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Open AccessArticle

Extractant Immobilization in Alginate Capsules (Matrix- and Mononuclear-Type): Application to Pb(II) Sorption from HCl Solutions

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Departamento de Química, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Guanajuato, C.P. 36040, Mexico
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Centre des Matériaux des Mines d’Alès, Ecole des mines d’Alès, F-30319 Alès cedex, France
*
Authors to whom correspondence should be addressed.
Academic Editor: Jaroslaw Drelich
Materials 2017, 10(6), 634; https://doi.org/10.3390/ma10060634
Received: 20 April 2017 / Revised: 1 June 2017 / Accepted: 6 June 2017 / Published: 9 June 2017
(This article belongs to the Special Issue Sorption Materials for Environment Purification)
The decontamination of dilute industrial effluents is a critical challenge for decreasing the environmental impact of mining and metallurgical activities. As an alternative to conventional processes, new extractant impregnated resins (EIRs) have been synthesized by the immobilization of Cyanex 301 and Cyanex 302 in alginate capsules using two different procedures (matrix-type immobilization vs. mononuclear encapsulation). These materials have been tested for Pb(II) sorption from acidic solutions. The Langmuir equation fitted well the sorption isotherms and the maximum sorption capacities vary between 24 and 80 mg·g−1 at pH 1, depending on the type and loading of the extractant in the EIR. Uptake kinetics were controlled by the resistance to intraparticle diffusion; though both the Crank equation (intraparticle diffusion) and pseudo-second order rate equation equally fitted uptake profiles. The amount of extractant immobilized in mononuclear capsules is lower than in matrix-type beads; this leads to lower sorption capacities but slightly better mass transfer properties. The balance between the advantages and drawbacks of the different systems makes more promising matrix-type capsules. The desorption of Pb(II) is possible using 1 M HNO3 solutions: metal ions were completely desorbed. However, the probable oxidation of the extractants (conversion to oxidized forms more sensitive to pH) reduces the sorption efficiency when they are re-used. View Full-Text
Keywords: Cyanex 301; Cyanex 302; lead; uptake kinetics; sorption isotherms; desorption; matrix-encapsulation; mononuclear encapsulation Cyanex 301; Cyanex 302; lead; uptake kinetics; sorption isotherms; desorption; matrix-encapsulation; mononuclear encapsulation
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MDPI and ACS Style

Alba, J.; Navarro, R.; Saucedo, I.; Vincent, T.; Guibal, E. Extractant Immobilization in Alginate Capsules (Matrix- and Mononuclear-Type): Application to Pb(II) Sorption from HCl Solutions. Materials 2017, 10, 634.

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