Enhancing the Permselectivity of Thin-Film Composite Membranes Interlayered with MoS2 Nanosheets via Precise Thickness Control

Siyu Cao; Akshay Deshmukh; Li Wang; Qi Han; Yufei Shu; How Yong Ng; Zhongying Wang; John H Lienhard

doi:10.1021/acs.est.2c00551

Enhancing the Permselectivity of Thin-Film Composite Membranes Interlayered with MoS₂ Nanosheets via Precise Thickness Control

Environ Sci Technol. 2022 Jun 21;56(12):8807-8818. doi: 10.1021/acs.est.2c00551. Epub 2022 May 18.

Authors

Siyu Cao^{1

2}, Akshay Deshmukh³, Li Wang^{1

4}, Qi Han¹, Yufei Shu¹, How Yong Ng², Zhongying Wang¹, John H Lienhard³

Affiliations

¹ School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
² Environmental Research Institute, National University of Singapore, Singapore 117411, Singapore.
³ Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, Untied States.
⁴ Department of Civil Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR 999077, P. R. China.

PMID: 35583029
DOI: 10.1021/acs.est.2c00551

Abstract

The demand for highly permeable and selective thin-film composite (TFC) nanofiltration membranes, which are essential for seawater and brackish water softening and resource recovery, is growing rapidly. However, improving and tuning membrane permeability and selectivity simultaneously remain highly challenging owing to the lack of thickness control in polyamide films. In this study, we fabricated a high-performance interlayered TFC membrane through classical interfacial polymerization on a MoS₂-coated polyethersulfone substrate. Due to the enhanced confinement effect on the interface degassing and the improved adsorption of the amine monomer by the MoS₂ interlayer, the MoS₂-interlayered TFC membrane exhibited enhanced roughness and crosslinking. Compared to the control TFC membrane, MoS₂-interlayered TFC membranes have a thinner polyamide layer, with thickness ranging from 60 to 85 nm, which can be tuned by altering the MoS₂ interlayer thickness. A multilayer permeation model was developed to delineate and analyze the transport resistance and permeability of the MoS₂ interlayer and polyamide film through the regression of experimental data. The optimized MoS₂-interlayered TFC membrane (0.3-inter) had a 96.8% Na₂SO₄ rejection combined with an excellent permeability of 15.9 L m^-2 h^-1 bar^-1 (LMH/bar), approximately 2.4 times that of the control membrane (6.6 LMH/bar). This research provides a feasible strategy for the rational design of tunable, high-performance NF membranes for environmental applications.

Keywords: interlayer; nanofiltration; polyamide tuning; thickness control; thin-film composite (TFC) membranes.