Fabrication of PVA/agar/modified ZSM-5 zeolite membrane for removal of anionic dye from aqueous solution

Abstract

This work reports the fabrication of a novel polyvinyl alcohol/agar/ZSM-5 zeolite membrane for the removal of Congo red from aqueous streams. The membranes were characterized by microscopic techniques (scanning electron microscopy (SEM) and optical microscopy (OM)), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), universal testing machine (UTM), thermogravimetric analysis (TGA) and contact angle analysis. Successful incorporation of zeolite in membrane was confirmed by XRD and SEM analysis. FT-IR data confirmed the physicochemical interaction between the polymer and the zeolite particles. Thermal and mechanical stability of the membrane was confirmed by TGA and UTM analysis. Contact angle and swelling measurements indicate that zeolite plays a key role in controlling the hydrophilicity of the membrane. The influence of operational parameter (zeolite content, initial concentration of Congo red, contact time, pH, ionic strength and temperature) on the adsorption process was summarized. The results showed that under the optimal conditions (zeolite content: 5 wt%; initial CR concentration: 10 ppm, temperature: 30 °C and pH 3) the membrane exhibits high adsorption capacity (qe). Adsorption kinetics results indicate that adsorption follow pseudo-second-order model. Adsorption isotherm examination demonstrates that adsorption process could be described in well manner by Freundlich isotherm model. The inhibitory effect of membrane on the growth of Escherichia coli (gram-negative) and Staphylococcus aureus (gram-positive) bacteria was confirmed by agar disk diffusion test. The adsorption–desorption analysis indicates that the membrane possesses good regeneration capacity. Thus, PVA/agar/ZSM-5 zeolite membrane could be potentially useful as an adsorbent for Congo red from water.