Polyvinyl alcohol/carboxymethyl cellulose/ZSM-5 zeolite biocomposite membranes for dye adsorption applications

Abstract

In this work, efficient biodegradable membranes were fabricated using polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC) and ZSM-5 zeolite, and their utility for the removal of a cationic dye, methylene blue (MB), was investigated. The physical properties of the membranes were assessed by FTIR, XRD, UTM, SEM, optical microscopy and thermogravimetry. The influence of various parameters viz., zeolite loading, initial dye concentration, temperature and contact time on the dye removal capability of the membranes was investigated. The results show that the adsorption capacity of the membranes increases with an increase in zeolite content and initial dye concentration, while an elevated temperature decreases the adsorption capacity. A high dye removal efficiency (97%) and high adsorption capacity (7.83) were observed for 5 wt% of zeolite loaded sample for an initial dye concentration of 10 ppm with a contact time of 10 h at 30 °C. The equilibrium adsorption data were analysed using Langmuir and Freundlich models. The regression results showed that the equilibrium adsorption data were more accurately described by the Freundlich model (R2 = 0.998) rather than the Langmuir adsorption isotherm (R2 = 0.961), suggesting heterogeneous adsorption. The adsorption kinetic results show that the pseudo second order model (R2 = 0.996) is the suitable model to describe the kinetic behavior of MB onto PVA/CMC/ZSM-5 zeolite membranes.The present study suggests that the PVA/CMC/ZSM-5 zeolite membranes are suitable candidates for the efficient removal of methylene blue, from aqueous streams.