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Thermoexfoliated commercial vermiculites for Ni2+ removal
AbstractThe aim of the present study was to investigate the effect of thermal expansion on the removal efficiency of commercial vermiculites towards Ni2+ ion from aqueous solutions. Three effects were studied: 1) Contact time between the adsorbent and Ni2+ dissolved in the retention process; 2) adsorbent mass; 3) concentration of Ni2+ in adsorption. Ni2+ uptake was quantitatively evaluated using the Langmuir, Freundlich and Dubinin–Kaganer–Radushkevich (DKR) models. In addition, the adsorption equilibrium was described well by the DKR isotherm model, indicative of a cooperative process. The maximum adsorption capacity obtained with DKR model of 3.13mol/g of Ni2+ on China vermiculite was higher than the value of 2.91 obtained for Piauí vermiculite. The kinetic experimental data were described using pseudo-first and pseudo-second order kinetic models, being well described by pseudo-second order model. The adsorption rate value in distilled water was the same with both vermiculites, 0.001h−1. Thermally exfoliated vermiculites type-2, as China, would be more suitable than vermiculites type-1, as Piauí, for recovering traces of Ni2+ in water because: a) its high mica-like content and therefore high degree of expansion, exfoliation and formation of larger pores; b) its maximum adsorption capacity.
HighlightsThermoexfoliated vermiculites with mica adsorb more Ni2+ in water than the purest ones.The adsorption equilibrium was described well by the DKR isotherm model.Experimental data of the thermoexfoliated vermiculites were well described by pseudo-second order model.
Thermoexfoliated commercial vermiculites for Ni2+ removal
AbstractThe aim of the present study was to investigate the effect of thermal expansion on the removal efficiency of commercial vermiculites towards Ni2+ ion from aqueous solutions. Three effects were studied: 1) Contact time between the adsorbent and Ni2+ dissolved in the retention process; 2) adsorbent mass; 3) concentration of Ni2+ in adsorption. Ni2+ uptake was quantitatively evaluated using the Langmuir, Freundlich and Dubinin–Kaganer–Radushkevich (DKR) models. In addition, the adsorption equilibrium was described well by the DKR isotherm model, indicative of a cooperative process. The maximum adsorption capacity obtained with DKR model of 3.13mol/g of Ni2+ on China vermiculite was higher than the value of 2.91 obtained for Piauí vermiculite. The kinetic experimental data were described using pseudo-first and pseudo-second order kinetic models, being well described by pseudo-second order model. The adsorption rate value in distilled water was the same with both vermiculites, 0.001h−1. Thermally exfoliated vermiculites type-2, as China, would be more suitable than vermiculites type-1, as Piauí, for recovering traces of Ni2+ in water because: a) its high mica-like content and therefore high degree of expansion, exfoliation and formation of larger pores; b) its maximum adsorption capacity.
HighlightsThermoexfoliated vermiculites with mica adsorb more Ni2+ in water than the purest ones.The adsorption equilibrium was described well by the DKR isotherm model.Experimental data of the thermoexfoliated vermiculites were well described by pseudo-second order model.
Thermoexfoliated commercial vermiculites for Ni2+ removal
Marcos, Celia (author) / Rodríguez, Irene (author)
Applied Clay Science ; 132-133 ; 685-693
2016-08-25
9 pages
Article (Journal)
Electronic Resource
English
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