Cellulose Derivatives Functionalized with Multidentate N‑Donor Atoms: Comparative Adsorption of Cadmium(II) and Lead(II) Ions from Water

Cellulose derivatives functionalized with multidentate N‑donor atoms containing two, three and four amino functional groups (as marked N 2 -CL, N 3 -CL and N 4 -CL) have been prepared by grafting of linear aliphatic polyamines into the cellulose backbone through the Schiff base reaction. Adsorption performances of these cellulose derivatives have been compared. An increase in the adsorptive amounts of Cd 2+ and Pb 2+ ions with increasing N‑donor atoms of the grafted polyamines onto the cellulose backbone is found to give the maximum capacity N 4 -CL > N 3 -CL > N 2 -CL for both the ions. The N 4 -CL with high N content (up to 5.2 mmol N g − 1 ) exhibits higher adsorptive capacities of 249.7 mg g − 1 for Cd 2+ and 401.2 mg g − 1 for Pb 2+ . 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 Cd 2+ and 4–6 for Pb 2+ , and can be satisfactorily fitted by Langmuir and pseudo-second-order equations. Thermodynamic parameters for the adsorption of both the ions suggest an endothermic and endothermic nature and favorable interactions between N‑donor atoms and the ions. The developed cellulose derivatives are promising for the enhanced removal of Cd 2+ and Pb 2+ from water.