Strong improvement of permeability and rejection performance of graphene oxide membrane by engineered interlayer spacing

Advanced membranes fabricated from multilayer/laminated graphene oxide (GO) are promising in water treatment applications as they provide very high flux and excellent rejection of various water pollutants. However, these membranes have limited viability, and suffer from instabilities and swelling due to the hydrophilic nature of GO. In this work, the permeability and rejection performance of laminated GO membranes were improved via functionalization with ethylenediamine (EDA) and polyethyleneimine (PEI). The membranes are fabricated via the pressure-assembly stacking technique, and their structure is well characterized. The performance, rejection, and stability of the fabricated functionalized GO membranes were evaluated. Pillaring the GO layers using diamine and polyamine resulted in exceptionally high water permeability of 113 L/m²h (LMH) compared to only 28 LMH for the pristine GO membrane while simultaneously satisfying high rejection of multivalent salts of 79.4, 35.4, and 19.6 % for Na₂SO₄, MgCl₂, and NaCl, respectively. The results obtained indicate that proper functionalization of GO provides a roadmap for the potential commercialization of such advanced membranes in water treatment applications.