Copper(II) removal from polluted water with alumina/chitosan composite membranes

In this paper, the manufacture of a tubular alumina/chitosan composite membrane is described. A porous alumina support was manufactured with a centrifugal casting technique. Pore radii varied between 45 and 100 nm using different types of powders and powder mixtures and sintering temperatures between 1050 and 1200 °C. Molar water permeability varied between 1 and 7×10−6 mol/m2 s Pa, which was of the same order as the molar N2-gas permeability. The support tubes were provided with a chitosan coating of about 15 μm thickness. The porosity of the coating was controlled with a phase inversion method using silica as a porogen. These composite membranes decreased a 50 mg/l Cu2+ solution to a concentration level below 1 mg/l. Capacity of adsorption was about 0.2 g Cu2+/g chitosan. Cross-linked chitosan membranes are preferred due to their chemical stability as a function of pH.