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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. Adsorption performances of these cellulose derivatives have been compared. An increase in the adsorptive amounts of Cd2+ and Pb2+ ions with increasing N‑donor atoms of the grafted polyamines onto the cellulose backbone is found to give the maximum capacity N4-CL > N3-CL > N2-CL for both the ions. The N4-CL with high N content (up to 5.2 mmol N g− 1) exhibits higher 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 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 Cd2+ and Pb2+ from water.

Cellulose is a renewable and promising material. However, native cellulose has to face the challenge of the removal of heavy metals with low efficiency which limits its application. In this work, a cellulose derivative with EDTA-like chelating groups is designed and prepared by the chemical grafting of cellulose. Cellulose is partially oxidized to dialdehyde cellulose which is treated with 20% excess of diethylenetriamine through a Schiff base reaction for the preparation of the aminated cellulose. The amine groups of the aminated cellulose are carboxymethylated by reacting with 20% excess of bromoacetic acid through a substitution reaction. A EDTA-like cellulose derivative functionalized with multidentate N,O‑donor atoms (EDTA-CL) is obtained for accessing the adsorptive property of Cd2+ and Pb2+. The high-efficient adsorption of the both ions by the EDTA-CL with high adsorptive amounts (Pb2+: 438.3 mg g− 1 and Cd2+: 287.2 mg g− 1) can be accomplished by controlled parameters (pH in the range of 4–6 with contact time 30 min) using the dosage of 1 g L− 1 of the EDTA-CL in aqueous solution. The adsorptive processes of the both ions onto the EDTA-CL can be well fitted by pseudo-second-order and Langmuir equations. Thermodynamics data reveal that the adsorption of the both ions onto the EDTA-CL is a spontaneous and endothermic process. The loaded EDTA-CL by simple acid-base treatment can be regenerated 5 times with loss of adsorptive amounts (Cd2+: 14% and Pb2+: 17%).

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