Recovery of Au(III) by encapsulated ionic liquid emulsions. Stabilization of emulsions using biopolymers and their effect on extraction performance
Year: 2026
Type: article
Abstract: The encapsulation of ionic liquid emulsions in polymeric microcapsules represents a promising strategy for the selective recovery of precious metals. However, the stability of the internal emulsion is one of the main factors limiting its long-term performance. In this study, we evaluated the influence of the formulation and emulsion preparation conditions on the structural stability and Au(III) extraction behavior of alginate microcapsules containing the ionic liquid (IL) Cyphos IL 101 as the extractant. To reach this objective, emulsions based on carboxymethylcellulose (CMC), gum Arabic, and gelatin (G) were prepared using different concentrations of biopolymers and emulsification speeds; these emulsions were subsequently encapsulated in alginate beads (through ionotropic gelation). Among the systems evaluated, the emulsions formulated with CMC/G (5%/2%) and emulsified at 4000 rpm exhibited the greatest stability for at least 22 weeks after preparation, characterized by the absence of phase separation, minimal growth in the average droplet diameter, and low variation in mass transfer parameters. The microcapsules obtained under these conditions maintained a virtually constant maximum Au(III) sorption capacity, reaching q m values close to 100 mg g −1 . Au(III) is retained by the IL inside the microcapsules which have a high preferential affinity for this metal. Furthermore, an extraction efficiency of 91% and a stripping efficiency of 99% were achieved using a 1 M thiourea/0.1 M HCl solution. Increasing the ionic liquid concentration from 2% to 40% increased the maximum sorption capacity from 63.2 to 113 mg g −1 , demonstrating the strong influence of ionic liquid content on the performance of the system. Taken together, the results demonstrate that the stability of the internal emulsion plays a key role in the structural stability and extraction performance of the microcapsules, and that the CMC/G (5%/2%) system constitutes an efficient, selective, and reusable platform for the recovery of Au(III) from aqueous solutions.
Source: Materials Research Express
Institutions: Universidad de Guanajuato, IMT Mines Alès
Language: English
Subfield: Metals and Alloys
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,000
Funder: Universidad de Guanajuato
OpenAlex ID: W7223359154