Sorption of tartrazine dye from aqueous solution using activated carbon prepared from Cocos nucifera husk

Abstract

Sorption of Tartrazine dye from aqueous solution using activated carbon prepared from Cocos nucifera (coconut) husk was investigated in this work. The coconut shell was first carbonized at 700°C in a muffle furnace and activated with NaOH for one hour. The activated carbon (AC) was applied to remove tartrazine from aqueous solutions over a concentration range of 50-250 mg/L respectively. Adsorbent features were determined using X-ray fluorescence (XRF), Fourier transformed infrared spectroscopy (FTIR), Scanning electron micrograph (SEM) techniques. Based on this investigation, adsorption of Tartrazine dye is strongly affected by initial solution pH, initial solution concentrations, dosage, and time of contact which favours the removal. Except for temperature which was found to decrease with increase temperature for AC, while adsorption capacity of Tartrazine was found to decrease with increase in adsorbent dosage for AC. The optimum pH for adsorption Tartrazine removal was found to be 3. The experimental data of Tartrazine was found to fit the linearized Langmuir isotherm better than the Freundlich isotherm and D-R model indicating a monolayer adsorption. On effect of initial solution concentration, adsorption capacity of Tartrazine was found to increase with increase in concentration for AC. Kinetic data fitted more into pseudo second order model than first order and intra particle diffusion model, suggesting that chemisorption dominate the rate limiting step. The calculated thermodynamic parameters – Gibbs free energy, enthalpy change and entropy change indicated that adsorption of Tartrazine was endothermic and not spontaneous meaning the chemisorption dominates physisorption.