Construction Of Efficient Cationic Dye Degradation Reaction System Based On Self Oxidation Process

Cationic dye wastewater has the characteristics of complex composition,high COD concentration,low p H,high chroma,and poor biodegradability.Traditional treatment methods are difficult to achieve discharge standards.Studies have shown that cationic dye molecules have self-oxidation characteristics.Dye molecules will generate electron and hole pairs after absorbing a specific wavelength of visible light.The electrons will be transported to the surface of the material in contact with them,and the holes will oxidize themselves.Therefore,the effective separation of electrons and holes is the key to determining the self-oxidation of dye molecules.There are two factors that limit self-oxidation:（1）The adsorption of semiconductor and the efficiency of electron injection into their surface;（2）The number of characteristic wavelength photons that the dye molecule can absorb.In this study,a cationic dye wastewater degradation system was constructed based on the self-oxidation characteristics of dye molecules.The self-oxidation of cationic dye wastewater was promoted by using semiconductors with high adsorption and charge implantation properties and characteristic light conversion films.This work is mainly carried out from the following two aspects:（1）The excellent adsorption performance and electron injection efficiency of semiconductor materials are necessary conditions for dye molecules to realize self-oxidation.In this design,triphasic Ti O₂ was successfully prepared by hydrothermal method by adjusting the amount and ratio of hydrochloric acid and acetic acid.Then the surface was modified with phosphoric acid to obtain a semiconductor material with good adsorption and electron injection performance.Experimental results show that the surface modification of H₃PO₄ on the triphasic Ti O₂ can effectively improve the electronegativity of the semiconductor surface,thereby achieving efficient adsorption of cationic dyes.The effective contact between the two also provides a channel for the electron transport of the cationic dye molecule,thereby improving the separation efficiency of its electrons and holes.Compared with the photolysis of dyes under natural light irradiation,after adding H₃PO₄ to modify the triphasic Ti O₂ semiconductor,the degradation efficiency was increased by 23.14times.（2）The self-oxidation of dye molecules needs to absorb visible light of characteristic wavelength.Increasing the number of photons of visible light of characteristic wavelength can further promote the efficiency of self-oxidation of dye molecules.Zn O quantum dots（Zn O-QD）with blue,green and yellow luminescence characteristics were prepared by the sol-gel method,and mixed into PDMS to prepare a highly transparent film with ultraviolet light conversion effect.The results show that the ultraviolet light conversion film can stably convert most of the ultraviolet light into visible light with a characteristic wavelength.In the cationic dye self-oxidation degradation experiment,the degradation efficiency increased by 8.8%after using the Zn O-QD ultraviolet light down-conversion film.This design makes full use of the self-oxidation characteristics of cationic dye molecules to construct a degradation reaction system,which effectively solves the problems of charge transfer and light absorption of cationic dye molecules.This work provides a reference for the efficient treatment of cationic dye wastewater.