Martín Torres

The present work reports the development of a low-cost Arduino-based optical device for real-time monitoring of silica formation via the sol–gel process using 90° light scattering. The system integrates 3D-printed components, four laser–photodetector systems, and custom software for the independent control, data acquisition, and visualization of each system. Its performance was evaluated during the synthesis of silica from sodium silicate under acidic conditions obtained from rice husk ash. The signal–time profiles exhibited a characteristic sigmoidal shape, enabling determination of the gelation onset time and the final gelation time. These characteristic values reflect the kinetics of gel formation, demonstrating the device´s utility for kinetic studies. Furthermore, the device showed good reproducibility across different laser–photodetector systems. Overall, the results demonstrate that the proposed optical system is a reliable, versatile, and effective alternative for real-time monitoring of sol–gel processes, with potential applicability to other colloidal systems.

The present work reports the development of a low-cost Arduino-based optical device for real-time monitoring of silica formation via the sol–gel process using 90° light scattering. The system integrates 3D-printed components, four laser–photodetector systems, and custom software for the independent control, data acquisition, and visualization of each system. Its performance was evaluated during the synthesis of silica from sodium silicate under acidic conditions obtained from rice husk ash. The signal–time profiles exhibited a characteristic sigmoidal shape, enabling determination of the gelation onset time and the final gelation time. These characteristic values reflect the kinetics of gel formation, demonstrating the device´s utility for kinetic studies. Furthermore, the device showed good reproducibility across different laser–photodetector systems. Overall, the results demonstrate that the proposed optical system is a reliable, versatile, and effective alternative for real-time monitoring of sol–gel processes, with potential applicability to other colloidal systems.

Este trabajo presenta el estudio experimental de la combustión latente (CL) aplicada al tratamiento de tierras contaminadas con hidrocarburos. Se empleó un reactor de CL a escala de laboratorio. Se evaluaron cuatro mezclas con diferentes proporciones de combustible auxiliar, analizando la autosostenibilidad del proceso, la remoción de hidrocarburos y el costo energético asociado. El residuo se caracterizó mediante análisis elemental, análisis próximo, termogravimetría y determinación del poder calorífico. Losresultados evidenciaron la necesidad de utilizar un combustible auxiliar para iniciar la reacción de CL. Para esto, se seleccionó aserrín de abeto y se prepararon cuatro mezclas con arena y tierra contaminada (M1, M2, M3 y M4) para evaluar su influencia en la autosostenibilidad del proceso. Los resultados indican que la M4, conteniendo un 10 % de aserrín y 90 % de tierra contaminada permitió mantener la CL, logrando una remoción del 95,23 % de los hidrocarburos. Adicionalmente, el análisis de costos estimóun valor de 0,3224 USD/kg de residuo tratado, destacando la viabilidad económica de la tecnología y ampliando las opciones de disposición final del residuo. La implementación de CL en Uruguay representa una alternativa eficiente y accesible para la gestión deresiduos peligrosos, reduciendo la dependencia de métodos convencionales promoviendo soluciones innovadoras.

Rice husk, a byproduct of rice production, poses significant environmental challenges due to disposal issues, while the emission of volatile organic compounds into the atmosphere further exacerbates these concerns. This study addresses both problems by exploring the potential of texturally enhanced SiO₂, derived from Uruguayan rice husk, as a catalytic support for manganese oxides in the combustion of volatile organic compounds. SiO₂ was synthesized from rice husk ash using a sustainable, acid-free pretreatment method, yielding a notably high silica purity of 96.5%—a level comparable to or exceeding previously reported values, highlighting the high silica quality inherent in Uruguayan rice husk. The catalytic activity was evaluated using acetone as a model volatile organic compound, achieving up to 90% conversion with 30 wt.% manganese oxide at 300 °C, with CO₂ as the primary product. Furthermore, a 24 h stability test demonstrated consistent performance, maintaining a conversion rate of around 95.6 ± 2.5%. These findings suggest that high-purity SiO₂ derived from Uruguayan rice husk, with its sustainability benefits, offers an effective solution for acetone removal when supporting an active phase such as manganese oxides, addressing both rice husk disposal and volatile organic compound emissions.

Rice husk, a byproduct of rice production, presents significant environmental challenges due to its disposal, while the emission of volatile organic compounds into the atmosphere poses additional concerns. This study addresses these issues by exploring the potential of texturally modified SiO₂ derived from Uruguayan rice husk as a catalytic support for manganese oxides in volatile organic compounds combustion. SiO₂ was synthesised from rice husk ash using a sustainable, acid-free pretreatment method, yielding a notably high silica purity of 96.5%—a level comparable to or exceeding those reported in previous studies, and underscoring the high silica quality inherent in Uruguayan rice husk. The catalytic performance of the catalysts was evaluated using acetone as a model of volatile organic compound, achieving up to 90% conversion with 30 wt.% manganese oxide at 300 °C, primarily yielding CO₂. Furthermore, a 24-hour stability test indicated consistent conversion, maintaining around 95.6 ± 2.5%. These findings suggest that Uruguayan rice husk-derived SiO₂, with its high purity and sustainability benefits, offers an effective solution for acetone removal when supporting an active phase such as manganese oxides, addressing both rice husk disposal and volatile organic compounds emissions.