Separation of acetic acid and water using reverse osmosis membranes

Abstract

This study focuses on utilizing the reverse osmosis membrane to separate the acetic acid from aqueous mixture. A commercially AG membrane and three laboratory synthesized polysulfone (PSU) membranes were used in this work. The synthesized membranes were prepared via phase inversion-immersion precipitation method. Two types of polymer concentrations were chosen; 17.5 wt% PSU and 20.0 wt% PSU. It was found that the water permeate flux of the 17.5 wt% PSU was the highest. Therefore this membrane was selected to further modified by interfacial polymerization to form a thin polyamide coating layer on top of the polysulfone membrane; (17.5 wt% PSU (M)). All membranes were tested in terms of its permeation flux and rejection rate in different type operating conditions. Dead end filtration was used to examine the membrane performances followed by, membrane morphology analysis using Field Emission Scanning Electron Microscopy (FESEM), and membrane functional group test by Fourier Transform Infrared Spectroscopy (FTIR). At 10.0 wt% HAc, the commercial AG membrane shows the highest rejection rate among all the membrane, which range from 20%26% and at pressure range of 15 bar to 25 bar. The highest water flux was discovers when using 17.5 wt% PSU membrane. It was observed that increasing the pressure effectively increases the flux. The result of osmotic pressure to solute concentration ratio demonstrated that the AG membrane has the lowest osmotic pressure range from 15.41 m2/h2 to 17.18 m2/h2. The result of top surface and cross sectional structure morphology showed that AG membrane and 17.5% PSU (M) consist of a thin polyamide layer on top of the polysulfone membrane. This was proven by the FTIR analysis. However the FESEM micrograph showed the thin film polyamide on the modified membrane was uneven. This was among the reasons for rejection and flux membranes percent is low compared with the membrane AG (commercial membrane