Textile Dye Removal from Single and Ternary Systems Using Date Stones: Kinetic, Isotherm, and Thermodynamic Studies

In this paper, the removal of the dyes acid green 25 (AG25), acid black 26 (AB26), and acid blue 7 (AB7) onto date stones (DS) from single and ternary systems was investigated. Surface studies of DS were investigated by Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). Experiments were carried out as a function of adsorbent dosage, initial dye concentration, inorganic anion (salt), pH, and temperature in single and ternary systems. The adsorption kinetics, isotherms, thermodynamics, and dye desorption were studied in single and ternary dye systems. The adsorption kinetics was modeled using the pseudofirst-order, pseudosecond-order, and intraparticle diffusion kinetics equations. The equilibrium adsorption data of AG25, AB26, and AB7 dyes on DS were analyzed. Thermodynamic parameters of dye adsorption were obtained. In addition, the regeneration of DS was studied using dye desorption in single and ternary dye systems. The adsorption kinetics of the dyes followed pseudosecond-order kinetics. The results indicate that the Langmuir model provides the best correlation of the experimental data. The thermodynamic studies showed that the dye adsorption onto DS was a spontaneous, endothermic, and physical reaction. A high desorption of AG25, AB26, and AB7 showed the regeneration of DS. It can be concluded that DS are suitable as an adsorbent material to remove AG25, AB26, and AB7 dyes from single and ternary systems.