Evaluation of various chitin-glucan derivatives from Aspergillus niger as transition metal adsorbents

A number of chelating resins were prepared by chemical derivatization of the chitin-glucan (CG) complex isolated from Aspergillus niger biomass, namely chitosan-glucan (CsG), O-carboxymethyl-chitin-glucan (CM-CG), O-(2-sulfoethyl)chitin-glucan (SE-CG), and N-(2-carboxyethyl)chitosan-glucan (CE-CsG). The chemical modification was confirmed by FT-IR and elemental analysis. Nanosecond electron beam irradiation was used to produce insoluble resins and to preserve the reactive functional groups. Batch experiments were carried out to evaluate the adsorption selectivity and capacity of the resins toward transition metal ions (Cu2+, Ni2+, Co2+, Zn2+). The resins showed good adsorption capability with the following selectivity series: Co2+ < Ni2+ < Cu2+ > Zn2+. The total metal adsorption capacities of CG, CsG, CM-CG, SE-CG, and CE-CsG resins at pH 6.5 (ammonium acetate buffer) were found to be 0.205, 0.382, 1.752, 0.319, and 0.350 mmol g−1, respectively. Our results suggest that, depending on the type of chemical modification, the chitin-glucan complexes can be used either for selective Cu2+ removal (CsG) or for total transition metal adsorption (CM-CG) from aqueous effluents.