Selective adsorption of methylene blue (MB) dye from aqueous mixture of MB and methyl orange (MO) using mesoporous titania (TiO2) – poly vinyl alcohol (PVA) nanocomposite

Abstract

A very simple, rapid and practical method was proposed for the synthesis of an inorganic – organic hybrid nanocomposite containing TiO2 and PVA, which possess remarkable selectivity for the adsorption of methylene blue (MB), from the mixture of methylene blue and methyl orange (MO) in aqueous environment. The nanocomposite was characterized by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–Vis spectroscopy, Photoluminescence spectroscopy (PL), Fourier transform Raman spectroscopy (FT Raman), Field emission scanning electron microscopy (FESEM) with (EDAX), and High-resolution transmission electron microscopy (HRTEM). The Surface charge of the nanocomposite was probed with Zeta potential (ζ) measurement by Dynamic Light Scattering (DLS) technique. The surface area and pore volume of the material were determined using BET method and achieved very high surface area of 475 m2g−1and high pore volume of 0.4535 cm3 g−1. The MB adsorption was investigated under various experimental conditions and results strongly dependent on temperature, pH, initial dye concentration, and catalyst dosage. The nanocomposite showed 97.1% of MB removal within 8 min. The experimental data give good fit for both Langmuir and Freundlich models and the adsorption kinetics can be well-described by pseudo-second-order pathway. The adsorption process was exothermic and the adsorbent could be regenerated in acid solution with good activity, even after 10 repeated cycles.