1Departments of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, P.O. Box 51666-16471 Tabriz, I.R. IRAN
2Department of Chemistry, Payame Nour University, Urmia, I.R. IRAN
3Drug Applied Research Center, Tabriz University of Medical Sciences, P.O. Box 51644-14766 Tabriz, I.R. IRAN
4Department of Chemistry, Faculty of Science, Urmia University, Urmia, I.R. IRAN
Graphene, a new member of the carbon family, was used as an adsorbent due to its exceptional capability to remove Rhodamine B (RB) and Malachite Green (MG), two organic dyes, from aqueous solutions. Adsorption kinetics of RB and MG onto graphene and adsorption capacity of the adsorbent were studied. Also the effects of parameters, including pH, contact time, temperature, and adsorbent dosage were studied. The adsorption process was followed using UV-visible spectroscopy. The isotherm analysis indicated that Freundlich and Langmuir isotherms are suitable for RB and MG, respectively. Pseudo-first- and pseudo-second-order models were considered to evaluate rate parameters. The kinetic experimental results fitted well the pseudo-second-order model for the two dyes, with correlation coefficients being greater than 0.99. Thermodynamic studies indicated that the adsorption processes is spontaneous for both the dyes, and exothermic for RB and endothermic for MG.