An efficient removal of malachite green dye from aqueous environment using ZSM-5 zeolite/polyvinyl alcohol/carboxymethyl cellulose/sodium alginate bio composite

Abstract

In this work, we examined ZSM-5 zeolite loaded polyvinyl alcohol-carboxymethyl cellulose-sodium alginate (PVA/CMC/SA) membrane for cationic dye (malachite green, MG) removal from aqueous environment. The crystallinity, chemical composition, surface morphology, hydrophilicity and thermal property of PVA/CMC/SA/ZSM-5 membrane was evaluated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), optical microscopy (OM), contact angle and thermogravimetric analysis (TGA) respectively. The successful incorporation of zeolite into PVA/CMC/SA membrane was confirmed by XRD, FT IR and SEM. TGA and contact angle measurement indicates that zeolite loaded PVA/CMC/SA membrane showed superior thermal stability and hydrophobicity than plain PVA/CMC/SA membrane. A series of adsorption studies was conducted to evaluate the influence of operational parameters such as initial dye concentration, zeolite dosage, contact time, temperature and pH on the dye (MG) adsorption behaviour of the prepared membrane. A maximum dye removal percentage (99.12%) was achieved at an initial dye concentration of 10 ppm, zeolite dosage-5 wt%, pH = 10 and temperature-25 °C. The kinetic studies revealed that adsorption of MG on PVA/CMC/SA/ZSM-5 membrane follows pseudo-second-order model while Freundlich isotherm model was founded to be the best isotherm model to describe the adsorption process. The results thus indicate a multilayer adsorption of MG on PVA/CMC/SA/ZSM-5 membrane. Finally, the recyclability test revealed that the membrane exhibits good recycle efficiency and is stable after 5 recycle.