Removal of the organic dye crystal violet from aqueous solutions by Kakuti plant ash

Abstract

In this study, the adsorption capacity of Kakuti plant ash which were collected from the mountains of Kib village, Jurm district of Badakhshan province on the removal of the organic dye crystal violet (CV) from aqueous solutions was studied. Initially, the adsorbent was prepared in its natural form and then powdered. The obtained powder was converted into ash by a furnace at a temperature of 500 °C. Kakuti plant ash was characterized by Fourier transform spectroscopy (FT-IR) and scanning electron microscopy (SEM). In this study, the effects of various factors such as pH, contact time, initial dye concentration, adsorbent amount, ionic strength and temperature were also investigated. Later, thermodynamic parameters such as standard enthalpy changes, standard entropy changes and standard Gibbs free energy changes were calculated. Thermodynamic studies showed that the amount of adsorption of the dye krestel violet increases with increasing temperature of the natural adsorbent kakuti plant ash, which indicates that the adsorption process is endothermic. The kinetic conditions of adsorption were investigated with pseudo-first-order and pseudo-second-order kinetic models, and the results showed that the adsorption process of krestel violet follows the pseudo-second-order kinetic model. The isotherm of the adsorption process was investigated using the Langmuir, Freundlich, Temkin and Dubinin-Radeshkevich models. The experimental results showed that the process with the maximum adsorption capacity (44.8 mg⁄g) for krestel violet follows the Langmuir model.