Novel Crayfish Shell Biochar Nanocomposites Loaded with Ag-TiO2 Nanoparticles Exhibit Robust Antibacterial Activity

Abstract

A fast sol-dipping-gel method was applied to load Ag and TiO2 nanoparticles on the surface of crayfish shell biochar to make an inexpensive and novel nanocomposite. Tetra-n-butyl titanate (Ti(OC4H9)4) and silver nitrate (AgNO3) were used as the nanoparticle precursors. Crayfish shell was pyrolyzed to produce the biochar host. Paper-disk diffusion method was applied to measure antibacterial activities of the nanocomposites to E. coli. The maximum loading rate of TiO2 and Ag nanoparticles on the biochar reached 7.54% and 3.20%, respectively. Results of long-term antibacterial effect experiment showed that the Ag-TiO2-biochar had robust antibacterial activity and could be reused for multiple times. The inactivation of E. coli of initial concentration of 105 CFU/mL by Ag-TiO2-biochar under solar light reached around 99% of sterilization ratio in 5 min. In addition, the antibacterial ability of the nanocomposite was better in light than that in dark due to the presence of TiO2. Findings of this study suggest that the novel nanocomposite is a promising material for water treatment units and household water purifiers.