morjchem Reading Tools

In this work,we investigated the capacity of activated carbon (AC) to adsorb Methylene Blue (MB) from aqueous solution. AC-H₃PO₄ and AC-ZnCl₂was obtained from date pits via a one-step chemical method using H₃PO₄ and ZnCl₂ as activating agents. The performance of AC was characterized by different analyses techniques: proximate analysis, SEM, XRD and FT- IR and TGA. The experiments results showed that the MB removal increased by increasing each of AC-H₃PO₄ and AC-ZnCl₂ concentration, contact time and temperature. The efficiency of the adsorption tests are evaluated by the Langmuir and Freundlich isotherm models. Equilibrium data fitted well by Freundlich modelwith a maximum of the adsorption capacity of 95 mg/g at 333 K for AC-ZnCl₂, However, the adsorption was well adapted to the Langmuir isotherm with a maximum of the adsorption capacity of 125 mg/g at 298 K for AC-H₃PO₄. The kinetics data was explained by the pseudo second-order model, and the intra-particle diffusion with some other rate controlling steps has been suggested as the adsorption mechanism. The pseudo-second-order model described better the adsorption process. The thermodynamic study suggested that MB adsorption on AC-ZnCl₂ was endothermic, spontaneous and non-spontaneous for AC-H₃PO₄.