Obtención de microfibras de quitosano funcionalizadas con nanopartículas de Fe3O4 para su aplicación como adsorbente en la remoción de cromo (VI) en soluciones acuosas

Abstract

Cr (VI) species from industrial processes such as leather tanning, are highly toxic to living beings. In order to reduce the presence of these pollutants in water, various techniques have been used, where adsorption has proved to be an effective, economical and easy to apply method. Chitosan (CS) has been proven as a powerful heavy metal biosorbent, due to the large amount of hydroxyl and amino groups present in its main chain. Magnetite (Fe3O4), also has been used in the environmental field due to its adsorbing and reducing properties. Notable results have been achieved based on the combination of polymeric fibers and functional nanomaterials. In the present work, the synthesis of chitosan microfibers functionalized with nanoparticles (NPs) of Fe3O4 was performed to remove Cr (VI) from aqueous solutions. The NPs were synthesized by chemical co-precipitation and the CS/NPs fibers used in the removal of Cr (VI) from aqueous solutions were obtained by electrospinning. NPs were characterized by TEM, while the CS / NPs fibers were analyzed by SEM, FTIR and DSC. Cr (VI) in aqueous solution was measured using the colorimetric method of 1,5-diphenylcarbazide by UV-Vis spectroscopy. Micrometric interconnected structures of chitosan functionalized with NPs of Fe3O4 were obtained, in which fibers and beads (pearls or polymer agglomerations) of a few micrometers in size coexist. Cr (VI) removal percentage of 88.3% was reached under conditions of pH 3 and contact time of 9 min, in addition, it was determined that adsorption process is favored by increasing initial concentration of Cr (VI), dosage of the adsorbent and temperature. Also, the study of equilibrium and kinetic of adsorption was carried out, fitting better to Langmuir and Pseudo Second Order models, respectively.