Water disinfection with geopolymer–bentonite composite foam containing silver nanoparticles

•Water disinfection with geopolymer composite foam is reported for the first time.•Geopolymer and Ag0-bentonite formed the matrix and dispersed phases, respectively.•Disinfection efficiency against E. coli and enterococci was promising for ∼1 d.•Leaching of Na, Al, Si, Ag, and pH remained within drinking water guideline values.