Removal of phenols from water environment by activated carbon, bagasse ash and wood charcoal

Adsorption process is gaining interest as one of the effective processes of advanced wastewater treatment for treatment of industrial effluent containing toxic materials. The present work involves an investigation of the use of three carbonaceous materials, activated carbon (AC), bagasse ash (BA) and wood charcoal (WC), as adsorbents for removal of phenol from water. Batch experiments were carried out to obtain adsorption equilibrium isotherms and kinetics with phenol spiked synthetic solutions. The study was performed with two initial phenol concentrations, viz. 30 and 50 mg/L, with an equal amount of adsorbent dose (50 g/L). The effects of solution pH, concentrations of EDTA, anions, and dosages of adsorbent on removal of phenol were examined. Desorption tests were also conducted in the present study. The suitability of the different isotherm models to the equilibrium data was studied for each phenol-adsorbent system. Experimental results showed that for phenol-AC, phenol-WC and phenol-BA adsorption systems, approximately 98%, 90% and 90% removal efficiencies were achieved at given adsorption conditions. The kinetic study indicates that the phenol removal with the selected adsorbents is a first order adsorption. Freundlich isotherm model was found to fit the data for adsorption of phenol with the adsorbents. Removal efficiency of phenol slightly increased when the pH of adsorption system decreased. The effect of nitrate ion and EDTA in the solution on the adsorption of phenol was found to be insignificant; however, the chloride ion has considerable negative effects on the removal by BA. The estimation of diffusion coefficients indicated that film diffusion may control the adsorption of phenol with the studied adsorbent materials. (c) 2006 Elsevier B.V. All rights reserved.