title: Equilibrium modelling of individual and simultaneous biosorption of chromium(VI) and nickel(II) onto dried activated sludge.
abstract: The biosorption of chromium(VI) and nickel(II) ions, both singly and in combination, by dried activated sludge was investigated in a batch system as a function of initial pH and single- and dual-metal ion concentrations. The working initial pH values for single chromium(VI) and nickel(II) biosorptions were determined as 1.0 and 4.5, respectively. It was observed that the co-ion effect on the equilibrium uptake became more pronounced as the co-ion concentration in solution increased and pH level increased for chromium(VI) and decreased for nickel(II). Adsorption isotherms were developed for both the single- and dual-metal ion systems at these two pH values and expressed by the mono- and multi-component Langmuir and Freundlich adsorption models and model parameters were estimated by the non-linear regression. It was seen that the mono-component adsorption equilibrium data fitted very well to both the mono-component adsorption models for both the components and the pH values studied while the multi-component Freundlich adsorption model adequately predicted the multi-component adsorption equilibrium data at moderate ranges of initial mixture concentrations for both the studied pH values.
authors.affiliation: Department of Chemical Engineering, Hacettepe University, Beytepe, Ankara, Turkey. zaksu@hacettepe.edu.tr
authors.forename: Z
authors.initials: Z
authors.lastname: Aksu
authors.forename: Ui
authors.initials: U
authors.lastname: Açikel
authors.forename: E
authors.initials: E
authors.lastname: Kabasakal
authors.forename: S
authors.initials: S
authors.lastname: Tezer
mesh_terms: D000327:Adsorption; D002857:Chromium / Q000302:isolation & purification / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D009532:Nickel / Q000302:isolation & purification / Q000378:metabolism*; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology*; D013816:Thermodynamics
chemical_list: D012722:Sewage; D002857:Chromium; C074702:chromium hexavalent ion; D009532:Nickel