Graphene oxide proton permselective membrane for electrodialysis-based waste acid reclamation: Simulation and validation

Nowadays, the development of novel technology for economical and efficient reclamation of waste acid containing metal ions is still the top priority. The graphene oxide (GO)-based membrane has gained attention in the relevant membrane processes driven by pressure gradient, concentration difference and even Donnan potential because of its special two-dimension (2D) structure and abundant hydrophilic sites. However, its work performances for electrodialysis (ED)-based acid recovery process are still unknown. In this work, GO-based proton permselective membranes (PPM) are designed and applied in the ED-based acid recovery. Above all, the possibility of selective separating protons from metal cations by GO membrane under a direct electric field and the related influencing factors are comprehensively explored by molecular dynamic simulation. Furthermore, a series of GO-based PPMs with designed thickness, interlayer spacing and charged state are prepared by adjusting GO loading, employing different crosslinking agents and attaching the relevant polyelectrolytes. Therein, the work performances of GO-based PPMs in a typical ion substitution ED process, including the metal cation leakage, water transport phenomenon and nonideal migration of anions are investigated and compared with those of commercial membrane. Results show that GO membranes prepared and used according to the optimized conditions embrace sharp separating property between protons and metal ions which is hardly deteriorated along with the change of their relative content. On the other hand, it is noticed that the leakage of organic anions and water transport seem to be unavoidable due to the exploitation of the porous support. Obviously, this work can contribute to not only developing a novel PPM for ED but extending the applications of the 2D nanomaterial as well.