Removal of cationic dye by high surface activated carbon prepared from biomass (date pits) by carbonization and activation processes

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.