Hydrophilic Nanocomposite Membranes for the Pervaporation Separation of Water - Ethanol Azeotropic Mixtures

Abstract

Bentonite nanoclay reinforced Poly (vinyl alcohol) (PVA) nanocomposite membranes were used for the separation of azeotropic composition of water – ethanol mixtures by pervaporation process. Fourier – transform infrared (FTIR) spectroscopic studies revealed the interaction of bentonite nanoclay and the PVA matrix. The dispersion and distribution of nanoclay in the polymer matrix was demonstrated by transmission electron microscopic analysis (TEM). The intrinsic membrane properties with filler loading were also investigated. The results indicate that the hydrophilic nature of the nanoclay influenced the pervaporation to a greater extent. The hydrophilic nature and surface roughness of the nanocomposite membranes was analyzed by atomic force microscopic (AFM) analysis. The pervaporation process illustrates that the permeation flux increases and the separation factor decreases with nanoclay loading. The instrinsic selectivity, which reflects the membrane performance was maximum for 1 wt% clay loaded membranes. PVA with 1 wt% nanoclay loading showed better pervaporation performance. The separation factor of the 1 wt% nanoclay membranes increased to 13, i.e. nearly 4 times more than that of neat PVA membranes. Membrane selectivity also increased to 254% than that of pristine PVA membranes. Thus at lower filler loading, maximum separation was achieved. The increase in nanoclay loading is favorable to improve intrinsic permeance at the cost of decrease in selectivity