Engineering fast water-selective pathways in graphene oxide membranes by porous vermiculite for efficient alcohol dehydration

Abstract

Graphene oxide (GO) lamellar membranes with well-aligned architecture hold promising potential for molecular separations. However, the tortuous transport pathways and weak interlamellar interactions between stacked GO nanosheets cause low flux and poor stability, which are major drawbacks for their practical applications. Herein, we report a strategy to engineer fast and robust water-selective pathways within GO-based lamellar membranes by porous vermiculite (PVMT), a naturally layered magnesium aluminosilicate. PVMT nanosheets conferred abundant in-plane pores, which decreased the tortuosity and shortened the mass transport distance inside lamellar membranes. Meanwhile, PVMT nanosheets enhanced the hydrophilicity and fixed the interlayer distance, contributing to robust water-selective transport. The physicochemical properties of membranes, such as thickness and hydrophilicity, were manipulated by the loading amount of PVMT nanosheets. The resulting lamellar membranes exhibited excellent n-butanol dehydration performance with a permeation flux of 9554 g m⁻² h⁻¹ and a separation factor of 2678, which increased by up to 91% and 328% compared to pristine GO/PTFE membranes. Moreover, membranes remain stable for 192 h operation. Our study may stimulate further research on precise construction of mass-transfer pathways within lamellar membranes.