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2884430 
Journal Article 
Liquid-phase adsorption of phenols using activated carbons derived from agricultural waste material 
Singh, KP; Malik, A; Sinha, S; Ojha, P 
2008 
Yes 
Journal of Hazardous Materials
ISSN: 0304-3894
EISSN: 1873-3336 
150 
3 
626-641 
English 
17582681 
WOS:000253219500020 
Physical and chemical properties of activated carbons prepared from coconut shells (SAC and ATSAC) were studied. The adsorption equilibria and kinetics of phenol and 2,4-dichlorophenol from aqueous solutions on such carbons were then examined at three different temperatures (10, 25 and 40 degrees C). Adsorption of both phenol and 2,4-dichlorophenol increased with an increase in temperature. The experimental data were analyzed using the Langmuir and Freundlich isotherm models. Both the isotherm models adequately fit the adsorption data for both the phenols. The carbon developed through the acid treatment of coconut shells (ATSAC) exhibited relatively higher monolayer adsorption capacity for phenol (0.53 mmol g(-1)) and 2,4-dichlorophenol (0.31 mmol g(-1)) as compared to that developed by thermal activation (SAC) with adsorption capacity of 0.36 and 0.20 mmol g(-1), for phenol and 2,4-dichlorophenol, respectively. The equilibrium sorption and kinetics model parameters and thermodynamic functions were estimated and discussed. The thermodynamic parameters (free energy, enthalpy and entropy changes) exhibited the feasibility and spontaneous nature of the adsorption process. The sorption kinetics was studied using the pseudo-first-order and second-order kinetics models. The adsorption kinetics data for both the phenol and 2,4-dichlorophenol fitted better to the second-order model. An attempt was also made to identify the rate-limiting step involved in the adsorption process. Results of mass transfer analysis suggested the endothermic nature of the reaction and change in the mechanism with time and initial concentration of the adsorbate. The results of the study show that the activated carbons derived from coconut shells can be used as potential adsorbent for phenols in water/wastewater. 
adsorption; equilibria; kinetics; phenols; activated carbons; coconut shell