title: Removal of dyes from aqueous solution using fly ash and red mud.
abstract: Fly ash and red mud have been employed as adsorbents for the removal of a typical basic dye, methylene blue, from aqueous solution. Heat treatment and chemical treatment have also been applied to the as-received fly ash and red mud samples. It is found that fly ash generally shows higher adsorption capacity than red mud. The raw fly ash and red mud show adsorption capacity at 1.4 x 10(-5) and 7.8 x 10(-6) mol/g, respectively. Heat treatment reduces the adsorption capacity for both fly ash and red mud but acid treatment by HNO(3) induces a different effect on fly ash and red mud. Nitric acid treatment results in an increase in adsorption capacity of fly ash (2.4 x 10(-5) mol/g) while it decreases the adsorption capacity for red mud (3.2 x 10(-6) mol/g). The adsorption data have been analysed using Langmuir, Freundlich and Redlich-Peterson isotherms. The results indicate that the Redlich-Peterson model provides the best correlation of the experimental data. Isotherms have also been used to obtain the thermodynamic parameters such as free energy, enthalpy and entropy of adsorption. For fly ash and red mud, adsorption of methylene blue is endothermic reaction with DeltaH(0) at 76.1 and 10.8 kJ/mol, respectively.
authors.affiliation: Department of Chemical Engineering, Curtin University of Technology, GPO Box U1987, Perth, WA 6845, Australia. wangshao@vesta.curtin.edu.au
authors.forename: Shaobin
authors.initials: S
authors.lastname: Wang
authors.forename: Y
authors.initials: Y
authors.lastname: Boyjoo
authors.forename: A
authors.initials: A
authors.lastname: Choueib
authors.forename: Z H
authors.initials: ZH
authors.lastname: Zhu
mesh_terms: D000327:Adsorption; D000535:Aluminum / Q000032:analysis; D002244:Carbon / Q000737:chemistry; D060729:Coal Ash; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste / Q000032:analysis; D008751:Methylene Blue / Q000737:chemistry / Q000302:isolation & purification*; D017942:Nitric Acid / Q000737:chemistry; D052638:Particulate Matter; D012996:Solutions; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D060729:Coal Ash; D007220:Industrial Waste; D052638:Particulate Matter; D012996:Solutions; D014874:Water Pollutants, Chemical; D017942:Nitric Acid; D002244:Carbon; D000535:Aluminum; D008751:Methylene Blue