Santosh K. Choudhari

Development of novel composite membranes using quaternized chitosan and Na+-MMT clay for the pervaporation dehydration of isopropanol

Novel polymer-clay-based composite membranes were prepared by incorporating sodium montmorillonite (Na(+)-MMT) clay into quaternized chitosan. The resulting membranes were characterized by Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WXAD), and thermogravimetric analysis (TGA). The effect of membrane swelling was studied by varying the water concentration in the feed. The membranes were employed for the pervaporation dehydration of isopropanol in terms of feed composition and Na(+)-MMT clay loading. The experimental results demonstrated that membrane containing 10 mass% of Na(+)-MMT clay showed the highest separation selectivity of 14,992 with a flux of 14.23x10(-2) kg/m(2) h at 30 degrees C for 10 mass% of water in the feed. The total flux and flux of water are found to be overlapping each other particularly for clay-incorporated membranes, signifying that the composite membranes developed in the present study involving quaternized chitosan and Na(+)-MMT clay are highly selective toward water. From the temperature-dependent diffusion and permeation values, the Arrhenius activation parameters were estimated. The resulting activation energy values obtained for water permeation (E(pw)) are much lower than those of isopropanol permeation (E(pIPA)), suggesting that the developed composite membranes have higher separation efficiency for the water-isopropanol system. The estimated E(p) and E(D) values ranged between 8.97 and 11.89, and 7.56 and 9.88 kJ/mol, respectively. The positive heat of sorption (DeltaH(s)) values were obtained for all the membranes, suggesting that Henrys mode of sorption is predominant in the process.

Preparation of zeolite-incorporated PDMS membranes for pervaporation separation of isopropanol-water mixtures

ZSM-5 zeolite-incorporated poly(dimethyl siloxane) membranes were prepared and molecular dispersion of zeolite in the membrane matrix was confirmed by scanning electron microscopy. After studying the behavior of membrane swelling at 30°C, the membranes were subjected to pervaporation separation of isopropanol-water mixtures at 30, 40 and 50°C. The effects of zeolite loading and feed composition on the pervaporation performances of the membranes were analyzed. Both permeation flux and selectivity increased simultaneously with increasing zeolite content in the membrane matrix. This was discussed on the basis of the enhancement of hydrophobicity, selective adsorption, and the establishment of molecular sieving action. The membrane containing the highest zeolite loading (30 mass%) exhibits the highest separation selectivity of 80.84 and flux of 6.78 × 10−2kg/m2h at 30°C for 5 mass% of isopropanol in the feed. From the temperature dependency of diffusion and permeation values, the Arrhenius activation parameters were estimated. A pure membrane (M) exhibits higher Ep and ED values compared to zeolite-incorporated membranes, signifying that permeation and diffusion require more energy for transport through a pure membrane, owing to its dense nature. Obviously, zeolite-incorporated membranes require less energy due to their molecular sieving action attributed to the presence of straight and sinusoidal channels in the framework of zeolite. All the zeolite-incorporated membranes exhibit positive ΔHs values, suggesting that the heat of sorption is dominated by the Henrys mode of sorption.

Electrospun Nanomaterials: Biotechnology, Food, Water, Environment, and Energy

Over the past decade, electrospinning and electrospraying techniques have become affordable platform techniques for growing numbers of students, researchers, academics, and businesses around the world, producing organic and inorganic nanofibres and nanoparticles for a range of purposes. This review illustrates various advances in the science and engineering of electrospun nanomaterials and their applicability in meeting the growing needs within five crucial sectors: clean water, environment, energy, healthcare, and food. Although most of these sectors are principally dominated by synthetic polymer systems, the emergence of natural polymer and hybrid natural-synthetic electrospun polymer systems offers particular advantages. Current scientific and materials engineering advancements have resulted in highly competitive nanofibre, electrospun products, offering credible solutions to real-world applications.