Separation of benzene–cyclohexane mixtures by filled blend membranes of carboxymethyl cellulose and sodium alginate

• Blend membranes were produced from sodium alginate and carboxymethyl cellulose.
• These blend membranes were filled with bentonite filler.
• Unfilled and filled membranes were used for separation of benzene from cyclohexane.
• A systematic method was used to identify the membrane showing optimum properties.
• Filled membranes showed moderate flux but high benzene selectivity.

Blend membranes were prepared by solution blending of sodium alginate (SA) and sodium carboxymethyl cellulose (CMC) in water with varied compositions. One of the blend membranes containing 25% SA and 75% CMC was found to show optimum flux and benzene selectivity for 19.6 wt% benzene in cyclohexane. This unfilled blend membrane designated as F0 was further filled with 2, 4, 6 and 8 wt% organophilic bentonite filler to obtained four filled membranes designated as F2, F4, F6 and F8, respectively. These five (one unfilled and four filled) membranes were characterized by various conventional methods like FTIR, XRD, DTA (for unfilled blend membranes) and SEM (for filled membranes). These membranes were used for pervaporative separation of benzene from its mixtures with cyclohexane over the concentration range of 0.5–20 wt% benzene. The filled F8 membrane showed lower flux (35.65 kg μm/m2 h) than the unfilled F0 membrane (77 kg μm/m2 h) but separation factor for benzene of the F8 membrane (212) was much higher than the F0 membrane (88.7).