Tea Polyphenols Functionalized and Reduced Graphene Oxide-ZnO Composites for Selective Pb²⁺ Removal and Enhanced...

New materials with good purification of water quality (heavy metal ions removal and inhibition of bacteria) have increasingly attracted more research attentions. Considering the advantages of zinc oxide (ZnO) and tea polyphenol functionalized and reduced graphene oxide (TPG), the TPG-ZnO composites were prepared under moderate hydrothermal method and characterized by various methods. Lead ions (Pb2+) and Streptococcus mutans (S. mutans) were used to evaluate the adsorption capacity and antimicrobial activity of the TPG-ZnO, respectively. The influencing factors for heavy metal ions removal (pH, contact time), adsorption kinetics, and isotherms were discussed in this article. Furthermore, their antibacterial properties against S. mutans were investigated by counting of colony-forming units (CFU), scanning electron microscope (SEM) and confocal laser scanning microscopy (CLSM). Results showed that the novel TPG-ZnO composites presented higher adsorption efficiency for Pb2+ (98.92%) compared with pure ZnO and enhanced antibacterial activity effects (99.99%) towards S. mutans, compared with pure ZnO and TPG (P < 0.05). The TPG-ZnO composites are therefore promising water purification materials for application in high-efficient removal of heavy metal ions and inhibition of bacterial growth.