Desenvolvimento de membranas catiônicas à base de acetato de celulose para potencial aplicação em eletrodiálise

Abstract

Water pollution by heavy metals poses serious environmental and public health risks, driving the development of treatment technologies that are both economically viable and sustainable. In this context, this work investigated the development and performance of cellulose acetate (CA)-based ion-exchange membranes through two complementary approaches: (i) incorporation of waste-derived keyboard particles and (ii) functionalization with polyethyleneimine (PEI). In the first approach, MStd (CA), MR (CA with commercial cation-exchange resin), and MKey (CA with keyboard particles) membranes were produced and evaluated with and without acid activation. Physicochemical analyses indicated that MR and MKey exhibited significant increases in ion-exchange capacity (IEC) and hydraulic permeability, while maintaining porosity and water uptake similar to MStd, demonstrating efficient incorporation of the added phases. Diffusion experiments with Cu²⁺ (1200 ppm) showed that acid-activated membranes reached equilibrium more rapidly (180–240 min), indicating improved ion transport kinetics. In the second approach, CA/PEI membranes were developed using a simple blending strategy without post-functionalization steps. PEI incorporation was confirmed by FTIR and IEC analyses, resulting in an approximately threefold increase in ion-exchange capacity without compromising hydraulic permeability. Diffusion experiments revealed preferential transport of Cu²⁺ over Zn²⁺ in binary systems, despite an overall flux reduction due to competition for active sites, indicating a higher affinity of PEI amine groups for copper ions. Overall, both strategies demonstrated potential to enhance the functionality and performance of CA-based membranes, either through the valorization of polymeric waste or chemical modification of the matrix. These findings highlight the promise of such approaches for the development of efficient membranes for heavy metal removal from aqueous systems.