Preparation And Application Of G-C₃N₄ Composites

With the development of modern industry and agriculture has brought serious water pollution problems.Biochar as a traditional adsorbent has the advantages of large specific surface area,low cost,non-toxic and good stability.However,its weak adsorption capacity limits its application in the field of pollution control.In recent years,photocatalysis technology is an effective way to control water pollution.g-C₃N₄ is a popular semiconductor material in the field of photocatalysts,which has a better sewage treatment ability than activated carbon.In addition,g-C₃N₄ has a suitable band structure and a good chemically stable structure.However,g-C₃N₄ also has some disadvantages,such as small specific surface area,photogenerated electrons and holes recombine easily,and insignificant photocatalytic efficiency.In view of these shortcomings,g-C₃N₄ was combined in this study with other materials to increase the specific surface area of g-C₃N₄,improve the separation efficiency of photocarriers,and enhance its photocatalytic activity.In addition,the introduction of h-BN with unique electronic properties will improve the adsorption of BC and the photocatalytic efficiency of g-C₃N₄.The specific contents are as follows:?1?Activated carbon adsorbent was prepared from pomelo peel?PP?by activation with sodium hypochlorite wastewater.The effects of such factors as carbonization temperature,concentration and activation time of sodium hypochlorite wastewater,activation temperature and time in high temperature upon the activated carbon yield and adsorption abilities have been investigated via L16?4⁵?orthogonal experiment.The performance of activated carbon products had been characterized by SEM,IR,XRD etc.The results show that the yield,iodine adsorption and methylene blue adsorption value of the prepared activated carbon are33.87%,875 mg/g,218.6 mg/g respectively under the condition of the optimal preparation of activated carbon.The methylene blue adsorption value is more than the national first-class standard of granular activated carbon from wood gourmet powder.?2?The preparation,characterization and removal capability of converting a novel waste biomass into value-added hierarchically porous carbonaceous sponges and their g-C₃N₄/CS composites were described.Possessing hierarchically porous structure,extreme large surface areas and special chemical bonds,g-C₃N₄/CS composites had demonstrated advantages in adsorption and photocatalytic activities.The adsorption and photocatalytic activities of the as-prepared catalysts were evaluated by the degradation of RhB,MO,Phenol.The best results exhibited that 97%decomposition of RhB was obtained by using g-C3N4/CS-60 composites within 20 min at 25°C under visible light irradiation.Besides,the g-C3N4/CS-60composites showed remarkable regeneration stability,which maintains high photocatalytic activity after the samples saturated.Furthermore,the degradation mechanisms of RhB and the photocatalytic mechanism had been explained in this paper.?3?BN/g-C₃N₄ composites were prepared by hydrothermal reaction.The BN/g-C₃N₄composites were successfully characterized by FTIR spectra,XRD,SEM,HRTEM,UV/Vis DRS,N2 adsorption–desorption isotherms and BET.The photocatalytic activities of the as-prepared catalysts were evaluated by the degradation of different organic pollutants,such as Acid Red?AR?,Rhodamine B?RhB?,Congo Red?CR?,Methyl Orange?MO?,Methyl Red?MR?,and Phenol.The best result showed that the 40 wt%BN was added to g-C₃N₄?BN/g-C₃N₄-4?achieved up to 99%decomposition of AR within 90 min under visible-light irradiation.The kinetics of BN/g-C₃N₄-4 for degradation of AR was almost six times than that of pure g-C₃N_4.Finally,the degradation processes of different pollutants and the photocatalytic mechanism had been explained concretely.?4?The preparation,characterization and removal capability of a novel biomass derived BC and their nanocomposites BCN were described.Possessing hierarchically porous structure,extreme large surface areas and special chemical bonds,porous BCN nanosheets had demonstrated advantages in adsorption and photocatalytic activities.The adsorption and photocatalytic activities of the as-prepared catalysts were evaluated by the degradation of RhB.And the best results exhibited that 97%and 95%decomposition of RhB were obtained by using porous BCN-40 nanosheets within 120 min at 25°C under UV light and visible light?>420 nm?irradiation respectively.The kinetic of porous BCN-40 nanosheets for degradation of RhB was more 16 times than that of pure h-BN.Besides,the porous BCN nanosheets showed remarkble cycling stability,which maintains high photocatalytic activity up to 94%after 5 cycles.Furthermore,the degradation mechanisms of RhB and the photocatalytic mechanism had been explained in this paper.