Highly Conductive Ultrafiltration Membrane via Vacuum Filtration Assisted Layer-by-Layer Deposition of Functionalized Carbon Nanotubes

Abstract

Conductive membranes can offer innovative solutions for membrane fouling control while maintaining enhanced filtration performance. Here, an emerging technique, vacuum filtration assisted layer-by-layer deposition of functionalized multiwalled carbon nanotubes (MWNTs), was used to prepare conductive surfaces on polysulfone (PSf) ultrafiltration membranes. PSf membranes were functionalized with oxygencontaining negatively charged functional groups through oxygen plasma treatment. MWNT-PSf membranes were prepared with 5, 10, 15, and 20 bilayers with amine-and carboxylic-functionalized MWNTs. The prepared membranes were characterized by the thickness, contact angle, and conductivity of the membranes. Scanning electron microscopy images of the membranes confirmed uniform MWNT distribution across the membrane surface. MWNT-PSf membranes exhibited slightly reduced permeability, improved selectivity, and greater conductivity with increasing number of MWNT bilayers and demonstrated almost complete inactivation of Escherichia coli at low applied DC potential (1−3 V). Furthermore, significant (around 99%) degradation of methyl orange during electrofiltration was observed, supporting an expected reduction in organic fouling of the membrane.

Large-Area Ti3C2Tx-MXene Coating: Toward Industrial-Scale Fabrication and Molecular Separation

“…However, this process is time-consuming and requires excess solvent for dilution. 11 Spin-coating is considered to be an effective pathway for fabricating a wellaligned MXene layer with compact interlayer spacing owing to the centrifugal force used. However, its feasibility is limited to several-inch scale.…”

“…Among the various types and shapes of MXene products, film-type fabrication is essential for industry-related purposes. , Therefore, fabrication methods used for graphene and other 2D materials have been frequently adapted to realize MXene coatings. − Most commonly, vacuum filtration is a state-of-the-art lab-scale fabrication approach that can be easily carried out by passing a diluted MXene dispersion through an ultrafiltration filter. However, this process is time-consuming and requires excess solvent for dilution . Spin-coating is considered to be an effective pathway for fabricating a well-aligned MXene layer with compact interlayer spacing owing to the centrifugal force used.…”

Recent Progress in One- and Two-Dimensional Nanomaterial-Based Electro-Responsive Membranes: Versatile and Smart Applications from Fouling Mitigation to Tuning Mass Transport

“…In addition to vacuum- (or pressure-) assisted filtration, there are several alternative methods for nanomaterial deposition. Omi et al [ 55 ] fabricated CNT-based ERMs via a vacuum-assisted layer-by-layer method. Also, electrophoretic deposition [ 56 ] and chemical vapor deposition [ 17 ] have been used to obtain hollow fiber type rGO-CNT and CNT-based ERMs, respectively.…”

Processing Methods Used in the Fabrication of Macrostructures Containing 1D Carbon Nanomaterials for Catalysis

“…The functionalized membrane surface could then create cross-links with amine-functionalized CNF. Moreover, layer-by-layer deposition of intercalated positively and negatively charged CNFs, respectively functionalized with carboxyl or aminated groups, was carried out to increase the thickness of the CNF layer [177]. A bilayered membrane has also been prepared using CNFs layered on top of a macroporous silica substrate to obtain a membrane with controlled hierarchal porosity, with the thin CNF top-layer forming a rough surface due to the macroporosity of the silica substrate underneath [178].…”