Pervaporation studies of sodium alginate (SA)/dextrin blend membranes for separation of water and isopropanol mixture

• Published in: Desalination Vol. 269; no. 1-3; pp. 177 - 183
• Main Authors: Saraswathi, M., Rao, K. Madhusudhan, Prabhakar, M.N., Prasad, C.V., Sudakar, K., Kumar, H.M.P. Naveen, Prasad, M., Rao, K. Chowdoji, Subha, M.C.S.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-03-2011; Elsevier
• Subjects: Applied sciences; Blends; Chemical engineering; Crosslinking; desalination; Dextrin; Exact sciences and technology; Flux; glutaraldehyde; Isopropanol; isopropyl alcohol; Membrane; Membrane separation (reverse osmosis, dialysis...); Membranes; Pervaporation; Pollution; Selectivity; Separation; Sodium alginate; sorption; Dextrin; Flux; Membrane; Selectivity; Sodium alginate; Pervaporation; Differential scanning calorimetry; Scanning electron microscopy; Swelling; Crosslinking; Sorption; Membrane separation; Casting; Binary mixture; Morphology
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2010.10.059

The blend membranes of sodium alginate (SA)/dextrin were prepared by solution casting method followed by crosslinking with glutaraldehyde and used for the separation of water+isopropanol mixtures at 30°C. Pervaporation (PV) separation characteristics were studied for the different water compositions (10–50mass%) in the water+isopropanol feed mixtures through the prepared blend membranes. The crosslinked and un-crosslinked membranes were characterized by FTIR, DSC and surface morphology of membranes studied by SEM. The membrane performance was studied by calculating the flux and selectivity. Sorption studies were carried out to evaluate the extent of interaction and the degree of swelling of the membranes in pure liquids as well as in binary mixtures. The observed flux was higher for crosslinked SA/dextrin blend membranes, compared to plain crosslinked SA membrane; nevertheless, the selectivity was also higher for SA/dextrin (40:60mass%), SA/dextrin (50:50mass%) and SA/dextrin (60:40mass%) blend membranes compared to the plain crosslinked SA membrane.
► Addition of hydrophilic dextrin, a natural polymer to another natural polymer such as SA converted the SA/dextrin blend membranes more hydrophilic to achieve higher levels of dehydration of isopropanol. ► Balance between blend compatibility and hydrophilicity of the overall blend is important in achieving high permeation flux and selectivity for the dehydration of isopropanol due to induced plasticization effect of the overall blend membrane in the presence of dextrin. ► Swelling studies indicate that effect of dextrin on sorption is responsible in controlling the PV separation characteristics of SA/dextrin membranes.