Multifunctional filtration membrane with anti-viscous-oils-fouling capacity and selective dyes adsorption ability for complex wastewater remediation.

Multifunctional filtration membranes (MFMs), which can both effectively separate oil and selectively remove dyes from polluted aquatic system with robust anti-viscous-oil-fouling capacity, strong chemical/physical resistance, and long cycled stability, are highly required but still a challenge to be realized. Herein, a simple route has been demonstrated to address this challenge aforementioned by decorating both halloysite nanotubes (HNTs) and zwitterionic poly (sulfobetaine methyl methacrylate) (PSBMA) on the microporous polyvinylidene fluoride (PVDF) membrane surface via modified polydopamine (PDA) coating route. The as-prepared membrane exhibits super-hydrophilic/underwater super-oleophobic performance and high water permeation flux (32529 ± 278 L m-2 h-1 at 0.85 bar) to purify the diverse viscous oil-in-water emulsions from oily wastewater accompanying with good cycled stability (the recovery rate of permeate flux is close to 100% after 5 cycles). Moreover, the as-prepared MFM possesses not only strong chemical resistance under wide range of pH value (from 1 to 12) and high saline (NaCl: 10 wt%) environment, but also physical resistance against ultrasound bath for 30 min. Given the presence of HNTs, PDA, and PSBMA, our MFM shows enough active sites to adsorb the soluble dyes and metallic ions in wastewater. These excellent properties endow our MFM with great potential for the remediation of complex wastewater.

Designing nanofibrous membrane with biomimetic caterpillar-like structured for highly-efficient and simultaneous removal of insoluble emulsified oils and soluble dyes towards sewage remediation.

Purification of insoluble emulsified oils and soluble organic pollutants from sewage has attracted tremendous attention in today's society. Herein, a stable and environmentally friendly nanofibrous membrane with hierarchical caterpillar-like structure was fabricated via in-situ hydrothermal growing the nickel-cobalt layered double hydroxides (NiCo-LDHs) on tche polyacrylonitrile (PAN) electrospun nanofibers. The wrapped hydrophilic NiCo-LDHs constructed the hierarchical structure and endowed the membrane attractive superhydrophilicity (≈ 0°)/underwater superoleophobicity (≈ 161°) and enhanced oil-repellency performance. Meanwhile, the NiCo-LDH@PANI/oPAN NFMs can display the ultra-fast flux of SSEs (xylene/water emulsion, 4175 L m-2 h-1) and satisfactory separation efficiency (99.07%). Moreover, the introduction of positively charged NiCo-LDHs increased plentiful adsorption active sites for membranes, which is beneficial to demulsify ionic SSEs and adsorb organic pollutants. Finally, for simultaneous purification of complex sewage by the dead-end and cross-flow filtration experiment, the composite membrane both displayed splendid removal rate of oil (> 99.0%) and dyes (> 99.0%), robust regeneration recycle-ability and no secondary pollution. Hence, it is expected that such strategy of combining electrospun and chelating-assisted in-situ hydrothermal can provide a low energy consumption and high decontamination technology for severe environmental crisis.

One-step in-situ fabrication of carbon nanotube/stainless steel mesh membrane with excellent anti-fouling properties for effective gravity-driven filtration of oil-in-water emulsions.

The occurrence of membrane fouling has resulted in limited wastewater treatment applications. The development of superhydrophilic-underwater superoleophobic materials has received significant attention owing to their good anti-fouling properties. However, to fabricate such materials need costly regents and tedious steps. Thus, developing a one-step process to prepare a low-cost material for oil/water separation is still desired. In this study, bio-inspired from an arachnid, inorganic carbon nanotube stainless steel meshes (CNT@SSMs) having superhydrophilic-underwater superoleophobic and excellent anti-fouling properties and a unique fiber structure were fabricated via a one-step thermal chemical vapor deposition method. The CNT@SSMs had a small pore size enabling a high water flux of 10,639 L m-2h-1 and the separation of oily wastewater, including various emulsions, at a high rejection ratio of >98.89%. As a result of its excellent chemical stability under high temperatures, a broad pH range, and saline environments, the CNT@SSM has the potential to be used in extreme conditions. In summary, these CNT@SSMs are easy to fabricate and are low-cost as a result of inexpensive reagents involved. Moreover, these novel superwetting membranes are promising candidates for treatment of hazardous oily wastewater.

TiO2@HNTs Robustly Decorated PVDF Membrane Prepared by a Bioinspired Accurate-Deposition Strategy for Complex Corrosive Wastewater Treatment.

As industrialization has spread all around the world, the problems of water pollution such as offshore oil spill and industrial sewage discharge have spread with it. Although many new separation materials have been successfully developed to deal with this crisis, a large number of water treatment materials only focus on the treatment of classified single water pollutant under mild conditions. It is a great challenge to treat soluble contaminants such as water-soluble dyes and insoluble contaminants, for example, emulsified oils simultaneously in a strong corrosive environment. Herein, in this work, corrosive resistance and multifunctional surface on a commercial polyvinylidene difluoride (PVDF) membrane via a tunicate-inspired gallic acid-assisted accurate-deposition strategy is created. Owing to the titanium-carboxylic coordination bonding and accurate-deposition strategy, the as-prepared membrane exhibits extraordinary stability, facing various harsh environmental challenges and incredibly corrosive situations (e.g., 4 M NaOH, 4 M HCl, and saturated NaCl solution). The robust multifunctional surface also endows commercial PVDF membrane with the ability for in situ separation and adsorption of surfactant-stabilized oil-in-water (corrosive and dyed) emulsions with high adsorption efficiencies up to 99.9%, separation efficiencies above 99.6%, and permeation flux as high as 15,698 ± 211 L/(m2·h·bar). Furthermore, the resultant membrane can be regenerated facilely and rapidly by flushing a small amount of HCl (4 M) or NaOH (4 M), making the corrosive resistance membrane attain a long-term and high-efficiency application for complex dyed wastewater treatment. Therefore, the multifunctional membrane has a broad application prospect in the industrial field.