Study On The Chemical Process Of Carbon-loaded Graphite-phase Carbon Nitride On The Degradation Of Petroleum Hydrocarbon In Soil

In this paper,the biochar was prepared by using agricultural and forestry wastes in Northeast China as raw materials.Melamine,which is cheap and easy to obtain,was selected as the raw material of graphite phase carbon nitride.A simple thermal synthesis method was used to load the two substances.The supported catalyst C/g-C₃N₄ can not only possess both the adsorption ability of biochar and the photocatalytic ability of graphite phase carbon nitride,but also improve the specific surface area of graphite phase carbon nitride.The energy band gap of graphite phase carbon nitride is increased,and the range of visible light is increased,which is more favorable for the effective removal of pollutants in the field of environmental purification.Soybean straw and corn cob were selected as raw materials for the preparation of biochar.The yield,pH,carbon content and nitrogen content of biochar prepared by different calcination temperature and calcination time were compared and the optimum calcining conditions were determined.It was found that calcination temperature of 500?and calcination time of 3 h could be used as the optimum preparation conditions of biochar after auxiliary testing with SEM.When the adsorption time was 30 days,the removal rates of soybean straw biochar and corn cob biochar were 51%and 45%,respectively.Graphite phase carbon nitride was prepared with melamine as precursor and various characterization methods were used to determine the product.The prepared g-C₃N₄ was used for photocatalytic degradation of soil petroleum hydrocarbons.Under 5 h illumination,the degradation rate of soil petroleum hydrocarbons was 40.1%.Compared with biocarbon adsorption,g-C₃N₄ was used as photocatalyst for degradation of petroleum hydrocarbons.It can significantly shorten the reaction time.Based on the results obtained,the biochar prepared under two optimal conditions was used as the carrier for the preparation of composite photocatalyst C/g-C₃N₄,and its characterization and determination were carried out.It is proved that the prepared catalyst is the desired target product and does not destroy the single component structure.The composite photocatalyst was used for photocatalytic degradation of soil petroleum hydrocarbons.When the illumination time was 5 h,the ratio of biocarbon to melamine was 1:2,and the amount of catalyst was 1.5%.The degradation rates of soil petroleum hydrocarbons by C_{soybean straw}/g-C₃N₄ and C_{corn cob}/g-C₃N₄ were 67.4%and 57.3%,respectively,which were higher than that of single component.Finally,microwave thermal remediation combined with catalyst was used to further enhance the effective degradation of petroleum hydrocarbons in soil.C?g-C₃N₄ and C/g-C₃N₄ were used as catalysts for the experimental determination.When the radiation time is 10 min,catalyst dosage is 5%and soil moisture content is 15%,the degradation rate of C_{soybean straw}/g-C₃N₄ to petroleum hydrocarbon can reach 91.5%,which greatly shortens the reaction time and improves the reaction efficiency.It has a high influence on the follow-up development of this experiment.