title: A comparison of basic dye adsorption onto zeolitic materials synthesized from fly ash.
abstract: This investigation reveals the adsorption characteristics of two basic dyes, thionine (TH) and safranine T (ST), onto fly ash (FA) and its three zeolitized products prepared at different hydrothermal conditions. Typical two-step isotherms were observed for TH adsorption onto four adsorbents, whereas the isotherms of the larger ST molecules were S-shaped. The adsorption capacities of the zeolitized fly ash (ZFA) estimated from the first plateau region of the TH isotherms was nearly twice the FA capacity. The capacities increased by up to five times in the second plateau region. The adsorption capacity of FA for ST is equivalent that of TH, whereas the capacities of ZFA are lower than those found for TH. The equilibrium results were well-described by the Freundlich isotherm model. The kinetic data obtained in the temperature range of 298-318 K was analyzed using Paterson's and Nernst Plank's approximations based on the homogeneous surface diffusion model (HSDM). The thermodynamic functions for the transition state were evaluated from the temperature-dependence of the surface diffusion coefficients by applying the Eyring model.
authors.affiliation: Faculty of Engineering, Department of Chemistry, Istanbul University, 34850 Avcılar, Istanbul, Turkey. gultena@istanbul.edu.tr
authors.forename: Gülten
authors.initials: G
authors.lastname: Atun
authors.forename: Gül
authors.initials: G
authors.lastname: Hisarlı
authors.forename: Ayşe Engin
authors.initials: AE
authors.lastname: Kurtoğlu
authors.forename: Nihat
authors.initials: N
authors.lastname: Ayar
mesh_terms: D000327:Adsorption; D002244:Carbon; D060729:Coal Ash; D004396:Coloring Agents / Q000737:chemistry*; D004058:Diffusion; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D052638:Particulate Matter; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D017641:Zeolites / Q000737:chemistry*
chemical_list: D060729:Coal Ash; D004396:Coloring Agents; D052638:Particulate Matter; D017641:Zeolites; D002244:Carbon