Application of gamma irradiation method to synthesize silver nanoparticle and fix them on porous ceramics for water treatment

The colloidal silver nanoparticles (AgNPs) solution with the AgNPs diameter of 10-15 nm was synthesized by gamma irradiation method using polyvinylpyrrolidone as stabilizer. Porous ceramic samples were functionalized by treatment with an aminosilane (AS) agent (3-aminopropyltriethoxysilane) and then impregnated in colloidal silver nanoparticles solution for fixing through coordination bonds between - NH₂ groups of the aminosilane and the silver atoms. The AgNPs content attached in porous ceramic (AgNPs/PC) was of about 200-250 mg/kg. The contents silver release from AgNPs/PC into filtrated water by flowing test with the rate of about 5 litters/h were less than 10 μg/L analyzed by neutron activation analysis method, it is satisfactory to the WHO guideline of 100 μg/L for drinking water. The antimicrobial effect of AgNPs/PC for E. coli was carried out by flowing test with an inoculated initial contamination of E.coli in water of about 10⁶ CFU/100 ml. Results showed that the contamination of E. coli in filtrated water through AgNPs/PC (up to 500 litters) was less than 1 CFU/100 ml compared to 2.5x10⁴ CFU/100 ml for base porous ceramic (only up to 60 litters). The antimicrobial effect of AgNPs/PC is in accordance with the TCVN 6096-2004 for bottled drinking. Thus, AgNPs/PC with the silver content of 200-250 mg/kg and the specific surface area of 1.51 m²/g, average pore size of 48.2 Å and pore volume of 1.8x10^-3 cm³/g has highly antimicrobial effect that can be applied for point-of-use drinking water treatment. (author)