Effects of chitosan membrane morphology on copper ion adsorption

The effect of chitosan membrane morphology on copper ion adsorption was investigated in this work. Dense and macroporous chitosan membranes with various polymer concentrations and silica to chitosan ratios were prepared. The membrane surfaces and cross-section morphologies were characterized by SEM and AFM, and the porosity of macroporous membranes was measured relative to dense membranes. Adsorption experiments were performed in batch processes; also sorption isotherms and kinetics were studied. Increasing the polymer concentration during membrane preparation resulted in increased copper adsorption. Increasing the silica to chitosan ratio resulted in greater membrane porosity and surface roughness, which made more amino groups accessible and therefore increased copper sorption. The membrane with the greatest porosity and membrane roughness could adsorb copper in the amount of 5.9 mg/g, the highest amount achieved at an initial copper concentration of 125 ppm. Due to its enhanced roughness, the membrane with a 3/1 silica to chitosan ratio had an active surface area that was nearly doubled compared to dense membrane.