Evaluation of Almond Shell Activated Carbon for Dyes (Methylene Blue and Green Malachite) Removal by Experimental and Simulation Studies

The present work analyses the behaviour of an activated carbon fabricated from almond shell for the removal of cationic dyes (methylene blue and malachite green) by adsorption from aqueous solutions. The carbonized precursor was activated with KOH at a 1:1 (w/w) ratio with the objective of increasing both surface area and pore volume. Both non-activated and activated carbon were characterized in different aspects of interest in dye adsorption studies (surface structure, point of zero charge, surface area, pore size distribution). The effect of dye initial concentration and adsorbent dosage upon dye removal efficiency and carbon adsorption capacity has been studied. Adsorption kinetics was analysed under different experimental conditions and different models were essayed to determine the adsorption mechanism. Dye adsorption in the adsorbent surface could be considered the rate-limiting step. Adsorption equilibrium isotherms have also been obtained, and Langmuir and Freundlich equations showed the best fitting to the experimental data. Moreover, Adsorption kinetic and equilibrium data have been used to simulate breakthrough curves in a packed-bed column using different conditions (bed length, liquid flowrate, dye initial concentration). Simulation results showed that almond shell activated carbon is a suitable adsorbent for methylene blue and malachite green removal from wastewater.