Effect of Experimental Variables on Phenol Adsorption on Activated Carbon Prepared from Coconut Husk by Single-step Steam Pyrolysis: Mass Transfer Process and Equilibrium Studies

128-138Industrial solid waste can be converted to activated carbon and is used as low cost adsorbent for wastewater treatment.Coconut husk, a waste product in coir industry was used for the preparation of activated carbon by single-step steam pyrolysis. The product exhibits a very high adsorption potential for phenol and under optimum condition more than 99 per cent removal has been achieved . The adsorption of phenol onto activated carbon has been studied, using batch technique under kinetic and equilibrium conditions. The effect of several variables such as initial concentration, temperature, agitation speed, particle size of the adsorbent and pH on phenol removal has been studied. Sorption of phenol depends on the pH of the solution with maximum uptake of 99 per cent occurring at 5.5 and an initial conc. of 25.0 mg/L. Both, external and intraparticular, mass transfer diffusion models have been tested to describe the kinetic data. The sorption mechanism is also discussed. The equilibrium data have been evaluated for compliance with Langmuir and Freundlich isotherm models. Temperature study reveals that the adsorption of phenol is exothermic in nature. Thermodynamic parameters have also been presented to predict the nature of adsorption. Isosteric heat of adsorption is varied with surface coverage. The adsorption data show that spent carbon can be regenerated for further use by hot water treatment.