High-stable bimetallic AgCu nanoalloys with core-shell structures for sustainable antibacterial and biofouling mitigation in nanofiltration

Wenjuan Zhang; Zhe Wang; Zilong Zhao; Peizhi Wang; Shaopo Wang; Jun Ma; Wei Cheng

doi:10.1016/j.watres.2024.122986

High-stable bimetallic AgCu nanoalloys with core-shell structures for sustainable antibacterial and biofouling mitigation in nanofiltration

Water Res. 2024 Dec 15:271:122986. doi: 10.1016/j.watres.2024.122986. Online ahead of print.

Authors

Wenjuan Zhang¹, Zhe Wang¹, Zilong Zhao¹, Peizhi Wang², Shaopo Wang³, Jun Ma², Wei Cheng⁴

Affiliations

¹ Tianjin Key Laboratory of Aquatic Science and Technology, School of Environmental and Municipal Engineering, Tianjin Chengjian University, Tianjin 300384, PR China.
² State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China.
³ Tianjin Key Laboratory of Aquatic Science and Technology, School of Environmental and Municipal Engineering, Tianjin Chengjian University, Tianjin 300384, PR China. Electronic address: wsp@tcu.edu.cn.
⁴ State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China. Electronic address: chengweihit@hotmail.com.

PMID: 39705753
DOI: 10.1016/j.watres.2024.122986

Abstract

Nanofiltration (NF) is crucial for advancing water purification and wastewater reuse technologies. Incorporating biocidal nanoparticles (NPs) such as AgNPs and CuNPs is promising for developing antibacterial and antibiofouling NF membranes, while their application is limited by NPs aggregation, high cost, and severe ion release. In this study, we developed novel NF membranes by integrating bimetallic AgCu nanoalloys via an in-situ reduction and coordination method facilitated by a polydopamine/polyethyleneimine (PDA/PEI) intermediate layer. The sequential deposition of Cu²⁺ onto nascent AgNPs formed uniform AgCuNPs with a unique core-shell structure. The Cu shell layer can shield the release of Ag⁺ from the Ag core and chelate with the PDA/PEI intermediate layer, thus controlling the release of biocidal ions and prolonging the biocidal properties of the membranes. As a result, the AgCuNP-modified membranes exhibited significantly improved membrane water permeability, salt rejection, and performance stability, along with reduced release of biocidal ions in the long-term operation. Notably, the bimetallic AgCuNP-modified membrane displayed superior antibacterial activity and biofouling reversibility compared to the commercial NF and monometallic Ag/Cu-modified membranes, achieving the highest sterilization rate (> 99 %), largest flux recovery rate (93 %), and lowest flux decline rate (16 %) in both static antibacterial and dynamic biofouling processes. The metal-semiconductor heterostructure of the AgCuNPs facilitated the electron transfer from the Ag core to the Cu shell, intensifying the substantial generation of reactive oxygen species (H₂O₂: 71.6 mmol l^-1 m^-2, ^•OH: 43.4 mmol l^-1 m^-2, and O₂^•-: 1.3 × 10^-4) at the membrane-bacteria interface. The synergistic effects of the unique properties of AgCuNPs including microstructure, atomic composition, charge transfer, and ROS generation significantly enhanced the antibacterial capacity of the AgCuNP-modified membrane. This study presents a facile method for modifying NF membranes with bimetallic AgCuNPs to achieve enhanced antibacterial activity and biofouling reversibility, providing fundamental insights and promising potential for water treatment applications.

Keywords: Nanofiltration; antibacterial activity; bimetallic AgCu nanoparticle; biofouling reversibility; in-situ reduction.