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

Abstract

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.