Cellulose derivatives functionalized with multidentate N‑donor atoms: comparative adsorption of cadmium (II) and lead (II) ions from water

Abstract

Cellulose derivatives functionalized with multidentate N‑donor atoms containing two, three and four amino functional groups (as marked N2–CL, N3–CL and N4–CL) have been prepared by grafting of linear aliphatic polyamines into the cellulose backbone through the Schiff base reaction. An increase in the adsorptive amounts of Cd2+ and Pb2+ with increasing N‑donor atoms of the grafted polyamines onto the cellulose backbone and the maximum capacity of N4–CL > N3–CL > N2–CL are found. The N4–CL with the highest N content (up to 5.2 mmol N g−1) exhibits the largest adsorptive capacities of 249.7 mg g−1 for Cd2+ and 401.2 mg g−1 for Pb2+. The adsorption of both the ions by the three cellulose derivatives is achieved within 30 min, is independent of pH in the range of 4.5–6 for Cd2+ and 4–6 for Pb2+, and can be satisfactorily fitted by Langmuir and pseudo-second-order equations. Thermodynamic parameters suggest an endothermic and endothermic nature.