title: Kinetic and thermodynamic studies of the Co(II) and Ni(II) ions removal from aqueous solutions by Ca-Mg phosphates.
abstract: The aim of this work was to study the sorption kinetics and thermodynamics of Co(II) and Ni(II) from aqueous solutions by sorbents on the basis of hydrogen (PD-1) and tertiary (PD-2) Ca-Mg phosphates depending on the solution temperature and sorbents chemical composition. Kinetic studies of adsorption of Co(II) and Ni(II) ions onto samples of phosphate sorbents were performed in batch experiment at the temperatures 288, 303, 318 and 333 K. The sorbent dose was fixed at 10 g L-1, initial pH value 2.6, and contact time varied from 5 to 600 min. The kinetics of Co(II) and Ni(II) adsorption were analyzed by using pseudo-first order, pseudo-second order and intraparticle diffusion models. Thermodynamic parameters (ΔG°, ΔH° and ΔS°) for the sorption of Co(II) and Ni(II) were determined using the Gibbs-Helmholtz equation. The calculated kinetic parameters and corresponding correlation coefficients revealed that Co(II) and Ni(II) uptake process followed the pseudo-second order rate expression. Thermodynamic studies confirmed the spontaneous and endothermic nature of removal process which indicate that sorption of Co(II) and Ni(II) ions onto both phosphate sorbents is favoured at higher temperatures and has the chemisorptive mechanism. The data thus obtained would be useful for practical application of the low cost and highly effective Ca-Mg phosphate sorbents.
authors.affiliation: Institute of General and Inorganic Chemistry of National Academy of Sciences of Belarus, st. Surganova 9/1, 220072 Minsk, Belarus. Electronic address: ivanets@igic.bas-net.by.
authors.forename: A I
authors.initials: AI
authors.lastname: Ivanets
authors.affiliation: Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, 50130 Mikkeli, Finland.
authors.forename: V
authors.initials: V
authors.lastname: Srivastava
authors.affiliation: Institute of General and Inorganic Chemistry of National Academy of Sciences of Belarus, st. Surganova 9/1, 220072 Minsk, Belarus.
authors.forename: N V
authors.initials: NV
authors.lastname: Kitikova
authors.affiliation: Institute of General and Inorganic Chemistry of National Academy of Sciences of Belarus, st. Surganova 9/1, 220072 Minsk, Belarus.
authors.forename: I L
authors.initials: IL
authors.lastname: Shashkova
authors.affiliation: Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, 50130 Mikkeli, Finland; Department of Civil and Environmental Engineering, Florida International University, Miami, FL 33174, USA.
authors.forename: M
authors.initials: M
authors.lastname: Sillanpää
mesh_terms: D000327:Adsorption; D002130:Calcium Phosphates / Q000737:chemistry*; D003300:Copper / Q000737:chemistry* / Q000302:isolation & purification*; D004058:Diffusion; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D017616:Magnesium Compounds / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry* / Q000302:isolation & purification*; D010710:Phosphates / Q000737:chemistry*; D012996:Solutions; D013696:Temperature; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D002130:Calcium Phosphates; D017616:Magnesium Compounds; D010710:Phosphates; D012996:Solutions; D014874:Water Pollutants, Chemical; D014867:Water; C030781:magnesium phosphate; D003300:Copper; D009532:Nickel; C020243:calcium phosphate
keywords: Cobalt (II); Kinetic modeling; Nickel (II); Sorption; Thermodynamic; Wastewater