Melamine-modified silicotungstic acid incorporated into the polyvinyl alcohol/polyvinyl amine blend membrane for pervaporation dehydration of water/isopropanol mixtures

Abstract

Silicotungstic acid (STA) was modified with melamine and mixed matrix membranes containing melamine-modified STA (M-STA) particles were prepared for the pervaporation dehydration of a water–isopropanol (IPA) mixture. The characterization of the membranes was conducted by FT-IR, SEM, EDS, AFM, XRD and contact angle measurements. The M-STA loaded mixed matrix membranes showed improved pervaporation performance compared to the original membrane. Amidst all the M-STA composite membrane, 8 wt % M-STA loaded (M8-MSTA) membrane gave an optimum pervaporation performance having flux = 0.36 kg/m2h, separation factor 485.6 for 20 wt % water –isopropanol feed composition at 60 °C was observed. The pervaporation performance for M8-STA was further evaluated for various feed composition, from water/IPA 10/90 to 20/80 w/w at 60 °C the flux (increased from 0.033 to 0.36 kg/m2h) and separation factor (decreased from 6425 to 485.6) were strongly influenced by the feed composition. With M8-MSTA membrane, at 80 wt % IPA feed solution, when the temperature increased from 40 to 70 °C, flux increased significantly from 0.29 kg/m2h to 0.47 kg/m2h while separation factor declined from 2171 to 443.0 was observed. In the membrane durability study, the M-STA composite membrane (M8-MSTA) displayed the good stability and constant pervaporation results for long time pervaporation operation which confirmed that melamine modification prevent the leaching of STA from the membrane.