Removal of organic dye methylene blue from aqueous solutions using Ziziphora plant ash

Abstract In this research, the adsorption capacity of the Ziziphora plant ash collected from the village of Kib, Jurm township of Badakhshan province of Afghanistan country were studied on the removal of methylene blue from aqueous solutions. At first, the adsorbent was prepared in its natural form and then turned into powder. The powder obtained by the furnace is turned into ash at 500 °C. Natural adsorbent Ziziphora plant ash were characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). In this study, investigated the effects of various factors such as pH, contact time, initial dye of concentration, dose of adsorbent, ionic strength and temperature. Then, the thermodynamic parameters of the adsorption process such as ∆H^°, ∆S^° and ∆G^° were calculated. Thermodynamic investigations showed that the adsorption of methylene blue dye increased by increasing the temperature on the natural adsorbent of the Ziziphora plant ash and that indicating the adsorption process was endothermic. The kinetic adsorption conditions were investigated with first and second order kinetic models and the results showed that the methylene blue absorption process were followed to the second-order kinetics model. The isotherm of the adsorption process were studied using Langmuir, Freundlich, Tamkin and Dobbin-Radskvich models. The results of the experiments showed that the adsorption process followed by Langmuir model with a maximum adsorption capacity (59.1 mg.g-1). Keywords: Removal, Methylene blue, Isotherm, Ziziphora plant ash