Ultra-strong polymeric hollow fiber membranes for saline dewatering and desalination

Can Zeng Liang,Tai-Shung Chung,Looh Tchuin Choong,Mohammad Askari

doi:10.1038/s41467-021-22684-1

Abstract

Osmotically assisted reverse osmosis (OARO) has become an emerging membrane technology to tackle the limitations of a reverse osmosis (RO) process for water desalination. A strong membrane that can withstand a high hydraulic pressure is crucial for the OARO process. Here, we develop ultra-strong polymeric thin film composite (TFC) hollow fiber membranes with exceptionally high hydraulic burst pressures of up to 110 bar, while maintaining high pure water permeance of around 3 litre/(m2 h bar) and a NaCl rejection of about 98%. The ultra-strong TFC hollow fiber membranes are achieved mainly by tuning the concentration of the host polymer in spinning dopes and engineering the fiber dimension and morphology. The optimal TFC membranes display promising water permeance under the OR and OARO operation modes. This work may shed new light on the fabrication of ultra-strong TFC hollow fiber membranes for water treatments and desalination.

Highlights

Assisted reverse osmosis (OARO) has become an emerging membrane technology to tackle the limitations of a reverse osmosis (RO) process for water desalination
In the osmotically assisted reverse osmosis (OARO) process, water is transported across the semi-permeable membrane driven by the hydraulic pressure that overcomes the transmembrane osmotic pressure difference[3,14]
A saline stream with a lower or equal salinity is employed in the permeate side as a sweep stream of the OARO process to reduce the difference of osmotic pressure across the membrane, thereby the water transport becomes possible even when the osmotic pressure of the feed is larger than the external applied hydraulic pressure[3,14]

Summary

Introduction

Assisted reverse osmosis (OARO) has become an emerging membrane technology to tackle the limitations of a reverse osmosis (RO) process for water desalination. One of the promising technologies to realize high water recovery (e.g., >50%) is the membrane-based osmotically assisted reverse osmosis (OARO) process[3,10,11,12,13,14]. Togo et al used Toyobo’s PRO hollow fiber membranes for OARO, in which a low pressure of 8–18 bar was applied at the shell side. They reported that the pressure drop along the lumen side could be up to about 30–60% of the operating pressures depending on the flow rate[13]

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