Polyelectrolyte complex membranes made of chitosan—PSSAMA for pervaporation separation of industrially important azeotropic mixtures

Abstract

Chitosan-based polyelectrolyte complex membranes (PECMs) were developed by incorporating polystyrene sulfonic acid-co-maleic acid (PSSAMA) in the chitosan membrane matrix as a pervaporation membrane by employing a solution technique. Fourier transform infrared (FTIR) spectroscopy, wide-angle X-ray diffraction (WAXD), thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) were used to characterize the membranes. PECMs were tested for their potentiality to separate various azeotropic mixtures; water/ter-butanol, water/isopropanol, water/n-propanol and water/1, 4 dioxane at their azeotropic point. The PECMs containing 9 mass% of PSSAMA manifest highest separation selectivity of 5352 with a flux of 4.145×10−2 kg /m2h for the azeotropic mixture of water/ter-butanol at 30ᵒC. To confirm their stability at the higher temperature, the PECMs were assessed for pervaporation (PV) separation at 40, 50 and 60ᵒC. For all PECMs total flux and flux of water appeared to be coinciding each other, signifying that PECMs could be used successfully to break the azeotropic point of various azeotropic mixtures. The Arrhenius activation parameters were determined by diffusion and permeation values. The activation energy values procured for water permeation (Epw) were considerably lower than ter-butanol permeation (EpTBOH). The heat of sorption (ΔHs) values obtained for PECMs were negative, showing that Langmuir’s mode of sorption is dominant.