SYNTHESIS OF Zn(II)/SILICA BY SOL-GEL METHOD AS AN ANTIBACTERIAL MATERIAL AGAINST Escherichia coli AND Staphylococcus aureus

Abstract

Synthesis of Zn(II)/silica by sol-gel method as antibacterial material against Escherichia coli (E.coli) and Staphylococcus aureus (S.aureus) has been done. Sol-gel process was carried out by reacting tetraethoxysilane, H2O, HCl, ethylene glycol and ZnCl2. The ZnCl2 concentrations varied 0.25, 0.5; 0.75, 1, and 1.25 M. Heat treatment were done by combination of microwave and oven, while the process of aging gel Zn(II)/silica carried out for 24 h and or without going through the process of aging. The Zn(II)/silica was then characterized by Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction method (XRD), and Transmission Electron Microscopy (TEM). The Zn(II) ions concentration that released from Zn(II)/silica was determined by AAS. Zn content in Zn(II)/silica was determined by X-Ray Fluoresence (XRF). Porosity of materials were determine by monolayer adsorption of N2 gas. Antibacterial test was done by calculate the number of bacteria surviving after contact with Zn(II)/silica by plate count method and compared to silica.

The XRD results showed that Zn(II)/silica phase composed of amorphous SiO₂ and y-ZnCl₂. The  porosity test results showed that Zn(II)/silica has surface area of 517.698 m²/g. The XRF analysis results showed that ZnCl₂ 0.25 M produced the optimum Zn content 35,60% in Zn(II)/silica. Zn(II)/silica synthesized by heating in the oven at 150^oC for 3 h after dried by microwave and aged resulted in the optimum Zn(II)/silica due to the least release of Zn(II) ions from Zn(II)/silica when analyzed by AAS (5.51%). Zn(II)/silica with concentration of 163 ppm could kill E.coli from concentration of 1.5 x10⁶ CFU/mL to 0 CFU/mL in 2,5 h contact time, and reduces S.aureus concentration 1,2 x 10⁶ CFU/mL with a contact time of 24 h. While the silica with the same concentration to that of the Zn(II)/silica showed no antibacterial effect against E.coli and S.aureus.