Adsorptive removal of bromocresol green dye using activated corn cob

Abstract

The adsorption of Bromocresol green (BCG) dye was investigated using activated carbon prepared from corn cob with sulphuric acid. Batch adsorption was carried out and the physical properties of the corn cob activated carbon (CCAC) was determined. The effects of pH, temperature, adsorbent dosage, contact time and concentration on the adsorption process and the Kinetics, Isotherms and Thermodynamics studies were all carried out. The adsorption kinetic study indicated that the First-order and Natarajan & Khalaf models best described the rate of adsorption of BCG with the highest correlation coefficient of 0.985 compared to the pseudo first-order and pseudo second-order model. The Isotherm models investigated confirmed that Freundlich and Halsay models gave the best fit for the equilibrium data and best representation of the BCG removal on to CCAC (R2=0.977). The thermodynamics study through the calculated enthalpy change (ΔH), entropy change (ΔS) and Gibbs free energy (ΔG) indicated that the process was exothermic, with a decreased randomness at the solid-solution interface and a non-spontaneous process respectively. The separation factor RL value for BCG removal by activated corn cob was calculated as 0.02 meaning that the adsorption process was favorable. The maximum adsorption capacity (qe) of 14.153 mg/g was obtained using CCAC as adsorbent in the adsorption process of BCG. The results showed that the adsorption of BCG yielded a good efficiency with CCAC.