Estratégias de funcionalização da Luffa cylindrica para a adsorção de contaminantes farmacêuticos da água

Abstract

Luffa cylindrica (LF) is an abundant plant-based biomass with a highly porous three-dimensional structure, offering great potential for environmental applications. However, the low density and predominantly hydrophilic nature of its active sites limit its adsorption capacity for pharmaceutical contaminants. This thesis hypothesizes that chemical functionalization of LF fibers can enhance their adsorption performance by introducing specific functional groups while preserving the native 3D architecture. To test this hypothesis, three complementary functionalization strategies were developed and systematically evaluated. The grafting of polyethyleneimine (PEI) introduced nitrogen-rich groups, significantly improving reactivity and enabling stable removal of antibiotics and antivirals with confirmed reusability. The coating of LF with polypyrrole and stearic acid increased fiber hydrophobicity, thereby enhancing interactions with less polar pharmaceuticals such as diclofenac, and further demonstrated feasibility under continuous-flow conditions relevant for scale-up. Finally, grafting with β-cyclodextrin (β-CD) created selective host–guest complexation sites, producing an efficient fixed-bed column adsorbent capable of removing non-steroidal anti-inflammatory drugs (NSAIDs) from large volumes of water. Collectively, these results demonstrate that distinct modifications routes can be applied to LF without compromising its structural integrity, while tailoring surface chemistry for adsorption of pharmaceuticals with diverse chemical properties. By correlating functionalization strategies with adsorption outcomes, this thesis advances the understanding of structure–function relationships in lignocellulosic adsorbents, provides new insights into the sustainable valorization of agricultural residues, and establishes a framework for designing scalable biomass-based materials for water treatment technologies.