Removal of phenol from aqueous solution by adsorption onto seashells: equilibrium, kinetic and thermodynamic studies

The efficacy of seashells as a new adsorbent for removal of phenol from aqueous solutions was studied by performing batch equilibrium tests under different operating parameters such as solution pH, adsorbent dose, initial phenol concentration, and temperature. The phenol removal efficiency remained unaffected when the initial pH of the phenol solution was in the range of 3–8. The amount of phenol adsorbed increased with increasing initial phenol concentration while it decreased with increasing temperature. The adsorption equilibrium data showed excellent fit to the Langmuir isotherm model with maximum monolayer adsorption capacity of 175.27 mg g 1 at pH 4.0, initial phenol concentration1⁄4 50 mg L , adsorbent dose1⁄4 2 g and temperature1⁄4 293 K. Analysis of kinetic data showed that the adsorption process followed pseudo-second-order kinetics. Activation energy of the adsorption process, calculated using the Arrhenius equation, was found to be 51.38 kJ mol , suggesting that adsorption of phenol onto seashells involved chemical ionexchange. The numerical value of the thermodynamic parameters (ΔG, ΔH and ΔS) indicated that adsorption of phenol onto seashells was feasible, spontaneous and endothermic under the examined conditions. The study shows that seashells can be used as an economic adsorbent for removal of phenol from aqueous solution. doi: 10.2166/wrd.2013.070 Papita Das Saha Jaya Srivastava Shamik Chowdhury (corresponding author) Department of Biotechnology, National Institute of Technology-Durgapur, Mahatma Gandhi Avenue, Durgapur (WB) 713209, India E-mail: [email protected]