These metabolites have important functional roles to regulate cellular metabolisms and broad use as food supplements, flavors and fragrances, solvents, and fuels. Volatile carboxylic acids, alcohols, and esters are natural fermentative products, typically derived from anaerobic digestion. En este sentido, la clave es conseguir que el estudiante no se muestre pasivo en el aula, sino que participe y actúe, e incluso que explore y descubra cosas motu proprio. Esta corriente es especialmente importante en las orientaciones metodológicas que los expertos proponen a los docentes de las asignaturas de ciencias, estimulando la comprensión frente a la mera memorización, esto es, desarrollando habilidades cognitivas de orden superior, de acuerdo con la taxonomía de Bloom de los objetivos didácticos.Ī este respecto, los laboratorios virtuales ofrecen simulaciones dinámicas e intuitivas cuyo uso en asignaturas de ciencias está actualmente en boga. Se pretende fomentar con su uso una mayor implicación por parte del alumnado, lo cual constituye la base del constructivismo, que persigue el aprendizaje activo y significativo. All rights reserved.Įn la enseñanza del siglo xxi, las TIC (Tecnolog.as de la Información y Comunicación) aplicadas a la educación (es decir, las TAC, Tecnologías del Aprendizaje y del Conocimiento) ocupan un lugar protagonista. As a result, it was determined that the occupied area is between 6% (for 20 mg chitosan g−1 cotton)‐24% (for 100 mg chitosan g−1 cotton) from the total area of cotton. Finally, the percentage of the area occupied by chromium ions on the surface was estimated by dividing the resulting specific surface area in terms of cotton mass by the specific surface area of cotton reported in literature.
Moreover, three different cross‐sectional areas of hexavalent chromium ions were calculated and used to estimate the specific surface area employed by active sites to adsorb metal ions in terms of chitosan or cotton mass. The most probable energy of adsorption corresponded to a physisorption with hydrogen bond interactions between chromium ions and ammonium groups. The kinetics of pseudo second‐order, pseudo first‐order, and adsorption isotherms type II were obtained, that is, a monolayer adsorption on nonporous adsorbents with physical adsorption was present. The adsorption of hexavalent chromium ions from water on the grafted chitosan was evaluated to determine, by means of linear and nonlinear models, the kinetic and isotherm adsorption of the process. Chitosan was grafted on the surface of a cotton gauze (20 mg chitosan g−1 cotton, 50 mg chitosan g−1 cotton, and 100 mg chitosan g−1 cotton) to improve its stability in aqueous solutions.
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