Browsing by Author "Caceres Jensen, L."

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    Corrigendum: Selective photocatalytic conversion of guaiacol using g-C3N4 metal free nanosheets photocatalyst to add-value products (vol 421, 113513, 2021)
    (ELSEVIER SCIENCE SA, 2022) Rojas, S. D.; Espinoza Villalobos, N.; Salazar, R.; Escalona, N.; Contreras, D.; Melin, V.; Laguna Bercero, M. A.; Sanchez Arenillas, M.; Vergara, E.; Caceres Jensen, L.; Rodriguez Becerra, J.; Barrientos, L.
    © 2021 Elsevier B.V.The authors regret that in the above article, affiliation c is mistaken. Therefore, afiliation c should be: c Departamento de Química de los materiales, Laboratorio de electroquímica Medio ambiental, LEQMA, Universidad de Santiago de Chile, Avenida Libertador Bernardo O'Higgins 3363, Estación Central, Santiago 9170376, Chile The authors would like to apologize for any inconvenience caused.
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    Selective photocatalytic conversion of guaiacol using g-C3N4 metal free nanosheets photocatalyst to add-value products
    (ELSEVIER SCIENCE SA, 2021) Rojas de la Fuente, Susana Dennis; Espinoza Villalobos, Nicole Margarita; Salazar, R.; Escalona, Néstor; Contreras, D.; Melin, V; Laguna Bercero, M. A.; Sanchez Arenillas, M.; Vergara, E.; Caceres Jensen, L.; Rodríguez Becerra, J.; Barrientos, Lorena
    Valorization of lignin into high valuable chemical is a critical challenge. Its availability is a key factor for the development of viable lignocellulosic processes to replace fossil derived compounds. In this work, new insights on the high photocatalytic conversion of guaiacol (82%) as a lignin model compound was achieved, also, high selectivity to p-benzoquinone (59%), catechol (27%), and pyrogallol (6%) was obtained using metal-free pyrolyzed g-C3N4 under visible light irradiation. To highlight the new insights, experimental parameters were modified to control the reaction mechanism to increase selectivity and photo-conversion. g-C3N4 photocatalyst was synthesized through urea calcination at 550 degrees C and the photocatalytic performance was assessed in terms of pyrolysis time, where higher time resulted in better photocatalytic activity. This effect was attributed to smaller structures and therefore better quantum confinement of the charges. The oxidation was promoted by OH radicals, which were detected through EPR operando mode and the addition of radical scavengers. A reaction pathway was proposed, in which the OH attacks guaiacol through a methoxy group. The photocatalytic reaction can be tuned using external oxidant agents such as O-2 and/or H2O2 to promote certain radical formation, enhancing conversion rates and promoting selectivity for a specific product, where yield shifting from p-benzoquinone to pyrogallol was experimentally observed.
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    Transport Mechanisms of the Anthropogenic Contaminant Sulfamethoxazole in Volcanic Ash Soils Evaluated Using the Hydrus-1d Model
    (2024) Urdiales, C.; Urdiales Flores, D.; Tapia, Y.; Caceres Jensen, L.; Šimůnek, J.; Antilén Lizana, Mónica
    The volcanic soils in Chile, where a significant portion of agricultural activities take place, are impacted by the presence of veterinary drugs, including sulfamethoxazole (SMX). The transport of SMX in soils Collipulli (CLL), Frutillar (FRU), Nueva Braunau (NBR), and Osorno (OSR) was explored. Aadsorption batch, kinetics, and column breakthrough curve (BTC) experiments were conducted, alongside transport modelling. The adsorption kinetics of SMX in CLL soil followed a pseudo-first-order (PPO) model, while FRU, NBR, and OSR soils aligned with a pseudo-second-order (PSO) model. Freundlich isotherms effectively described SMX adsorption in CLL and OSR soils, indicating multilayer adsorption, while Langmuir isotherms fit the FRU and NBR soils, suggesting monolayer adsorption. Using HYDRUS-1D software, we simulated SMX transport in soil columns. BTCs were best modelled using a two-site sorption model with both equilibrium and kinetic adsorption. SMX was more mobile in CLL soil, due to its lower organic matter (OM) content and adsorption capacity, while FRU, NBR, and OSR soils showed slower transport, reflecting higher OM content and greater adsorption capacity, reducing SMX leaching. These findings emphasize the importance of soil properties, such as OM content, in influencing SMX behavior, and are vital for assessing environmental impacts and developing mitigation strategies.