Preparation, Characterization And Mechanism Study Of Molybdenum-containing Photocatalytic Antibacterial Materials

Most of the compound organic dyes used in leather,cosmetics,papermaking,printing,textile and other industries are toxic and not easily decomposed by microorganisms.Improper treatment of wastewater from these industries will lead to large-scale water pollution.In addition,there are a large number of bacteria(such as seabacterium and Bacillus,etc.)in the wastewater,even after death,there will still be residual,release endotoxin substances,cause typhoid and cholera,causing secondary pollution to the environment.With the widespread use of antibiotics,bacterial resistance has also increased.Compared with the clinical application of antibiotics,the new biomaterials have a broad application prospect because of their high antibacterial activity,good biocompatibility and difficulty in producing drug resistance.It is well known that traditional TiO₂ photocatalysis materials exist nanoparticles easy reunion,surface area is small,light raw electronic-hole some shortcomings of restructuring faster,adsorption performance,compared to new biological photocatalytic materials more flexible in terms of structure,the selectivity of metal atoms more,therefore,the molybdenum element with higher visible light utilization was selected for the following experimental discussion.This study first half adopts the method of combining theory with experiment.The silica gel was prepared from sodium silicate and sodium bicarbonate using micron mesoporous SiO₂ as the carrier with excellent physical and chemical properties,high thermal stability and large specific surface area.A new hybrid photocatalytic antimicrobial material(MoO₃@SiO₂)was prepared by loading the rhombic phase MoO₃ onto the surface of silica gel by sol-gel method.While giving certain properties,the basic structure and morphology of silica gel were not changed.The results of single factor experiment showed that the best performance of MoO₃@SiO₂ hybrid material was obtained when the temperature was 90?,the p H was between 5 and 6,the reaction time was 1 h,and the molybdenum ion added concentration was 1.19 mol/L.At the same time,XRD,ICP,SEM,EDS,XPS and BET were used to characterize the crystal structure,apparent morphology,loading form and specific surface area of the material.The results show that:Molybdenum photocatalytic antibacterial material was successfully prepared without changing the structure and morphology of silica gel,and the bactericidal effect on Escherichia coli under the best preparation condition was over 99%;98%of the dyes can be degraded after 240 min of continuous irradiation with UV-light,and 93.5%after 360 min of continuous irradiation with visible light.After the expected material was successfully prepared and its performance was tested,it was found that compared with the traditional antibacterial agents,molybdenum-based photocatalytic antibacterial agents had problems such as unclear antibacterial mechanism and unsatisfactory antibacterial effect.Therefore,in the second part of this paper,combined with the experimental results of the previous part,a new experiment was designed by taking full advantage of the advantages of small band gap energy of molybdenum element and good catalytic effect under visible light.Using simple hydrothermal method,copper ion and silver ion were introduced to modify the material to improve the antibacterial rate,and the rod-like copper molybdate(Cu₃Mo₂O₉)and layered silver molybdate nanomaterials(Ag₂MoO₄)were successfully prepared.The crystal structure,morphology,elemental composition and thermal stability of the material were analyzed.The results show that the prepared Cu₃Mo₂O₉ and Ag₂MoO₄ hybrid materials have better antibacterial properties and photocatalytic activity than the hybrid materials.Finally,combined with the experimental results of lipid peroxidation and respiratory chain dehydrogenase activity,it was comprehensively judged that the antibacterial mechanism of the material was mainly ion sterilization,assisted by the synergistic sterilization of some reactive oxygen species produced by the material and medium acidification.The photocatalytic antimicrobial material designed in this experiment is expected to be an antimicrobial agent for cleaning microbial polluted water environment.In addition,the work in this paper further deepened our understanding of the antibacterial mechanism of Cu/Ag-molybdate.