Hydrophobic Filter Research Articles

Hydrophobic regulation enhances the filtration and dehydration for coal preparation products, an experimental exploration

To enhance the filtration and dewatering performance while reducing the moisture content of coal preparation products, we conducted an investigation into the dehydration efficacy of various coal preparation products using different filter aids. The study involved examining the dehydration effects of both conventional hydrophobic filter aids and novel alternatives on flotation cleaned coal and coarse fine slime at the Huaibei Linhuan coal preparation plant. Our findings revealed a significantly superior dehydration performance of the new filter aids compared to conventional hydrophobic ones. Subsequently, we explored the dehydration efficacy of a specific new filter aid, designated as 1239, on four types of coal samples sourced from the Huainan mining area. The results demonstrated that filter aid 1239 exhibited remarkable effectiveness on both flotation cleaned coal and coarse fine slime, with a discernible impact on coal slime as well. By modulating the hydrophobicity of particle surfaces, hydrophobic filter aids effectively facilitated the dehydration of coal preparation products. These findings bear substantial significance for improving the dewatering and transportation processes of coal preparation products.

Rapid analysis of spilled petroleum oils by direct analysis in real time time-of-flight mass spectrometry with hydrophobic paper sample collection

BackgroundOil spills are widespread and can cause devastating environmental consequences. Rapid oil identification is critical to find the origin of the spill, monitor the environment, and lead to informed mitigation measures. The current standard methods in oil spill identification are precise and reliable, but require extensive sample preparation, long instrument runs, and time-consuming data processing. Direct analysis in real time time-of-flight mass spectrometry (DART-ToF MS) has been employed to screen for spilled petroleum oils, with results obtained in mere hours. The present study introduced an innovative, simple, and fast oil sampling method using hydrophobic filter paper and demonstrated its compatibility with DART-ToF MS analysis. Motor oils, jet fuels, marine diesels, crude oils, intermediate fuel oils, heavy fuel oils, and diluted bitumen were collected using the filter paper sampling method. Classification models were constructed from the spectral data by heat map inspection followed by principal component analysis (PCA) and discriminant analysis of principal components (DAPC). Oil slicks and weathered oil slicks were prepared from five oil types, and samples from each slick were collected using filter paper.ResultsThe filter paper technique allowed for effective oil sampling and data acquisition by DART-ToF MS for diluted source oils, oil slicks and weathered oil slicks. Classification via the constructed DAPC models indicated that the DART-ToF MS instrument in tandem with filter paper sampling and multivariate statistics can accurately identify common oil types, with significant improvement of sample collection and turnaround time.ConclusionsThe promising classification results, simple sample collection, and rapid data analysis illustrate the potential use of hydrophobic filter paper and DART-ToF MS as tools in managing large scale oil spill emergency situations.

Electrochemical CO2 Reduction in the Presence of Flue Gas Impurities: Effect of NOx, SOx and O2

Electrochemically converting CO2 to valuable chemical products using renewable energy sources may present solutions to alter current increasing CO2 emission trends. Currently, electrolyzer research is almost exclusively done with pure CO2 streams that - in practice - would originate from carbon capture units that prevent CO2 release to the atmosphere [1]. The capture and purification steps are cost intensive processes which is why direct usage of flue gases that contain impurities is a highly interesting approach. For this reason, the performance of CO2 electrolyzers equipped with state-of-the-art Bi2O3 or Ag catalysts is investigated in this work with an impure CO2 feed stream containing SO2, NO or O2. The short-term effect of highly concentrated SO2 (10 000 ppm) and NO (8 300 ppm) impurities during CO2 electrolysis was previously described [2,3]. Our work [4] elaborates further on this matter through 20 h experiments with flue gas-like concentrations of 200 ppm SO2 or NO. The results show a stable operation without severe FE losses (remains >90%) and structural adaptations to neither Ag nor Bi2O3 by these impurities. The presence of oxygen in flue gas streams at concentrations of several percent is common and causes a major decrease in FE to the target products (CO or HCOO-) during electrolysis. This is a result of the competition between the ORR and CO2RR with the former occurring more preferentially. To overcome this, we have discovered two possible strategies, which allow high FE’s to CO2RR products even in the presence of oxygen. (1) By operating the electrolyzer at a sufficiently high overall current density, all of the O2 entering and reaching the electrode surface gets reduced, allowing the CO2RR to become the dominant reaction. Although this approach has a higher electricity penalty, the extra cost is negligible compared to the cost otherwise associated with the CO2 purification for CO2 streams with an O2 content below 3%. (2) Given that the ORR is mostly occurring at the carbon-based gas diffusion layers another approach to improve CO2RR efficiency in the presence of oxygen is to replace this conventional support with ultra hydrophobic PTFE membrane filters. Since they are inefficient oxygen reduction catalysts, CO2RR again takes up the major fraction of the applied current density. A downside of using PTFE is that an additional conductive layer is required in case the catalyst itself (e.g. for bismuth oxide) is not conductive enough. These results thus not only offer new insights into the impact of gaseous impurities during CO2 electrolysis, but also suggest a strategy to improve electrolyzer performance with O2-containing feed streams. Bibliography [1] Lee M.Y., Environ. Sci. and Technol.; DOI: 10.1080/10643389.2019.1631991[2] Luc W.; JACS, DOI: 10.1021/jacs.9b03215[3] Ko B., Nature Comm. DOI : 10.1038/s41467-020-19731-8[4] Van Daele S ., J. Appl. Catal. B, Environ.; DOI: 10.1016/J.APCATB.2023.123345 Figure 1

Silver nanoparticles incorporated polydimethylsiloxane nanocomposite film as hydrophobic infrared filters

Silver nanoparticles incorporated <scp>polydimethylsiloxane</scp> nanocomposite film as hydrophobic infrared filters

Molecular mechanism of anion permeation through aquaporin 6

Aquaporins (AQPs) are recognized as transmembrane water channels that facilitate selective water permeation through their monomeric pores. Among the AQP family, AQP6 has an intriguing characteristic as an anion channel, which is allosterically controlled by pH conditions and is eliminated by a single amino acid mutation. However, the molecular mechanism of anion permeation through AQP6 remains unclear. Using molecular dynamics simulations in the presence of a transmembrane voltage utilizing an ion concentration gradient, we show that chloride ions permeate through the pore corresponding to the central axis of the AQP6 homotetramer. Under low pH conditions, a subtle opening of the hydrophobic selectivity filter (SF), located near the extracellular part of the central pore, becomes wetted and enables anion permeation. Our simulations also indicate that a single mutation (N63G) in human AQP6, located at the central pore, significantly reduces anion conduction, consistent with experimental data. Moreover, we demonstrate that the pH-sensing mechanism in which the protonation of H184 and H189 under low pH conditions allosterically triggers the gating of the SF region. These results suggest a unique pH-dependent allosteric anion permeation mechanism in AQP6 and could clarify the role of the central pore in some of the AQP tetramers.

Bio-Based Copolyester PEIFT: Enhanced Hydrophilicity, Rigidity, and Applications in Nanofibers.

The raw materials of Poly(ethylene terephthalate) (PET) are derived from petroleum-based resources, which are no sustainable. Therefore, previous researchers introduced biomass-derived 2,5-tetrahydrofurfuryl dimethanol (THFDM) into PET. However, its heat resistance has decreased compared to PET. In this paper, a novel bio-based copolyester, poly(ethylene glycol-co-2,5-tetrahydrofuran dimethanol-co-isosorbide terephthalate) (PEIFT), is prepared by introducing biomass-derived isosorbide (ISB) and THFDM into the PET chains through melting copolymerization process. With the introduction of ISB content, copolyesters' hydrophilicity and rigidity improve. Compared to PET, glass transition temperature (Tg) increases by over 5°C. In addition, the toughness and spinning performance of PEIFT have also been improved as a result of the addition of THFDM components. The hydrophobicity of PEIFTs electrospinning is greatly improved, with a contact angle exceeding 135°. Finally, due to the good hydrophobicity of PEIFTs nanofibers, they have potential application value in the manufacture of hydrophobic nanofiber and filter films. Given its biomass source and excellent performance, they make it easier to replace materials derived from petroleum.

Photothermal Performance of Lignin-Based Nanospheres and Their Applications in Water Surface Actuators.

In this study, the photothermal performance of lignin-based nanospheres was investigated. Subsequently, a photothermal actuator was prepared using lignin-based carbon nanospheres (LCNSs). The results demonstrated that LCNSs exhibited an impressive photothermal conversion efficiency of up to 83.8%. This extreme efficiency significantly surpasses that of lignin nanospheres (LNSs) and covalently stabilized LNSs (HT-LNSs). As a structural material, a hydrophobic coating was effectively engineered by LCNSs on the filter paper, achieving a water contact angle of 151.9° ± 4.6°, while maintaining excellent photothermal effects (with a temperature increment from room temperature to 138 °C in 2 s). When employing hydrophobic filter paper as the substrate for the photothermaldriven actuator, under the influence of a 1.0 W/cm2 power-density NIR laser, the material exhibited outstanding photothermal actuation, achieving speeds up to 16.4 mm/s. In addition, the direction of motion of the actuator can be adjusted in accordance with the location of the NIR light irradiation. This study offers valuable perspectives on the application of LNSs for highvalue applications and the development of innovative photothermal-driven actuators.

Density-gradient water-based air filters: Gas/solid-permeable and liquid-impermeable design

A water-based air filter (WAF) composed of an inner cylindrical hydrophilic filter and an outer hollow cylindrical hydrophobic filter was installed in an output chamber filled with water. The WAF with water (WAF-WW) showed outstanding recyclability (average PM2.5 RE = 96.5 %) for up to 100 cycles with consistent long-term performance (ΔREmin and max = 1.4 %) and low pressure drops (ΔP1st and 100th = 3 Pa), which were better than those of commercial HEPA filters (H13) (average PM2.5 RE = 96.2 %, ΔRE = 4 %, and ΔP = 21 Pa), at similar PM2.5 concentrations (1,721 μg/m3) and air velocities (0.92 m/s). The WAF-WW also exhibited excellent recyclability up to the 50th cycle with fast and complete removal (HCHO REat 2-13 min = 100 %) of HCHO gas at very low concentrations (0.08–4.98 ppm). Furthermore, since small PM0.3/PM2.5 particles and total volatile organic compound (TVOC) that are hardly filtered by air filters can be easily and quickly removed by the WAF-WW due to the water filter, this is another extraordinary benefit of the wet process over the dry process.

An easy preparation of carbon nanoparticle-coated hydrophobic substrates for highly efficient oil/water separation

Hydrophobic cotton fabrics and sponges were fabricated using a simple hydrothermal method in a mixed solution of carbon nanoparticles (CNPs) generated from candle soot and n-octadecyltrimethoxysilane, within which a cotton fabric was immersed. The negatively charged CNPs firmly bonded to the positively charged surface of the fabric and sponge through electrostatic interactions, resulting in the formation of a chemically durable hydrophobic filter. The separation efficiencies of the hydrophobic fabric and sponge were high for different types of oil, including hexane, iso-octane, chloroform, and canola oil, which had different viscosities and densities. The CNP-coated fabric showed outstanding recycling ability and chemical durability in corrosive chemical environments such as in highly acidic, alkaline, saline, and hot solutions. Moreover, the CNP-coated sponge showed strong absorption of a diverse range of oils, up to 64.1 times the weight of the sponge. The proposed synthesis method shows considerable technical potential for the application of CNP-based hydrophobic coating technology in various methods used for the separation of oily waste.

A SiC membrane resistance recovery methodology based on dynamically dust cake layer analysis

Filter cake-induced resistance is a significant contributor to energy consumption in dust filtration processes. This can be optimized by adjusting inlet gas composition, membrane characteristics, and back-flushing parameters. In this study, calcium carbonate (CaCO3) dust with varying hygroscopicity was utilized to investigate the evolution mechanism of the filter cake on SiC membranes under different humidity conditions. The interacting force between particles and between the cake and membrane were analyzed to elucidate the fragmentation mechanism of the cake. It was observed that particles at higher relative humidity (increased RH from 40 % to 85 %) tend to form a more loosely packed cake (hydrophilic filter cake porosity and hydrophobic filter cake porosity increased from 70.8 % to 80.5 % and from 61.4 % to 69 %, respectively) with greater fragility (reduced cohesive force). This characteristic is advantageous for efficient backflushing operations. The strong adhesion between the filter cake and membrane hindered the recovery of the initial filtration resistance. For SiC membrane, the optimized back-flushing parameter is reservoir pressures of 0.2 and 0.15 MPa and pluse-jet intervals of 40 min to hydrophilic and hydrophobic dusts, respectively.

Intelligent control of emulsion stability and evaluation of selective water shutoff performance

Using hydrophobic nano-SiO2 and a tiny amount of non-ionic and anionic surfactants as stabilizers, a Pickering emulsion system for oil-in-water in high-temperature and high-mineralization reservoirs was developed. At high temperatures (120 °C) and high mineralization (37000 mg/L), the emulsion system shows outstanding stability. The addition of the auxiliary agent can effectively control the time of emulsion breaking and nanoparticle release. The auxiliary agent will "compete" with the surfactant for adsorption on nanoparticles at the oil/water interface, weakening the surfactant's anchoring effect and causing a decrease in the surface roughness of the nanoparticles, resulting in a decrease in the mechanical strength of the interfacial film. Furthermore, the presence of H+ in the solution neutralizes part of the negative charges on the surface of emulsion droplets, which is detrimental to emulsion stability because electrostatic repulsion between droplets is diminished. The released SiO2 particles agglomerate in the pore throat to form a hydrophobic filter cake, which can be used to achieve intelligent water control in high-temperature and high-mineralization reservoirs (1000 mD), with an aqueous phase plugging rate of 95.83% and an oil phase plugging rate of 25.32%.

Development of Filtering Electrospray Ionization-Ion Trap Mass Spectrometry Technique for the Rapid Detection of Antibiotic Residues in Food

This article reports on the development of an atmospheric pressure filtering electrospray ionization (FESI) source – composed of a syringe, a filter, and the ESI source – for the determination of furazolidone, amoxicillin, nitrofurantoin, and nitrofural, common antibiotics. Spiked food samples were also analyzed; the analytes were placed in the filter head, and the flow rate of the extraction solution from the syringe pump was adjusted. Using a mixture of oleic acid and antibiotics, hydrophilic and hydrophobic filters were compared, demonstrating the advantage of FESI in reducing the background and noise for the mixture. The device simplifies not only the experimental procedure but also the sample pretreatment process. Additionally, the limits of detection of the antibiotics were determined to be 1 mg L−1 for furazolidone, amoxicillin, and nitrofurantoin and 2 mg L−1 for nitrofural. The linear regression coefficients (R 2) of the antibiotic standard solutions were all ≥0.99. Furthermore, the spiked recovery rates of pork, chicken, and egg samples ranged from 73.3% to 107.5%, with relative standard deviations (RSDs) from 1.1% to 15.6%. This study uncovers the potential capabilities of ion trap mass spectrometry (ITMS) for the on-site detection of antibiotics and offers a new method for ensuring food safety.

Microbial consortia degrade several widely used organic UV filters, but a number of hydrophobic filters remain recalcitrant to biodegradation

Organic UV filters are important ingredients in many personal care products, including sunscreens. Evaluating the biodegradability of organic UV filters is key to estimate their recalcitrance and environmental fate and thus central to their overall environmental risk assessment. In order to further understand the degradation process, the aim was to investigate whether specific consortia could degrade certain UV filters. Several bacterial strains were isolated from enrichment cultures actively degrading octocrylene (OC), butyl methoxydibenzoylmethane (BM), homosalate (HS), and 2-ethylhexyl salicylate (ES) and were utilized to construct an in-house consortium. This synthetic consortium contained 27 bacterial strains and degraded OC, BM, HS, and ES 60–80% after 12 days, but not benzophenone-3 (BP3), methoxyphenyl triazine (BEMT), methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT), diethylhexyl butamido triazone (DBT), ethylhexyl triazone (EHT), or diethylamino hydroxybenzoyl hexyl benzoate (DHHB). Furthermore, several commercial microbial mixtures from Greencell were tested to assess their degradation activity toward the same organic UV filters. ES and HS were degraded by some of the commercial consortia, but to a lesser extent. The rest of the tested UV filters were not degraded by any of the commercial bacterial mixes. These results confirm that some organic UV filters are recalcitrant to biodegradation, while others are degraded by a specific set of microorganisms.

Fabrication of Ultra-High-Performance PVDF-HFP Air Filters by Electrospinning

This research aims to fabricate hydrophobic electrospun air filters with ultra-high performance against virions. In order to achieve this goal, constant basis weight electrospun poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) with low-bead, high-bead, and ultra-high-bead fibre structures were used to fabricate single and multilayer filters by controlling the Dimethylformamide (DMF)-to-acetone ratio of the solvent. The water contact angle of the fabricated layers ranged from 131° for low-bead structures to 135° for ultra-high-bead structures, indicating their overall high hydrophobicity. The size-resolved filtering efficiency and pressure drop tests on the fabricated filters showed that low-bead structure for both single and multilayer filters and high-bead structure for single-layer filters enhance the quality factor remarkably. The results showed that the single-layer ultra-high-bead structure air filters had a filtering efficiency of 99.33%, superior to N95 air filters (96.54%) and comparable to double N95 filters (99.86%). However, the electrospun air filter showed a pressure drop of 169.3 Pa and a quality factor of 27.6×10−3 Pa−1compared to a pressure drop of 388 Pa and quality factor of 16.9×10−3 Pa−1 for double N95 air filters. Therefore, it has a high potential to be used as the filtration media in hospitals, long-term care centers, and masks to provide superior protection against virions for healthcare providers and patients.

A simple and low-energy strategy for the separation of water and acetonitrile.

As acetonitrile is a widely used solvent for the chemical industry, the recovery of acetonitrile from acetonitrile wastewater is significant for both industrial cost reduction and environmental protection. In this article, a simple, low-energy, and low-cost strategy is proposed for the effective separation of acetonitrile from high-concentration acetonitrile wastewater. The approach is based on a sequential combination of two steps: salt-induced phase separation and hydrophobic filtration. The acetonitrile wastewater was first induced to split into two phases by salt, that is, the acetonitrile-rich phase and the water-rich phase, then the above two phases were poured into the hydrophobic filter paper funnel for the separation. It was shown that NaCl is a suitable salting-out reagent, and that hydrophobic filter papers-obtained from modification by butyltrichlorosilane and octyltrichlorosilane were the optimal choice for hydrophobic filtration. The salt-induced phase separation process is able to increase the volume fraction of acetonitrile in the acetonitrile-rich phase up to 92%. The acetonitrile-rich phase can pass through the hydrophobic filter paper, whereas the water-rich phase was intercepted. The hydrophobic filter paper retained strong hydrophobicity and high acetonitrile-separating capacity after 3 months storage, or upon immersion in acetonitrile-water mixtures for 12h, or applied for 25 consecutive separations.

Optimization of a method designed to extract and characterize microplastics in different packaged fish products

The study of the presence of microplastics (MPs) in seafood products is usually carried out by analyzing the gastrointestinal tract. However, this part is mostly removed during food processing. Moreover, few studies have produced results from processed fishery products. The primary objective of this study was to optimize methods for evaluating the presence of MPs in the edible portions of several products available in supermarkets. Seven seafood products, including smoked, canned, marinated, and those stored in polystyrene trays, were selected for analysis, with saithe fillets (Pollachius virens) and canned tuna (Thunnus alalunga) among them. To achieve optimal digestion of the samples, a 10% KOH solution at 40 °C was used. For the fattiest samples, such as marinated anchovies, hydrophobic filters were employed. Additionally, bleach was utilized to lighten dark filters obtained, ensuring readability under the microscope. These parameters were defined to obtain suitable methods for each product. The average concentrations in different seafood matrices ranged from 0.05 ± 0.04 to 0.33 ± 0.08 MP/g for saithe fillets and canned tuna, respectively. After extrapolation of these values to all the particles observed on each filter, the concentrations increased from 0.06 ± 0.05 MP/g to 2.17 ± 0.33 MP/g. Particles identification across all samples, using a microscope coupled with Fournier transform infrared spectroscopy (μ-FTIR), confirmed the presence of MPs, including PET, PP, and EVA.

Green-Solvent-Processable Composite Micro/Nanofiber Membrane with Gradient Asymmetric Structure for Efficient Microfiltration.

Electrospinning technology has attracted extensive attention in recent decades and is widely used to prepare nanofiber membranes from hundreds of polymers. Polyvinyl formal acetal (PVFA), as a polymer with excellent properties such as high strength and heat resistance, is not reported on the electrospun water treatment membrane. In this paper, the preparation process of electrospun PVFA nanofiber membrane is optimized, and the effect of sodium chloride (NaCl) addition on the physical and mechanical properties and microfiltration performance of nanofiber membrane is also explored. And the hydrophobic PVFA nanofiber filter layer is then combined with a hydrophilic nonwoven support layer to construct a composite micro/nanofiber membrane with a pore-size gradient structure and a hydrophilic/hydrophobic asymmetric structure. Finally, unidirectional water transport and water treatment performance are further investigated. The results show that the tensile breaking strength of the composite membrane can reach up to 37.8 MPa, the retention rate for particles with the size of 0.1-0.3 µm is 99.7%, and the water flux is 513.4 L m-2 h-1 under the hydrostatic pressure. Moreover, it still has a retention of more than 98% after three repeated uses. Therefore, the electrospun PVFA composite membrane has a great potential in microfiltration.

Efficient adsorption of aromatic and aliphatic hydrocarbons by electrospun hydrophobic PTFE-NiO composite nanofiber filter mats

Aromatic and aliphatic hydrocarbons (AAHs) are comprised of a variety of gaseous chemicals that may affect human and environmental health. To remove AAHs from air, polytetrafluoroethylene-nickel oxide (PTFE-NiO) composite nanofiber filter mats (NFMs) were synthesized and characterized for their ability to effectively adsorb AAHs. The NiO-nanoparticle-doped mats were fabricated by green electrospinning of PTFE and polyvinyl alcohol (PVA) mixtures added with nickel (II) nitrate hexahydrate in the spinning solution followed by surface heat treatment. FE-SEM FTIR, Raman spectroscopy, sessile drop and Jar methods were applied as characterization techniques. The diameter of the electrospun nanofibers without NiO dopant ranged from 0.34 ± 21.61 to 0.23 ± 10.12 µm, whereas a reduction in diameter of NiO-doped nanofibers was obtained, ranging between pristine to 0.25 ± 24.12 µm and 0.12 ± 85.75 µm with heat treatment. 6% (by weight) NiO-doped PTFE composite NFMs exhibited a high water-contact angle of 120 ± 2.20 degrees; the high hydrophobicity value aided self-cleansing property of NFMs for practical applications. UV adsorption capability for heat-treated PTFE-NiO NFMs was evaluated for three AAHs, and the results showed that 6 wt% NiO adsorbed 1.41, 0.67, and 0.73 µg/mg of toluene, formaldehyde and acetone, respectively. These findings reveal the potential applicability of the prepared filter mats for capturing various AAHs from polluted air.

High-efficiency oil/water separation of hydrophobic stainless steel Mesh filter through carbon and fluorine surface treatment

High-efficiency oil/water separation of hydrophobic stainless steel Mesh filter through carbon and fluorine surface treatment

Surface DBD plasma microbubble reactor for degrading methylene blue

Water contaminants such as endocrine inhibitors, pharmaceuticals, and chlorine treatment by-products are only recently being identified as significant hazards to human health. Since current chlorine treatment does not address many of these compounds and conventional ozone processing is not seen as an economic alternative, water adjacent plasma treatment has been investigated as a more efficient and effective decontamination method. This work investigates the use of a surface dielectric barrier discharge electrode as a reduced discharge voltage portable plasma water treatment method. The gas passes through holes in the electrodes, normal to the discharge surface, so that the entire cross-sectional area of the feed gas is exposed to plasma, prior to passing through a hydrophobic filter and bubbling into the water. The decontamination effectiveness is quantified by measuring the degradation of methylene blue with absorption spectroscopy. Studies of the different processing parameters (treatment time, solution volume, initial concentration, electrode-filter distance, and gas flow rate) clarify the potential range of performance for this plasma treatment configuration. The setup has a yield energy of 0.45 g/kW·h at 25 ml of 1 mg/100 ml methylene blue treated over 5 minutes for a 92% degradation. The degradation rate is dependent upon the volume ratio of air to methylene blue solution, suggesting a first order chemical reaction process. The reaction rate is increased by increasing the quantity of either reactant. There is no change in the degradation between when the plasma is 1 mm or 1 cm from the water surface.