Geopolymer from tin mining tailings waste using Salacca leaves ash as activator for dyes and peat water adsorption

•Geopolymer adsorbents were prepared from tin mine tailing waste.•Salacca leaves ash was utilized as geopolymer activator.•The geopolymers exhibits the capability to adsorb methylene blue and methyl orange.•The geopolymer also shows capability to enhance peat water quality.•The COD and NOM removal of peat water were 100 and 92%, respectively.