Effect of surface equilibria on the electrokinetic behaviour of Pb and Cd ions in kaolinite. Issue 7 (10th June 2014)

• Record Type: Journal Article
• Authors: Mascia, Michele; Vacca, Annalisa; Palmas, Simonetta
• Is Part Of: Journal of chemical technology & biotechnology. Volume 90:Issue 7(2015:Jul.)
• Page Start: 1290
• Page End: 1298
• Publication Date: 2014-06-10
• Subjects: Biotechnology -- Periodicals; Chemistry, Technical -- Periodicals; Chemical engineering -- Periodicals; Industries -- Environmental aspects -- Periodicals; 660
• DOI: 10.1002/jctb.4435
• Languages: English
• ISSNs: 0268-2575

Abstract

<abstract abstract-type="main" id="jctb4435-abs-0001"> <title>Abstract</title> <sec id="jctb4435-sec-0001" sec-type="section"> <title>BACKGROUND</title> <p id="jctb4435-para-0001">Electrokinetic remediation of fine‐grained soils polluted by heavy metals is affected by the equilibria between dissolved and sorbed ions; pH can also influence the surface equilibria. Geochemical models which describe the behaviour of different surface sites and their interactions with heavy metal ions have to be considered for a good mathematical representation of an electrokinetic process.</p> </sec> <sec id="jctb4435-sec-0002" sec-type="section"> <title>RESULTS</title> <p id="jctb4435-para-0002">Cd<sup>2+</sup> and Pb<sup>2+</sup> sorption isotherms were performed at different pH values using kaolinite as sorbent. Electrokinetic tests were performed with samples of kaolinite spiked with Cd<sup>2+</sup> and Pb<sup>2+</sup> at 0.7 and 2 V cm<sup>−1</sup>: the concentration profiles were obtained experimentally at different treatment times. The pH in the compartments was conditioned by acetate buffer. On the basis of the experimental results, a numerical model was formulated to simulate ion transport under an electric field combining the diffusion–advection equations with a two‐sites geochemical model taking into account ion exchange and surface complexation of the metal ions, as well as the protonation–deprotonation reactions of the surface sites.</p> </sec> <sec id="jctb4435-sec-0003" sec-type="section"> <title>CONCLUSIONS</title> <p id="jctb4435-para-0003">The process was effective for cadmium removal, while a strong dependence on pH was observed for lead removal. The model allowed prediction of time/space profiles in solid and liquid phase: a good agreement with the experimental data was obtained under all the conditions adopted. © 2014 Society of Chemical Industry</p> </sec> </abstract>