An Investigation of the Selective Adsorptions of Metals on Mesoporous NH₂-MCM-41

The adsorption selectivity of NH 2 -MCM-41 follows the Irving-William order observed in transition metal complexes (i.e., Cu 2+ > Zn 2+ > Co 2+ > Ni 2+ ) that is consistent with X-ray photoelectron spectroscopy (XPS) and adsorption thermodynamics data. The interplays between surface aminopropyl ligands and the transition metals are adequately explained by the Pearson HSAB principle, but a multicomponent Freundlich adsorption model based on the single component adsorption data gives a more accurate prediction and description of the metal adsorptions from binary, ternary and quaternary solutions at different pHs and from complex water sources (i.e., tap water, runoff water, and seawater) that contained myriad humic substances, dissolved minerals, and various anions.