Preparation of electrospun cellulose acetate/chitosan membranes for efficient sorption of heavy metals from aqueous solutions

Guided by efficient utilization of natural abundant cellulose and chitosan as separation materials, it is desired to tailor the composition of electrospun cellulose acetate/chitosan (CL/CS) membranes to achieve their optimal application in the management of aquatic heavy metal pollution. In this work, CL/CS membranes with enhanced surface area of 11.3-38.6 m2/g were successfully fabricated via electrospinning technique by dissolving cellulose acetate and chitosan into the environmental-friendly electrospinning solvent of LiOH/thiourea/H2O. Electrospun CL/CS membranes allowed the efficient sorption of Cr(VI), Pb(II) and Cu(II) with favorable kinetics (8.0 h), and excellent capacities (127.6 mg/g for Cr(VI), 66.2 mg/g for Pb(II), 46.7 mg/g for Cu(II) at pH 5.0, T 298 K). Meanwhile, they presented favorable efficiencies in the removal of these multiple heavy metals from acid simulated wastewaters. The spectroscopic analysis results indicated that the sorption mechanism should be dominant by the surface complexation of heavy metals with hydroxyl O-/amino N-species, the electrostatic attraction (protonated NH3+ with negatively charged HCrO4 -, deprotonated O- with positively charged Pb(II) and Cu(II)), as well as the reduction of Cr(VI) to Cr(III) by surface reductive N-species. This work demonstrated the feasibility of electrospun CL/CS membranes as a promising choice for the remediation of aquatic heavy metals.