Preparation, characterization, and dye removal study of activated carbon prepared from palm kernel shell.

Abstract

Palm oil mill wastes (palm kernel shell (PKS)) were used to prepare activated carbons, which were tested in the removal of colorants from water. The adsorbents were prepared by 1-h impregnation of PKS with ZnCl2 as the activating agent (PKS:ZnCl2 mass ratios of 1:1 and 2:1), followed by carbonization in autogenous atmosphere at 500 and 550°C during 1h. The characterization of the activated carbons included textural properties (porosity), surface chemistry (functional groups), and surface morphology. The dye removal performance of the different activated carbons was investigated by means of the uptake of methylene blue (MB) in solutions with various initial concentrations (25-400mg/L of MB) at 30°C, using a 0.05-g carbon/50-mL solution relationship. The sample prepared with 1:1 PKS:ZnCl2 and carbonized at 550°C showed the highest MB adsorption capacity (maximum uptake at the equilibrium, q max=225.3mg MB / g adsorbent), resulting from its elevated specific surface area (BET, 1058m2/g) and microporosity (micropore surface area, 721m2/g). The kinetic experiments showed that removals over 90% of the equilibrium adsorptions were achieved after 4-h contact time in all the cases. The study showed that palm oil mill waste biomass could be used in the preparation of adsorbents efficient in the removal of colorants in wastewaters.