Highly permeable PVDF membrane with PS/ZnO nanocomposite incorporated for distillation process

A versatile route for the fabrication of micro-patterned polylactic-acid (PLA)-based membranes with tailored morphology via breath figure imprinting

Breath figure imprinting, based on surface instabilities combined with fast polymer evaporation in a humid environment, enables the creation of micro-patterned membranes with tailored pore sizes. Despite being a simple procedure, it is still challenging to fully understand the dynamics behind the formation of hierarchical structuring. In this work, we used the breath figure technique to prepare porous PLA-based (polylactic acid) membranes with two distinctive additives, polyvinylidene fluoride (PVDF) and zinc oxide nanoparticles (ZnO NPs). The selection of these additives was governed by their unique properties and the potential synergistic effects; when blended with PLA, the addition of NPs leads to more uniform structures with tunable characteristics and potential multifunctionality. This article sheds light on the multifaced interactions that intricate the interplays between PLA, PVDF, and ZnO, thus governing their assembly. Through a comprehensive investigation, we scrutinize the impact of blending PVDF and different concentrations of ZnO NPs on the morphology and chemical properties of the final self-assembled PLA membranes while presenting an advanced understanding of the potential applications of PLA-self-assembly porous membranes in various industrial sectors.

Fabrication and Investigation of Acid Functionalized CNT Blended Nanocomposite Hollow Fiber Membrane for High Filtration and Antifouling Performance in Ultrafiltration Process

In this study, we fabricated a nanocomposite polyethersulfone (PES) HF membrane by blending acid functionalized carbon nanotubes (FCNT) to address the issue of reduced membrane life, increased energy consumption, and operating costs due to low permeability and membrane fouling in the ultrafiltration process. Additionally, we investigated the effect of FCNT blending on the membrane in terms of the physicochemical properties of the membrane and the filtration and antifouling performance. The FCNT/PES nanocomposite HF membrane exhibited increased water permeance from 110.1 to 194.3 LMH/bar without sacrificing rejection performance and increased the flux recovery ratio from 89.0 to 95.4%, compared to a pristine PES HF membrane. This study successfully developed a high filtration and antifouling polymer-based HF membrane by blending FCNT. Furthermore, it was validated that blending FCNT into the membrane enhances the filtration and antifouling performance in the ultrafiltration process.

Polyvinylidene Difluoride (PVDF) Hollow Fiber Membrane Incorporated with Antibacterial and Anti-Fouling by Zinc Oxide for Water and Wastewater Treatment

The addition of antibacterial material to hollow fiber membranes improves the membrane anti-biofouling characteristics. Antibacterial membranes were fabricated in this study to improve membrane function while also extending membrane lifetime. Neat polyvinylidene difluoride (PVDF) and PVDF hollow fiber membrane with the incorporation of antibacterial agent zinc oxide (ZnO) nanoparticles with various loading (2.5–7.5 wt.%) were fabricated by using dry/wet spinning method. The membrane structure, particle distribution, functional group, hydrophilicity, and pore size of each membrane were all assessed. The result shows that all ZnO/PVDF hollow fiber membranes have the asymmetric structure with even dispersion of ZnO nanoparticles throughout the membranes. The results showed that increased ZnO loadings considerably improved membrane hydrophilicity, and average pore size, in addition to good performance of pure water flux. Antibacterial testing shows that ZnO incorporated in the membrane matrix and membrane surfaces prevents bacteria that cause biofouling from adhering to the membrane. ZnO/PVDF membrane recorded excellent bovine serum albumin (BSA) rejection at 93.4% ± 0.4 with flux recovery rate at 70.9% ± 2.1. These results suggest that antibacterial ZnO/PVDF hollow fiber membranes are promising in relation to reducing biofouling for various water and wastewater treatment.

Metal oxide and carbon nanomaterial based membranes for reverse osmosis and membrane distillation: A comparative review

Commercial membranes typically suffer from fouling and wetting during membrane distillation (MD). In contrast, reverse osmosis (RO) can be subject to the fouling issue if applied for highly saline feed solutions containing foulants (e.g., organics, oils, and surfactants). Among the diverse treatment options, the nanomaterial-based membranes have recently gained great interest due to their advantageous properties (e.g., enhanced flux and roughness, better pore size distribution, and higher conductivity). This review focuses on recent advances in the mechanical properties, anti-fouling capabilities, salt rejection, and economic viability of metal oxide (SiO₂, TiO₂, and ZnO) and carbon nanomaterial (graphene oxide/carbon nanotube)-based membranes. Current challenges in applying nanomaterial-based membranes are also discussed. The study further describes the preparation methods, mechanisms, commercial applications, and economical feasibility of metal oxide- and carbon nanomaterial-based membrane technologies.

Exfoliated Bi2Te3-enabled membranes for new concept water desalination: Freshwater production meets new routes

Water scarcity forces the science to find the most environmentally friendly propulsion technology for supplying plentiful freshwater at low energy costs. Membrane Distillation well meets criteria of eco-friendly management of natural resources, but it is not yet competitive on scale. Herein, we use a dichalchogenide compound (Bi₂Te₃) as a conceivable source to accelerate the redesign of advanced membranes technologies such as thermally driven membrane distillation. A procedure based on assisted dispersant liquid phase exfoliation is used to fill PVDF membranes. Key insights are gained in the crucial role of this topological material confined in hydrophobic membranes dedicated to recovery of freshwater from synthetic seawater. Intensified water flux together with reduced energy consumption is obtained into one pot, thereby gathering ultrafast production and thermal efficiency in a single device. Bi₂Te₃-enabled membranes show ability to reduce the resistance to mass transfer while high resistance to heat loss is opposite. Permeate flux is kept stable and salt rejection is higher than 99.99% during 23 h-MD test. Our results confirm the effectiveness of chalcogenides as frontier materials for new-concept water desalination through breakthrough thermally-driven membrane distillation, which is regarded as a new low-energy and sustainable solution to address the growing demand for access to freshwater.

Development of eco-friendly, self-cleaning, antibacterial membrane for the elimination of chromium (VI) from tannery wastewater

Hydrophobic polyvinylidene fluoride membrane was reformed to the hydrophilic membrane by incorporating synthesized titanium dioxide nanoparticles using Cajanus cajan seed extract. Spectroscopic and microscopic techniques characterized the composite membrane. The X-ray diffraction confirms the anatase phase of titanium dioxide nanoparticles of crystalline size 15.89 nm. The effect of titanium dioxide concentration on the thermodynamical and rheological properties on the polyvinylidene fluoride casting solution was investigated by the triangle phase diagram and viscosity measurement. It was concluded that titanium dioxide introduction caused thermodynamic enhancement, but the impact of rheological hinderance was higher at high concentrations. The polyvinylidene fluoride/titanium dioxide membranes were used as a bi-functional membrane to evaluate the rejection of chromium (VI) from wastewater; then, they were applied as sunlight-active catalyst membrane to reduce the concentrated chromium (VI) to chromium (III) by reduction. It was concluded that at 0.02 wt% of titanium dioxide, the maximum rejection of 85.59% and a% reduction of 92% was achieved with enhanced flux.

PFOM fillers embedded PVDF/cellulose dual-layered membranes with hydrophobic-hydrophilic channels for desalination via direct contact membrane distillation process

In this research work, novel perfluorooctanoic acid-modified melamine (PFOM) was synthesized as a hydrophobic filler using a facile one-pot synthesis. PFOM incorporating polyvinylidene fluoride (PVDF) solution was cast on a cellulose sheet to prepare a dual-layered membrane employing the phase-inversion technique for direct contact membrane distillation (DCMD) application. The influence of PFOM to tailor the dual-layered membrane performance was then investigated. The long perfluoro chain in PFOM hydrophobic fillers increased the surface roughness of the membranes due to its random overlapping with PVDF backbone, and these membranes exhibited a higher water contact angle value. The increase in pore size and membrane porosity did not significantly influence the liquid entry pressure of water (LEPw). The microporous membranes displayed good mechanical strength for use in the test setup. Pure water permeation was the highest (6.9 kg m-2 h-1) for membrane (M1) with 1 wt% of PFOM when tested with a simulated sea-water solution (3.5% w/v NaCl) in the direct contact distillation mode. These membranes also achieved the theoretical salt-rejection of 99.9%, thus confirming the potential of these membranes to be investigated for large scale membrane distillation (MD) applications like desalination of seawater.