Water disinfection with geopolymer–bentonite composite foam containing silver nanoparticles

Abstract Geopolymers resemble conventional ceramics but can be manufactured at near-ambient temperatures. In this work, geopolymer–bentonite composite foam with silver nanoparticles was prepared and applied for water disinfection, inspired by point-of-use ceramic water filters. The inactivation efficiency against Escherichia coli and intestinal enterococci bacteria was found to be promising (0.6–2.4 and 0.3–1.4 log₁₀ reductions, respectively) for ∼1 d. However, the inactivation efficiency against somatic coliphage viruses was poor (<0.05 log₁₀). The geopolymer matrix did not alter the chemical water quality. Thus, the pH and the concentrations of Ag, Si, Al, and Na remained in compliance with drinking water guideline values, and the foam showed no physical disintegration. These results provide preliminary proof of concept of the suitability of geopolymer foam composites for point-of-use water disinfection