Kinetic and thermodynamic parameters of iron adsorption onto olive stones

Different pretreatment of olive stones for iron adsorption. •Olive stones have considerable potential for the removal of metal ions from effluents.•Adsorption mechanism is predominantly physisorption with some chemisorption.•The removal efficiency of Fe(III) ions increase with incrementing temperatu...

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Bibliographic Details
Published in:Industrial crops and products 2013-08, Vol.49, p.526-534
Main Authors: Hodaifa, Gassan, Ochando-Pulido, J.M., Driss Alami, Saloua Ben, Rodriguez-Vives, S., Martinez-Ferez, A.
Format: Article
Language:English
Subjects:
activation energy
Adsorption
biomass
effluents
energy
enthalpy
entropy
Industrial wastewaters
industry
Iron
Kinetic study
Olea
olive oil
Olive stones
olives
sorption isotherms
temperature
washing
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Summary:Different pretreatment of olive stones for iron adsorption. •Olive stones have considerable potential for the removal of metal ions from effluents.•Adsorption mechanism is predominantly physisorption with some chemisorption.•The removal efficiency of Fe(III) ions increase with incrementing temperature.•Olive stone is adequate adsorbent for small and medium-scale industry. Olive stones biomass, by-product of olive oil industry, has been addressed in the present study as adsorbent for iron. Experimental results have shown that the pretreatments performed have not favored the iron adsorption capacity, demonstrating that direct reuse (as manufactured) or a simple washing with cold and hot water is sufficient. Results obtained indicate that the adsorption process is fast and spontaneous within the first 10–20min. The experimental data supports both pseudo-first and pseudo-second order models. Kinetic parameters and equilibrium adsorption capacity were found to be increased upon stirring rates above 75rpm. Also temperature effect was studied. Adsorption capacity values, qe, raise as temperature increases from 278 to 343K, pin-pointing for an endothermic adsorption process. The adsorption isotherms were obtained from 5 different temperatures in the ranges of 278–343K and 5–100mgdm−3 iron (III) concentrations. These adsorption data were fitted with Langmuir isotherm. In addition, the mean values of thermodynamic parameters of activation energy (Ea=8.04kJmol−1), standard free energy (ΔG0=−19.51kJmol−1), standard enthalpy (ΔH0=8.86kJmol−1) and standard entropy (ΔS0=91.4Jmol−1K−1) of the adsorption mechanism were determined. What is more, the present process is environmentally friendly and may be able to reduce the iron load from different effluents, also providing an affordable technology for small and medium-scale industry.
ISSN:0926-6690
1872-633X
DOI:10.1016/j.indcrop.2013.05.039