INVESTIGATION OF CONGO RED ADSORPTION ON ACTIVATED CARBON PREPARED FROM ARACHIS HYPOGAEA SHELLS

Adsorption of congo red on activated carbon prepared from Arachis hypogaea shells was investigated. Screening experiments conducted using Plackett-Burman design reveal that, among the five factors tested, solution pH, dye concentration and mass of activated carbon produced significant effects on the quantity of congo red adsorbed on the activated carbon at p < 0.10. Optimization experiments conducted using Box-Behnken design indicated that the combination of variable settings that produced maximum congo red adsorption with a desirability value of 0.8054 were solution pH of 2.0, dye concentration of 45.86 mg/L and 1.2 g of activated carbon. At these optimal variable settings, the predicted and actual amounts of congo red adsorbed on the adsorbent were 23.57 mg/g and 21.94 mg/g respectively. Findings also revealed that among the kinetic and equilibrium models tested, the experimental data fitted well to pseudo-second order model (􀀀  = 0.9996) and Tempkin adsorption isotherm (􀀀  = 0.9314), suggesting that congo red adsorption on the adsorbent involves chemisorption. The results presented in this paper demonstrated that the activated carbon prepared from the shells of Arachis hypogaea could serve as a low-cost and eco-friendly adsorbent for removing congo red from contaminated wastewater. Keywords: Activated carbon, Arachis hypogaea, Congo red, Isotherms, Kinetics, Optimization