PVA/PDADMAC/ZSM-5 zeolite hybrid matrix membranes for dye adsorption: Fabrication, characterization, adsorption, kinetics and antimicrobial properties

Abstract

Novel poly vinyl alcohol/poly (diallyldimethylammonium chloride)/ZSM-5 zeolite (PVA/PDADMAC/ZSM-5) membranes have been prepared by solvent casting route. They were characterized by techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and optical microscopy (OM). XRD analysis indicated an enhanced crystallinity for the PVA/PDADMAC matrix after zeolite incorporation. SEM and optical microscopic results confirmed that the zeolite particles were well distributed throughout the matrix. The membranes exhibited good thermal and mechanical stability as confirmed by TGA and universal testing machine (UTM) examinations. The membranes were applied as adsorbents for the removal of methyl orange (MO) dye from aqueous solutions. The effects of parameters such as zeolite content, contact time, initial concentration of dye, pH and temperature on the adsorption capacity was evaluated. It has been found that the membrane with 5 wt% zeolite loading exhibits a high MO removal efficiency (95%). Non-linear and linear forms of pseudo-first-order and pseudo-second-order models were used to study the adsorption kinetics. The results indicate that the adsorption of MO on the membrane follows pseudo-second-order kinetics. The equilibrium data was modelled by Freundlich and Langmuir isotherm in their linear and non-linear forms. A relatively higher R2 value for the Freundlich isotherm indicate that this model could fit the experimental data better than the Langmuir model. The recycling studies revealed that the adsorption efficiency of the membrane was unaltered even after four adsorption-desorption cycles.