Selective Molecular Separation on Ti₃C₂T_x–Graphene Oxide Membranes during Pressure-Driven Filtration: Comparison with Graphene Oxide and MXenes

Abstract

In this work, we prepared 90 nm thick TiCT-graphene oxide (GO) membranes laminated on a porous support by mixing GO with TiCT. This process was chosen to prevent the penetration of target molecules through inter-edge defects or voids with poor packing. The lattice period of the prepared membrane was 14.28 Å, as being swelled with water, resulting in an effective interlayer spacing of around 5 Å, which corresponds to two layers of water molecules. The composite membranes effectively rejected dye molecules with hydrated radii above 5 Å, as well as positively charged dye molecules, during pressure-driven filtration at 5 bar. Rejection rates were 68% for methyl red, 99.5% for methylene blue, 93.5% for rose Bengal, and 100% for brilliant blue (hydrated radii of 4.87, 5.04, 5.88, and 7.98 Å, respectively). Additionally, the rejections of composite membrane were compared with GO membrane and TiCT membrane.

Modulating oxygen coverage of Ti3C2Tx MXenes to boost catalytic activity for HCOOH dehydrogenation

“…As shown in Fig. 2b, the Ti 2p spectra of these samples were fitted with six main constituent peaks, corresponding to Ti-C at 461.1 and 455.3 eV, Ti-O at 464.4 and 458.8 eV, and Ti-F at 461.9 eV and 457.8 eV, respectively [33][34][35][36][37] . As for Ti 3 C 2 T x -250, the peaks for Ti-O were significantly strengthened compared with those for Ti 3 C 2 T x -25 and Ti 3 C 2 T x -150.…”

Review of MXenes as new nanomaterials for energy storage/delivery and selected environmental applications

“…The poor removal of methyl red is attributable to its relatively small size and hydrodynamic diameter, and its neutral charge. However, Rose Bengal removal was less effective than that of methylene blue although the former molecule is larger, presumably because the negative charge of the former molecule triggered low-level electrostatic attraction to the MXene surface [196]. Ionic salts (NaCl, Na2SO4, MgSO4, and MgCl2) were very poorly removed (< 10%).…”

“…[191], © Royal Society of Chemistry 2018) and (b) schematic diagrams for the steric exclusion mechanisms for hydrated ions and dye molecules on the Ti3C2Tx-GO membrane (reproduced with permission from Ref. [196], © American Chemistry Society 2017).…”

“…Graphene is impermeable [193], and many studies have used graphene-based membranes for water treatment [138,139,183,184,194,195]. Kang et al fabricated a 90-nm-thick Ti3C2Tx-GO membrane on a porous support (polycarbonate/nylon) that inhibited target solute movement through inter-edge defects or poorly packed spaces [196]. A membrane with an effective interlayer spacing of approximately 0.5 nm exhibited high-level removal rates (68% for methyl red (neutral, 0.49 nm), 99% for methylene blue (positive, 0.51 nm), 94% for Rose Bengal (negative, 0.59 nm), and 100% for Coomassie brilliant blue (negative, 0.8 nm)).…”

“…Thus, at pH 7, E. coli with a relatively more negative charge could resist the Ti3C2Tx MXene more so than Bacillus subtilis [209]. [196] a Co = organic initial concentration; NA = not available.…”