Nanoparticle-templated nanofiltration membranes for ultrahigh performance desalination

Zhenyi Wang,Zhangxin Wang,Shihong Lin,Yuzhang Zhu,Jian Jin,Huile Jin,Shoujian Gao,Shoujian Gao

doi:10.1038/s41467-018-04467-3

Abstract

Nanofiltration (NF) membranes with ultrahigh permeance and high rejection are highly beneficial for efficient desalination and wastewater treatment. Improving water permeance while maintaining the high rejection of state-of-the-art thin film composite (TFC) NF membranes remains a great challenge. Herein, we report the fabrication of a TFC NF membrane with a crumpled polyamide (PA) layer via interfacial polymerization on a single-walled carbon nanotubes/polyether sulfone composite support loaded with nanoparticles as a sacrificial templating material, using metal-organic framework nanoparticles (ZIF-8) as an example. The nanoparticles, which can be removed by water dissolution after interfacial polymerization, facilitate the formation of a rough PA active layer with crumpled nanostructure. The NF membrane obtained thereby exhibits high permeance up to 53.5 l m−2h−1 bar−1 with a rejection above 95% for Na2SO4, yielding an overall desalination performance superior to state-of-the-art NF membranes reported so far. Our work provides a simple avenue to fabricate advanced PA NF membranes with outstanding performance.

Highlights

Nanofiltration (NF) membranes with ultrahigh permeance and high rejection are highly beneficial for efficient desalination and wastewater treatment
A typical interfacial polymerization process, in which diamine monomer piperazine (PIP) and trimesoyl chloride (TMC) reacts at water–hexane interface to form the PA selective layer, was induced on the surface of such a support loaded with PD/ZIF-8 nanoparticles
The thickness of PD/SWCNTs film used in this work was around 75 nm as confirmed by atomic force microscope (AFM) measurement

Summary

Introduction

Nanofiltration (NF) membranes with ultrahigh permeance and high rejection are highly beneficial for efficient desalination and wastewater treatment. State-of-the-art NF membranes are based on a thin film composite (TFC) design[11], which deposits a polyamide (PA) active layer, formed by interfacial polymerization, on top of a porous support layer that is typically an ultrafiltration (UF)[12] or a microfiltration (MF) membrane[13,14] Such a TFC structure yields high performance membranes with strong mechanical integrity, and enables costeffective and scalable membrane manufacturing. These interlayer media provide more uniform substrate pores and optimized water wetting property than conventional polymeric UF/MF membranes, which in turn enable more homogeneous distribution of the monomer solutions and more effective control of monomer release in interfacial polymerization Using this approach, thin PA active layers with thickness near 10 nm have been achieved successfully. While this strategy of reducing active layer is effective in enhancing membrane permeance, further improvement of membrane performance following this strategy is limited, as it will become extremely challenging to prepare defectfree active layers that are even thinner than the state-of-the-art

Methods

Results

Conclusion