Cadmium(II) adsorption using functional mesoporous silica and activated carbon

► Mono-amino-functional groups were found better than di- and tri-amino for Cd(II) adsorption. ► Amino-functional group would serve as a basic adsorption site for heavy metal ions. ► Mercapto- and carboxyl-groups were found to behave as ion exchange sites for proton. ► Introduction of amino- and mercapto-groups onto silica was proven by XPS and FT-IR measurements.