Browsing by Author "Martinez, Natalia P. "

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    Assessing the Technical Suitability of Precipitated Materials from the Electrochemical Decarbonation of Limestones for Cement and Hydrated Lime Production: A Reproducibility Study Performed in Canada and Chile
    (2025) Ramirez Amaya, Dario Alonso; Mahmood, Osamah; Noël, Martin; Kavgic, Miroslava; Martinez, Natalia P.; Troncoso P., Felipe; Gazzano, Valeria; Dreyse, Paulina; Canales Muñoz, Roberto; González, Marcelo
    Concrete is essential for most civil engineering applications, but its use faces pressing challenges to reduce CO2 emissions. These emissions are linked principally to the chains of cement production that calcinate limestones (CaCO3 → CaO þ CO2) for quicklime, hydrated lime, and clinker production. Electrochemical decarbonation is a novel technology with the potential to introduce synergistic strategies to mitigate CO2 emissions from this chemical reaction. However, its early incorporation in the current chains of cement and lime production requires evidence of the quality of materials produced by this technique under the broad conditions of the cement and lime industries worldwide. In this reproducibility study performed in Canada and Chile, multiple sources of limestone feedstock used for lime and cement production were subjected to an electrochemical decarbonation process to precipitate low-CO2 intermediary feedstock materials. The potential of the precipitate materials (PMs) as an intermediary for cement manufacturing and as a final hydrated lime product was assessed by contrasting the lime saturation factor, lime concentration, content of secondary oxides (MgO, K2O, and Na2O), and content of CO2 with those of theirprecursor limestones and the requirements established by the state of practice of these industries. Results showed that regardless of their origin, the obtained PMs mainly comprised calcium hydroxide [CaðOHÞ2 > 78.8% by mass], with increased lime concentration (CaO > 65.39%) and decreased other primary oxides (SiO2, Al2O3, and Fe2O3 < 1%) and carbon dioxide content (CO2 < 9.42% by mass). Several PMs had suitable chemical and physical characteristics to be considered directly for clinker and lime manufacturing, which is critical to the scalability of the electrochemical decarbonation process.
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    Comparison of the electrochemical decarbonation of different-grade limestones used in cement manufacturing
    (2023) Ramirez-Amaya, Dario; Dreyse, Paulina; Martinez, Natalia P.; Troncoso, Felipe; Navarrete, Ivan; Noel, Martin; Canales, Roberto I.; Gonzalez, Marcelo
    Electrochemical decarbonation (ED) of CaCO3 is a promising method to reduce CO2 emissions from limestone calcination for cement manufacturing. Most cement plants are located near accessible deposits of limestone; therefore, the feasibility of ED deployment depends on the efficiency of natural limestone decarbonation, which has variable CaCO3 content. Accordingly, this research compares the ED efficiency of different limestones (CaCO3 content between 84 % and 68 %) and the chemical and physical characteristics of precipitate materials (PM) obtained from this process. The obtained PMs were comprised mainly of Ca(OH)(2) (similar to 59 %) and had similar particle size distributions. At the same time, the efficiency of Ca(OH)(2) precipitation, energy consumption, and CaO recovery were comparable to the ED of a pure CaCO3 reagent (>99 %). The PMs were found to have higher CaO content and lower loss on ignition than the feedstock material, independent of the type of limestone, facilitating the future ED implementation in cement manufacturing.
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    Highly efficient hydrogen evolution reaction, plasmon-enhanced by AuNP-l-TiO2NP photocatalysts
    (2020) Castillo-Rodriguez, Judith ; Ortiz, Pedro D. ; Isaacs, Mauricio ; Martinez, Natalia P. ; O’Shea, James N. ; Hart, Jack ; Temperton, Robert ; Zarate, Ximena ; Contreras, David ; Schott, Eduardo
    A set of AuNPs-l-TiO2NP nanoaggregates which showed efficient covering of the semiconductor's surface by AuNPs, as well as appropriate AuNP sizes for effective sensibilization were used as photocatalysts for the hydrogen evolution reaction (HER). Three aliphatic short-chain linkers: 3-mercaptopropionic acid (MPA), thioglycolic acid (TGA) and thiolactic acid (TLA) were used as stabilizing agents. The slight structure variations of the linkers did not produce differences in the AuNP size and morphology. However, it was interesting to show how the photocatalytic performance of the nanoaggregates is dependent on the linker present, as well as to determine the influence of the Au/TiO(2)ratio. It was found that TGA gave the best performance at a longer irradiation time, though high amounts of H(2)were also obtained for the other two linkers. Furthermore, for all samples large amounts of hydrogen were obtained, which are significantly higher than that usually obtained with plasmon-sensitized TiO(2)nanostructures. In addition, high amounts of H(2)were obtained after five catalytic cycles for all samples, showing the suitability of these nanoaggregates for the photoinduced HER.