Effective recovery of acids from iron-based electrolytes using graphene oxide membrane filters

The efficient recovery of acids from iron-based electrolytes using graphene oxide (GO) membranes was demonstrated for the first time. The results revealed that the amount of H+ permeating the GO membranes and reaching drains was two orders of magnitude larger than that of Fe3+. Notably, when the FeCl3 source concentration was reduced to certain extent, Fe3+ could be completely blocked by GO membranes. The mechanism for the effective separation of H+ from Fe3+ was studied, suggesting that the molecular sieving effect of GO nanocapillaries and the coordination between Fe3+ and GO were responsible for the effective blockage of Fe3+ while the rapid propagation of H+ through hydrogen-bonding networks along water layers within the interlayer spacing was responsible for the fast migration of H+. These properties made GO membranes promising cation-exchange membranes for applications of wastewater reuse and membrane separation.