Permeability Of Filter Research Articles

Simultaneous catalytic removal of NO and chlorobenzene over Mn–Ce-Sm-Sn-Ox/P84 composite catalytic filter

The integration of surface filtration and catalytic decomposition functions in catalytic bags enables the synergistic removal of multiple pollutants (such as dust, nitrogen oxide, acid gases, and dioxins) in a single reactor, thus effectively reducing the cost and operational difficulties associated with flue gas treatment. In this study, Mn–Ce-Sm-Sn (MCSS) catalysts were prepared and loaded onto high-temperature resistant polyimide (P84) filter through ultrasonic impregnation to create composite catalytic filter. The results demonstrate that the NO conversion rates of the composite catalytic filter consistently achieve above 95 % within the temperature range of 160–260 °C, with a chlorobenzene T90 value of 230 °C. The ultrasonic impregnation method effectively loaded the catalyst onto the filter, ensuring high dispersion both on the surface and inside the filter. This increased exposure of catalyst active sites enhances the catalytic activity of the composite catalytic filter. Additionally, increasing the catalyst loading leads to a gradual decrease in permeability, an increase in pressure drops and the long residence time of the flue gas, thereby improving catalytic activity. Compared to ordinary impregnation methods, ultrasonic impregnation improves the bonding strength between the catalyst and filter, as well as the permeability of the composite catalytic filter under the same loading conditions. Overall, this study presents a novel approach to prepare composite catalytic filter for the simultaneous removal of NO and chlorobenzene at low temperatures.

Investigation of filtration properties of a formate-based mud system under high temperature conditions

Using the methods of design of experiments, filtration properties of the bentonite-free mud system that contains xanthan gum, starch, sodium and potassium formate salts, calcium carbonate and Alevron agent at temperature range of 130–170 °C, differential pressure of 1–5 MPa and initial permeability of ceramic filters of 0.95–7.20 D were studied. Regression models were built for the НТНР filtration loss and permeability of a ceramic filter after mud cake build-up depending on mud additives concentrations, temperature, differential pressure and initial filter permeability, which provide high accuracy of experimental data approximation. • Regression models for НТНР filtration loss and permeability of mud cake. • Filtration properties of formate-based mud system. • Elaboration of formate-based mud optimal formulations for high-temperature drilling. • Filtration properties of drilling muds tested on ceramic disks of various pore sizes.

Correlation between the Porosity and Permeability of a Polymer Filter Fabricated via CO2-Assisted Polymer Compression.

A porous filter was fabricated by plasticizing polymer fibers with CO2, followed by pressing and adhering; then, its gas permeability, a basic physical property of filters, was measured using N2. The as-obtained filter was well compressed and expected to approximate a sintered porous material. Therefore, the fabricated filter was analyzed by applying the Darcy law, and the correlation between its gas permeability and porosity was clarified. The gas permeability decreased owing to both pore size and porosity reduction upon increasing the degree of compression, which is a feature of the CO2-assisted polymer compression method. In particular, without any contradiction of pore size data previously reported, the gas permeability was clearly determined by the filter porosity and pore size. This study can serve as a guide for designing filters via CO2-assisted polymer compression.

Mechanical activation of TRPV4 channels controls albumin reabsorption by proximal tubule cells.

Defects in protein reabsorption by the proximal tubule are toxic for epithelial cells in the nephron and may result in nephropathy. In this study, we showed that the ion channel TRPV4 modulated the endocytosis of albumin and low-molecular weight proteins in the proximal tubule. TRPV4 was found at the basolateral side of proximal tubule cells, and its mechanical activation by cell stretching induced Ca2+ entry into the cytosol, which promoted endocytosis. Trpv4-/- mice presented with mild proximal tubule dysfunction under basal conditions. To challenge endocytic function, the permeability of the glomerular filter was altered by systemic delivery of angiotensin II. The proteinuria induced by this treatment was more severe in Trpv4-/- than in Trpv4+/+ mice. Injecting antibodies against the glomerular basement membrane to induce glomerulonephritis is a more pathophysiologically relevant method of impairing glomerular filter permeability. Albuminuria was more severe in mice that lacked TRPV4 specifically in the proximal tubule than in control mice. These results emphasize the importance of TRPV4 in sensing pressure in the proximal tubule in response to variations in the amount of ultrafiltrate and unveil a mechanism that controls protein reabsorption.

A molecular mechanism explaining albuminuria in kidney disease.

Mammalian kidneys constantly filter large amounts of liquid, with almost complete retention of albumin and other macromolecules in the plasma. Breakdown of the three-layered renal filtration barrier results in loss of albumin into urine (albuminuria) across the wall of small renal capillaries, and is a leading cause of chronic kidney disease. However, exactly how the renal filter works and why its permeability is altered in kidney diseases is poorly understood. Here we show that the permeability of the renal filter is modulated through compression of the capillary wall. We collect morphometric data prior to and after onset of albuminuria in a mouse model equivalent to a human genetic disease affecting the renal filtration barrier. Combining quantitative analyses with mathematical modelling, we demonstrate that morphological alterations of the glomerular filtration barrier lead to reduced compressive forces that counteract filtration pressure, thereby resulting in capillary dilatation, and ultimately albuminuria. Our results reveal distinct functions of the different layers of the filtration barrier and expand the molecular understanding of defective renal filtration in chronic kidney disease.

Permeability and dust filtration behaviour of porous SiC ceramic candle filter

Porous SiC candle filter (∼660 mm L and 75 mm OD) were fabricated by ramming process using commercially available SiC powder (d 50 = 212 μm), with and without alumina and small amount (3 wt%) of clay as the major binder phase additives, following heat treatment at 1400 °C in air. Depending on the composition, porosity of the candle filters varied from 36 to 39 vol% and C-ring strength varied from 15 to 23 MPa. The air permeability and dust filtration efficiency of the candle filter were evaluated using laboratory made test set up. At room temperature, Darcian (k 1 ) and non-Darcian (k 2 ) permeability parameters varied from 1.9 to 2.2 × 10 −12 m 2 and 5.4–9.72 × 10 −8 m, respectively. Airborne fly ash particle filtration tests showed good performance of SiC candle filter with filtration efficiency of >97%.

Preparation of geopolymer-based porous filter using the quartz sand compact method

With the increasing of high temperature oil wells and steam ones, the traditional sands control filter cannot be used in those wells. Therefore, based on the conditions, using particle compact method, round quartz sands with a certain particle size and an inorganic polymer (geopolymer) material with good heat resistance is selected to prepare a heat-resistant filter with suitable pore diameter. By adjusting the contents of water-glass, water, sand and thickening agent of the geopolymer-based sand control filters, open space structure is built by low-cost geopolymer slurry and sand. When the size of quartz sand is mainly of 450–600 µm, and the volume ratio of quartz sand to slurry is 4.3:1, the compressive strength and permeability of this sand control filter reach 10.33 MPa and 18 D, respectively. Thermal gravimetry and calcination experiments show heat-resistance up to 736 °C. Scanning electron microscopy shows that the sand particles are wrapped by the geopolymer slurry and that pore sizes of 170–210 µm are present between the particles. Mercury intrusion porosimetry measurement finds the pore size distribution to be close to 150–280 µm. Measurement of sand retaining precision indicates that the filter can intercept particles larger than 45 µm and allow clay particles to pass through. Deformation measurements confirm no significant deformation occurred for up to 210 days and durability of the filter. In measurement of chemical resistance, the compressive strength decreases in the acid solution, and no significant changes in the compressive strength are observed in air, water, diesel oil and salt solutions. Therefore, compared to the approach of improving the heat-resistance of a resin sand control filter, the use of the geopolymer-based sand control filter should be a better choice in many cases due to its heat resistance, ease of preparation and minor deformation.

A bio-inspired highly selective enzymatic glucose sensor using a red blood cell membrane.

In the development of enzymatic glucose sensors, accurate glucose sensing has been a challenging task because of the existence of numerous interfering molecules in the blood. Meanwhile, red blood cells (RBCs) selectively uptake glucose via a membrane protein called glucose transporter-1. In this study, we developed the RBC membrane (RBCM)-coated enzymatic glucose sensors that mimic the glucose uptake. The RBCM-coated sensors were examined via scanning electron microscopy, atomic force microscopy, and ATR-FTIR. We optimized the glucose permeability of the RBCM filter by controlling the thickness of the filter. The sensing range of the optimized sensor was 1-15 mM, the detection limit was 0.66 mM, and the sensitivity was 2.978 μA mM-1. Intriguingly, the RBCM-coated sensor was highly accurate and precise, despite the coexistence of glucose and interfering molecules (e.g., mannose, galactose, ascorbic acid, uric acid, and cysteine). For each interfering molecule, the errors of our sensor were 0.8 to 2.3%, which was 4.8-14.2 times more accurate than the uncoated one. A similar result was verified for a human serum sample containing countless interfering molecules. Also, the sensing performance of the sensor was consistent after 4 weeks of storage. The results suggest that applying RBCM may improve the selectivity of various types of glucose sensors including the continuous monitoring system.

Modelling of hydraulic deterioration of geotextile filter in tunnel drainage system

The discharge capacity of a tunnel drainage system generally decreases with time because of the hydraulic deterioration of the geotextile filter. Hydraulic deterioration restricts groundwater flow into a tunnel and increases water pressure resulting in detrimental effects on the tunnel lining. Hydraulic deterioration of tunnel drainage system is unique in terms of clogging materials, deterioration mechanism, and flow conditions. Current studies and models investigating the clogging mechanism and hydraulic deterioration are not directly applicable to the geotextile filter of the tunnel drainage system. In this study, a theoretical model of the hydraulic deterioration of tunnel geotextile filter has been proposed considering the mechanical and hydraulic behavior of blinding, clogging and squeezing. A parametric study was carried out to evaluate the performance of the model. An experimental study has been conducted to investigate the clogging behavior of the tunnel drainage system and validate the theoretical model. Several types of clogging materials were selected: cement-leaching calcium oxide, calcium carbonate, iron oxide, and bentonite. Agglutinated clogging was mainly observed during the short-term testing. The findings suggest that the in-plane permeability of the geotextile filter decreased by approximately 90%. The proposed model corroborated the experimental results.

Mathematical modeling of the process of fluid filtration through a multi-layer filtering element

The paper presents a mathematical model of the fluid filtration process in a porous medium. The mathematical model of fluid filtration in a porous medium is based on the equation of continuity and the Darcy law for a hollow porous cylinder. The porous cylinder consists of three materials having different mechanical and filtration properties, made of polypropylene fibers by extrusion, consisting of seven layers. Filtration is described by different types of research laws that establish the relationship between a velocity vector of the fluid filtration and the field of pressure. There are several ways to describe mathematically the process of filter colmatation. Present work considers a single-component model of the flow of suspension through a porous medium. An analysis of this model revealed that it can be implemented in the presence of empirical coefficients that take into account porosity of the sediment deposited on the walls of a porous space, linear functions that describe adsorption and desorption of precipitation on the pore walls, as well as functional dependences for the permeability of filter and the viscosity of suspension. An efficient technique to calculate complex models is to apply parallel programming methods, which make it possible to split calculations into streams performed on the basis of supercomputers, clusters, and other high-performance computing systems. The proposed method for organizing distributed calculations for a finite-element filter model could be used to construct a hydrodynamic model of the filtration process, as well as its program implementation, which is planned in the future.

Impact of convective transport and inert membrane on action of the bio-catalytic filter

We describe two types of enzyme-containing filters. The first type consists of a semi-permeable membrane with immobilized enzyme covered with inert membrane, permeable for the substrate and badly permeable for the product. The second filter type is a semi-permeable enzyme containing a membrane where substrate is pumping through the membrane. The first type is described by a system of two reaction–diffusion equations. The diffusion is described by Fick’s law, and the reaction is described by the Michaelis–Menten term. We obtain mathematical expression of the effectiveness of the bio-catalytic active filters to generate flux of the product and parameter describing permeability of the bio-catalytic filter for substrate. An inert membrane leads to the increase of the product flow through the bio-catalytic membrane about three times and possesses the optimal thickness of the later. Decreasing permeability of inert membrane for product decreases the product flow back, and increases product flow forward about six times. The second-type filter is described by a system of two reaction–diffusion–convection equations. The included convection term is a principal innovation of the research. The convection term increases the transport of the substrate and restricts the flux of the product in the back direction. The convection term increases both rate of the product generation and the capacity to consume the substrate more than 12 times.

Protein composition of human urine during five-day immersion

Dynamics of protein spectrum (12 groups of proteins) of the native daily urine was studied by gradient polyacrylamide gel electrophoresis in the experiment on five-day dry immersion in 14 subjects aged from 19 to 26 years. It was established that changes in the level of urinary protein excretion were not observed during the experiment. Nevertheless, the tendency towards formation of a number of shifts in the urinary protein spectrum was found. The excretion of low-molecular-weight proteins was decreased and that of albumin was increased, which reflects the development of tubular reabsorption remodulation under the influence of experimental exposure. The level of Tamm-Horsfall protein was steadily increased, which is likely to be a protective reaction of the body. An incremental reduction of immunoglobulin content in the urine was observed, which is probably related to decreasing permeability of the glomerular filter for high-molecular-weight proteins.

Airflow resistance and bio-filtering performance of carbon nanotube filters and current facepiece respirators

This study aimed to study airflow resistance of carbon nanotube (CNT)-based filtration material and compare its bioaerosol filtering performances with commercially available facepiece respirators. Firstly, we developed a manikin-based system to evaluate the filtering performances of six respiratory masks for biological aerosol particles using an Ultraviolet Aerodynamic Particle Sizer (UV-APS). Secondly, CNT filters with a base filter with a pore size of 10μm were prepared using single-walled carbon nanotube (SWNT) loadings of 0.05, 0.1 and 0.2mg/cm2. In addition, mask filter membranes were also made by manually cutting the materials of the tested respiratory masks, and their filtration efficiencies and pressure drops were measured and compared with those of CNT-based filters.Results indicated that most of the studied respirator masks achieved a practical protection efficiency of >90%, while N95 types obtained more than 99% absolute protection efficiency under fully sealed conditions. Increasing CNT loading was shown to increase the quality factor (QF) for the CNT filter given all the sizes considered. For the loading of 0.2mg/cm2, CNT filters achieved 87% filtration efficiency against indoor viable bioaerosols and 70% for outdoor aerosol particles; and its QF was significantly higher than those of base filter, activated carbon and surgical mask filters. Different from other mask filters, CNT filters were observed to have higher biological aerosol particle filtration efficiencies than the total aerosol particles. Future work in improving air permeability of CNT filter and CNT distribution on filter support would lead to next generation respiratory mask.

SAT0227 Urinary heparanase activity is elevated in patients with lupus nephritis and correlate with protein excretion

BackgroundThe heparin sulphate proteoglycans (HSPGs) in the glomerular basement membrane (GBM) play an important role in the charge-selective permeability of the glomerular filter. The β-D-endoglycosidase heparanase has been proposed to...

Preparation and gas permeability of the surface-modified porous Al2O3 ceramic filter for CO2 gas separation

Al2O3 filters for CO2 gas separation were prepared by slip casting method. Average pore size and porosity of the obtained Al2O3 filters were about 74 nm and 40%, respectively. To evaluate the pore size effect, the Al2O3 filters having average pore size of 760 nm were also prepared. FE-SEM micrographs show fine new crystals on the pore surface. They were synthesized by hydrothermal treatment, and were identified to AlOOH by XRD and XPS. Both gas selectivity of the filter having larger pore size were about 1, which indicated that this filter has no gas separation capability. In contrast, the gas selectivity of the Al2O3 filter with 74 nm pores became about 1.47 at 0.01 MPa. The N2/CO2 gas selectivity was improved by controlling the pore size and the chemical properties of a pore surface precisely and by setting an appropriate gas permeation pressure.

Filtration performances of a novel submerged nonwoven filter for particle separation

This study focuses on filtration performances of a novel submerged nonwoven filter for particle separation under aeration conditions. TiO 2 particles of different size were used to investigate the effects of transnonwoven pressure, aeration intensity, and particle size on filtration behaviors of the nonwoven filter. Experimental results demonstrated that both transnonwoven pressure and aeration intensity dominated the flux of submerged nonwoven filter. The flux increased in proportion to transnonwoven pressure in the range of 1.0–4.0 kPa. The specific permeability of the nonwoven filter was 0.239 m 3/m 2.d.kPa. Additions of mixed-particles brought about considerable flux reduction under the conditions of high transnonwoven pressure. Meanwhile, a compact cake layer of particles was formed in nonwoven fabrics, resulting in excellent performance on removal of suspended solids. In addition, high aeration intensity would cause sharp flux reduction due to a hydrodynamic effect. The flux was reduced by 3.5, 6.2, 14.1, and 26.2%, respectively, when the aeration intensity was fixed at 0.19, 0.38, 0.77, and 1.03 m 3/m 3.min. High aeration intensity also resulted in high efficiency in particle separation, especially for small particles (0.2–0.4 and 1.0–2.0 μm). Furthermore, mixed-particles of different size were significant for cake layer formation and removal of suspended solids.

Emission Behavior of Condensable Suspended Particulate Matter from a Laboratory Scale RDF Fluidized Bed Combustor

Characterization and measurement of condensable suspended particulate matter emitted from stationary sources, such as coal-fired power plants and waste incinerators, are very difficult since dust concentration in exhaust gas is usually measured at the downstream of dust collectors kept at relatively high temperatures compared with atmospheric air. In the cooling process of flue gas, compounds having solidification points between dust collector temperature and atmospheric temperature have the possibility to become condensable suspended particulate matters. In this work exit gas after bag filtering emitted from a laboratory scale fluidized bed combustor burning refuse-derived fuel (RDF) was sampled by two kinds of cooling methods and elemental analysis was performed. In the experimental results the elemental permeability of a bag filter was high for Pb, Cd, and Zn. To discuss the contribution of fuel composing elements as the origin of measured condensable suspended particulate matters, thermodynamic calculation was performed and the possibility of Cd emission was supported.

Role of endothelial dysfunction in the development of cardiorenal syndrome in patients with type 1 diabetes mellitus

We examined the role of endothelial dysfunction in the development and progression of cardiorenal syndrome in 93 patients with type 1 diabetes mellitus. Patients: According to the stage of renal insufficiency all patients were divided into equal groups: those with normal albumin excretion rate, with microalbuminuria, with proteinuria, and with chronic renal failure. We analyzed endothelial flow-mediated dilation of the brachial artery, levels of endothelin-1, von Willerbrand factor, C-reactive protein, renal:albumin and protein excretion rates, glomerular filtration rate (GFR), and cardiovascular (ECG, echocardiography, blood pressure monitoring) functions. Results: There were negative correlations between the GFR, BP level and endothelial dysfunction markers. At the same time GFR correlated positively with the coefficient of sensitivity of endothelium to shear stress. There were also positive correlations between BP, permeability of glomerular filter and endothelial dysfunction markers and negative correlation with the coefficient of sensitivity of endothelium to shear stress and GFR. Left ventricle mass correlated with markers of endothelial dysfunction and stage of renal disease. Patients with chronic renal failure had negative correlations between LVM and GFR, ILVM and GFR and a positive correlation between ejection fraction and GFR. Conclusions: There is a close relationship between endothelial dysfunction and development and progression of renal and cardiovascular pathology in patients with type 1 diabetes mellitus.

Thermal effects on CR-39 detector response and permeability of some membranes used in radon measurements

Passive technique based on a diffusion chamber fitted with permeable membrane and CR-39 detector is applied in the present study. The detector response and the filter permeability for radon were measured as a function of exposure temperature. The combined effects on the detector and membrane are studied in the temperature range from 27 to 58 °C. Two membrane categories, the paper-type and the polymer-type, are used. The obtained results show advantages of paper-type membranes over polymer-type, where the permeability of paper filter is temperature independent. As a result, the detector response is increased with temperature by a higher rate in case of polymer membrane. Consequently, the using polymer type in radon measurement at unusual temperature needs corrections. The measurements were taking into consideration the effect of temperature on the radon source emanation power which increased from 0.518 to 0.724 in the studied temperature range. The combined uncertainty for all measured parameters is calculated and discussed.

Heparan sulfate proteoglycans in glomerular inflammation

Heparan sulfate proteoglycans (HSPGs) are glycoproteins consisting of a core protein to which linear heparan sulfate side chains are covalently attached. These heparan sulfate side chains can be modified at different positions by several enzymes, which include N-deacetylases, N- and O-sulfotransferases, and an epimerase. These heparan sulfate modifications give rise to an enormous structural diversity, which corresponds to the variety of biologic functions mediated by heparan sulfate, including its role in inflammation. The HSPGs in the glomerular basement membrane (GBM), perlecan, agrin, and collagen XVIII, play an important role in the charge-selective permeability of the glomerular filter. In addition to these HSPGs, various cell types express HSPGs at their cell surface, which include syndecans, glypicans, CD44, and betaglycan. During inflammation, HSPGs, especially heparan sulfate, in the extracellular matrix (ECM) and at the surface of endothelial cells bind chemokines, which establishes a local concentration gradient recruiting leukocytes. Endothelial and leukocyte cell surface HSPGs also play a role in their direct adhesive interactions via other cell surface adhesion molecules, such as selectins and beta2 integrin. Activated leukocytes and endothelial cells exert heparanase activity, resulting in degradation of heparan sulfate moieties in the ECM, which facilitates leukocyte passage into tissues and the release of heparan sulfate-bound factors. In various renal inflammatory diseases the expression of agrin and GBM-associated heparan sulfate is decreased, while the expression of CD44 is increased. Heparan sulfate or heparin preparations affect inflammatory cell behavior and have promising therapeutic, anti-inflammatory properties by preventing leukocyte adhesion/influx and tissue damage.