The Preparation And Purification Mechanism Of Graphene Based Antibacterial Materials

Antibacterial nanomaterials have been widely concerned in drinking water disinfection because of their good sterilizing effect and no harmful by-products. Graphene oxide ?GO? has large surface area, good water disperisibility and abundant surface functional groups, so the surface modification of GO has become a hotspot of current research. Titanium dioxide ?TiO₂? and silver ?Ag? nanoparticles are the two most studied antimicrobial agents in the present study. In this paper, nanocomposites based on GOmodified TiO₂ and Ag were prepared to overcome the photo-generated hole electron recombination, the low photocatalytic activity,the separation from water of TiO₂ and the agglomeration in water of Ag. Firstly, GO was prepared and used as a substrate material to prepare magnetic graphene oxide-TiO₂ ?MGO-TiO₂? and GO-Ag by ultrasonic dispersion and chemical reduction methods, respectively. The synthesized MGO-TiO₂ and GO-Ag composites were characterized by TEM and SEM. The results demonstrated that TiO₂ and Ag nanoparticles were uniformly dispersed on the surface of GO. The photocatalytic properties of MGO-TiO₂ were analyzed by Ultraviolet-visible spectrometer ?UV-vis?. Results showed that, compared with the pure TiO₂, the MGO-TiO₂ nanocomposite's light utilization efficiency was improved obviously. In addition, the vibrating sample magnetometer experiment proved that MGO-TiO₂ can be easily separated from the water. GO-Ag particle size analysis showed that GO-Ag had a good dispersion in water.The activity of MGO-TiO₂ compound as disinfectant against Escherichia coli ?E. coli? was investigated. The researched method was plate counting.The MGO-TiO₂ composite showed high disinfection activity against E.coli. When the concentration of MGO-TiO₂ was 180 mg/L, the antibacterial rate of E. coli reached 99.99% after 30min. Besides, the effects of inorganic ions present in E. coli suspension were also evaluated. Compared with other ions, HCO3- and HPO42- had a greater influence on the antibacterial property. The activities of GO-Ag compound as an antibacterial agent against E. coli and Staphylococcus aureus ?S. aureus? were investigated. GO-Ag had a strong antibacterial activity against both. When the concentration of GO-Ag was 200 mg/mL, the antibacterial rate of E.coli and S.aureus reached 99.99% after 25min. In this study, we also made a discussion about the disinfection mechanism of GO-Ag. The effective antibacterial properties of MGO-TiO₂ and GO-Ag indicate that MGO-TiO₂ and GO-Ag are promising candidates in water disinfection treatment.