Development of Highly Water-Permeable Robust PSQ-Based RO Membranes by Introducing Hydroxyethylurea-Based Hydrophilic Water Channels

Dian Zhang; Masakoto Kanezashi; Toshinori Tsuru; Kazuki Yamamoto; Takahiro Gunji; Yohei Adachi; Joji Ohshita

doi:10.1021/acsami.2c01469

Development of Highly Water-Permeable Robust PSQ-Based RO Membranes by Introducing Hydroxyethylurea-Based Hydrophilic Water Channels

ACS Appl Mater Interfaces. 2022 May 11;14(18):21426-21435. doi: 10.1021/acsami.2c01469. Epub 2022 Apr 29.

Authors

Dian Zhang¹, Masakoto Kanezashi², Toshinori Tsuru², Kazuki Yamamoto³, Takahiro Gunji³, Yohei Adachi¹, Joji Ohshita^{1

4}

Affiliations

¹ Smart Innovation Program, Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima739-8527, Japan.
² Chemical Engineering Program, Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima739-8527, Japan.
³ Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, Chiba278-8510, Japan.
⁴ Division of Materials Model-Based Research, Digital Monozukuri (Manufacturing) Education and Research Center, Hiroshima University, Higashi-Hiroshima739-0046, Japan.

PMID: 35486525
DOI: 10.1021/acsami.2c01469

Abstract

Copolymerization of bis[3-(triethoxysilyl)propyl]amine (BTESPA) and N-(2-hydroxyethyl)-N'-[3-(triethoxysilyl)propyl]urea (HETESPU) provided highly permeable robust reverse osmosis (RO) membranes that have an organically bridged polysilsesquioxane (PSQ) structure. The RO experiments with NaCl aqueous solution (2000 ppm) indicated that the introduction of hydroxyethylurea groups markedly improved the permeability of water (1.86 × 10^-12 m³/m²sPa) to approximately 19 times higher than that of a membrane prepared via the BTESPA homopolymerization, with NaCl rejection remaining nearly unchanged (96%). This is the highest water permeability obtained so far for PSQ-based membranes that show higher than 90% NaCl rejection. The improvement of water permeability is likely due to aggregation through hydrogen bonding in the PSQ layer, which can be regarded as a hydrophilic water channel.

Keywords: RO membrane; hydrogen bonding; polysilsesquioxane; urea; water channel.