Prepration Of Photocatalyst Of Graphene-based Aerogel Silver Phosphate And Its Efficacy

Photocatalytic process has the characteristics of high effective degradation,energy conservation and pollution-free,therefore it’s considered as a promising wastewater treatment method.Photocatalyst is the core material.Compared with traditional photocatalysts,new photocatalysts such as Ag₃PO₄have better photoresponse capacity and higher quantum yield,so they are more likely to be applied in wastewater treatment.Because of the large specific surface area and excellent electrical conductivity,graphene is considered as an ideal material for preparing composite photocatalysts.Graphene aerogels,as the derivatives of graphene,in addition to having excellent physical and chemical properities of graphene,it also has developed pore structure.The properties make it can be used as a carrier to improve the photocatalytic performance of the photocatalyst.In this paper,the preparation method and the best preparation conditions of graphene aerogel silver phosphate composite photocatalyst（GA@Ag₃PO₄）were studied,the catalytic efficiency of the catalyst was studied with carbazepine as the typical target pollutant,the stability of the catalyst and its catalytic performance when used to simulate wastewater were analyzed.The best preparation method of GA@Ag₃PO₄is the impregnation method.The results showed that the degradation rate of carbazepine was 94.2%with GA@Ag₃PO₄prepared by impregnation method,higher than that by hydrothermal method（70.5%）.GA@Ag₃PO₄was prepared by impregnation method under the following conditions:GA proportion was 5%,GO dispersion concentration was 3.0 mg/m L,impregnation concentration was 150 g/L,impregnation time was 1.5 h.Characterization of GA@Ag₃PO₄showed that the addition of GA had positive effects on grain growth（including grain size and crystal surface proportion）,specific surface area,bond type and band gap width of the composite,thus improving the photocatalytic performance of GA@Ag₃PO₄.The factors affecting the degradation of carbamazepine by GA@Ag₃PO₄were investigated.Results indicate that the low temperature（10℃）and the weak acid（pH of about 5）is more suitable for GA@Ag₃PO₄photocatalytic degradation of carbamazepine,GA@Ag₃PO₄dosing quantity increase the degradation effect of promoting role,but the performance improvement is not obvious more than the optimal dosing quantity（700 mg/L）.Most inorganic salt ions,heavy metal ions and organic compounds have different degrees of inhibition on photocatalytic processes.The application efficiency of GA@Ag₃PO₄was studied.GA@Ag₃PO₄was used to remove carbamazepine in the simulated pharmaceutical tail water and sewage effluent,and the simulated wastewater quality weakened the degradation effect obviously.Under the same reaction conditions,the degradation rate of carbamazepine in simulated pharmaceutical tail water was 27.4%lower than that of the same concentration of carbamazepine solution,while it was 67.9%in the discharged water of simulated sewage treatment plant.Therefore,it is necessary to increase the dosage of GA@Ag₃PO₄and extend the reaction time to obtain better treatment effect.