Efecto de la temperatura sobre los parámetros termodinámicos de la isoterma de GAB en flor de Jamaica (Hibiscus sabdariffa L.) y moringa (Moringa oleífera)
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Date
2025
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Universidad Nacional de Trujillo
Abstract
El estudio de las propiedades termodinámicas en las isotermas de adsorción es crucial para comprender los mecanismos de adsorción, optimizar procesos de deshidratación y conservación de productos en la industria alimentaria. En ese sentido, el objetivo de este estudio fue evaluar el efecto de la temperatura sobre los parámetros termodinámicos de las isoterma de adsorción de humedad mediante el modelo de GAB (Guggenheim, Anderson y de Boer) en flor de Jamaica (Hibiscus sabdariffa L.) y hojas de moringa (Moringa oleífera). Las isotermas se realizaron a tres temperaturas (20, 30 y 40 °C) con actividades de agua (Aw) desde 0.1 – 0.9. Se analizaron parámetros como el valor de monocapa (X0), la constante de adsorción de monocapa (C), la constante de adsorción de multicapa (K), el calor isostérico de adsorción (Qst), la entropía de adsorción (ΔS), la energía libre de Gibbs (ΔG) y el área de adsorción (S). Los resultados mostraron que el valor de X0 para los pétalos de flor de Jamaica aumentó de 0.0771 g H2O/g m.s. a 40 °C, a 0.0989 g H2O/g m.s. a 20 °C. En las hojas de moringa, los valores fueron 0.0697 g H2O/g m.s. a 40 °C, 0.0763 g H2O/g m.s. a 20 °C. La constante de adsorción (C) para la flor de Jamaica disminuyó de 19.3 a 20 °C a 16.19 a 40 °C, mientras que para moringa pasó de 12.05 a 20 °C a 6.46 a 40 °C. El parámetro K mostró un aumento general a medida que la temperatura aumentó en ambas muestras vegetales, con valores de 0.771 a 20 °C y 0.822 a 40 °C para la flor de Jamaica y 0.805 a 20 °C y 0.872 a 40 °C para hojas de moringa. La energía libre de Gibbs (ΔG) fue negativa en todos los casos, indicando un proceso espontáneo. El análisis estadístico evidencia un efecto estadísticamente significativo (p < 0.05) por parte de la temperatura sobre los parámetros de GAB y termodinámicos analizados.
ABSTRACT The study of thermodynamic properties in adsorption isotherms is crucial to understand adsorption mechanisms, optimize dehydration processes and preserve products in the food industry. In this sense, the objective of this study was to evaluate the effect of temperature on the thermodynamic parameters of moisture adsorption isotherms using the GAB (Guggenheim, Anderson y de Boer) model in hibiscus flower (Hibiscus sabdariffa L.) and moringa (Moringa oleífera) leaves. The isotherms were performed at three temperatures (20, 30 and 40 °C) with water activities (Aw) from 0.1 – 0.9. Parameters such as monolayer value (X0), monolayer adsorption constant (C), multilayer adsorption constant (K), isosteric heat of adsorption (Qst), adsorption entropy (ΔS), Gibbs free energy (ΔG) and adsorption area (S) were analyzed. The results showed that the value of X0 for hibiscus petals increased from 0.0771 g H2O/g d.m. at 40 °C, to 0.0989 g H2O/g d.m. at 20 °C. For moringa leaves, the values were 0.0697 g H2O/g d.m. at 40 °C, 0.0763 g H2O/g d.m. at 20 °C. The adsorption constant (C) for hibiscus decreased from 19.3 at 20 °C to 16.19 at 40 °C, while for moringa it decreased from 12.05 at 20 °C to 6.46 at 40 °C. The parameter K showed a general increase as temperature increased in both plant samples, with values of 0.771 at 20 °C and 0.822 at 40 °C for hibiscus flower and 0.805 at 20 °C and 0.872 at 40 °C for moringa leaves. The Gibbs free energy (ΔG) was negative in all cases, indicating a spontaneous process. Statistical analysis shows a statistically significant effect (p < 0.05) of temperature on the GAB and thermodynamic parameters analyzed.
ABSTRACT The study of thermodynamic properties in adsorption isotherms is crucial to understand adsorption mechanisms, optimize dehydration processes and preserve products in the food industry. In this sense, the objective of this study was to evaluate the effect of temperature on the thermodynamic parameters of moisture adsorption isotherms using the GAB (Guggenheim, Anderson y de Boer) model in hibiscus flower (Hibiscus sabdariffa L.) and moringa (Moringa oleífera) leaves. The isotherms were performed at three temperatures (20, 30 and 40 °C) with water activities (Aw) from 0.1 – 0.9. Parameters such as monolayer value (X0), monolayer adsorption constant (C), multilayer adsorption constant (K), isosteric heat of adsorption (Qst), adsorption entropy (ΔS), Gibbs free energy (ΔG) and adsorption area (S) were analyzed. The results showed that the value of X0 for hibiscus petals increased from 0.0771 g H2O/g d.m. at 40 °C, to 0.0989 g H2O/g d.m. at 20 °C. For moringa leaves, the values were 0.0697 g H2O/g d.m. at 40 °C, 0.0763 g H2O/g d.m. at 20 °C. The adsorption constant (C) for hibiscus decreased from 19.3 at 20 °C to 16.19 at 40 °C, while for moringa it decreased from 12.05 at 20 °C to 6.46 at 40 °C. The parameter K showed a general increase as temperature increased in both plant samples, with values of 0.771 at 20 °C and 0.822 at 40 °C for hibiscus flower and 0.805 at 20 °C and 0.872 at 40 °C for moringa leaves. The Gibbs free energy (ΔG) was negative in all cases, indicating a spontaneous process. Statistical analysis shows a statistically significant effect (p < 0.05) of temperature on the GAB and thermodynamic parameters analyzed.
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Keywords
Flor de Jamaica, Hojas de moringa, Isoterma de adsorción, Modelo de GAB, Parámetros termodinámicos