Porous Filtration Research Articles

Water Filtering and Management System using IoT

Water scarcity is the lack of enough water (quantity) or the lack of access to safe water (quality). The problem of water scarcity is growing every day. Clean and safe drinking water is scarce. Current water purification methods such as reverse osmosis and vacuum distillation are energy intensive. High pressure (800 to 1180psi) is needed for water purification in these methods. A membrane of micro porous filtration has large pore size and rejects only a certain amount of solutes. The proposed work is to reveal the potential of nano materials in water and the aim for proper water distribution in the environment, as well as avoid the wastage of water like unexpected leak ageing and cross connection or illegal connections in pipelines which can also to check the contaminates of water using flow meters, temperature, TDS, Salinity, pH which interface with Wi-Fi module through the controller and it monitors water supply time.

Water Filtering and Management System using IoT

Water scarcity is the lack of enough water (quantity) or the lack of access to safe water (quality). The problem of water scarcity is growing every day. Clean and safe drinking water is scarce. Current water purification methods such as reverse osmosis and vacuum distillation are energy intensive. High pressure (800 to 1180psi) is needed for water purification in these methods. A membrane of micro porous filtration has large pore size and rejects only a certain amount of solutes. The proposed work is to reveal the potential of nano materials in water and the aim for proper water distribution in the environment, as well as avoid the wastage of water like unexpected leak ageing and cross connection or illegal connections in pipelines which can also to check the contaminates of water using flow meters, temperature, TDS, Salinity, pH which interface with Wi-Fi module through the controller and it monitors water supply time

All-in-one microfluidic device with an integrated porous filtration membrane for on-site detection of multiple salivary biomarkers

A hand-held microfluidic device is developed with an integrated filtration membrane for electrochemical monitoring of multiple salivary biomarkers. The platform consists of array of screen-printed electrodes, integrated with a high throughput microfluidic system that was developed via clean-room free 3D-printing technique. A ‘channel-inside-channel’ configuration is introduced to facilitate pump-less passive flow of saliva at the broad sensing chambers. In order to eliminate the salivary protein based biofouling problems, a flexible porous filtration membrane is integrated at the microfluidic inlet that avoids the passage of bulkier protein constituents. As the presence of separate insulator layer on the sensing electrodes adversely affects its integration with the fluidic channel, the electrode substrate itself is utilized as the insulator by exposing the bottom region of the printed electrodes as active region. Enzyme based electrochemical sensors are developed with suitable nanomaterials for monitoring glucose, lactate, cholesterol and uric acid from collected saliva samples. The device showed distinct differences in salivary glucose levels for healthy subjects before and after consuming glucose-rich drinks. The glucose sensor responses are validated with high performance liquid chromatography and commercial colorimetric assay methods, and observed good correlation with parallel finger prick blood glucose measurements with an average Pearson coefficient of 0.9161, demonstrating its efficacy in saliva based point-of-care analysis.

In situ reactive coating of porous filtration membranes with functional polymer layers to integrate boron adsorber property

The state-of-the-art reverse osmosis membranes for seawater desalination have limited competence to efficiently remove boron. One promising approach for boron removal is to integrate membrane-based separation with selective adsorption of boron in pre- or posttreatment of seawater desalination; the porous support layer of established filtration membranes, constituting the largest part of total membrane volume shall be utilized for this function. Therefore, this study focuses on performing in situ modification of commercial polyethersulfone (PES) microfiltration membranes toward reactive coating the pore surface with a boron affinity polymer-based hydrogel. Modification is carried out in two steps: 1) adsorption of an amphiphilic copolymer which contains tertiary amine groups as co-initiator for surface-selective free radical generation; 2) grafting of a hydrogel layer by using a monomer solution comprising polyol-containing monomer as boron ligand, a cross-linker monomer, and the redox initiator ammonium persulfate (APS). The entire modification process is performed under flow-through conditions. Membranes with different pore sizes were modified; modification parameters, such as molar mass of macromolecular co-initiator as well as composition of reactive monomer solution, were systematically varied. It was found that using an “integrated” initiation system with low molecular weight co-initiator N,N,N′,N′-tetraethyl ethylenediamine (TEMED) added to the reactive solution, yielded significantly higher degree of grafting and therefore superior adsorber properties. Boron binding capacity of modified membranes was evaluated in terms of boron adsorption isotherms, adsorption kinetics, break-through behavior under filtration conditions and regeneration of the adsorber. The trade-off between permeance and boron binding capacity of modified membrane was studied in order to identify promising materials with competitive overall separation performance, i.e. high permeance at a specific filter cut-off in combination with high boron binding capacity.

Multiscale Analysis of the Performance of Micro/nano Porous Filtration Membranes with Double Concentric Cylindrical Pores: Part II-Optimization Results

The multiscale calculation results for the values of the optimized parameters are presented for the micro/nano porous filtration membranes with double concentric cylindrical pores where multiscale flows occur. For a weak liquid-pore wall interaction, the optimum ratio of the radius of the bigger pore to the radius of the smaller pore (i.e. the filtration pore) can be calculated from the classical equation, however the corresponding lowest flow resistance of the membrane should still be calculated from the multiscale analysis owing to the adsorbed layer effect when the ratio Landax of the thickness of the adsorbed layer to the radius of the smaller pore is greater than 0.1. For medium and strong liquid-pore wall interactions, the optimum ratios of the pore radii should be calculated from the multiscale analysis, and the corresponding lowest flow resistances of the membrane are much higher than the classical calculation showing the significant effect of the adsorbed layer when Landax>=0.1.

The solution of stationary hydrodynamic task on the replacement of incompressible viscous-plastic oil with thickened water in homogeneous porous medium

The paper reviews the stationary hydrodynamic task on the replacement of the incompressible viscous-plastic oil with the thickened water in the horizontal circular reservoir, in the centre of which a vertical oil well is operated. The formula of filtration rates in different zones, the oil recovery rate, current pressure, current pressure gradients, the pressure in the border of oil and thickened water, as well as the formula of the partial and full duration of oil motion in the reservoir have been developed using generalized Darcy filtration law. All hydrodynamic calculation formulas developed should be applied in the solution of various theoretic tasks on the development of such oil fields, as well as when planning the projects on the exploration of new oil fields. Moreover, using the well known analytical dependence between the average actual rate of fluid motion in the porous channels and filtration rate, the formulas for the time calculation of the fluid motion though the border, in one case - on its current position, in another one – from the saturation contour to the well, have been developed. The formula of the first case is applied in the isolation of the produced water flooded with the contour water (in the formation of liquid fingers) in the wells via the hydrodynamic method for the time calculation of repeated flooding after the implementation of the first cycle of corresponding measure, i.e. after the viscous oil, which is also viscous-plastic fluid in the formation conditions, is injected into the layer.

Multiscale calculation results of the flow behavior in micro/nano porous filtration membrane with the adsorbed layer-fluid interfacial slippage

The paper presents the multiscale calculation results for the multiscale flow in micro/nano porous filtration membranes where the adsorbed layer effect is involved, by considering the adsorbed layer-fluid interfacial slippage. The analysis consists of the molecular scale analysis for the adsorbed layer flow and the continuum analysis for the intermediate fluid flow. The calculation results are respectively compared with the classical flow theory calculations and those based on the solid layer assumption. The adsorbed layer flow rate is also compared with the flow rate of the intermediate continuum fluid. It is shown that for a strong fluid-pore wall interaction or for a large adsorbed layer-fluid interfacial slippage the adsorbed layer can be treated as a solid layer; otherwise it should be treated as a flowing layer. The large interfacial slippage results in the flow rate through the pore far greater than the classical Hagen-Poiseuille equation calculation; it largely propels the flow of the intermediate continuum fluid and makes the adsorbed layer flow negligible particularly for the medium and strong fluid-pore wall interactions. The increasing fluid-pore wall interaction strength significantly reduces the flow rate through the pore.

A Study on Characteristics of Unsaturated Sandy Soils Based on the CT Scanning Method

In the hydrologic cycle, sandy soils play the role of a connecting reservoir of surface water and groundwater, particularly in arid areas. Therefore, to provide water conservation and ecological environment protection, it is important to study the soil water behavior in the unsaturated zone. At present, the CT-scan method is commonly used to study the soil hydraulic properties. In the field of materials science, the industrial CT high-resolution instruments are applied for quantitative research on the porous microstructure and fluid filtration law in sandy soils. In this study, we have studied five samples of sand scans of the quartz sand and CUGB coarse sand types. The industrial-type CT instrument XTH225ST was used for the sample microstructure scanning. In order to identify water: air, and solid particle distribution of the sample cross section, and to analyze the particle size distribution and moisture content, the scanned images were processed using the VG-Studio and ImageJ software. Comparing the CT-scan results of the four quartz sand samples, it can be concluded that the optimal particle size, ranges from 1 to 2 mm. According to the porosity quantitative analysis, with decrease in the particle size, the total porosity grate soil sample increases. After applying the image recognition and VG- Studio software, we can see that for different particle sizes of the sand sample, the average pore size increases with increase in the particle size. To study the moisture absorption and desorption phenomenon, two samples of the CUGB coarse sand are experimentally studied. The particle size of the samples range: from 1 to 2 mm. The CT scanning analysis is used to obtain the unsaturated characteristic curve of the soil when the moisture content reaches stability. Due to the lag phenomenon, the characteristic curve of the soil moisture has an obvious “loop,” or hysteresis, shape. As shown by a 3D modeling, the distribution of capillary water in the sand column is complex, and the water flow forms multiple winding paths, like “worms” creeping in the soil. The CT-scan method is used to overcome the limitations of the traditional experimental methods and to evaluate the relationship between the moisture content and the matrix suction. The obtained characteristic curve of soil moisture can be used to improve the efficiency of technological operations. The CT-scan method provides a new way of evaluating the water distribution characteristics of unsaturated soil.

Functionalized porous filtration media for gravity-driven filtration: Reviewing a new emerging approach for oil and water emulsions separation

Oil and water separation technology has been continuously progressing throughout the years. Recently, gravity-assisted filtration has gained considerable attention, although most of the studies have focused on oil and water synthetic mixtures which can be easily separated under gravity. It is deemed challenging for mechanically and chemically stabilized emulsions to be separated without the addition of an external pressure other than static gravity head. For this to be realized, filtration media should have high porosity to attain high flux but controlled pore size to achieve high selectivity. Moreover, in order to break down the emulsion, the surfaces of the filtration media should be endowed with superwetting properties. In this paper, different porous filtration media (metallic meshes, organic membranes, inorganic membranes, filter paper, and 3D materials) and the corresponding modification techniques and/or functionalization strategies utilized to improve their properties for efficient gravity-driven filtration applications are comprehensively reviewed.

The Impact of Microstructure of Filtration Materials on Its Auto-Activation for Manganese Removal from Groundwater

The study investigates the impact of pore structure parameters of three chemically non-active filtration materials on the auto-activation time and the height of the filtration zone for manganese removal from groundwater. At a technical scale, the activation is a long process which may require a period of up to three months. The process can be shortened by the use of porous filtration materials. In this study, three filtration materials (silica sand, chalcedonite sand, GAC—granulated activated carbon) were investigated using subcritical nitrogen adsorption and mercury injection capillary pressure measurements. These methods provide a comprehensive evaluation of pore structure parameters, including specific surface area (SSA), micro- and mesopore volumes, and an extended range of pore size distribution (PSD). The studied materials provided a wide range of micro- and mesopore volumes as well as SSA. In order to investigate the auto-activation time of filtration material—the time required to achieve the requested quality of the filtrate—and the height of the filtration zone, a pilot experiment was conducted for 1950 h. The pilot installation consisted of three-meters-high (10 cm diameter) filtration columns filled with the tested filtration materials. The results indicate that the internal pore structure and the investigated auto-activation parameters are correlated. Both auto-activation time and the size of the filtration zone were influenced by the mesopore volume and the associated SSA of the tested materials. The micropore volume was less effective in improving the autoactivation parameters. The research results indicated the importance of pore structure characteristics which should be considered prior to time-consuming pilot and technological tests.

Porous Metallic Membranes As High-Performance Gas Diffusion Electrodes for CO2 Reduction in a MEA-Type Electrolyzer

Combining the electrochemical reduction of CO2 (eCO2RR) with carbon-neutral energy sources creates groundbreaking possibilities for using CO2 as a raw material for the sustainable production of fuels and chemicals. Recent technoeconomic analyses have emphasized the importance of achieving high current densities (i.e., hundreds of mA cm‒2) for the eCO2RR to be practically viable,[1] leading to a growing awareness of the need to evaluate catalysts under industrially-relevant operating conditions.[2] Cell designs that integrate selective eCO2RR catalysts into a membrane electrode assembly (MEA) are a promising approach to reduce ohmic losses and achieve high energy efficiency at elevated current densities.[2,3] In this context, we recently demonstrated that unmodified silver membranes—commonly used as porous filtration media in biotechnological applications—sustain high rates of CO2 reduction to CO (> 200 mA cm‒2) when used as gas diffusion electrodes (GDEs) in a zero-gap configuration.[4] These metallic electrodes are simple, highly stable, and cost-competitive vis-à-vis carbon-based GDEs. However, CO2 crossover across the anion-exchange membrane (AEM)—required to suppress the hydrogen evolution reaction—results in poor reactant utilization and in the early onset of mass transfer limitations. These findings highlight the importance of carrying out a carbon balance, in addition to traditional measurements of activity and selectivity, to adequately assess the performance and to identify the operational limitations of realistic devices for CO2 reduction.We will also discuss how these porous silver membranes can be employed as templates for the synthesis of freestanding copper GDEs and, particularly, how different electrode morphologies and compositions can be targeted via the synthesis procedure to tune the resulting selectivity toward multi-carbon products. In addition, we will show how the homogeneous structure and uniform pore network of these porous metallic membranes provides insights into the influence of the GDE’s mass transport properties on CO2 reduction in a zero-gap configuration.[1] M. Jouny, W. Luc, F. Jiao, Ind. Eng. Chem. Res. 2018, 57, 2165-2177[2] T. Burdyny, W.A. Smith, Energy Environ Sci. 2019, 12, 1442-1453[3] D. Higgins, C. Hahn, C. Xiang, T.F. Jaramillo, A.Z. Weber, ACS Energy Lett. 2019, 4, 317-324[4] G.O. Larrazábal, P. Strøm-Hansen, J.P. Heli, K. Zeiter, K.T. Therkildsen, I. Chorkendorff, B. Seger, ACS Appl. Mater. Interfaces 2019, 11, 41281-41288

Fungal melanin-based electrospun membranes for heavy metal detoxification of water

In recent years, heavy metal pollution in water resources has become a severe environmental and public health problem worldwide. Thereby, enhanced treatments are urgently needed with respect to eco-friendliness, filtration efficiencies and low operational costs. This study demonstrates how fungal melanin extracted from Armillaria cepistipes (Empa 655) can be applied as a promising biosorbent for removal of toxic heavy metals from water. For this aim, an electrospinning technique was developed to incorporate fungal melanin particles, a novel source of adsorptive species, into polymeric nanofibrous membranes to obtain stable and highly porous filtration systems. Starting spinning dispersions were investigated with respect to their rheological behaviour and electrical conductivity and related to morphological and surface properties of the resulting composite fibres and membranes. Metal adsorption assays were then performed on both raw melanin and melanised membranes. At the physiotoxic concentrations of Pb2+, Cd2+, Ni2+ and Cr3+, fungal melanin was able to remove >90% of heavy metals in single-component solutions. In multi-component solutions incorporating Ca2+ and Zn2+, fungal melanin showed a different affinity to different metals in the following order: Pb2+ > Cr3+ > Ni2+ > Cd2+ > Zn2+> Ca2+ with an extreme preference for Pb2+ (80% removal) over the essential metals (0% and 12% removal for Ca2+ and Zn2+, respectively). The metal adsorption profiles also showed that melanised membranes were able to maintain the adsorption capacity of the raw melanin. Thus, these novel membranes can be efficiently used as filtration membranes for removal of heavy metals from water.

Thermodynamic analysis of polymer solutions for the production of polymeric membranes

Phase separation is a commonly used mechanism for the preparation of porous filtration membranes. In order to control the membrane structures for obtaining required membrane characteristics and performances, the examination of the thermodynamics of the membrane formation mechanisms is essential. This is why several studies have already been conducted to determine the phase diagrams of polymeric casting solution systems. However, most of the commonly used methods have certain limitations. This is the reason why a new method for the investigation of ternary polymeric systems was developed and evaluated in this study. The new method provides reproducible data which does not only provide information on the position of the binodal curve but also on the compositions of the phases which are formed after the phase separation. The tie-lines of the ternary system polyethersulfone/N-methyl-2-pyrrolidon/water were determined at different temperatures and compared to cloud point titrations conducted under the same experimental conditions. It could be shown that the location of the miscibility gap of the examined system is not visibly dependent on the phase separation temperature within the examined temperature range, especially in the region of the polymer-poor phases. This finding was comparable in all experiments, irrespectively of the method which was used. However, in the region of the polymer-rich phases within the phase diagram, the results of both methods differ from each other as the binodal determined by the tie-line method showed a temperature-dependent shift which cannot be found for the binodal curves extrapolated from cloud point measurements. Apart from determining the binodal curves, the molecular weight distributions of the polymer in the polymer-poor and the polymer-rich phases were determined in the frame of the tie-line determination. Hereby it was found that the distribution in the polymer-poor phase shows a temperature-dependence, as the average molecular weight raised from around 6 kDa at 10 °C to above 10 kDa at 40 °C.

Filtration performance of novel microfibrous media embedded with nanofiber flocs for aerosol particle removal

Ingestion and accumulation of sea salt and other impurities is a major challenge for high speed vessels, turbine engines, and other air breathing systems. The performance and reliability of filters are anticipated to be improved significantly after the rate of performance degradation is reduced via enhanced filtration media and well-designed filtration approaches. This study proposes to apply anionic surfactant to disperse the nanofibers thoroughly and employ cationic surfactant to flocculate the dispersed nanofibers into numerous small groups of nanofiber flocs. Using the wet-lay procedure in the lab, the novel porous microfiber media was then fabricated with small groups of nanofiber flocs together with activated carbon and polyester fibers. The unique nanofiber filter media was then evaluated for filtration performance using face velocity, pressure drop, and filtration efficiency parameters. Due to nanoflocced fiber inclusion, an anomalous region in the filtration efficiency versus pressure drop regime was observed where wall slip occurring at the nanostructured surface provided an unusually high level of filtration efficiency near the most penetrating particle size (MPPS) region of 0.1–0.4 μm with a concomitant reduction in the normally encountered levels of pressure drop. This anomalous increase in the filtration efficiency versus pressure drop is a novel phenomenon and it is highly beneficial to aerosol filtration. The enhanced filtration reveals that the quality factor near the MPPS region increases significantly due to the inclusion of nanofiber flocs. The unique porous filtration media is expected to increase the dirt holding capacity and prolong the lifecycle of the turbine air filter systems.

Brinkman-Forchheimr model for fat accumulation in arterial wall

A new model based on Brinkman-Forchheimr equation on transport of low-density lipoprotein (LDL) in artery wall has been developed that includes the multi-layered model. Artery wall has been considered as homogeneous porous media, Staverman filtration and osmotic reflection coefficient has been considered. The realistic physical properties are available and have been obtained from the literature. Various models have been compared with the proposed model. The results are consistent with the other numerical and experimental studies. Effects of hypertension and pulsatile flow on LDL transport in arterial multi-layered wall have been studied in detail. Effect of pulsatile flow is imperative since blood flow in artery is a pulsatile flow. Hyperthermia is important for the treatment of cancer. Soret effect on LDL concentration distribution has been analysed for the hyperthermia condition. This model will help to better understand the effect of hypertension and hyperthermia on atherosclerotic diseases. Results reveal that LDL accumulation is directly related to the transmural pressure. For the straight artery, effect of hyperthermia is negligible for LDL accumulation due to the very thin arterial wall. Effect of pulsatile flow in LDL transport has been found negligible.

PAC/UF processes: Current application, potentials, bottlenecks and fundamentals: A Review

ABSTRACTThe increase of human population and activity is leading to localized discrepancies in water demand and fresh water availability in arid and highly populated areas. Combined with stricter water regulations this development has already and will continue to pose higher demands on water treatment technologies and their efficiencies.Activated carbon adsorption has been successfully applied to remove a broad range of dissolved molecules in various applications while porous membrane processes are typically applied to retain suspended particles. The combination of both processes promises superior product water quality and improved process stability. However, improved process performance and water quality is not a given for all combinations of adsorption and porous membrane filtration but rather depending on a variety of different influencing factors.This review provides a comprehensive overview on these influencing factors by careful analysis of the available literature, covering aspects from adsorption mechanisms and membrane fouling phenomena over differences in process configurations as well as water composition. Thereby, the review aims to broaden the knowledge and understanding of the process combination with respect to optimal process configuration and long term operation for best process performance and further contribution towards the technical realization of the process combination for other treatment tasks.

Optimization of Thermal Insulation Performance for the Porous Materials

ABSTRACTPorous materials are widely used in porous media filtration, membrane separation, catalyst substrates, solid fuel cells, insulation, and other fields. When the porous material used in the field of insulation, heat transfer characteristics become its most important performance parameters. The heat transfer characteristics of porous material is a complex issue affected not only by solid elements and porosity, it is also affected by composite structures. Therefore, how to optimize the heat transfer properties of porous materials is a problem to be urgently solved. In this paper, the numerical method is used to study the effects of pore size, pore shape, pore connectivity, porosity and so on. It is found that pore shape, pore connectivity and gas conductivity have great impacts on the heat transfer of porous materials. The effect of pore arrangement is very little. The design optimization of porosity is affected by porous material mechanical property.

Does clogging affect long-term removal of organics and suspended solids in gravel-based horizontal subsurface flow constructed wetlands?

Constructed wetlands with horizontal subsurface flow (HF CWs) are primarily designed to remove organics and suspended solids. The major principle of this treatment process is that wastewater flows through the porous medium planted with wetland vegetation in order to achieve removal of pollutants. During the process the void spaces in the filtration material are slowly filled due to sedimentation and filtration of suspended solids, creation of biofilms on filtration material particles, chemical precipitation and growth of roots and rhizomes of the vegetation. Therefore, the clogging process is inevitable. However, the use of suitable porous filtration materials, responsible maintenance of pretreatment units and suitable loadings of organics and suspended solids may greatly slow down the clogging process. The purpose of this study was to evaluate the effect of partial ponding on treatment performance of four HF CWs that have been in operation for at least 20years. The results revealed that if the inflow loading rates are <10gBOD5m−2d−1, <20gCODm−2d−1, <10gTSSm−2d−1, the partial ponding may occur after about 15years of operation. The results also revealed that partial ponding have no significant effect on the quality of discharged water and the replacement of inflow zone filtration material did not results in any significant improvement either.

Biomass-Derived Carbon Sorbents for Cd(II) Removal: Activation and Adsorption Mechanism

Producing an ideal sorbent for removing heavy metals from aqueous solutions is still very challenging. A well-organized microporous structure and nitrogen-rich functional groups in a sorbent are proposed as an excellent platform for Cd(II) removal. Urea phosphate (UP) was used as an activating agent for preparing carbon sorbents derived from biomass. The activating procedure was examined by thermogravimetric analysis (TGA), which indicated that a well-developed microporous structure and nitrogen-rich functional groups were present in the sorbents due to the UP with urea and phosphoric acid molecules in its chemical structure and liberated in the activation process. The mechanisms of Cd(II) removal by sorbents were determined by X-ray photoelectron spectroscopy (XPS), which indicated that porous filtration and chemical reactions (ion exchange, electrostatic attraction and surface complexation) were involved in Cd(II) removal.

Polymer-Capped Nanoparticle Transport in Granular Media Filtration: Deviation from the Colloidal Filtration Model

AbstractThe single-collector removal efficiency based on the colloidal filtration model is widely used to quantify deposition of nanoparticles in porous media filtration. The validity of this theor...