Study On Fabrication And Photocatalytic Performance Of Biomass Carbon/titanium Dioxide Composite

The rapid development of industry has made the problem of water pollution more and more serious.The existence of organic pollutants in water bodies seriously endangers the ecological environment and the health of humans.Photocatalysis is a green and effective advanced oxidation technology to solve the above problems.The TiO₂ semiconductor photocatalyst is widely studied because of its low cost,high thermochemical stability,simple structure and easy control,and suitable electric potential.However,TiO₂ can only absorb ultraviolet light,the utilization rate of sunlight is too low,and the recombination rate of photo-generated electrons and holes is relatively high.Therefore,TiO₂ needs to be modified to improve its photocatalytic degradation activity.Biomass carbon has a natural composition and structure,with a wide source,low cost,simple preparation and excellent electrical conductivity.The composite of TiO₂ and biomass carbon material can not only improve the photogenerated electron transfer efficiency of TiO₂,but also form the synergistic effect of adsorption-catalysis degradation to promote the removal of organic pollutants.At the same time,doping TiO₂ with non-metallic elements can effectively reduce the band gap width,make the light absorption edge red shift,and enhance the response to visible light.Therefore,in this study,TiO₂ semiconductor photocatalyst was composite with different biomass carbon materials and doped with non-metallic elements to study its degradation performance of organic pollutants.The main content is as follows:（1）Sulfate lignin is extracted from reeds,the viscosity of the lignin solution is adjusted by introduced on the surface of the TiO₂ particles after carbonization treatment to prepare ultra-thin carbon coated TiO₂ composite photocatalyst（TiO₂@C）.The results show that the conductivity of the carbon layer can promote the rapid transfer of photogenerated electrons,and reduce the band gap width of TiO₂,which increases the response of the catalyst to visible light.The ultra-thin carbon layer ensures light penetration into TiO₂ and makes the TiO₂@C catalyst hydrophobic and loose structure,so that it can float on the water surface,and can be in contact with wastewater while ensuring full absorption of sunlight.TiO₂@C has good photocatalytic activity for methylene blue（MB）and tetracycline（TC）.Under dynamic environment（300 rpm）,MB and TC can be almost completely degraded in 10 min and 35 min,respectively.（2）C,N co-doped TiO₂-supported biomass carbon composite photocatalyst（C,N-TiO₂@ACG）was prepared by sol-gel and carbonization method using tetra-butyl titanate as titanium source and carbon source,nitric acid as nitrogen source and coffee grounds carbon as porous carbon precursor material.The results showed that:Loaded with biological carbon and doped with non-metallic elements C,N narrowed the band gap of TiO₂ from 3.31 eV to 2.34 eV,greatly improving its photocatalytic activity.The degradation rate of 1:1 C,N-TiO₂@ACG on MB can reach 97%within 45 min,which is much higher than that of pure TiO₂（58%）,and has good cycle stability.1:1 C,N-TiO₂@ACG also has excellent degradation ability to methyl orange and MB mixed dye（MOMB）.This work provides an extensible method and theoretical basis for the development of TiO₂ supported biomass carbon composite photocatalyst.