Adsorption isotherm and kinetic studies of pentachlorophenol removal from aqueous solution onto coconut shell-based granular activated carbon

Abstract

Background and Objective: Pentachlorophenol (PCP) is the most toxic organic pollutants of chlorophenols especially found in pulp and paper mill wastewater. Recently, contagion of PCP in water body has become typical issue due to its toxicity and strong resistance to degradation. The aim of this study was to assess the adsorption isotherms and kinetics of PCP from aqueous solution using granular activated carbon (GAC) from coconut shell. Methodology: The effect of equilibrium time, initial concentration and adsorbent dose were investigated in batch mode. Two models namely, Freundlich and Langmuir were used to analyze the equilibrium data via linear regression technique while X-ray Fluorescence spectroscopy (XRF) was used to analyze the adsorbent surface. Results: It was found that the adsorption equilibrium data were absolutely fit with a Freundlich isotherm hence, the adsorption of PCP onto coconut shell-based GAC is heterogeneous. The Freundlich adsorption capacity, Kf, was 23.31 mg g-1 at 37°C. In the kinetic studies conducted, it was also found that the adsorption process follows a pseudo-first-order model (R2>0.97). Analysis of the XRF data exhibited that PCP was adsorbed onto the GAC. Conclusion: Coconut shell-based GAC is an attractive material for use as a low cost adsorbent to eliminate PCP from aqueous solutions.