Ion sieving by a two-dimensional Ti3C2Tx alginate lamellar membrane with stable interlayer spacing

Abstract

Two-dimensional membranes attract extensive interest due to the anomalous transport phenomena; however, the ion separation performance is below the theoretical prediction. The stabilization of d-spacing is a key step for enhancing ion selectivity. Here, we demonstrate a strategy for stabilizing the Ti 3 C 2 T x laminar architecture by alginate hydrogel pillars. After pillared by Ca-alginate, the nanochannel diameters are effectively fixed at 7.4 ± 0.2 Å, and the membrane presents a permeation cutoff and an outstanding sieving property towards valent cations. When applied for acid recovery, the outstanding H + /Fe 2+ selectivity makes the membrane a promising substitution for traditional ion-exchange membranes. Moreover, the ultrathin Mn-alginate pillared membrane with identical d-spacing exhibits 100% Na 2 SO 4 rejection with high water permeance, which is superior to the state-of-the-art nanofiltration membranes. Building on these findings, we demonstrate an efficient method to tune the ion selectivity and introduce a new perspective for energy-and environment-related applications.

Super-assembly of freestanding graphene oxide-aramid fiber membrane with T-mode subnanochannels for sensitive ion transport

“…For example, a stable Ti 3 C 2 T x membrane laminar architecture was obtained via the formation of alginate hydrogel pillars in the interlayer spacing, and the final membrane presented outstanding sieving property towards cations. 17 To achieve precise ion sieving, an Al 13 –Ti 3 C 2 T x lamellar membrane with an adjustable interlayer spacing in angstrom-scale precision over a wide range (2.7–11.2 Å) was applied to achieve selective ion sieving. 18 GO membranes, as a member of 2D membranes, have inspired scientists to study their transport properties and mechanisms owing to their abundant water-transport pathways through assembled GO laminates.…”

Recent Advances in MXene‐based Separation Membranes

“…Recently, Wang et al. 36 fabricated Ti 3 C 2 T x lamellar membranes using multivalent ions as hydrogel pillar in the interlayer spacing (Fig. 1g).…”

“…In this regard, Wang et al. 36 prepared pillared M‐SAT lamellar membranes with advance separation properties, in which metal cations such as Ca 2+ , Mn 2+ , etc. act as pillar between MXene nanosheets, which increased the d‐ spacing of pristine Ti 3 C 2 T x membrane from 13.8 to 15.2 Å.…”

Ion‐Selective MXene‐Based Membranes: Current Status and Prospects

“…Additionally, the lamellar Ti 3 C 2 T x MXene membranes synthesized by Wang et al via pillaring the SA in the interlayer spacing. [209] As revealed, the ion permeation can be affected strongly by the structure of lamellar membranes.…”