Preparation of alkali-activated fly ash-based geopolymer and their application in the adsorption of copper (II) and zinc (II) ionsLita Darmayanti, Suprihanto Notodarmojo, Enri Damanhuri, Grandprix T. M. Kadja and Rino R MuktiMATEC Web Conf., 276 (2019) 06012DOI: https://doi.org/10.1051/matecconf/201927606012