Locking Patterned Carbon Nanotube Cages by Nanofibrous Mats to Construct Cucurbituril[n]-Based Ultrapermselective Dye/Salt Separation Membranes.

Surface patterning is a promising strategy to overcome the trade-off effect of separation membranes. Herein, a bottom-up patterning strategy of locking micron-sized carbon nanotube cages (CNCs) onto a nanofibrous substrate is developed. The strongly enhanced capillary force triggered by the abundant narrow channels in CNCs endows the precisely patterned substrate with excellent wettability and antigravity water transport. Both are crucial for the preloading of cucurbit[n]uril (CB6)-embeded amine solution to form an ultrathin (∼20 nm) polyamide selective layer clinging to CNCs-patterned substrate. The CNCs-patterning and CB6 modification result in a 40.2% increased transmission area, a reduced thickness, and a lowered cross-linking degree of selective layer, leading to a high water permeability of 124.9 L·m-2 h-1 bar-1 and a rejection of 99.9% for Janus Green B (511.07 Da), an order of magnitude higher than that of commercial membranes. The new patterning strategy provides technical and theoretical guidance for designing next-generation dye/salt separation membranes.

Precisely Patterned Nanostrand Surface of Cucurbituril[n]-Based Nanofiltration Membranes for Effective Alcohol-Water Condensation.

Low concentration alcohols produced by state-of-the-art biological fermentation restrict subsequent purification processes for chemical, pharmaceutical, biofuel, and other applications. Herein, a rarely reported cucurbituril[n] (n = 6, 8) is employed to pattern the thin-film composite membranes with controllable and quantifiable nanostrand structures through a host-guest strategy. The resulting nanofiltration membrane with such morphology is the first report that exhibits excellent separation performance for isopropyl alcohol (IPA) and water, condensing the initial 0.5 wt % IPA aqueous solution to 9.0 wt %. This not only provides a novel strategy for patterning nanostructural morphology but also makes nanofiltration membranes promising for alcohol condensation in the biological fermentation industry that may reduce energy consumption and postprocessing costs.

MoS2 Membranes for Organic Solvent Nanofiltration: Stability and Structural Control.

This paper reveals the chemical, structural, and separation stability of stacked molybdenum disulfide (MoS2) membranes and establishes a low-cost and facile approach to developing stable, selective membranes for efficient molecular separation in an organic solvent. MoS2 nanoflakes that were dominant  by monolayer MoS2 sheets as prepared via direct chemical exfoliation (chem-MoS2) were found to be chemically and structurally instable, with a sharp decrease in the level of solute rejection within a few days. Few-layer MoS2 nanoflakes were then fabricated using a hydrothermal method (hydro-MoS2). A "supportive" drying process involving glycerol pretreatment and drying in an oven was established to allow realignment of nanoflakes and adjustment of interflake spacing. We have shown that the hydro-MoS2 membranes provide a mean interflake free spacing of ∼1 nm, which is ideal for the separation of a model solute (Rose Bengal, size of ∼1.45 nm) from the solvent isopropanol (size of 0.58 nm) with good long-term stability over a 7 day test.