Flake size-dependent water transport through graphene oxide membranes and rejection of geosmin (GSM) and 2-methylisoborneol (MIB) from drinking water
Xinyue Wen, Vanesa Quintano, Zongli Xie, Xiaojun Ren, Gregory Stonehouse, Heriberto Bustamante, Xiaoheng Jin, Rakesh Joshi
Abstract
Water transport through graphene oxide membranes (GOMs) and the rejection of inorganic and organic solutes have been extensively studied. However, the influence of the lateral size of GO flakes on membrane performance remains unclear. Here, we investigate the water permeation and separation performance of GOMs fabricated using various sizes of flakes. The membranes prepared with larger flakes showed higher water flux. Our experiment clearly shows that GOMs consist of both lamellae and void structures. Monte Carlo simulations indicate that water transport through the voids is faster than that through the lamellae in GO membranes. Moreover, the voids are more predominant for the membranes prepared with larger sizes of GO flakes and, hence, higher water flux for larger flake membranes. Additionally, the GOMs prepared with the large flakes effectively rejected more than 98 % of geosmin (GSM) and 2-methylisoborneol (MIB) with high reproducibility and a stable water flux of 1.49 LMH. Our results contribute to a better understanding of the complex structure of GOMs, where the rejection performance of membranes mainly depends on the interlayer space, but the water transport is governed by the voids. Our study also demonstrated the industrial potential of GOMs in drinking water purification technology.