The roles of oxygen-containing functional groups in modulating water purification performance of graphene oxide-based membrane

Abstract Due to the excellent mechanical properties and tunable inter-layer distance spacing (D-spacing), graphene oxide based nanofiltration membranes (GONMs) have attracted tremendous attention for wastewater treatment and seawater desalination. However, GONMs with different reduction degrees or originate from different graphite resources present totally distinct purification performance. The principal consideration of the differences between those GONMs is the oxygen-containing functional groups (carboxyl (-COOH), hydroxyl (-OH) and epoxy (-COC-)). While, it is still not fully understood what role do different oxygen-contained functional groups play. Herein, in order to reveal this knowledge gap, we fabricated and systematically studied three oxygen-containing functional groups dominant (C-GO, H-GO and E-GO) GO membranes. Zeta potential was measured to analysis the surface properties of C-GO, H-GO and E-GO nanosheets. Furthermore, XRD was used to observe the D-spacing of GONMs. The results showed that the oxygen-contained functional groups with different hydrophilicity and electricity modulated the D-spacing of GONMs effectively, which resulted in different water permeance and sieving performance of the GONMs. Besides, C-GONMs with abundant negative charges exhibited excellent antifouling capacity for Trypan blue (dye) owing to the electrostatic interaction effect. Such differences between GONMs with three kinds of oxygen-contained functional groups pave a powerful platform to better understand and design the GO based separation membrane.