Preparation and characterization of activated carbons from Terminalia arjuna nut with zinc chloride activation for the removal of phenol from wastewater

Nuts of Terminalia Arjuna, an agricultural waste, were used to prepare activated carbons by zinc chloride activation under four different activation atmospheres, to develop carbons with substantial capability, and to adsorb phenol from dilute aqueous solutions. Experiments were carried out at different chemical ratios (activating agent/precursor). Effect of carbonization temperature and time are the important variables, which had significant effect on the pore structure of carbon. Developed activated carbon was characterized by SEM analysis. Pore volume and surface area were estimated by Hg porosimetry and BET surface area analyses. The carbons showed surface area and micropore volumes of around 1260 m(2)/g and 0.522 cm(3)/g, respectively. The activated carbon developed shows substantial capability to adsorb phenol from dilute aqueous solutions. The kinetic data were fitted to the models of intraparticle diffusion, pseudo-second-order, and Lagergren model which followed more closely the pseudo-second-order chemisorption model. The isotherm equilibrium data were well-fitted by the Langmuir and Freundlich models. The maximum removal of phenol was obtained at pH 3.5 (about 93 % for adsorbent dose of 10 g/L and 100 g/L initial concentration).