Thin-Film Composite Membranes with a Hybrid Dimensional Titania Interlayer for Ultrapermeable Nanofiltration

Abstract

The interfacial properties within a composite structure of membranes play a vital role in the separation properties and application performances. Building an interlayer can facilitate the formation of a highly selective layer as well as improve the interfacial properties of the composite membrane. However, it is difficult for a nanomaterial-based interlayer to increase the flux and retention of nanofiltration membranes simultaneously. Here, we report a nanofiltration membrane with a hybrid dimensional titania interlayer that exhibits excellent separation performance. The interlayer, composed of Fe-doped titania nanosheets and titania nanoparticles, helps the formation of an ultrathin (∼30 nm thick) and defect-free polyamide selective layer with an ideal nanostructure. The hybrid dimensional interlayer endows the membrane with a superior permeability and alleviates flux decline. In addition, the rigid interlayer framework on a PVDF support drastically improves the pressure resistance of nanofiltration membranes and shows negligible flux loss up to 1.5 MPa of pressure.

Hybrid Dimensional MXene/CNC Framework-Regulated Nanofiltration Membrane with High Separation Performance

“…As shown in Figure c, the incorporation of a relatively low amount of CNC into MXene (for example, MxC 35 ) resulted in a continuously interconnected surface accompanied by a greater root mean surface roughness (RMS, 61.3 ± 3.5 nm) compared to that of the MxC 0 (46.7 ± 4.2 nm) (Figure S3), indicating the intercalation of CNC into MXene nanosheets. Meanwhile, excessive addition of CNC (for example, MxC 50 ) increased the unevenness, surface roughness (65.1 ± 1.7 nm), and visible defects of the surface (Figure d), which are unfavorable for the formation of a PA layer with high integrity . In addition, the surface hydrophilicity and surface area of the substrate were increased with the intercalation of CNC (Table S4), which may contribute to the surface wetting and uptake of aqueous phase amine monomer.…”

“…As evidenced by the SEM and XRD characterization, the interlayer spacing was largely increased and the interconnected MXene/CNC framework was disrupted due to the excessive CNC addition, resulting in uncontrollable release of PIP monomers. In addition, the greatly enhanced hydrophilicity of the MxC 50 substrate might hinder the diffusion of PIP molecules to the interface due to the hydrogen bonds between the hydrophilic sites with the PIP molecules, which likely formed the smaller polyamide nuclei, and eventually evolved into the discrete spotted nodules. , The emergence of the textured structure especially for the PA-MxC 35 membrane resulted in a rougher surface (84.2 ± 2.9 nm) and 16.6% increase in surface area compared to TFC (Table S5), offering an enlarged effective filtration area for water permeation. ,− …”

Surface Mineralization of the TiO2–SiO2/PES Composite Membrane with Outstanding Separation Property via Facile Vapor-Ventilated In Situ Chemical Deposition

“…Milli-Q water was pumped through the lumen side of HFs under a transmembrane pressure of 0.5 bar and a cross-flow velocity of 0.5 m/s. The water permeance was calculated according to eq J = Q normalΔ P × A = Q n π italicDl normalΔ P where J represents the water permeance (L·m –2 ·h –1 ·bar –1 ), Q represents the water permeating flux (L·h –1 ), Δ P represents the transmembrane pressure (bar), A represents the specific filtration area (m 2 ), n represents the number of employed HFs inside the module, D represents the outer diameter of HF (m), and l represents the HF length (m).…”

“…Water scarcity caused by global climate change and rapid population growth has been a worldwide challenge, and a strong need for the design and development of efficient separation technologies in wastewater treatment is a growing requirement to ensure an adequate water supply. , Different from conventional water treatment methods such as distillation or multistage adsorption, which demand large energy consumption and operation costs, membrane-based technology is a promising approach in wastewater remediation because of its well-defined sieving capability under mild conditions. − …”

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

“…Thin-film composites (TFCs), prepared by interfacial polymerization (IP), are greatly influenced by patterned design in terms of structural properties and separation performance. − Prof. Zhang employed poly­(vinyl alcohol) as an aqueous phase additive to reduce the diffusion of the piperazine at the water–oil interface, resulting in a Turing-patterned polyamide (PA) layer, accompanied by significantly increased permeability and undiminished selectivity . Our group adopted cucurbit­[n]­uril (CBn) to control the interfacial reaction by encapsulating the amine monomers via host–guest chemistry, thus realizing the controllable construction of surface nanostrand structures and the multifold enhanced permeability. − Prof. Jin applied the fractal branching NaCl as a template to construct a patterned surface, achieving three to 4-fold improved permeability after washing off the templates .…”