Effect of Zn Content on Physicochemical Characteristics, Photocatalytic Activity and Antibacterial Activity of Hydrothermally Synthesized Zn-Doped Hydroxyapatite

This study explores the effect of zinc (Zn) content on the physicochemical characteristics, photocatalytic activity, and antibacterial activity of hydrothermally synthesized hydroxyapatite (HAp). Zinc doped HAp (Zn-HAp) was synthesized with varying Zn content of 1, 2 and 5 wt%, and characterized using XRD, FTIR, UV-Vis DRS, TEM, and zeta potential analysis. Characterization results showed that Zn was successfully dopped into the HAp structure without forming its own ZnO phase, with a decrease in crystallite size and band gap. Photocatalytic activity test was conducted by degradation of tetracycline (TC) antibiotic using UV light. The results show that Zn-HAp has higher photocatalytic activity than pure HAp, with the highest degradation efficiency of 90.48% obtained at 1Zn-HAp. The photocatalytic activity increased as the band gap decreased, which was facilitated by Zn doping. In addition, antibacterial tests against Escherichia coli and Staphylococcus aureus showed that Zn-HAp had a larger inhibition zone than pure HAp, indicating an increase in antibacterial activity, especially at higher Zn concentrations. HIGHLIGHTS Zinc-doped hydroxyapatite with a varied zinc have been synthesized by hydrothermal method. Increasing Zn content in Zn-HAp affects to reduce crystallite size and band gap energies The reduced band gap energy leads to the enhanced photocatalytic activity. Zn-HAp samples show the higher tetracycline photocatalytic activity compared to HAp at 90.84 %. Zn-HAp samples showed good antibacterial activity against Eschericia coli and Staphylococcus aureus. GRAPHICAL ABSTRACT