Banca de QUALIFICAÇÃO: NADIA ANDRADE ALEIXO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : NADIA ANDRADE ALEIXO
DATE: 21/03/2023
TIME: 09:00
LOCAL: online
TITLE:

ECO-BENIGN CELLULOSE NANOFIBRILS-BASED AEROGELS AS A SUSTAINABLE ALTERNATIVE FOR THE REMOVAL OF BIOLOGICAL CONTAMINANTS

PAGES: 70
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Química de Interfaces
SUMMARY:

Currently, the United Nations (UN) and the major world organizations active in disease prevention and control have shown growing concern about the presence of chemical and biological emerging contaminants (EC) in river systems. Furthermore, these EC decrease the drinking water quality, even in low concentrations (≤µgL-1), and consequently can develop organisms resistant to conventional antimicrobial agents. In this context, a new strategy to remove EC dealing with the diversity of biological pollutants through sustainable methodologies is necessary. Cellulose nanofibrils (CNF)-based porous materials are potential candidates for the sorption of many contaminants in aqueous media because of their renewability, high specific surface area and absorption capacity, and the feasibility of being functionalized with nanoparticles (NPs). In this context, metallic NPs appear attractive due to the possibility of adding antimicrobial properties to the final nanocomposites. However, there are challenges to overcome since this functionalization must be effective and avoid any leaching of these nanostructures in an aqueous medium. It is worth mentioning that incorporating natural rubber latex (NR) into CNF produces NCs with greater hydrophobicity and, consequently, the capacity to absorb several chemical pollutants and promote structural resilience in aqueous media. On the other hand, no related antimicrobial activity has been reported for these CNF/NR nanocomposites. Based on that, in this work, CNF/NR nanocomposite aerogels functionalized with copper oxide NPs (NC@CuO) were developed for the remediation of systems contaminated with biological EC. The combined ice-templating process was used to prepare CNF/NR nanocomposites. The functionalization of CNF/NR nanocomposites with CuO NPs (NC@CuO) was performed through chemical reduction of the metallic salt. CNF/NR and NC@CuO were characterized in terms of morphology and structure (scanning electron microscopy, X-ray tomography), their surface (X-ray excited photoelectron spectroscopy, wettability, and atomic force microscopy), in addition to their compressive strength, resilience in water and bulk density. They showed high porosity (~90-98%), low density (~23-56 mg.cm-3), elastic modulus correlated to nanocellulose-based aerogels (65-59 kPa), as well as wettability (ɵ = 26-95°), and roughness (0.3-4 µm). The antimicrobial activity was also evaluated by viability assay and cell culture of Escherichia coli bacterium sensitive (AmpS) and resistant to ampicillin (AmpR). Only NC@CuO inhibited the growth of both E. coli strains, indicating great antibacterial activity. In this way, we obtained material from renewable sources, which the structural modifications of CNF, together with compatibility with NR, resulted in a porous material, resilient in aqueous media and suitable for the NPs incorporation. When functionalized, these NC@CuO showed effective control against AmpR and AmpS bacteria growth, preventing the propagation of biological EC and being a sustainable alternative for river systems remediation.  

COMMITTEE MEMBERS:
Presidente - Interno ao Programa - 052.991.506-52 - JULIANA DA SILVA BERNARDES - UFABC
Membro Titular - Examinador(a) Interno ao Programa - 2347767 - MATHILDE JULIENNE GISELE CHAMPEAU
Membro Titular - Examinador(a) Externo à Instituição - ELISA SILVA FERREIRA
Membro Titular - Examinador(a) Externo à Instituição - MURILO DE CARVALHO
Membro Suplente - Examinador(a) Interno ao Programa - 1676364 - JULIANA MARCHI
Membro Suplente - Examinador(a) Interno ao Programa - 1763443 - MARCIA APARECIDA DA SILVA SPINACE
Membro Suplente - Examinador(a) Externo à Instituição - DIEGO MAGALHAES NASCIMENTO