Electrospun alginate nanofibres as potential bio-sorption agent of heavy metals in water treatment

Abstract

This paper reports on the potential of electrospun alginate nanofibre membranes to be used for the bio-sorption of heavy metals from aqueous solutions. Poly(ethylene oxide) (PEO) and its blends were electrospun at an applied voltage of 1-1.3 kV/cm and a solution flow rate of 0.8 mL·hr-1. The electrospinnability of the nanofibre blends was enhanced by storing the blend solutions in a controlled environmental chamber. The electrospun nanofibre membranes were washed with calcium chloride to remove PEO. Beadless nanofibres with average diameters of 114 nm and a surface area of 18.03 m2 ·g-1 were obtained. Fourier transform infra-red (FTIR) spectroscopy and thermogravimetric analysis (TGA) confirmed the re- moval of PEO after washing with calcium chloride. The adsorption behaviour of the nanofibrous membranes was investigated using Cu(II) as model metalloid at different concentrations (0-1000 mg·L-1), temperatures (25, 40, and 60°C) and pH values (2-6). The Langmuir isotherm better presented the equilibrium experimental data than the Freundlich model. The electrospun alginate membranes displayed a maximum monolayer sorption capacity (Q0) of 15.6 mg·g-1 at a pH of 4. In a competitive adsoption experiment the removal of metal ions in a mixture followed the order Cu > Ni > Cd > Co.