Batch Removal of Metanil Yellow (MY) from Aqueous Solution by Adsorption on HNO3-Treated-H3PO4-Activated Carbon (NATPAAC) from Gmelina arborea Roxb.: Kinetic and Mechanism Studies

As metanil Yellow dye is removed from aqueous solution by batch adsorption on NATPAAC derived from G. arborea bark, we studied the effects of initial dye concentration (Co), initial pH and adsorbent dosage at 29 °C. The experimental equilibrium adsorption capacities (qe) obtained, were 2.35, 1.00, and 0.48 mg/g for Co 25, 50, and 100 mg/L, respectively. The kinetics and mechanism of the adsorption were then modeled by fitting experimental data into the pseudo-second order (PSO). Based on correlation coefficient R2 (> 0.95) values, results show that the PSO and Elovich models simulated experimental data well, but the PSO model simulated it the best. The Boyd model confirmed that the adsorption process was controlled by liquid film diffusion and the effective diffusion coefficients were very low. Moreover, the qe values decreased with increase in Co, increase in pH, and increase in adsorbent dosage. However, the removal of MY from aqueous solution was very low. In addition, treatment of carbon with diluted HNO3 had no favorable impact.