Journal of Advanced Chemical Sciences (JACS)

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Article – Journal of Environmental Sciences

Journal of Environmental Science and Pollution Research, Volume 2,Issue 4,2016 Pages 134-139

Equilibrium, Kinetic and Thermodynamic Studies for Adsorption of Phenol on Modified Coal Fly Ash (MCFA)
Y.P. Chauhan*, M. Talib

Modified coal fly ash (MCFA) is prepared from coal fly ash (CFA) by hydrothermal treatment with alkali. This MCFA is used to remove the phenol from wastewater. The effect of adsorption process variables such as adsorbent dosage, contact time, phenol concentration, pH and temperature has been investigated. The suitability of Freundlich and Langmuir adsorption models to the equilibrium data was found for phenol-MCFA system. The adsorption kinetics and thermodynamics also performed for the phenol removal. The results showed that the percentage removal of phenol increased and adsorption rate was decreased as adsorbent dosage is increased. Equilibrium time required for the adsorption of phenol on MCFA was almost 90 minutes. As initial phenol concentration increases, it resulted in increased phenol uptake. The uptake of phenol by MCFA was almost constant in the pH range of 2.0-6.0. Then the adsorption decreased with increasing pH. Adsorption capacity of MCFA increased with increasing temperature which indicates that the adsorption process was endothermic. The optimum temperature of MCFA was found to be 40 °C within the temperature range studied. Good fit was observed by both Freundlich and Langmuir models. Pseudo-second-order kinetic model gives the good correlation for the adsorption of phenol onto MCFA amongst the model studied. Gibbs free energy (ΔG) values found negative indicating the adsorption process is spontaneous and favorable for phenol-MCFA system. The positive value of ΔH (21508.318 kJ/mol) and ΔS (121.30126 kJ/mol) denotes that the process is endothermic and aided by increased randomness for phenol. The studies showed that MCFA can be used as an efficient adsorbent material for removal of phenol from wastewater.

Keywords: MCFA; Phenol; Adsorption; Langmuir; Freundlich;