Preparation of Highly Antibacterial MXene Nanofiltration Membranes and Investigation of Their Separation Performance

Abstract

In this study, polyethersulfone (PES)/sulfonated polyethersulfone (SPES) composite nanofiltration membranes doped with different contents of monolayer titanium carbide nanosheets (Ti₃C₂T_X) were prepared by the nonsolvent induced phase inversion (NIPS) method. The effects of Ti₃C₂T_X on membrane structure, separation performance and antibacterial activity were investigated systematically. The results demonstrated that the viscosity of the casting solution increased significantly with the increasing content of Ti₃C₂T_X. In addition, the pore size of the membrane surface first decreased and then increased; porosity and hydrophilicity were optimized synchronously; and the density of negative charges on the surface increased. The M2 membrane showed a rejection rate of more than 90% for Metanil yellow (MY) and methylene blue (MEB). The order of salt ion rejection rates was magnesium sulfate (MgSO₄) > sodium sulfate (Na₂SO₄) > sodium chloride (NaCl), and water flux reached the peak (18.5 L/m²·h·bar). The antibacterial activity of the M2 membrane was significantly enhanced, and its antibacterial rate against Bacillus subtilis increased from 15% (M0) to 58%. This phenomenon was attributed to the synergistic mechanism of the Ti₃C₂T_X physical capture effect, reactive oxygen species (ROS) generation and sharp edge damage to bacterial cell membranes. This study provides theoretical support and a technical path for the development of MXene composite membranes with high separation efficiency and excellent antibacterial properties.

Keywords: PES/SPES membrane; Ti3C2TX; antibacterial activity; blend membrane.

Figure 1

Viscosity of PES/SPES membranes doped with different contents of Ti₃C₂T_X.

Figure 2

SEM surface images of M0–M3 at 1 nm (a1–a4); Energy Dispersive Spectroscopy (EDS) diagrams of Ti for M0–M3 at 1 μm (b1–b4); cross-sectional diagrams of M0–M3 at 100 μm (c1–c4); cross-sectional diagrams of M0–M3 at 20 μm (d1–d4).

Figure 3

AFM images of M0–M3 (a). Roughness of M0–M3 (b).

Figure 4

Average pore diameter of M0–M3 (a); porosity of M0–M3 (b).

Figure 5

Water contact angle of M0–M3 (a); surface zeta potential of M0–M3 (b).

Figure 6

Line diagram of tensile strength and elongation at break of M0–M3 (a); histogram of tensile strength and elongation at break of M0–M3 (b).

Figure 7

Retention rates of M0–M3 for different dyes.

Figure 8

Pure water flux of M0 to M3 (a); salt ion rejection rates of M0 to M3 (b).

Figure 9

Flux recovery rates of M0–M3.

Figure 10

Bacterial inhibition of M0–M3 against Bacillus subtilis (a–e); control group without membrane (e); bacteriostatic rate of M0–M3 against Bacillus subtilis (f).

Figure 11

Mechanistic diagram of MXene antibacterial activity.