Well-structured 3D channels within GO-based membranes enable ultrafast wastewater treatment

Graphene oxide (GO)-based membranes have been widely studied for realizing efficient wastewater treatment, due to their easily functionalizeable surfaces and tunable interlayer structures. However, the irregular structure of water channels within GO-based membrane has largely confined water permeance and prevented the simultaneously improvement of purification performance. Herein, we purposely construct the well-structured three-dimensional (3D) water channels featuring regular and negatively-charged properties in the GO/SiO2 composite membrane via in situ close-packing assembly of SiO2 nanoparticles onto GO nanosheets. Such regular 3D channels can improve the water permeance to a record-high value of 33,431.5 559.9 L.m(-2).h(-1) (LMH) bar(-1), which is several-fold higher than those of current state-of-the-art GO-based membranes. We further demonstrate that benefiting from negative charges on both GO and SiO2, these negatively-charged 3D channels enable the charge selectivity well toward dye in wastewater where the rejection for positive-charged and negative-charged dye molecules is 99.6% vs. 7.2%, respectively. The 3D channels can also accelerate oil/water (O/W) separation process, in which the O/W permeance and oil rejection can reach 19,589.2 1,189.7 LMH bar(-1) and 98.2%, respectively. The present work unveils the positive role of well-structured 3D channels on synchronizing the remarkable improvement of both water permeance and purification performance for highly efficient wastewater treatment.

Automated summary

This study successfully improves water permeance and purification performance for efficient wastewater treatment by constructing well-structured three-dimensional water channels in GO/SiO2 composite membranes. The 3D channels achieve a record-high water permeance and demonstrate excellent charge selectivity towards dye molecules in wastewater.