Produção de membranas de troca iônica para células de eletrodiálise

Abstract

Ion exchange membranes are widely used in solution separation processes, mainly for the removal of heavy metals and in the treatment of contaminated effluents. In this study, the objective was to produce and characterize heterogeneous ion exchange membranes using the phase inversion technique. membranes were produced from polymeric matrices of polysulfone and polyethersulfone with the incorporation of ion-exchange resins, in the proportion of 5% (w/w). The anion exchange membranes used is Duolite AP143/1083 resin and the cation exchange membranes used Amberlit IRP69 resin (Dow company). This study also included the incorporation of 2.5% and 5,0% (w/w) of graphene oxide concomitantly with resins. The membranes were characterized for permeability, structure, and morphology of the cross-section, mechanical strength, and ion-exchange capacity. The polysulfone membranes with the addition of anionic resin and 2.5% of OG presented a hydraulic permeability flux of 59.5 L h-1 m-2, whereas the anionic and cationic polyethersulfone membranes 20.81 and 16.03 L h-1 m-2, respectively. The ion-exchange index of pure polysulfone and polyethersulfone membranes was 0.26 and 0.23 mm g-1, showing an increase with the addition of resins and OG, reaching 1.08 mm g-1 in anionic polyethersulfone membranes with 2.5% of OG. The membranes produced were tested in an electrodialysis cell to remove manganese ions, showing removal of Mn+2 ions greater than 90% of the diluted solution using polysulfone membranes with graphene oxide before and after cleaning. For polyethersulfone membranes, the removal percentages of Mn+2 ions exceeded 94% for ion-exchange membranes and 95% for conditions with graphene oxide, even after membrane regeneration. The membranes were regenerated with 0.1 M NaCl and HCl solutions and again applied in the electrodialysis process with removal rates above 90% for membranes regenerated with the addition of graphene oxide. A study of the applicability of this electrodialysis process was carried out with the membranes produced in the removal of metal ions from two water samples collected, one in the Rio Gualaxo do Norte and the other in the Rio Doce, both affected by the collapse of the Fundão dam in Mariana – MG The collected samples were characterized for the presence of suspended solids with values of 0.23 and 0.13 g L-1, in the Rio Gualaxo do Norte and Rio Doce, respectively, the concentration of metallic ions (0.67 and 0.42 g L-1/Cr+6; 239.18 and 83.96 mg L-1/Fe+2; 12.39 and 2.39 mg L-1/Mn+2 from the Rio Gualaxo do Norte and Rio Doce, respectively). The application of samples collected from rivers in the electrodialysis cell with polyethersulfone membranes with the addition of 2.5% of graphene oxide showed removal rates of chromium, iron, and manganese of 72.8%, 91.3%, and 85.7%, respectively. The addition of graphene oxide proved to be promising to produce heterogeneous ion exchange membranes, with potential for the application to remove metal ions in different contaminated effluents.