Study On Catalytic Activity Enhancement And Selective Removal Of Dye Wastewater By G-C₃N₄ Composite Modified TiO₂

The titanium-based photocatalytic material TiO₂ has the advantages of good catalytic activity,stable chemical properties,and low price.It is considered to be the most promising photocatalytic material.However,due to its weak adsorption and selection properties,it has been greatly restricted in actual sewage treatment.In recent years,it has been found that by adjusting the surface charge of TiO₂,it can exhibit better selectivity and adsorption,but its catalytic activity has declined.Based on this,this paper takes TiO₂ modified by Na2CO3 as the research object,and uses polymer semiconductor g-C₃N₄ as a composite material to prepare a composite modified TiO₂ nanocatalytic material by solvothermal method,in order to maintain its good selectivity and adsorption The premise of improving the catalytic activity of TiO₂.This article focuses on the following:?1?TiO₂ nanomaterials with different g-C₃N₄ composite ratios were prepared by solvothermal method.Photocatalytic experiments were performed with typical dyes as target pollutants to investigate the optimal g-C₃N₄ composite ratio and the catalytic activity of composite TiO₂ nanomaterials.The experimental results show that the catalytic effect is best when the composite ratio of g-C₃N₄ is 15%,and the photocatalytic reaction for 90 min,the removal rate of active yellow by composite TiO₂ is as high as 93.9%,while that of pure TiO₂ is only 65%.The dark reaction adsorption for 15 min,the composite TiO₂ adsorption and removal rates of basic fuchsin and methylene blue reached 86.13% and 87.52%,while the active yellow adsorption and removal rate was only 4.62%,the composite TiO₂ showed selective adsorption capacity for cationic dyes.?2?The cationic dyes basic magenta and methylene blue were used as target pollutants for adsorption and removal experiments to study the adsorption performance and mechanism of composite TiO₂ nanomaterials.The experimental results show that the dye adsorption process is controlled by the diffusion step and the chemical adsorption mechanism.The adsorption process of basic fuchsin is a kind of adsorption dominated by chemical adsorption,which is greatly affected by temperature,and its separation coefficient RL is increased by temperature.It is 1.285 ? 1.333 times;the adsorption process for methylene blue is a chemical adsorption dominated by single moleculeadsorption,which is less affected by temperature,and the increase of its separation coefficient RL by temperature is only 1.077 ? 1.103 times.?3?A mixed solution of anionic,cationic dye active yellow and basic fuchsin was used as the target pollutant,and the selective removal ability of the composite TiO₂ nanomaterials was investigated through dark environment adsorption and photoenvironment catalysis.The experimental results show that the composite TiO₂ catalyst shows selective removal of basic fuchsin with a selectivity coefficient of 5.09,which is 5.3 times that of pure TiO₂.Our results of this study show that the composite catalyst obtained by g-C₃N₄ composite modification of TiO₂ can improve the catalytic activity of TiO₂ while maintaining the better selectivity and adsorption of modified TiO₂,which has great practical significance in the field of catalytic water treatment.