Nitrate sorption by organosmectites

The use of organoclays as adsorbents in the remediation of polluted water has been the subject of many recent studies. In this present work, a Tunisian smectite modified by two cationic surfactants was used as a sorbent for the investigation of the adsorption kinetics, isotherms and thermodynamic pa...

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Bibliographic Details
Published in:Engineering geology 2012-01, Vol.124, p.119-129
Main Authors: Gammoudi, S., Frini-Srasra, N., Srasra, E.
Format: Article
Language:English
Subjects:
Applied sciences
Buildings. Public works
Exact sciences and technology
Geotechnics
Nitrate ions
Organo-smectite
Soil investigations. Testing
Sorption
Surface proprieties
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Summary:The use of organoclays as adsorbents in the remediation of polluted water has been the subject of many recent studies. In this present work, a Tunisian smectite modified by two cationic surfactants was used as a sorbent for the investigation of the adsorption kinetics, isotherms and thermodynamic parameters of nitrate ions at various contact time, initial concentrations and temperatures. Two simplified kinetic models, first-order and second-order, were used to predict the adsorption constants. It was found that the adsorption kinetics of nitrate was best described by the second-order model. Adsorption isotherms and equilibrium adsorption capacities were determined by the fittings of the experimental data to two well-known isotherm models including Langmuir and Freundlich. The results showed that Langmuir model appears to fit the adsorption better than Freundlich model. The equilibrium constants were used to calculate thermodynamic parameters, such as the change of free energy, enthalpy and entropy. [Display omitted] ► Properties of the organoclays modify according to the nature of exchangeable cations. ► Modified-smectite can remove nitrate ions from wastewater ► Sorption capacities increase with contact time and initial concentration. ► Sorption capacities of modified smectites decrease with pH and temperature.
ISSN:0013-7952
1872-6917
DOI:10.1016/j.enggeo.2011.10.009