Algarra González, Manuel
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Algarra González
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Manuel
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Ciencias
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InaMat2. Instituto de Investigación en Materiales Avanzados y Matemáticas
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Publication Open Access Nitrogen doped carbon dots as a photocatalyst based on biomass: a life cycle assessment(Elsevier, 2023) Rodríguez-Carballo, Gabriela; Moreno-Tost, Ramón; Fernandes, Sónia; Esteves da Silva, Joaquim C.G.; Pinto da Silva, Luís; Castro Galiano, Eulogio; Algarra González, Manuel; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2The effectiveness of various transition metal phosphate-based acid catalysts, including vanadium and niobium, in the hydrothermal synthesis of carbon dots (CDs), has been assessed. Two sources of carbohydrates were employed for this: commercial xylose and liquor of xylose produced by processing olive pits. Catalysts were identified using the NH3-TPD, DTA/TG, XRD, and XPS techniques. The reaction was conducted for 4 h at a temperature of 180 °C. The existence of such nanoparticles, regardless of the carbohydrate source, was confirmed by an analysis of the features and characteristics of CDs nanoparticles. N-doped CDs with increased fluorescence were also created at the same time using a similar hydrothermal technique, and their photocatalytic activity was investigated. A Life Cycle Assessment (LCA) was conducted for both syntheses with the goal of comparing the environmental effects of the synthesis from commercial xylose to the synthesis from biomass. It was revealed that, although energy is the primary driver of both synthesis pathways' effect categories, the fundamental variations that seem to determine their relative sustainability are connected to the nature of the carbon precursor. Regarding the latter, it is determined that electricity has the greatest environmental impact.Publication Open Access Low-cost Titania-Hydroxyapatite (TiHAp) nanocomposites were synthesized for removal of methylene blue under solar and UV irradiation(Elsevier, 2025-07-01) Latifi, Souhayla; Saoiabi, Sanaa ; Alanazi, Mohammed M. ; Boukra, Omar ; Krime, Anas ; El Hammari, Larbi; Azzaoui, Khalil; Hammouti, Belkheir; Hanbali, Ghadir; Jodeh, Shehdeh; Saoiabi, Ahmad ; Sabbahi, Rachid ; Algarra González, Manuel; Abidi, Noureddine ; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2Water pollution from industrial dyes like methylene blue (MB) poses significant environmental and health risks due to their toxicity and persistence. In this study, we synthesized a novel titania-hydroxyapatite (TiHAp) nanocomposite via a low-cost, scalable sol-gel method to address these challenges. The composite was comprehensively characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Photocatalytic degradation of MB under both solar and UV irradiation was evaluated using kinetic (pseudo-first-order and pseudo-second-order) and isotherm (Langmuir and Freundlich) models, demonstrating hydroxyapatite's key role in enhancing adsorption and facilitating effective interactions with the catalyst. Under optimized conditions, the TiHAp nanocomposite achieved 96.58 % degradation of MB at an initial concentration of 120 mg/L and retained over 95 % activity after five reuse cycles. These results illustrate that the synergistic combination of TiO₂'s photocatalytic activity and HAp's adsorptive capacity produces a highly effective composite for degrading organic pollutants. The study underscores the potential of TiHAp nanocomposites as sustainable materials for wastewater treatment applications, while future work will explore their performance against a broader range of contaminants under realistic environmental conditions.Publication Open Access One-pot synthesis of green-emitting nitrogen-doped carbon dots from xylose(MDPI, 2023) Rodríguez-Carballo, Gabriela; García-Sancho, Cristina; Algarra González, Manuel; Castro, Eulogio; Moreno-Tost, Ramón; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2Carbon dots (CDs) are interesting carbon nanomaterials that exhibit great photoluminescent features, low cytotoxicity, and excellent water stability and solubility. For these reasons, many fields are starting to integrate their use for a variety of purposes. The catalytic performance of VOPO4 has been evaluated in the synthesis of nitrogen-doped carbon dots (N-CDs). The synthesis reaction was carried out at 180 °C using VOPO4 as a heterogeneous catalyst for 2 to 4 h of reaction time. After reaction, the N-CDs were purified using a novel method for the protection of the functional groups over the surfaces of the N-CDs. The morphological, superficial, and photoelectronic properties of the N-CDs were thoroughly studied by means of TEM, HRTEM, XPS, and photoluminescence measurements. The conversion of the carbon precursor was followed by HPLC. After three catalytic runs, the catalyst was still active while ensuring the quality of the N-CDs obtained. After the third cycle, the catalyst was regenerated, and it recovered its full activity. The obtained N-CDs showed a great degree of oxidized groups in their surfaces that translated into high photoluminescence when irradiated under different lasers. Due to the observed photoelectronic properties, they were then assayed in the photocatalytic degradation of methyl orange.Publication Open Access Visible-light-driven photocatalytic degradation of organic dyes using a TiO2 and waste-based carbon dots nanocomposite(Elsevier, 2025-05-20) Sendão, Ricardo M.S.; Algarra González, Manuel; Lázaro-Martínez, Juan; Brandão, Ana T.S.C.; Gil Bravo, Antonio; Pereira, Carlos; Esteves da Silva, Joaquim C.G.; Pinto da Silva, Luís; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2Herein we report a visible-light-active photocatalytic nanocomposite (NC50:50) prepared from carbon dots (CDs) and TiO2 nanoparticles, which was applied to the photodegradation of organic dyes in water. The CDs incorporated corn stover, a major agricultural waste, and were prepared via hydrothermal treatment. Using a visible-light irradiation source and the dye methylene blue as a representative of the organic dyes class, we observed that a 374% enhancement of the catalytic performance was achieved by adding CDs relative to bare TiO2. This was possible due to increased visible-light absorption and better photonic efficiency. Tests using reactive species scavengers indicated that three active species (superoxide anion, hydroxyl radicals, and electrons) were responsible for the photodegradation process, differing from bare TiO2 in which only the hydroxyl radical has a relevant role. Photocatalytic degradation was also observed toward Rhodamine B, Orange II and Methyl Orange. Finally, we performed a life cycle assessment (LCA) study to assess and analyse the associated environmental impacts of NC50:50 compared with other alternatives, which revealed that NC50:50 is the alternative resulting in the least environmental impacts. In summary, NC50:50 could, under visible-light irradiation, efficiently remove different organic dyes while incorporating organic waste materials and reducing the impacts associated with their use. We expect that this study provides a base for a more environmentally sustainable design of visible-light-active photocatalysts via waste upcycling.