Adsorption of methylene blue from aqueous solutions by modified expanded graphite powder.pdf

Desalination 249 (2009) 331–336 Contents lists available at ScienceDirect Desalination j ourna l homepage: www.e lsev ie / locate /desa lAdsorption of methylene blue from aqueous solutions by modified expanded graphite powder Mingfei Zhao, Peng Liu ? Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, China? Corresponding author. Tel.: +86 931 8912516; fax: E-mail address: pliu@ (P. Liu). 0011-9164/$ – see front matter ? 2009 Elsevier B.V. Al doi:10.1016/j.desal.2009.01.037a b s t r a c ta r t i c l e i n f oArticle history: Accepted 28 January 2009 Available online 2 October 2009 Keywords: Adsorption Modified expanded graphite Methylene blue Kinetics Isotherm ModelingThe modified expanded graphite (MEG) powder was used as a porous adsorbent for the removal of the cationic dye, methylene blue (MB), from aqueous solutions. The dye adsorption experiments were carried out with the bath procedure. Experimental results showed that the basic pH, increasing initial dye concentration and high temperature favored the adsorption. The dye adsorption equilibriumwas attained rapidly after 5 min of contact time. Experimental data related to the adsorption of MB on the MEG under different conditions were applied to the pseudo-first-order equation, the pseudo-second-order equation and the intraparticle diffusion equation, and the rate constants of first-order adsorption (k1), the rate constants of second-order adsorption (k2) and intraparticle diffusion rate constants (kint)were calculated, respectively. The experimental datafitted verywell in the pseudo-second-order kinetic model. The thermodynamic parameters of activation such as Gibbs free energy, enthalpy, and entropy were also evaluated. The results indicated that theMEG powder could be employed as an efficient adsorbent for the removal of textile dyes from effluents.+86 931 8912582. l rights reserved.? 2009 Elsevier B.V. All rights reserved.1.