Sistema híbrido funcional a base de hidróxido duplo lamelar e pontos quânticos de carbono

Abstract

Hybrid materials, resulting from the synergistic integration of organic and inorganic components, have emerged as an innovative strategy to achieve unique and enhanced physicochemical properties. Among these materials, layered double hydroxides (LDHs) exhibit high anion exchange capacity, while carbon quantum dots (CQDs) offer high electrical conductivity and ease of surface functionalization. In this work, a hybrid nanomaterial (LDH-CQD) was developed by incorporating CQDs into an LDH matrix via in situ co-precipitation, and the materials were characterized by FTIR, XRD, UV-Vis, DSC, TGA-DTG, TEM, SEM-EDS, nitrogen adsorption/desorption analysis, and point of zero charge (pHpzc) determination. XRD results confirmed the successful formation of LDH in the presence of CQDs, while FTIR, N2 adsorption/desorption data, and pHpzc analysis indicated the presence of CQD functional groups in the hybrid material, a significant increase in surface area, and modifications in surface chemistry of LDH after CQD functionalization, confirming the formation of a hybrid structure. Hemolysis assays using sheep erythrocytes demonstrated that the LDH-CQD hybrid material is non-toxic, suggesting potential for biomedical

applications. On the other hand, adsorption tests were performed for the removal of the anti- inflammatory drug ibuprofen in aqueous medium, and the LDH-CQD exhibited superior adsorptive

performance compared to its pristine counterpart, with a maximum capacity of 22.13 mg·g−1 (R(%) = 88.53%) at 25 ppm. At lower concentrations (5 and 10 ppm), the hybrid material achieved 100% removal. Kinetic modeling showed that the pseudo-second-order model best described the data, suggesting that chemisorption mechanisms dominate the adsorption process. The isotherm data were best fitted by the Sips model, indicating mixed adsorption behavior resulting from multiple physical and chemical interactions. Thus, the functionalization of layered double hydroxides with carbon quantum dots proved to be an effective strategy to enhance the adsorptive performance of these materials, enabling their applicability in the environmental field.