Uso del hidrocarbón generado en la carbonización hidrotérmica de desechos de café como catalizador para la remoción de contaminantes emergentes mediante ozonización catalítica
Fecha
2022
Tipo
tesis de maestría
Autores
Ramírez Madriz, Fabiola
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Resumen
En el presente trabajo de investigación se evaluó el uso del hidrocarbón generado en la carbonización hidrotérmica de desechos de café como catalizador para la remoción de contaminantes emergentes mediante ozonización catalítica heterogénea; con el objetivo de buscar una forma de mejorar los procesos de oxidación avanzada aprovechando residuos biomásicos lignocelulósicos de la industria cafetalera.
El rendimiento del proceso de generación de hidrocarbón fue del 47 %, con un tamaño de partícula entre los (75 – 300) µm. Este fue modificado con hidróxido de sodio e hierro para valorar su uso como catalizador en los procesos de ozonización. Los materiales fueron caracterizados utilizando análisis elemental, termogravimetría, infrarrojo por espectroscopia de transformada de Fourier, fluorescencia de rayos x y el punto de carga cero.
Para encontrar las mejores condiciones para la remoción del contaminante emergente modelo seleccionado (ácido rojo 1) los tres hidrocarbones (sin modificar, modificado con hidróxido de sodio y el modificado con hierro) fueron evaluados mediante un diseño experimental Taguchi L9. El tiempo de ozonización, tipo de catalizador, concentración del catalizador y pH del medio de reacción fueron los factores estudiados. Los resultados indican que, en un tiempo de 10 minutos, con el hidrocarbón sin modificar a una concentración de 0,25 g/L y a un pH alrededor de 10, se consiguieron las mayores remociones del contaminante modelo. Al ensayarlas se alcanzó remociones del 100 % del contaminante modelo. No obstante, se obtuvieron los mismos resultados cuando se realizó la ozonización convencional, probablemente por el aporte de compuesto orgánicos que se lixivian del propio hidrocarbón.
Utilizando una matriz de aguas residuales, se logró una remoción del 98 % para ambos procesos de ozonización (convencional y heterogénea). La menor remoción, respecto a la matriz de agua sintética, se debe a la composición de la matriz y la posibilidad de la presencia de compuestos que actúan como inhibidores. A las muestras de aguas residuales se les determinó el carbono orgánico total. Los resultados evidencian un incremento para las muestras tratadas con el hidrocarbón y una disminución en los ensayos realizados sin este. Los aumentos se relacionan a los compuestos orgánicos que se lixivian del catalizador.
The use of the hydrochar generated in the hydrothermal carbonization of coffee waste as catalyst for the removal of emerging pollutants by heterogeneous catalytic ozonation was evaluated, in order to find a way to improve advanced oxidation processes taking advantage of lignocellulosic biomass waste from the coffee industry. The hydrochar production yield was 47% with a particle size between 75 – 300 µm. The hydrochar was modified with sodium hydroxide and iron to assess its use as a catalyst in the ozonation processes. The materials were characterized by elemental analysis, thermogravimetry, infrared by Fourier transform spectroscopy, x-ray fluorescence, and the point of zero charge. In addition, to find the best conditions for the removal of the selected model emergent pollutant (acid red 1) the three hydrochars (unmodified, modified with sodium hydroxide and modified with iron) were evaluated using a Taguchi L9 experimental design. The ozonation time, type of catalyst, concentration of the catalyst, and pH of the reaction medium were the factors studied. The highest removals of the pollutant were observed after 10 minutes of treatment with a concentration of unmodified hydrochar of 0,25 g/L and a pH of 10. During testing, removals of 100% of the model pollutant were achieved. However, the same results were obtained when conventional ozonation was carried out, probably due to the contribution of organic compounds that are leached from the hydrochar itself. Using a wastewater matrix, a removal of 98% was achieved for both ozonation processes (conventional and heterogeneous). The lower removal, with respect to the synthetic water matrix, is due to the composition of the wastewater matrix and the possibility of the presence of compounds that act as inhibitors. The total organic carbon was determined for the wastewater samples. The results show an increase for the samples treated with hydrochar, and a decrease in the tests carried out without it. The increases are related to the organic compounds that are leached from the catalyst.
The use of the hydrochar generated in the hydrothermal carbonization of coffee waste as catalyst for the removal of emerging pollutants by heterogeneous catalytic ozonation was evaluated, in order to find a way to improve advanced oxidation processes taking advantage of lignocellulosic biomass waste from the coffee industry. The hydrochar production yield was 47% with a particle size between 75 – 300 µm. The hydrochar was modified with sodium hydroxide and iron to assess its use as a catalyst in the ozonation processes. The materials were characterized by elemental analysis, thermogravimetry, infrared by Fourier transform spectroscopy, x-ray fluorescence, and the point of zero charge. In addition, to find the best conditions for the removal of the selected model emergent pollutant (acid red 1) the three hydrochars (unmodified, modified with sodium hydroxide and modified with iron) were evaluated using a Taguchi L9 experimental design. The ozonation time, type of catalyst, concentration of the catalyst, and pH of the reaction medium were the factors studied. The highest removals of the pollutant were observed after 10 minutes of treatment with a concentration of unmodified hydrochar of 0,25 g/L and a pH of 10. During testing, removals of 100% of the model pollutant were achieved. However, the same results were obtained when conventional ozonation was carried out, probably due to the contribution of organic compounds that are leached from the hydrochar itself. Using a wastewater matrix, a removal of 98% was achieved for both ozonation processes (conventional and heterogeneous). The lower removal, with respect to the synthetic water matrix, is due to the composition of the wastewater matrix and the possibility of the presence of compounds that act as inhibitors. The total organic carbon was determined for the wastewater samples. The results show an increase for the samples treated with hydrochar, and a decrease in the tests carried out without it. The increases are related to the organic compounds that are leached from the catalyst.
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Palabras clave
Ozono, Hidrocarbón, Carbonización Hidrotérmica, CAFÉ, COSTA RICA, MEDIO AMBIENTE, PRODUCTO QUÍMICO, CONTAMINANTE