Efecto de la temperatura sobre los parámetros de la isoterma de GAB y calor isostérico en filtrantes de muña (Minthostachys mollis)
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Date
2025
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Universidad Nacional de Trujillo
Abstract
El presente estudio evaluó el efecto de la temperatura sobre los parámetros de la isoterma de GAB y calor isostérico en filtrantes de muña (Minthostachys mollis). Para ello, se transformó las hojas de muña en polvo y luego se envasó en bolsas para filtrantes. Estas fueron acondicionadas en ambientes con actividad de agua entre 0.1 y 0.9 a las temperaturas de 20, 30 y 40 °C por un periodo de 7 días, al cabo del cual se determinó la humedad de equilibrio mediante método gravimétrico. Además, se ajustó la isoterma con el modelo de GAB, determinando sus parámetros. Los resultados mostraron que la cantidad de agua adsorbida en una misma actividad de agua, disminuye con el incremento de la temperatura, mostrando un comportamiento de adsorción de tipo II en la clasificación de Brunauer. Los parámetros de GAB mostraron una reducción de la humedad de monocapa (X0) de 0.0942 a 0.0838 g H2O/g m.s. de 20 a 40 °C, respectivamente. La constante CG disminuyó de 14.85 a 11.12, mientras que el coeficiente KG varió de 0.874 a 0.853 en el mismo intervalo de temperatura. El calor isostérico de adsorción disminuyó con el incremento de la humedad de equilibrio, pasando de 51.45 a 49.06 kJ/kmol a 20 y 40 °C, respectivamente. Esto sugiere que a bajas humedades el material requiere más energía para retener el agua, mientras que a mayores niveles de humedad la adsorción es menos energética. El análisis estadístico indicó un efecto significativo (p < 0.05) por parte de la temperatura sobre los parámetros evaluados.
ABSTRACT The present study evaluated the effect of temperature on the parameters of the GAB isotherm and isosteric heat in Andean mint (Minthostachys mollis) filter media. For this purpose, Andean mint leaves were ground into powder and then packed into tea filter bags. These were conditioned in environments with water activity between 0.1 and 0.9 at temperatures of 20, 30 and 40 °C for a period of 7 days, after which the equilibrium humidity was determined by gravimetric method. In addition, the isotherm was adjusted with the GAB model, determining its parameters. The results showed that the amount of water adsorbed at the same water activity decreases with increasing temperature, showing a type II adsorption behavior in the Brunauer classification. The GAB parameters showed a reduction in monolayer humidity (X0) from 0.0942 to 0.0838 g H2O/g d.m. The CG constant decreased from 14.85 to 11.12, while the KG coefficient varied from 0.874 to 0.853 in the same interval of temperature. The isosteric heat of adsorption decreased with increasing equilibrium humidity, from 51.45 to 49.06 kJ/kmol at 20 and 40 °C, respectively. This suggests that at low humidity levels the material requires more energy to retain water, while at higher humidity levels adsorption is less energetic. Statistical analysis indicated a significant effect (p < 0.05) of temperature on the evaluated parameters.
ABSTRACT The present study evaluated the effect of temperature on the parameters of the GAB isotherm and isosteric heat in Andean mint (Minthostachys mollis) filter media. For this purpose, Andean mint leaves were ground into powder and then packed into tea filter bags. These were conditioned in environments with water activity between 0.1 and 0.9 at temperatures of 20, 30 and 40 °C for a period of 7 days, after which the equilibrium humidity was determined by gravimetric method. In addition, the isotherm was adjusted with the GAB model, determining its parameters. The results showed that the amount of water adsorbed at the same water activity decreases with increasing temperature, showing a type II adsorption behavior in the Brunauer classification. The GAB parameters showed a reduction in monolayer humidity (X0) from 0.0942 to 0.0838 g H2O/g d.m. The CG constant decreased from 14.85 to 11.12, while the KG coefficient varied from 0.874 to 0.853 in the same interval of temperature. The isosteric heat of adsorption decreased with increasing equilibrium humidity, from 51.45 to 49.06 kJ/kmol at 20 and 40 °C, respectively. This suggests that at low humidity levels the material requires more energy to retain water, while at higher humidity levels adsorption is less energetic. Statistical analysis indicated a significant effect (p < 0.05) of temperature on the evaluated parameters.
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Keywords
Muña, Isotermas de adsorción, Modelo GAB, Calor isostérico, Monocapa