Functionalized Cellulose with EDTA-like Chelating Groups for Removal of Heavy Metals

Abstract

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%).