Incorporation of Core-Shell-Structured Zwitterionic Carbon Dots in Thin-Film Nanocomposite Membranes for Simultaneously Improved Perm-Selectivity and Antifouling Properties

Han Zheng; Zihao Mou; Kun Zhou

doi:10.1021/acsami.0c13386

Incorporation of Core-Shell-Structured Zwitterionic Carbon Dots in Thin-Film Nanocomposite Membranes for Simultaneously Improved Perm-Selectivity and Antifouling Properties

ACS Appl Mater Interfaces. 2020 Nov 25;12(47):53215-53229. doi: 10.1021/acsami.0c13386. Epub 2020 Nov 13.

Authors

Han Zheng¹, Zihao Mou^{1

2}, Kun Zhou^{1

3}

Affiliations

¹ Environmental Process Modelling Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore 637141, Singapore.
² College of Chemistry and Chemical Engineering, Southwest Petroleum University, 8 Xindu Avenue, Chengdu 610500, PR China.
³ School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.

PMID: 33185418
DOI: 10.1021/acsami.0c13386

Abstract

The development of highly efficient thin-film nanocomposite (TFN) membranes with superior water permeability, maintained rejection performance, and excellent antifouling capacity is critical to meeting the ever-escalating demand for fresh water. Herein, carbon dots (CDs) grafted with hyperbranched zwitterions, denoted as CDs-ZPEI_0.6-10k, were first prepared by the hydrothermal treatment of citric acid in the presence of zwitterionic hyperbranched polyethylenimine (ZPEI_0.6-10k) with different molecular weights (0.6, 1.8, and 10 kDa). Subsequently, the synthesized nanoparticles were introduced in membrane fabrication to form CDs-ZPEI_0.6-10k-embedded TFN (TFN-CDs-ZPEI_0.6-10k) membranes. The grafted shells of superhydrophilic ZPEI not only increased the chemical compatibility of CDs in the polyamide layer to suppress the formation of nonselective voids but also created a densely packed network for efficient water transportation and effective divalent salt rejection. The TFN-CDs-ZPEI_10k membrane demonstrated a 2.8-fold enhancement in the permeate flux with an increased Na₂SO₄ rejection rate of 98.1% and improved antifouling properties than the pristine thin-film composite (TFC) membrane. This work provides an insight into the development of functionalized core-shell structured nanoparticles to effectively overcome the permeability-selectivity trade-off limitations and fouling problems in TFC membranes.

Keywords: antifouling; carbon dots; core−shell structures; thin-film nanocomposites; zwitterionic polymers.