Chitosan/silica composite membrane: Performance on water permeability and rejection of lead(II) ion from aqueous solution

Abstract

Heavy metal such as lead can be classified as non-biodegradable inorganic pollutants which can contaminate the soils, ground water, sediments and surface water. It cannot be broken down or decomposed by living organism and can continue to exist over a prolonged period, generating harmful effects to the living things. Thus, lead removal is necessary in order to reduce the amount of heavy metals contaminated in water. The purpose of this study was to fabricate chitosan/silica based composite membrane for removal of Pb(II) metal ions from aqueous solution by membrane filtration technique. The composite membranes were characterized in terms of morphological studies and functional group analysis by using Scanning Electron Microscopy (SEM) and Fourier Transform Infrared-Attenuated Total Reflectance (FTIR-ATR) analysis, respectively. The membrane permeation performance, in terms of water permeability and rejection of Pb(II) ions from aqueous solution, was conducted by using membrane permeation system. SEM images illustrated that the presence of macrovoids on the cross-section of the chitosan/silica composite membrane has improved the morphology of pure chitosan membrane and assisted in the rejection of Pb(II) ions. Meanwhile, FTIR-ATR spectra showed the presence of new adsorption peaks, contributed by silica interaction with hydroxyl group of chitosan. The addition of silica to chitosan membrane has significantly enhanced the pure water permeability from 37.36 L/m2h to 42.43 L/m2h. Furthermore, the rejection of Pb(II) metal ions by chitosan/silica composite membrane was slightly higher compared to pure chitosan membrane with the removal efficiency of 13.78% at 0.5 bar applied pressure. These findings indicate the potential use of silica to improve chitosan membrane properties and reduce heavy metal pollution in water.