Hierarchical cartridges based on porous materials dispersed on Bacterial Cellulose

• Ano de defesa: 2021
• Autor(a) principal: Bessa, Raquel de Andrade
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Palavras-chave em Português: Zeolite; Hierarchization; Adsorption; Bacterial cellulose
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/60177

The present work deals about the formation of hierarchical cartridges by means of Bacterial Cellulose impregnation with nanoporous materials: mesoporous clay, microporous zeolites A and X, and a multiporous zeolite A. Cellulose was successfully produced by Komagataeibacter organisms and all the nanoporous materials obtained by hydrothermal route. The oxidation influence of the cellulose nanofibrils was studied, as well as different weight concentrations for the components. Several characterization techniques such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), solid-state nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal analyses (TGA), and N2 adsorption–desorption isotherms were employed to investigate physical, chemical and textural properties of the samples. The crystallinity for the components is kept in all the studies performed and differences are seen for the sample with multiporous zeolite A suggesting changes due to rehydration of the zeolite structure when interacting with cellulose structure. From the IR and NMR results, it is observed the positive effect that the carboxylate groups play in the interaction between cellulose and nanoporous material. In SEM images, nanofibers are pushed together forming better-assembled laminae in the oxidized aerogels where the crystals are distributed. Even that the nanofibers entangle the crystals in the structure, the porosity is not damaged and for all the studies, there are improvements in the thermal stability for the final materials. The presence of the mesopores in the zeolite structure is even more beneficial and when performing Ca2+ ionic exchange and adsorption experiments, improvements are observed to removal and qe values. The selectivity for Pb2+ in presence of Cd2+ is enhanced as result from improved intraparticle diffusion and from the kinetic models, the pseudo-second order model fits better to the experimental data suggesting chemisorption as the governing process in adsorption. Thus, hierarchical materials using bacterial cellulose, and even better, having a connected multiporous structure, allow the Pb2+ to move into the inner pores on the zeolite structure and present a potential use for either Pb2+ adsorptive or analytical devices. Foi bolsista durante o curso? * Se sim, qual agencia de fomento?