| SM ISO690:2012|
IVANETS, Andrei; SRIVASTAVA, V.; KITIKOVA, N.; SHASHKOVA, I.; SILLANPÄÄ, M.. Kinetic and thermodynamic studies of the Co(II) and Ni(II) ions removal from aqueous solutions by Ca-Mg phosphate sorbents. In: Ecological and environmental chemistry 2017The 6th International Conference. 2-3 martie 2017, Chișinău. Chisinau, Republic of Moldova: Academy of Sciences of Moldova, 2017, p. 106.
|Ecological and environmental chemistry 2017 2017|
Conferința "Ecological and environmental chemistry 2017" |
Chișinău, Moldova, 2-3 martie 2017
Cobalt and nickel compounds are widely used in metallurgy, are part of the oxide catalysts, and are also one of the components of batteries for electronic devices. This leads to the inevitable increase of Co (II) and Ni (II) ions in waste waters, which may lead to serious contamination of water and soil. Calcium and magnesium phosphates obtained from the carbonate-containing minerals have been shown to be highly effective for removing metal ions from model and real waste water solutions. 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 15, 30, 45 and 60 °C (±1 °C). 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 onto sorbents were analyzed 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 reveal that Co (II) and Ni (II) uptake process followed the pseudo-second order rate expression. The negative values of ΔG° and the positive values of ΔS° indicate the spontaneous nature of metal ions sorption on the both sorbents. More negative value with the increase of temperature favors the sorption process. The positive values of ΔH° indicate that the sorption process was endothermic in nature. The data thus obtained would be useful for practical application of the low cost and highly effective Ca-Mg phosphate sorbents.