{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,5]],"date-time":"2026-08-05T03:40:03Z","timestamp":1785901203876,"version":"3.56.0"},"reference-count":49,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2020,6,24]],"date-time":"2020-06-24T00:00:00Z","timestamp":1592956800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Thiosulfate leaching combined with ion-exchange resins is an innovative alternative for gold recovery. According to the properties of activated carbon, it could replace resins in the gold recovery process, improve efficiency, and reduce operating cost. In this research, the adsorption process of gold thiosulfate complex on thiol-modified activated carbon was studied. Thioglycolic acid (ATG) was impregnated in activated carbon, and its adsorption ability was tested with synthetic solutions of gold and sodium thiosulfate (Au 10 mg\u00b7L\u22121, Na2S2O3 0.1 mol\u00b7L\u22121, pH = 10.0). Carbon was characterized by infrared spectroscopy, SEM-EDS, PZC titration, hardness number measures, and proximal analysis. Synthetic solutions were also characterized by UV-vis spectroscopy and cyclic voltammetry. The percentage of volatile material increased from 10.0 to 13.9% due to the impregnation process of ATG. Infrared spectra show characteristic bands of C-H, S-H, and C-S bonds. In the adsorption tests, the ATG-impregnated carbon achieved 91% of gold recovery, while the same amount of ATG in the liquid phase stirred with unmodified activated carbon reached 90% of gold recovery. The 44.9% of gold recovered with activated carbon impregnated with ATG was eluted with sodium cyanide ([NaCN] = 0.2 mol\u00b7L\u22121; [NaOH] = 0.25 mol\u00b7L\u22121; [CH3CH2OH] = 30% V\/V; pH = 12.0; t = 24 h). These results suggest the gold transferred from the thiosulfate complex to a new gold thiolate complex.<\/jats:p>","DOI":"10.3390\/molecules25122902","type":"journal-article","created":{"date-parts":[[2020,6,24]],"date-time":"2020-06-24T10:54:59Z","timestamp":1592996099000},"page":"2902","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["Increased Recovery of Gold Thiosulfate Alkaline Solutions by Adding Thiol Groups in the Porous Structure of Activated Carbon"],"prefix":"10.3390","volume":"25","author":[{"given":"Freddy R.","family":"Escobar-Ledesma","sequence":"first","affiliation":[{"name":"Department of Extractive Metallurgy, Escuela Polit\u00e9cnica Nacional, Ladr\u00f3n de Guevara E11-253, P.O. Box 17-01-2759, Quito 170525, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9683-7184","authenticated-orcid":false,"given":"Carlos F.","family":"Arag\u00f3n-Tobar","sequence":"additional","affiliation":[{"name":"Department of Extractive Metallurgy, Escuela Polit\u00e9cnica Nacional, Ladr\u00f3n de Guevara E11-253, P.O. Box 17-01-2759, Quito 170525, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0592-8652","authenticated-orcid":false,"given":"Patricio J.","family":"Espinoza-Montero","sequence":"additional","affiliation":[{"name":"Escuela de Ciencias Qu\u00edmicas, Pontificia Universidad Cat\u00f3lica del Ecuador, Avenida 12 de Octubre y Roca, Apartado: 17-01-2184, Quito 170525, Pichincha, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ernesto","family":"de la Torre-Chauvin","sequence":"additional","affiliation":[{"name":"Department of Extractive Metallurgy, Escuela Polit\u00e9cnica Nacional, Ladr\u00f3n de Guevara E11-253, P.O. Box 17-01-2759, Quito 170525, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2020,6,24]]},"reference":[{"key":"ref_1","unstructured":"Francesco, V., and Ionela, B. (2018). 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