Kinetic and Thermodynamic Study of the Adsorption of Crystal Violet by Activated Carbon Based on Azadirachta indica Seed Cakes

Activated carbon prepared from Azadirachta indica seeds oil cake was effectively used to remove the cationic dye crystal violet (CV) from aqueous solutions. In this study, activated carbons prepared by activation with orthophosphoric acid followed by carbonization at different temperatures were used as adsorbents to remove crystal violet, a basic dye, from aqueous solutions. The results show that the adsorption rate increases slightly with increasing particle size (from 87.6% to 89.9%) for a size range from 160 to 500 μm. Beyond 500 μm, a reduction in the rate was observed down to 69.96%. The results show that the maximum adsorption rate of the purple crystal obtained is 89.87% for an optimal particle size of 500 μm, 90.39% for a mass of 2 g, 90.50% for a time of 50 minutes, 92.51% for an agitation speed of 250 rpm, 99.04% for a volume of 200 mL, and 93.53% for a CV concentration of 8 mg/L. In addition, the pH and temperature have a considerable influence. The model that best describes the adsorption isotherm is that of Freundlich with pseudo-second-order kinetics. Results show the effectiveness of Neem seed meats for the removal of the purple crystal from aqueous solution.