Efficient adsorption of Europhtal onto activated carbon modified with ligands (1E,2E)-1,2-bis(pyridin-4-ylmethylene)hydrazine (M) and (1E,2E)-1,2-bis(pyridin-3-ylmethylene)hydrazine (SCH-4); response surface methodology

Porous activated carbon was modified with (1E,2E)-1,2-bis(pyridin-4-ylmethylene)hydrazine (M) and (1E,2E)-1,2-bis(pyridin-3-ylmethylene)hydrazine (SCH-4). Characterization was performed using different techniques such as SEM, FTIR and H-1 NMR analysis. Then, these new adsorbents were used for the efficient removal of Europhtal (sulfonated cobalt phthalocyanine). Response surface methodology (RSM) was used to achieve operational conditions for the efficient removal of Europhtal using an activated carbon modified with novel ligands. To investigate the individual effect of variables involved and the effect of their possible interactions on the adsorption process, several systematic experiments were designed by varying the variables such as pH, sonication time, adsorbent dosage and dye concentration in the range of 2.0-11, 2-8 min, 0.005-0.035 g and 4-30 mg L-1, respectively. The optimum values of pH, sonication time, adsorbent dosage and Europhtal concentration were found to be 7, 2 min, 30 mg L-1 and 0.03 g for the sample modified with M and 7, 5 min, 30 mg L-1 and 0.03 g for the one modified with SCH-4, at which the removal percentages were more than 98%. Adsorption equilibrium data were well fitted to the Freundlich model with maximum adsorption capacities of 56.69 and 17.84 mg g(-1) for M and SCH-4, respectively. The study of adsorption kinetics indicated that the dye uptake process follows the pseudo second-order and saturation type rate expressions for each ligand.