Fouling remains a long-standing unsolved problem that hinders the widespread use of membrane applications in industry. This article reports the use of numerical simulations coupled with extensive ...material synthesis and characterization to fabricate fouling-resistant 3D printed composite membranes. The membranes consist of a thin polyethersulfone selective layer deposited onto a 3D printed flat and double sinusoidal (wavy) support. Fouling and cleaning of the composite membranes were tested by using bovine serum albumin solution in a cross-flow ultrafiltration setup. The transmembrane pressure was regulated at 1 bar and the cross-flow Reynolds number (Re) varied between 400 and 1000. In comparison to the flat membrane, the wavy membrane showed superior performance in terms of pure water permeance (PWP) (10% higher) and permeance recovery ratio (87% vs 53%) after the first filtration cycle at Re = 1000. Prolong testing showed that the wavy membrane could retain approximately 87% of its initial PWP after 10 complete filtration cycles. This impressive fouling-resistant behavior is attributed to the localized fluid turbulence induced by the 3D printed wavy structure. These results show that not only the lifetime of membrane operations could be favorably extended but also the operational costs and environmental damage of membrane-based processes could also be significantly reduced.
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IJS, KILJ, NUK, PNG, UL, UM
•Membrane and batch ozonation of humic-rich groundwater reduce color but form bromate.•Operating conditions in membrane ozonation affect NOM degradation and bromate formation.•Bromate formation is ...reduced at long hydraulic retention time and high Hatta number.•Mass transfer limitation may decrease bromate formation in membrane ozonation.•Module geometry affects bromate formation in membrane ozonation.
Membrane ozonation of bromide-containing, high-color natural organic matter (NOM) containing groundwater was performed using single-tube polydimethylsiloxane (PDMS) and multi-tube polytetrafluoroethylene (PTFE) membrane contactors, and compared to batch ozonation. For membrane ozonation, dissolved ozone concentration, water color (VIS436), ultraviolet light absorption (UV254) and bromate formation were correlated with ozone dose, ozone gas concentration, hydraulic retention time and Hatta number (Ha). NOM color removal of up to 45 % for the single-tube contactor and 17 % for the multi-tube contactor were achieved while containing bromate formation below 10 µg L−1. Higher color removal using higher ozone doses was associated with high bromate formation i.e. >>10 µg L−1. In membrane ozonation, low ozone gas concentrations, long hydraulic retention times and high Ha resulted in low dissolved ozone concentrations due to quenching of ozone by NOM. At specific ozone doses of < 0.5 mg O3/mg DOC and Ha > 1, single-tube ozonation resulted in comparable results to batch ozonation while bromate formation was higher in the single-tube contactor at specific ozone doses > 0.5 mg O3/mg DOC and Ha < 1. At comparable ozone doses and Ha, bromate formation in the multi-tube contactor was always higher compared to single-tube and batch ozonation. This could be associated with the uneven ozone distribution within the multi-tube contactor. Results show that ozone dose is the major driver for selectivity between bromate formation and NOM color removal in both membrane and batch ozonation. Bromate formation in membrane ozonation may be controlled by adjusting gas concentration, Ha and hydraulic retention time. Membrane module design and process parameters of membrane ozonation reactors significantly affect treatment performance and should be optimized for selective target compound removal over by-product formation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The rejection of particles with different charges and sizes, ranging from a few Ångstroms to tens of nanometers, is key to a wide range of industrial applications, from wastewater treatment to ...product purification in biotech processes. Carbon nanotubes (CNTs) have long held the promise to revolutionize filtration, with orders of magnitude higher fluxes compared to commercial membranes. CNTs, however, can only reject particles and ions wider than their internal diameter. In this work, the fabrication of aligned boron nitride nanotube (BNNT) membranes capable of rejecting nanoparticles smaller than their internal diameter is reported for the first time. This is due to a mechanism of charge-based rejection in addition to the size-based one, enabled by the BNNTs surface structure and chemistry and elucidated here using high fidelity molecular dynamics and Brownian dynamics simulations. This results in ∼40% higher rejection of the same particles by BNNT membranes than CNT ones with comparable nanotube diameter. Furthermore, since permeance is proportional to the square of the nanotubes' diameter, using BNNT membranes with ∼30% larger nanotube diameter than a CNT membrane with comparable rejection would result in up to 70% higher permeance. These results open the way to the design of more effective nanotube membranes, capable of high particle rejection and, at the same time, high water permeance.
We demonstrate enhanced rejection of nanoparticles and higher water permeance by boron nitride nanotube membranes compared to carbon nanotube ones.
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•Cellulose acetate membranes of different molecular weight cut offs were fouled with orange juice and cleaned with Ultrasil-11.•Streaming current has been used to investigate the ...membrane surface charge.•Porosity has been characterised by Brunauer-Emmett-Teller (BET) technique.•Membrane with the highest magnitude of negative surface charge was linked to an increased fouling tendency.•Fouling increased the total surface area and the total pore volume of membranes.
The ultrafiltration of orange juice has been performed to separate phytosterols from proteins. Commercial regenerated cellulose acetate (RCA) ultrafiltration membranes of different molecular weight cut offs (MWCOs) of 10 kDa, 30 kDa and 100 kDa were fouled with orange juice and cleaned with Ultrasil 11 over two operational cycles. Fouling and cleaning mechanisms were investigated by using surface zeta potential, Brunauer-Emmet-Teller (BET) analysis and Fourier transform infrared (FTIR) analysis. The RCA conditioned membranes displayed zeta potential values of −0.2 to −31.5 mV. Fouling caused RCA membranes to have a greater magnitude of negative surface charge and cleaning restored the membrane surface charges close to its pristine state. Fouling increased both the total surface area and the total pore volume of all membranes. The total surface area and total pore volume for RCA 100 kDa after fouling increased by 102% and 185%, respectively. Pore area and volume distributions revealed that the porosities were returned close to the original level after cleaning. The recovery flux ratios of RCA 10, RCA 30 and RCA 100 decreased after fouling by 27%, 6% and 10% respectively; and changes were 25%, 9% and 1% respectively after cleaning. The charge of membrane surfaces after two operational cycles and the IR intensity of RCA membrane deposits, varied with MWCO such that RCA 30 > RCA 100 > RCA 10. Ultrafiltration using RCA 10 kDa membrane displayed the best separation efficiency, with 32 ± 4% rejection of phytosterols. and 96 ± 1% rejection of proteins. Changes in membrane surface charge and porosity have been found to affect the RCA membrane performance due to fouling and cleaning during the isolation of phytosterols from orange juice.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Hydrophobic, chemically resistant nanofiltration (NF) polymeric membranes could provide major improvements to a wide range of processes, from pharmaceutical manufacturing to hazardous waste ...treatment. Here, we report the fabrication of the first poly (vinylidene fluoride) (PVDF) NF membranes retaining their hydrophobicity and surface chemistry. This was achieved by incorporating in the polymer 2D siloxene, which induce a compaction of the PVDF chains, resulting in low free volume and a highly ordered microstructure. Siloxene nanosheets were obtained from deintercalation of Ca from CaSi2 using HCl, followed by exfoliation and size fractionation, with average lateral dimension of 1–2 μm and thickness of 3–4 nm. The resulting membranes, containing 0.075 wt% of siloxene, have a pure water permeance of 22 ± 2 L m-2 h-1 bar-1 and molecular weight cut-off (MWCO) of 530 Da. The same membrane also showed stable hexane permeance of 11 L m-2 h-1 bar-1 for 24 h with MWCO of around 535 Da. These results supersede the performance of commercial NF membranes, expanding the potential application of nanofiltration to processes requiring stable, chemically resistant and hydrophobic nanofiltration membranes.
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•The addition of 0.75 wt% of 2D siloxene shifted PVDF performance from UF to NF.•The PVDF/Siloxene NF membrane maintains its hydrophobicity and chemical resistance.•The PVDF/Siloxene NF membrane has a MWCO of 530 Da in water and 535 Da in hexane.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The independent effect of nanotube surface chemistry and structure on the flow of water under nanoscale confinement is demonstrated in this paper for the first time via the synthesis of novel carbon ...nitride nanotube (CNNT) membranes. Using a combination of experiments and high-fidelity molecular dynamics (MD) simulations, it is shown here that the hydrophilization of the sp2 carbon structure, induced by the presence of the C–N bonds, decreases the pure water permeance in CNNTs when compared with pristine and turbostratic carbon nanotubes (CNTs). The MD simulations are based on a model true to the chemical structure of the synthesized nanotubes, built from spectroscopy measurements and calibrated potentials using droplet experiments. The effect on permeance is explained in terms of solid–liquid interactions at the nanotube wall with increased water viscosity and decreased surface diffusion near the CNNT wall, when compared to CNTs. A model directly linking the solid–liquid interactions to the water permeance is presented, showing good agreement with both experiments and MD simulations. This work opens the way to tailoring surface chemistry and structure inside nanotube membranes for a wide range of transport and separation processes.
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IJS, KILJ, NUK, PNG, UL, UM
The fabrication of three dimensional (3D) printed composite membranes by depositing a thin polyethersulfone (PES) selective layer onto ABS-like 3D printed flat and wavy structured supports is ...presented here for the first time. The 50 mm disk supports were printed using an industrial 3D printer with both flat and double sinusoidal, i.e. wavy, surface structures. The thin selective layers were deposited onto the 3D supports via vacuum filtration. The resulting flat and wavy composite membranes were characterised and tested in terms of permeance, rejection, and cleanability by filtering oil-in-water emulsions of 0.3−0.5 vol% through a cross-flow (Reynolds number, Re = 100, 500 and 1000) ultrafiltration set-up under a constant transmembrane pressure of 1 bar. Results showed that pure water permeance through the wavy membrane was 30% higher than the flat membrane for Re = 1000. The wavy 3D printed membrane had a 52% higher permeance recovery ratio compared to the flat one after the first filtration cycle, with both membranes having an oil rejection of 96% ± 3%. The wavy 3D composite membrane maintained some level of permeation after 5 complete filtration cycles using only water as the cleaning/rinsing agent, whereas the flat one was completely fouled after the first cycle. Cleaning with NaOCl after the sixth cycle restored ~70% of the initial permeance for the wavy membrane. These results demonstrate that 3D printed wavy composite membranes can be used to significantly improve permeation and cleanability performance, particularly in terms of reducing fouling build-up, i.e. the main obstacle limiting more widespread adoption of membranes in industrial applications.
•First 3D printed composite membrane, with PES UF layer onto 3D printed wavy support.•Wavy 3D printed membrane had a 52% higher permeance recovery compared to flat one.•Membrane maintained permeation after 5 filtration cycles using only water cleaning.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The Federal Pain Research Strategy recommended development of nonopioid analgesics as a top priority in its strategic plan to address the significant public health crisis and individual burden of ...chronic pain faced by >100 million Americans. Motivated by this challenge, a natural product extracts library was screened and identified a plant extract that targets activity of voltage-gated calcium channels. This profile is of interest as a potential treatment for neuropathic pain. The active extract derived from the desert lavender plant native to southwestern United States, when subjected to bioassay-guided fractionation, afforded 3 compounds identified as pentacyclic triterpenoids, betulinic acid (BA), oleanolic acid, and ursolic acid. Betulinic acid inhibited depolarization-evoked calcium influx in dorsal root ganglion (DRG) neurons predominantly through targeting low-voltage-gated (Cav3 or T-type) and CaV2.2 (N-type) calcium channels. Voltage-clamp electrophysiology experiments revealed a reduction of Ca, but not Na, currents in sensory neurons after BA exposure. Betulinic acid inhibited spontaneous excitatory postsynaptic currents and depolarization-evoked release of calcitonin gene-related peptide from lumbar spinal cord slices. Notably, BA did not engage human mu, delta, or kappa opioid receptors. Intrathecal administration of BA reversed mechanical allodynia in rat models of chemotherapy-induced peripheral neuropathy and HIV-associated peripheral sensory neuropathy as well as a mouse model of partial sciatic nerve ligation without effects on locomotion. The broad-spectrum biological and medicinal properties reported, including anti-HIV and anticancer activities of BA and its derivatives, position this plant-derived small molecule natural product as a potential nonopioid therapy for management of chronic pain.
Current battery energy storage system (BESS) safety approaches leads to frequent failures due to safety gaps. A holistic approach aims to comprehensively improve BESS safety design and management ...shortcomings.
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The integration of battery energy storage systems (BESS) throughout our energy chain poses concerns regarding safety, especially since batteries have high energy density and numerous BESS failure events have occurred. Wider spread adoption will only increase the prevalence of these failure events unless there is a step change in the management and design of BESS. To understand the causes of failure, the main challenges of BESS safety are summarised. BESS consequences and failure events are discussed, including specific focus on the chain of events causing thermal runaway, and a case study of a BESS explosion in Surprise Arizona is analysed. Based on the technology and past events, a paradigm shift is required to improve BESS safety. In this review, a holistic approach is proposed. This combines currently adopted approaches including battery cell testing, lumped cell mathematical modelling, and calorimetry, alongside additional measures taken to ensure BESS safety including the requirement for computational fluid dynamics and kinetic modelling, assessment of installation level testing of the full BESS system and not simply a single cell battery test, hazard and layers of protection analysis, gas chromatography, and composition testing. The holistic approach proposed in this study aims to address challenges of BESS safety and form the basis of a paradigm shift in the safety management and design of these systems.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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