title: The adsorption kinetics of the cationic dye, methylene blue, onto clay.
abstract: In this study, adsorption kinetics of a cationic dye, methylene blue, onto clay from aqueous solution with respect to the initial dye concentration, temperature, pH, mixing rate and sorbent dosage were investigated. In order to understand the adsorption mechanism in detail, zeta potentials and the conductivities of clay suspensions at various pH (1-11) and cation exchange capacity (CEC) were measured. Porosity and BET surface area of clay studied were determined. The results showed that the adsorption has been reached to equilibrium in 1 h. It was found that the amount adsorbed of methylene blue increases with decreasing temperature and also with increasing both sorbent dosage and increasing initial dye concentration. Adsorption capacity decreases with increasing pH, except for the natural pH (5.6) of clay suspensions. The adsorption kinetics of methylene blue has been studied in terms of pseudo-first-order, pseudo-second-order sorption and intraparticle diffusion processes thus comparing chemical sorption and diffusion sorption processes. It was found that the pseudo-second-order mechanism is predominant and the overall rate of the dye adsorption process appears to be controlled by the more than one-step.
authors.affiliation: Ataturk University, K.K. Eitim Fakultesi, Department of Chemistry, 25240 Erzurum, Turkey. ahmetgu@yahoo.com
authors.forename: A
authors.initials: A
authors.lastname: Gürses
authors.forename: C
authors.initials: C
authors.lastname: Doğar
authors.forename: M
authors.initials: M
authors.lastname: Yalçin
authors.forename: M
authors.initials: M
authors.lastname: Açikyildiz
authors.forename: R
authors.initials: R
authors.lastname: Bayrak
authors.forename: S
authors.initials: S
authors.lastname: Karaca
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates; D000077215:Clay; D004791:Enzyme Inhibitors / Q000493:pharmacokinetics*; D006863:Hydrogen-Ion Concentration; D008751:Methylene Blue / Q000493:pharmacokinetics*; D016062:Porosity; D013696:Temperature
chemical_list: D000538:Aluminum Silicates; D004791:Enzyme Inhibitors; D000077215:Clay; D008751:Methylene Blue