Surpass 3

The Ti₃AlC₂ powders, Ti₃C₂T_x nanosheets and d-spacing values were characterized by XRD (Ultima lV, Japan) with Cu Kα radiation at a step of 0.02° and a collection time of 6 s/step. SEM (Zeiss Gemini SEM 300, Germany) was used to study the surface topography and structural characteristics of the nanosheets and membranes. AFM (Bruker Multimode 8) was used to obtain a topographical image of the nanosheets in tapping mode. The morphology of the nanosheets was characterized by TEM (JEOL JEM-F200, Japan). XPS analysis was performed using a Thermo Fisher ESCALAB Xi⁺ instrument with monochromated Al-Kα radiation. FTIR characterization was performed using a Bruker VERTEX 33 unit over the wavenumber range of 1500–4000 cm⁻¹. In situ infrared absorption spectroscopy measurements were conducted in transmission geometry by using a Thermo Scientific Nicolet iN10. The solid surface zeta potential was measured by a solid surface analyzer using Anton Paar SurPASSTM 3, and the colloidal solution zeta potential was measured by a laser particle size analyzer using a Zetasizer Nano ZS 90.

The zeta potential was measured using a special measuring cell for ceramic membranes within an electrokinetic analyzer (SurPASS^TM3, Anton Paar GmbH, Graz, Austria). The membranes were wetted with a 0.001 M KCl solution, which was also used as a background electrolyte. 0.1 M NaOH was used as the titration liquid for the determination of the zeta potential on the pH dependence in the range from pH = 3 to pH = 9. The zeta potential was calculated from the measured streaming flow using the Helmholtz–Smoluchowski equation, as in our previous work [15 (link)].

The microfluidic device was fabricated by conventional photolithography technique using polydimethylsiloxane (PDMS, Sylgard 184, Dow Corning, NY, USA) with the membrane mimic design. The required membrane design was replicated from a 4″ silicon master mold. The microfluidic design consists of a straight channel with a set of staggered array of pillars near the mid-section (Fig. 1(b)), which acts as a MF membrane mimic. The staggered arrangement of pillars has a height h = 5 µm and diameter d = 50 µm, and the gap between pillars p = 2 µm (Fig. 1(b)). Hence, the device provides a pore size which is comparable to an MF membrane pore (0.1–10 μm). The thickness, t, of the membrane is 102 µm and the width, w, of the microchannel is 504 µm, as shown in Fig. 1(b). The inlet and outlet pores were drilled carefully and the PDMS stamps and coverslip were bonded together by using oxygen plasma-activated bonding at 500mTor pressure for 30 seconds. Next, they were annealed at 80 ºC for 1 hour to ensure proper bonding. Additional details about the fabrication process is provided elsewhere^{38 (link)}. The zeta potential of the PDMS surface (ξ_PDMS) was measured to be ∼−45 mV at pH 7 after plasma treatment (SurPASS^TM 3, Anton Paar, Graz, Austria).