Preparation And Performance Study Of In-situ TiO₂ Composite Photocatalytic Material

The treatment of dye wastewater has always been an issue of keen concern to the society,which can seriously endanger the ecological safety if not properly handled.The TiO₂-based photocatalytic oxidation technology is expected to be a green,environmentally friendly,safe and efficient wastewater treatment method.Meanwhile,to solve the problem that photocatalysts are prone to secondary pollution and difficult to be recycled,it is proposed to load photocatalysts onto suitable substrates to obtain monolithic photocatalytic materials.In this paper,TiO₂ series composite photocatalytic materials were prepared by in-situ growth method using polydopamine as template and cotton fabric and melamine foam as substrate,and their performance in degrading methylene blue（MB）and antibacterial properties were investigated.The main results of the study are summarized as follows.（1）The cotton fabric was used as a matrix to form a polydopamine film on the fabric surface through the dopamine self-polymerization process,and the Ag/TiO₂@cotton was prepared by in-situ synthesis of TiO₂ nanoparticles on the fabric surface using its chemical properties and reduction of Ag⁺with the aid of the amino group of polydopamine.The physical phase,elemental valence and morphology of modified fabrics are tested by SEM（scanning electron microscope）,XRD（X-ray diffractometer）,PL（photoluminescence spectroscopy）,TG（thermogravimetric curve）and other characterization means,and methylene blue（MB）was used as a simulated pollutant for photocatalytic degradation experiments.The results showed that the photocatalytic degradation experiments were carried out in the visible light area,and the removal rate of MB by the composite fabric could reach 85.6%when the degradation proceeded to 210 min,and the apparent rate constant of the degradation process was calculated as K=0.00863 min^-1 using the quasi-level kinetic equation,indicating that the Ag/TiO₂@cotton has good photocatalytic efficiency.The results of the inhibition experiments for E.coli and S.aureus showed that the Ag/TiO₂@cotton exhibited certain antibacterial properties with inhibition circle radii of 2.67 mm and 2.72 mm for the two bacteria,respectively.（2）The melamine foam（MF）was used as a substrate,and nano BiVO₄ synthesized by hydrothermal method was introduced in the process of dopamine self-polymerization.The polymerized polydopamine（PDA）film wrapped BiVO₄ uniformly on the sponge substrate,and then TiO₂/BiVO₄@MF was prepared by in situ deposition method to grow nano TiO₂ on the surface of BiVO4@MF.The microscopic morphology and chemical state of TiO₂/BiVO₄@MF was characterized by SEM,XRD,FTIR（Fourier infrared spectroscopy）and PL,and methylene blue（MB）was used as a simulated pollutant for photocatalytic degradation experiments.The results showed that the TiO₂/BiVO₄@MF was subjected to MB degradation experiments under visible light irradiation,and the removal rate of MB was 94.06%when the experimental reaction was carried out to 190 min.The apparent rate constant of the degradation process was calculated as K=0.01562 min^-1 by using the quasi-level kinetic equation.after three cycles of experiments,the photocatalytic efficiency of the TiO₂/BiVO₄@MF reached 72.81%,indicating that the composite material has high photocatalytic efficiency and good cycling stability.