Fabrication and Characterization of Chitosan/Alginate Multilayer Composite Membrane Supported by a Porous Poly (Acrylonitrile) Substrate for Pervaporation Dehydration of Alcohol

Abstract

<span class="fontstyle0">Chitosan (CS) and alginate (Alg) are complementary in their membrane performance, but the combination of them is normally difcult to use due to their different solubilities. Layer-by-Layer deposition appears to be an effective method for improving the separation efciency of a composite membrane. In this work, the polyelectrolyte multilayer composite membranes (PEMCMs) were fabricated by depositing CS and Alg solutions alternatively onto a hydrolyzed porous poly(acrylonitrile) (PAN) substrate under a reduced pressure, as evidenced by Attenuated total reflectance Fourier transform infrared spectroscopy, contact angle and zeta potential measurement. Pervaporation results showed that the water selectivity increased while the flux decreased with the growth of CS/Alg-based polyelectrolyte layer. It was interesting that the sorption process dominated the pervaporation process when the numbers of polyelectrolyte layers were less than 7. However, the diffusion effect was more profound than the sorption effect as more than 8 polyelectrolyte layers were deposited on the PAN substrate. In particular, the prepared CS/Alg PEMCMs exhibited highly improved water selectivities towards alcohol/water mixtures, and a good compromise between flux and separation factor was observed when compared to other polyelectrolyte-based membranes. For separating 90% IPA/water mixtures at 60 ºC, the (CS/Alg)</span><span class="fontstyle0" style="font-size: 4pt;">4 </span><span class="fontstyle0">composite membrane displayed a separation factor of 4491 and a flux of 596 g/m</span><span class="fontstyle0" style="font-size: 4pt;">2</span><span class="fontstyle0">.h, respectively. These results indicate that the fabricated CS/Alg composite membranes are excellent waterpermselective ones for alcohol dehydration.</span>