Kinetic Studies on Adsorption Behavior of Methyl Orange Using Modified Halloysite, As an Eco-Friendly Adsorbent

In this work, modified halloysite was successfully prepared and its adsorptive capacity was studied using methyl orange dye solution. The adsorption behavior was systematically performed as a function of initial dye concentration and time. The halloysite-mineral (Al2O3·2SiO2·4H2O) used in this study was an aqueous alumino silicate mineral consisting of layers with similar structural composition and was gathered from the Biga Peninsula, Western Anatolia. Characterization of the prepared material was examined using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Differential Thermal Analyzer (DTA). The adsorptive capacity of the modified halloysite in methyl orange was increased by increasing the contact time and initial dye concentration. Lagergren pseudo first-order and pseudo second-order kinetics were performed and pseudo second-order model was found to be the best fit model for the adsorption kinetic. Langmuir, Freundlich, Sips and Dubinin–Radushkewich isotherm models were applied to the experimental data to find the suitable model for describing the adsorption equilibrium. Unmodified-clay was also used in the adsorption process of methyl orange to compare the adsorptive property of the modified-clay. It was found that modified halloysite performed better as an adsorbent than untreated clay for the adsorption of methyl orange.