Effect of Activating Solution Modulus on the Synthesis of Sustainable Geopolymer Binders Using Spent Oil Bleaching Earths as Precursor

P. Delgado-Plana, A. Rodríguez-Expósito, S. Bueno-Rodríguez, L. Pérez-Villarejo, D. M. Tobaldi, J. A. Labrincha and D. Eliche-Quesada
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P. Delgado-Plana: Department of Chemical, Environmental, and Materials Engineering, Campus Las Lagunillas, Higher Polytechnic School of Jaén, University of Jaén, s/n, 23071 Jaén, Spain
A. Rodríguez-Expósito: Department of Chemical, Environmental, and Materials Engineering, Campus Las Lagunillas, Higher Polytechnic School of Jaén, University of Jaén, s/n, 23071 Jaén, Spain
S. Bueno-Rodríguez: Department of Chemical, Environmental, and Materials Engineering, Campus Las Lagunillas, Higher Polytechnic School of Jaén, University of Jaén, s/n, 23071 Jaén, Spain
L. Pérez-Villarejo: Center for Advanced Studies in Earth Sciences, Energy and Environment (CEACTEMA), Campus Las Lagunillas, University of Jaén, s/n, 23071 Jaén, Spain
D. M. Tobaldi: Department of Materials and Ceramic Engineering & CICECO—Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal
J. A. Labrincha: Department of Materials and Ceramic Engineering & CICECO—Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal
D. Eliche-Quesada: Department of Chemical, Environmental, and Materials Engineering, Campus Las Lagunillas, Higher Polytechnic School of Jaén, University of Jaén, s/n, 23071 Jaén, Spain

Sustainability, 2021, vol. 13, issue 13, 1-18

Abstract: 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 (Na 2 SiO 3 ) and 6 M sodium hydroxide (NaOH) (activating solution modulus) (Na 2 SiO 3 /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 °C (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 Na 2 SiO 3 /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.

Keywords: spent bleaching earth; geopolymers; activating solution; activator modulus; compressive strength; microstructure (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2021
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