{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,4]],"date-time":"2026-03-04T02:12:00Z","timestamp":1772590320345,"version":"3.50.1"},"reference-count":93,"publisher":"MDPI AG","issue":"13","license":[{"start":{"date-parts":[[2021,7,5]],"date-time":"2021-07-05T00:00:00Z","timestamp":1625443200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"The Consejer\u00eda de Econom\u00eda, Conocimiento y Universidad of the Junta de Andaluc\u00eda","award":["P18-RT-3504"],"award-info":[{"award-number":["P18-RT-3504"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sustainability"],"abstract":"<jats:p>The valorization of spent oil bleaching earths (SOBE) is crucial for the protection of the environment and the reuse of resources. In this research, alkali-activated binders were manufactured at room temperature using SOBE as a precursor by varying the mass ratio between the activating solutions of sodium silicate (Na2SiO3) and 6 M sodium hydroxide (NaOH) (activating solution modulus) (Na2SiO3\/NaOH ratio = 1\/1; 1\/2; 1\/3; 1\/4) to investigate the influence on the technological properties of the materials. This process intends to evaluate the potential of SOBE, heat-treated at 550 \u00b0C (1 h), as a precursor of the reaction (source of aluminosilicates). Samples produced with higher amounts of sodium silicate developed a denser structure, with lower porosity and a higher amount of geopolymer gel. Maximum flexural (8.35 MPa) and compressive (28.4 MPa) strengths of samples cured at room temperature for 28 days were obtained with a Na2SiO3\/NaOH mass ratio of 1\/1. The study demonstrates that SOBE waste can be used as a precursor in the manufacture of geopolymer binders that show a good compromise between physical, mechanical and thermally insulating characteristics.<\/jats:p>","DOI":"10.3390\/su13137501","type":"journal-article","created":{"date-parts":[[2021,7,5]],"date-time":"2021-07-05T22:02:04Z","timestamp":1625522524000},"page":"7501","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Effect of Activating Solution Modulus on the Synthesis of Sustainable Geopolymer Binders Using Spent Oil Bleaching Earths as Precursor"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6080-2388","authenticated-orcid":false,"given":"P.","family":"Delgado-Plana","sequence":"first","affiliation":[{"name":"Department of Chemical, Environmental, and Materials Engineering, Campus Las Lagunillas, Higher Polytechnic School of Ja\u00e9n, University of Ja\u00e9n, s\/n, 23071 Ja\u00e9n, Spain"}]},{"given":"A.","family":"Rodr\u00edguez-Exp\u00f3sito","sequence":"additional","affiliation":[{"name":"Department of Chemical, Environmental, and Materials Engineering, Campus Las Lagunillas, Higher Polytechnic School of Ja\u00e9n, University of Ja\u00e9n, s\/n, 23071 Ja\u00e9n, Spain"}]},{"given":"S.","family":"Bueno-Rodr\u00edguez","sequence":"additional","affiliation":[{"name":"Department of Chemical, Environmental, and Materials Engineering, Campus Las Lagunillas, Higher Polytechnic School of Ja\u00e9n, University of Ja\u00e9n, s\/n, 23071 Ja\u00e9n, Spain"},{"name":"Center for Advanced Studies in Earth Sciences, Energy and Environment (CEACTEMA), Campus Las Lagunillas, University of Ja\u00e9n, s\/n, 23071 Ja\u00e9n, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6912-9844","authenticated-orcid":false,"given":"L.","family":"P\u00e9rez-Villarejo","sequence":"additional","affiliation":[{"name":"Center for Advanced Studies in Earth Sciences, Energy and Environment (CEACTEMA), Campus Las Lagunillas, University of Ja\u00e9n, s\/n, 23071 Ja\u00e9n, Spain"},{"name":"Department of Chemical, Environmental, and Materials Engineering, Campus Cient\u00edfico-Tecnol\u00f3gico, Higher Polytechnic School of Linares, University of Ja\u00e9n, Cintur\u00f3n Sur s\/n, 23700 Linares, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0112-8570","authenticated-orcid":false,"given":"D. M.","family":"Tobaldi","sequence":"additional","affiliation":[{"name":"Department of Materials and Ceramic Engineering & CICECO\u2014Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal"},{"name":"CNR Nanotec, Campus Ecoteckne, Institute of Nanotechnology, 73100 Lecce, Italy"}]},{"given":"J. A.","family":"Labrincha","sequence":"additional","affiliation":[{"name":"Department of Materials and Ceramic Engineering & CICECO\u2014Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3803-9595","authenticated-orcid":false,"given":"D.","family":"Eliche-Quesada","sequence":"additional","affiliation":[{"name":"Department of Chemical, Environmental, and Materials Engineering, Campus Las Lagunillas, Higher Polytechnic School of Ja\u00e9n, University of Ja\u00e9n, s\/n, 23071 Ja\u00e9n, Spain"},{"name":"Center for Advanced Studies in Earth Sciences, Energy and Environment (CEACTEMA), Campus Las Lagunillas, University of Ja\u00e9n, s\/n, 23071 Ja\u00e9n, Spain"}]}],"member":"1968","published-online":{"date-parts":[[2021,7,5]]},"reference":[{"key":"ref_1","unstructured":"Asociaci\u00f3n de Productores de Cemento (ASOCEM) (2021, May 22). World Overview of the Cement Industry. 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