Decontamination of 4-Chloro-2-Nitrophenol from Aqueous Solution by Graphene Adsorption: Equilibrium, Kinetic, and Thermodynamic Studies
Ali Mehrizad1, Parvin Gharbani2
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1Department of Chemistry, College of Sciences, East Azarbaijan Science and Research Branch,
Islamic Azad University, Tabriz, Iran
2Department of Chemistry, College of Sciences, Ahar Branch, Islamic Azad University, Ahar, Iran
Submission date: 2014-03-24
Final revision date: 2014-05-19
Acceptance date: 2014-05-30
Publication date: 2014-12-16
Pol. J. Environ. Stud. 2014;23(6):2111–2116
4-Chloro-2-nitrophenol (4C2NP) is an important chemical widely used in the pharmaceuticals, herbicide, and pesticide industries. The ability of graphene to remove 4C2NP from aqueous solutions was performed as a function of contact time, amounts of adsorbent, pH, initial 4C2NP concentrations, and temperatures using a batch technique. Based on the results, the amount of 4C2NP adsorption increased with increasing initial concentration, whereas the alkaline pH range, higher graphene dosage, and higher temperature were unfavorable. Non-linear regression methods suggest that the isotherm data can be well described by the Freundlich isotherm equation. The adsorption kinetic data were analyzed using the non-linear rate equations of pseudo-first and pseudo-second order. It was found that the pseudo-second-order kinetic model was the most appropriate model, describing the adsorption kinetics. The observed changes in the standard Gibbs free energy (ΔGº), standard enthalpy (ΔHº), and standard entropy (ΔSº) show that the adsorption of 4C2NP by graphene is feasible, spontaneous, and exothermic in the temperature range 298-328 K.