Membranas poliméricas híbridas policarbonato/grafeno: correlação estrutura e propriedades de transporte

Abstract

Polymeric membranes are an interesting alternative for the nanofiltration/desalination processes of marine and brackish water bodies, aiming to increase the availability of drinking water. However, these processes are actively influenced by the reduction of the filtration performance due to fouling. The fouling formation is a result of specific interactions arising from concentration polarization. Therefore, the knowledge about the mechanisms of interactions between the structure/surface of the membrane and the permeated flux is a fundamental point for the understanding the fouling process and the possible alternatives in the sense of mitigating it. This research aimed at the modification of the polymer membrane structure/surface through nanostructuring with the incorporation of graphene and chemically modified graphene. From the structural and physical-chemical point of view, the unique nature of graphene can favor and synergistically alter the surface polarization of the membrane and the internal nanostructure. Thus, the correlation between the obtained nanostructure and the transport properties inherent to the nanofiltration/desalination process as a function of the presence of the graphene was investigated, focusing on membranes with high antifouling performance and high permeate flow. For this, characterizations were carried out using spectroscopic, morphological, thermal and salt and water transport analyses. It was observed that the presence of the different particles even at low concentrations is able to alter the characteristics of these membranes mainly at local level with consequent changes in the transport properties. The thermal stability increased with GO and GOA presence. FEG showed the exfoliated, agglomerated and enovelled particles. The different graphene surface groups altered both matrix compatibilty and affnity between the given permeant as well as the matrix tortuosity. Thus, membranes containing graphene were more resistant to salt permeation and fouling formation.