3 results for Araneda, C

  • Microencapsulation of trioctylamine in polymeric matrices for removing Zn(II) and Cu(II) from chloride aqueous solutions

    Fonseca, C; Araneda, C; Yazdani-Pedram, M; Borrmann, T; Basualto, C; Sapag, J; Valenzuela, F (2010)

    Journal article
    The University of Auckland Library

    The microencapsulation of the non-specific basic extractant trioctylamine in polymeric matrices synthesized from styrene and divinylbenzene was studied. The microcapsules were prepared by adding the amine compound during in situ free radical suspension polymerization using benzoyl peroxide as the initiator and using variable proportions of both monomers. SEM analysis shows that the microcapsules have a spherical shape presenting an average surface area of 480 m2 g-1 and a pore size around 0.5 to 1.8 nm. Synthesis of the microspheres was affected by the amount of extractant used and by the proportion of both monomers during their preparation. The obtained microcapsules were used for the sorptive removal of Zn(II) and Cu(II) ions from chloride aqueous solutions, reaching extraction extents near 90% under the best conditions, following an anion-exchange mechanism between the metallic ions and the extractant immobilized onto the microcapsules. Zn(II) and Cu(II) sorption kinetics experiments were performed and efficient uptake of both metals within a few minutes was measured. The experimental results were explained using a pseudo-second-order rate kinetics model, which fit the results of chemisorption of both metals onto the microcapsules well.

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  • A kinetics analysis applied to the recovery of Zn(II) content from mine drainage by using a surfactant liquid membrane

    Valenzuela, F; Basualto, C; Sapag, J; Romero, J; Höll, W; Fonseca, C; Araneda, C (2010)

    Journal article
    The University of Auckland Library

    A kinetics analysis was conducted for the recovery of zinc (II) ions from a mine drainage sample by a liquid surfactant membrane containing di-(2-ethylhexyl)phosphoric acid as a carrier extractant and Span-80 as the surfactant. The extraction of metal was proportional to the concentration of carrier in the organic phase, inversely proportional to the zinc content in the feed solution, and was enhanced as the pH of the feed phase was increased. A minimum sulfuric acid content of 150 g/L in the stripping solution was necessary to favor the transport of metals from the external aqueous solution to the metal-receiving strip liquor. The experimentally observed results were analyzed by a metal extraction kinetics mechanism based on a facilitated transport model, which considers the interfacial chemical reaction between the metal and the carrier at the external interface of the liquid membrane as kinetic controlling step. The experimental results were fairly well explained by the model that takes into account the interfacial activity of both the surfactant and the carrier compound.

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  • Removal of metal ions from aqueous solutions by sorption onto microcapsules prepared by copolymerization of ethylene glycol dimethacrylate with styrene

    Araneda, C; Fonseca, C; Sapag, J; Basualto, C; Yazdani-Pedram, M; Kondo, K; Kamio, E; Valenzuela, F (2008-11-03)

    Journal article
    The University of Auckland Library

    The removal of Cd(II) and Cu(II) ions from aqueous solutions was studied by sorption onto microcapsules prepared by copolymerizing ethylene glycol dimethacrylate (EGDMA) and styrene (ST). The microcapsules were prepared by an in situ radical polymerization method by adding the extractant compound, 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester, and the monomers to the continuous aqueous phase. The extractant was immobilized within the microcapsules (MCs) which presented a spherical shape with rough surface. High productions of MCs with an important retention of extractant were achieved. Microcapsules constituted by a copolymer of 65% EGDMA and 35% ST presented best capacity of sorption of both metals. These MCs presented sufficient degree of cross-linking and a suitable balance of hydrophilic–hydrophobic character. The experimental data from chemisorption of metals onto the microcapsules fitted well the applied pseudo-second-order kinetics model. The alkylphosphonic extractant presented a higher rate constant and a higher equilibrium sorption capacity for Cd(II) than for Cu(II) at the pH used in this study.

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