Adsorption of the Textile Dye RED 6 on Activated Carbons Derived from Neem Bark (Azadirachta indica)

Abstract

The elimination of dyes is a major challenge in our developing countries. The aim of this work is to demonstrate the effectiveness of activated carbon from local biomass in eliminating the textile dye RED 6 using adsorption. The activated carbons were prepared chemically using phosphoric acid (H3PO4) as the activating agent. RED 6 was prepared by dissolving the powdered dye in distilled water. To eliminate the RED 6 dye, a series of adsorption tests were carried out. The influences of contact time, dye concentration, mass, pH and temperature were determined and expressed as adsorption rate and adsorbed quantity. The preparation yielded activated carbons CA 30 and CA 60. The dye solution RED 6 with a concentration of 1 g/L was obtained. The optimum adsorption mass is 15 g for CA 60 carbon and 24 g for CA 30 carbon. The RED 6 dye is adsorbed in large quantities throughout the chosen pH range. These results show that the optimum concentration for both carbons is 100 mg/L. The influence of contact time indicates that the best adsorption occurs at 40 and 60 min for carbons CA 60 and CA 30 respectively. The results of the temperature study show better adsorption of the RED 6 dye, with an adsorbed quantity of 4.13 mg/g for temperatures of 30 and 35°C. All these results show that CA 60 and CA 30 carbons produced from neem bark adsorb the RED 6 dye effectively and can be used to eliminate coloured effluents.