4 composite catalyst was studied by changing the type of light source,reducing agent and different methods of surfactant removal.The results showed that the CuPd/g-C3N4 composite catalyst has excellent catalytic activity in the catalytic reduction of nitrate in water,and the removal rate of nitrate reached 71.02%.Secondly,AgPd alloy nanowires were synthesized by one-pot method in this study,and then AgPd/g-C3N4 nanocomposite was prepared by permeation method.The effect of changing the ratio of Ag and Pd precursors,the ratio of C and N of g-C3N4 and the weight of g-C3N4 carrier on the catalytic activity were studied.The AgPd,g-C3N4 and AgPd/g-C3N4 were characterized by XRD,TEM,ICP,EDS and so on.By comparing the catalytic properties of the catalysts,the composite catalyst with the best catalytic activity and highest selectivity was selected.It was found that the removal rate of nitrate was up to 87.35%,and the selectivity of N2 was up to 99%.Compared with other catalysts for catalytic reduction of nitrate in water at this present stage,AgPd/g-C3N4 composite catalyst shows quite high catalytic activity without adding any hole trapping agent to the water,and the possibility of water pollution caused by adding reducing agent is avoided from the beginning of the reaction,so it is a green and efficient catalyst.