Filtration Of Solution Research Articles

Visible-light-driven photocatalytic PVDF-TiO2/CNT/BiVO4 hybrid nanocomposite ultrafiltration membrane for dairy wastewater treatment

Enhancing the performance of polymeric membranes by nanomaterials has become of great interest in the field of membrane technology. The present work aimed to fabricate polyvinylidene fluoride (PVDF)–hybrid nanocomposite membranes and modify them with TiO2 and/or BiVO4 nanoparticles and/or carbon nanotubes (CNTs) in various ratios. Their photocatalytic performance under visible light was also investigated. All modified PVDF membranes exhibited higher hydrophilicity (lower contact angle of water droplets) than that of the neat membrane used as a reference. The membranes were characterized by using bovine serum albumin (BSA) as model dairy wastewater. The hybrid membranes had better antifouling properties as they had lower irreversible filtration resistance than that of the neat membrane. Hybrid PVDF membranes containing TiO2/CNT/BiVO4 showed the highest flux and lowest irreversible resistance during the filtration of the BSA solution. PVDF-TiO2/BiVO4 had the highest flux recovery ratio under visible light (70% for the PVDF mixed with 0.5% TiO2 and 0.5% BiVO4). The hydrophilicity of membrane surfaces increased with the incorporation of nanoparticles, preventing BSA to bind to the surface. This resulted in a slight decrease in BSA and chemical oxygen demand rejections, which were still above 97% in all cases.

Modification of Thin Film Composite PVA/PAN Membranes for Pervaporation Using Aluminosilicate Nanoparticles.

The effect of the modification of the polyvinyl alcohol (PVA) selective layer of thin film composite (TFC) membranes by aluminosilicate (Al2O3·SiO2) nanoparticles on the structure and pervaporation performance was studied. For the first time, PVA-Al2O3·SiO2/polyacrylonitrile (PAN) thin film nanocomposite (TFN) membranes for pervaporation separation of ethanol/water mixture were developed via the formation of the selective layer in dynamic mode. Selective layers of PVA/PAN and PVA-Al2O3·SiO2/PAN membranes were formed via filtration of PVA aqueous solutions or PVA-Al2O3·SiO2 aqueous dispersions through the ultrafiltration PAN membrane for 10 min at 0.3 MPa in dead-end mode. Average particle size and zeta potential of aluminosilicate nanoparticles in PVA aqueous solution were analyzed using the dynamic light scattering technique. Structure and surface properties of membranes were studied using scanning electron microscopy (SEM), atomic force microscopy (AFM) and water contact angle measurements. Membrane performance was investigated in pervaporation dehydration of ethanol/water mixtures in the broad concentration range. It was found that flux of TFN membranes decreased with addition of Al2O3·SiO2 nanoparticles into the selective layer due to the increase in selective layer thickness. However, ethanol/water separation factor of TFN membranes was found to be significantly higher compared to the reference TFC membrane in the whole range of studied ethanol/water feed mixtures with different concentrations, which is attributed to the increase in membrane hydrophilicity. It was found that developed PVA-Al2O3·SiO2/PAN TFN membranes were more stable in the dehydration of ethanol in the whole range of investigated concentrations as well as at different temperatures of the feed mixtures (25 °C, 35 °C, 50 °C) compared to the reference membrane which is due to the additional cross-linking of the selective layer by formation hydrogen and donor-acceptor bonds between aluminosilicate nanoparticles and PVA macromolecules.

Pore-Directed Solid-State Selective Photoinduced E – Z Isomerization and Dimerization within Metal–Organic Frameworks

Pore-Directed Solid-State Selective Photoinduced <i>E</i> – <i>Z</i> Isomerization and Dimerization within Metal–Organic Frameworks

Preparation of High-Purity Calcium Carbonate by Mineral Carbonation Using Concrete Sludge.

A new type of mineral carbonation process for concrete sludge, a waste of fresh concrete under hydration, was developed, and the carbonation performances of the process were examined by laboratory-scale experiments. The process is composed of two steps; filtration of concrete sludge and bubbling of CO2 into the filtrate to form calcium carbonate. Model concrete sludge, a mixture of cement and water, was filtered through a cellulose filter after hydration for 24 h to obtain a solution containing dissolved calcium ions. Then, the model flue gas containing CO2 (10%) was bubbled through the filtrate solution, and calcium carbonate was precipitated by the carbonation reaction. About 3% of calcium in the concrete sludge could be extracted into the filtrate in a single filtration step, and more than 95% of dissolved calcium was recovered as calcium carbonate by the bubbling of CO2. The obtained calcium carbonate was calcite with a high purity (>95%) and 5–10 μm. The solid residue (concrete sludge) after filtration was mixed with fresh water and filtered through a cellulose filter. Then, the model flue gas was bubbled into the filtrate solution for carbonation. This filtration–bubbling step was repeated 5 times, and 10.8% of calcium in the feed cement was extracted into the filtrates in total. More than 95% of the extracted calcium could be recovered as calcium carbonate with high purity (>97%), and the overall conversion of calcium in the feed cement to calcium carbonate was 10.1%. The purity of calcium carbonate and the calcium conversion were much higher than those for the direct bubbling method, where the model flue gas is bubbled into concrete sludge.

Ultra-Low-Pressure Membrane Filtration for Simultaneous Recovery of Detergent and Water from Laundry Wastewater.

Reusing water and excess detergent from the laundry industry has become an attractive method to combat water shortages. Membrane filtration is considered an advanced technique and highly attractive due to its excellent advantages. However, the conventional membrane filtration method suffers from membrane fouling, which restricts its performance and diminishes its economic viability. This study assesses the preliminary performance of submerged, gravity-driven membrane filtration—under ultra-low trans-membrane pressure (△P) of <0.1 bar—to combat membrane fouling issues for detergent and water recovery from laundry wastewater. The results show that even under ultra-low pressure, the membrane suffered from compaction that lowered its permeability by 14% under △P of 6 and 10 kPa, with corresponding permeabilities of 2085 ± 259 and 1791 ± 42 L/(m2 h bar). Filtration of a detergent solution also led to up to 8% permeability loss due to membrane fouling. During the filtration of laundry wastewater, 80–91% permeability loss was observed, leading to the lowest flux of 15.6 L/(m2·h) at △P of 10 kPa, 38% lower than △P of 6 kPa (of 25.2 L/(m2·h)). High △P led to both the membrane and the foulant compaction inflating the filtration resistance. The system could recover 83.6% of excess residual detergent, while most micelles were rejected (ascribed from 71% of COD removal). The TDS content could not be retained, disallowing maximum resource recovery. A gravity-driven filtration system can be self-sustained with minimum supervision in residential and industrial laundries. Nevertheless, a detailed study on long-term filtration performance and multiple cleaning cycles is still required in the future.

Water Treatment Using High Performance Antifouling Ultrafiltration Polyether Sulfone Membranes Incorporated with Activated Carbon

Membrane fouling is a continued critical challenge for ultrafiltration membranes performance. In this work, polyether sulfone (PES) ultrafiltration (UF) membranes were fabricated via phase-inversion method by incorporating varying concentrations of APTMS modified activated carbon (mAC). The mAC was thoroughly characterized and the fabricated membranes were studied for their surface morphology, functional groups, contact angle, water retention, swelling (%) porosity, and water flux. The hydrophilicity of mAC membranes also resulted in lower contact angle and higher values of porosity, roughness, water retention as well as water flux. Also, the membranes incorporated with mAC exhibited antibacterial performance against model test strains of gram-negative Ecoil and gram-positive S. aureus. The antifouling studies based on bovine serum albumin protein (BSA) solution filtration showed that mAC membranes have better BSA flux. The higher flux and antifouling characteristics of the mAC membranes were attributed to the electrostatic repulsion of the BSA protein from the unique functional properties of AC and network structure of APTMS. The novel mAC ultrafiltration membranes developed and studied in present work can provide higher flux and less BSA rejection thus can find antifouling applications for the isolation and concentration of proteins and macromolecules.

The Comparison Effect of NaOH and KOH as The Leaching Solution for Silica from Two Different Coal Fly Ashes

One of the environmental problems is the waste from the coal combustion process from coal power plants or other industries that use coal as an energy source. The combustion process produces coal fly ash, which will accumulate in the environment. Subsequently, much research about the utilization of coal fly ash has been developed. Silica extraction from coal fly ash is one of the methods that can be used to utilize coal fly ash. This study carried out silica extraction using the Direct Alkaline Leaching (DAL) method. The coal ash was contacted with alkaline solvents (KOH and NaOH) with the variations of concentrations and the leaching time. The leaching solution filtrate will be precipitated with the addition of HCl. The characteristics of this silica from CFA and CFA B were analyzed by using Scanning Electron Microscopy (SEM). Based on the results, it could be known that each of the coal fly ashes has different results for both alkaline solvents. CFA A has relatively less silica extraction results in both types of solvents. Meanwhile, CFA B gave higher silica extraction results with coal fly ash and solvent contact time for one hour.

Experimental and numerical investigation of specific behaviour of fluoride ions during filtration of pure salt water solutions with titania membrane

This work addresses the specific interactions between titania membrane and fluoride anions during ultrafiltration operation. In general, the salt transmission increases with salt concentration when pure salt-water solutions are ultrafiltrated, except for fluoride-based salts observed in our study, for which transmission decreased at low concentrations. This phenomenon was only observed with titanium dioxide membrane. A numerical tool based on a physical description of ionic mass transfer in porous material (generalized Nernst-Planck approach) was used to explore the modification-induced changes due to fluoride anions. Numerical investigations showed a modification of the electric charge of the membrane surface in the pore at low fluoride concentrations. This phenomenon screened the electric effect in a completely reversible way, and then enhanced the ion mass transfer through the porous membrane. These modifications can be explained by the substitution of oxygen atom (providing the surface electric charge) with a fluoride ion which was screening the electric charge and facilitated the ion transfer.

Anti-fouling nanofiltration membranes based on macromolecule crosslinked polyvinyl alcohol

Nanofiltration membranes with excellent anti-fouling properties were fabricated through a green surface crosslink method. Poly (styrene-maleic anhydride) (SMA) blended polyethersulfone (PES) membrane was used as a support. The SMA in the PES support served as a macromolecular crosslinker. After coating of polyvinyl alcohol (PVA) on the surface of the SMA-PES support, a PVA selective layer with gradient cross-linked structure was formed, through the esterification between the anhydride groups in SMA and the hydroxyl groups in PVA. This process adopts a full-water fabrication strategy without secondary pollution. The gradiently cross-linked PVA/SMA-PES membrane, with molecular weight cut-off (MWCO) about 600 Da and permeance around 10-12 L/(m2·h·bar), exhibited good dye/salts separation performance. In the filtration of a mixed solution of Congo Red (CR) and calcium chloride (CaCl2), the membrane rejected 98% CR and only had 10% rejection of CaCl2. In addition, this membrane processed an excellent anti-fouling property. In the BSA fouling test, the pure water flux recovery ratio (FRR) was 99%. It is expected that the PVA/SMA-PES membrane can be used in organic desalination.

Regio- and Diastereoselective Construction of Functionalized Benzo[b]oxepines and Benzo[b]azepines via Recyclable Gold(I)-Catalyzed Cyclizations.

The heterogeneous gold-catalyzed cyclization of (o-alkynyl)phenoxy- or N-(o-alkynylphenyl)tolylsulfonamidoacrylates with alcohols has been developed by using an MCM-41-anchored diphenylphosphine-Au(I) complex [MCM-41-Ph2P-AuNTf2] as the catalyst under mild reaction conditions, yielding diverse functionalized benzo[b]oxepines or benzo[b]azepines with good to high yields and excellent diastereoselectivity. This heterogenized gold(I) catalyst exhibits a comparable activity to homogeneous Ph3PAuNTf2 and can be facilely recovered by a simple filtration of the reaction solution and reused more than seven times with almost a consistent catalytic efficiency.

Critical Care Nurses' Knowledge of Correct Line Types for Administration of Common Intravenous Medications: Assessment and Intervention Study.

BackgroundThere is a paucity of information in the literature on core nursing staff knowledge on the requirements of specific intravenous administration lines for medications regularly given in critical care. There is also a lack of well-researched and appropriate information in the literature for intravenous administration line selection, and the need for filtration, protection from light, and other line-material selection precautions for many critical and noncritical medications used in these settings to maintain their potency and efficacy.ObjectiveWe aimed to assess the knowledge gap of clinicians with respect to intravenous administration line set material requirements for critical care medications.MethodsData were drawn from a clinician knowledge questionnaire, a region-wide database of administered infusions, and regional data on standard and special intravenous administration line consumption for 1 year (2019-2020) from an enterprise resource planning system log. The clinician knowledge questionnaire was validated with 3 groups (n=35) and then released for a general survey of critical care nurses (n=72) by assessing response dispersal and interrater reliability (Cronbach α=.889). Correct answers were determined by referencing available literature, with consensus between the team’s pharmacists. Percentage deviations from correct answers (which had multiple possible selections) were calculated for control and test groups. We reviewed all 3 sources of information to identify the gap between required usage and real usage, and the impact of knowledge deficits on this disparity.ResultsPercentage deviations from correct answers were substantial in the control groups and extensive in the test group for all medications tested (percentage deviation range –43% to 93%), with the exception of for total parenteral nutrition. Respondents scored poorly on questions about medications requiring light protection, and there was a difference of 2.75% between actual consumption of lines and expected consumption based on medication type requirement. Confusion over the requirements for low-sorbing lines, light protection of infusions, and the requirement for filtration of specific solutions was evident in all evidence sources. The consumption of low-sorbing lines (125,090/1,454,440, 8.60%) was larger than the regional data of medication usage data would suggest as being appropriate (15,063/592,392, 2.54%).ConclusionsThere is no single source of truth for clinicians on the interactions of critical care intravenous medications and administration line materials, protection from light, and filtration. Nursing staff showed limited knowledge of these requirements. To reduce clinical variability in this area, it is desirable to have succinct easy-to-access information available for clinicians to make decisions on which administration line type to use for each medication. The study’s results will be used to formulate solutions for bedside delivery of accurate information on special intravenous line requirements for critical care medications.

Etiology and Pathophysiological Pathways of Ocular Complications Associated with Local Dental Anesthesia and Odontogenic Infections: A Systematic Review.

Ocular complications during or after dental extraction have been reported in the literature. These complications were either due to infiltration of local anesthetic solution or due to spread of odontogenic infection extending to the ocular region. The purpose of the present study is to outline the pathophysiological pathway of such ocular complications pertaining to dental procedures due to infiltration/local anesthesia block or spread of odontogenic infection. An exhaustive literature search was conducted in October 2020 on various online research databases to identify various etiological factors causing ocular complications during dental procedures or followed by odontogenic infections. The findings of all the articles recruited for the review were recorded and analyzed. The search protocol revealed a total of 897 articles related to the study where only 208 relevant articles were recruited for detailed evaluation, which led to the exclusion of 123 articles and a total of 85 articles were included in the study. Out of the total 113 cases in 85 articles, 92 cases (81.42%) showed complications associated with the use of local anesthetic agent and 21 cases (18.58%) exhibited ocular complications due to spread of infections. Most common ocular complications reported were diplopia, followed by ptosis and ophthalmoplegia. Dental anesthesia can cause a reversible or irreversible ophthalmic complication, while the infectious afflictions of the orbit still remain a challenge to the practicing maxillofacial surgeon.

Development of dynamic PVA/PAN membranes for pervaporation: Correlation between kinetics of gel layer formation, preparation conditions, and separation performance

Thin film composite (TFC) membranes possessing polyvinyl alcohol (PVA) selective layer and polyacrylonitrile membrane-support were developed via dynamic mode technique based on concentration polarization phenomenon. The effect of the molecular weight cut-off (MWCO) of membrane-support, concentration of PVA solution and filtration mode on the gel layer formation was studied via the analysis of kinetic curves of flux and PVA rejection in ultrafiltration. The effects of concentrations of PVA, glutaraldehyde (GA) and hydrochloric acid (HA), filtration time, and transmembrane pressure (TMP) on the structure and pervaporation (PV) performance of TFC membranes for ethanol dehydration were investigated. It was found that an increase in PVA concentration, duration of filtration and TMP results in an increase in the TFC membrane selective layer thickness. It was shown that pervaporation permeate flux decreased when TFC membranes were prepared using higher PVA concentration and longer time of PVA filtration. The pervaporative permeate flux through TFC membranes passed through the maximum at TMP of 3 bar, then became practically stable for membranes prepared at TMP in the range of 4-8 bar. It was attributed to the formation of microdefects of the selective layer due to the compaction-relaxation behavior of membrane support during selective layer formation at elevated pressures. It was also shown that the dependence of PV separation factor on the duration of PVA solution filtration passes through the maximum which is consistent with the time of the stable gel-layer formation calculated from the kinetic curves. The found optimal conditions for preparation of TFC dynamic membranes were following: dead-end ultrafiltration mode, the component concentrations in the solution — 1.0 wt.% PVA, 0.06 wt.% GA, 0.5 wt.% HA, using the simultaneous application technique (SimAT) with the filtration time — 10 min and TMP — 3 bar.

Comparing the Efficiency of Tumescent Infiltration Techniques in Burn Surgery.

Tangential excision and grafting of burn wounds result in significant intraoperative blood loss, and infiltration of a dilute epinephrine solution (tumescence) is routinely performed to reduce such bleeding. Tumescent infiltration has been described using both a manual technique (syringe) and a pump device. The purpose of this study is to compare the efficiency of these two methods in terms of time and economy of motion. Consecutive adult burn patients at a single center requiring excision and grafting were enrolled in the study and randomized into either the manual or pump technique. Excisions involving less than 2% TBSA were excluded, along with specific anatomic regions (eg, head and neck). Infiltration with epinephrine solution (1:500,000) was performed to the endpoint of tumescence by a single surgeon and filmed/coded for duration, number of maneuvers, and volume of tumescence injected. Fourteen patients were enrolled, and 16 cases were randomized to either manual (N = 8) or pump infiltration (N = 8). The pump method required less time (2.0 vs 1.1 cm2/s, P < .001) and fewer maneuvers (37.8 vs 1.1 cm2/move, P < .001) to reach the desired endpoint of tumescence. Use of the infiltration pump also resulted in a reduced volume of tumescent fluid required to reach this point of tumescence (1.7 vs 2.4 mL/cm2, P = .01). Compared to the manual technique, an infiltration pump was significantly more efficient in terms of both time and economy of motion. These reductions are potentially useful for improving operating room efficiency as well as minimizing operator fatigue.

Triethanolamine impregnation/steam synergistic softening of teakwood to improve bending properties and its mechanism

ABSTRACT Solid wood bending component has good mechanical properties and unique artistic characteristics. To investigate bending properties of solid wood and its mechanism, this paper has conducted the studies of softening and bending teakwood which is chosen as raw material, vacuum impregnation was carried out with environmentally friendly triethanolamine (TEA), sodium chloride (NaCl) and sodium dodecyl benzene sulfonate (SDBS) as compound softening solution, and the wood was softened with superheated steam as the medium. The results show that the infiltration of softening solution can increase the content of O and N elements in the wood and form C-NH2 and C–N bonds with C element. When the concentration of softening solution is 15%(m/m), the wood presents the best bending property, and the bending coefficient can reach 1/9.24, which is 20.48% higher than that of the untreated wood, and the qualification rate of bending components is increased to 85%. After drying and shaping, compression strength parallel to grain and bending strength increased by 22.91% and 20.82%, as well the indentation modulus and hardness of the cell wall increased by 16.70% and 21.45%, respectively. Meanwhile, the wet swelling rate and chord length change rate decreased by 51.39% and 3.37%.

Evaluation of hydro-mechano-chemical behaviour of bentonite-sand mixtures

Bentonite-sand mixtures are widely used in engineering barrier of deep geological disposal of high-level radioactive nuclear waste and anti-seepage barrier of civil geotechnical engineering. Under the action of groundwater solution infiltration and external stress, the hydro-mechanical (HM) behaviour of bentonite-sand mixtures, i.e. the swelling characteristics and permeability, will change. Once the anti-seepage and filtration effect is weakened or lost, the pollutants will spread to the biosphere. Therefore, it is necessary to study the swelling characteristics and permeability of bentonite-sand mixtures under coupled mechano-chemical (MC) effect and to establish corresponding prediction model. For this reason, swelling tests under salt solution with different concentrations are conducted on pure bentonite and its mixtures with 30%, 70% and 90% sand contents, the compression tests are carried out on saturated samples, and the saturated permeability coefficient k of the sample under each load is calculated by Terzaghi's one-dimensional consolidation theory. The concepts of true effective stress p e , montmorillonite void ratio e m and critical sand content α s are introduced to determine the e m - p e relationship and finally the k - e m relationship of bentonite-sand mixtures. It is found that when the sand content α ≤ α s , the e m - p e relationship of the mixture is linear and independent of the salt solution concentration, and when α > α s , the e m - p e relationship of bentonite-sand mixture is bi-linear with the true effective deviatoric stress p esα as the intersection. In addition, the e m - k relationship also shows the linear trend when α ≤ α s , and the slope of the line increases with the increase of the salt solution concentration. When α > α s , the k - e m relationship will deviate from the linear relationship. Moreover, the larger the sand content is, the farther the deviation is. On the basis of summing the regularity, a model for predicting the HM behaviour of bentonite-sand mixture under the coupled MC effect is proposed. By comparing the swelling and permeability test results with model prediction results of different types of bentonite and its sand mixtures, the predictive model is verified. The study on the HM behaviour of bentonite-sand mixtures under salt solution infiltration and the model establishment can provide experimental and theoretical basis for the design and construction of anti-seepage engineering by bentonite-sand mixtures.

Facile zwitterionization of polyvinylidene fluoride microfiltration membranes for biofouling mitigation

Styrene maleic anhydride (SM) is a commercially available copolymer able to react with diamines. The ring-opening reaction results in the formation of a zwitterionic compound of prime interest to the development of fouling-resistant membranes. To this end, we designed microfiltration antifouling polyvinylidene fluoride (PVDF) membranes by blending PVDF with a copolymer obtained from the reaction of SM with N,N-dimethylamino-1,3-propanediamine, and then by inducing phase inversion of the casting solution from the vapor phase. The resulting membranes possess excellent surface and bulk hydrophilicity, compared to the pristine membrane. Besides, as adding copolymer shifts the zeta potential closer to electroneutrality, biofouling is alleviated, as tested in static conditions with Escherichia coli , blood cells or bovine serum albumin. Filtration of a bacterial solution also demonstrated the superior performances of the as-prepared membrane to those of a commercial hydrophilic PVDF membrane, with a higher flux recovery ratio (90% vs. 65%) and lower irreversible flux decline ratio (10% vs. 32%). Given also the stability of the design and the low costs involved in the making of the membranes (all materials are commercially available and inexpensive), the present membranes are suitable alternatives to commercial hydrophilic PVDF membranes, but with better fouling mitigation. • The facile zwitterionization of a commercial copolymer is introduced. • The zwitterionic copolymer is solubilized with polyvinylidene fluoride. • Stable zwitterionic bi-continuous are fabricated. • Effective anti-biofouling property is demonstrated with various biofoulants.

Bulk cross-linked hydroxyethyl cellulose-silica composite membrane for acid-stable nanofiltration

This work focused on the construction of an acid-resistant composite nanofiltration membrane with the selective layer of bulk cross-linked hydroxyethyl cellulose (HEC)-silica and a support of porous polypropylene. Membranes were fabricated through in-situ sol-gel reaction and slot-die coating method employing tetraethyl orthosilicate (TEOS) as the silica precursor and cross-linking agent of HEC. Membrane structure and performance were tuned by controlling the hydrolysis time of TEOS and differentiating TEOS and HEC contents, and systematically characterized in terms of physico-chemical property, permeation attribution and acid stability. It was found that membrane performance was strongly correlated with the relative contents of C–O–Si and Si–O–Si bonds of the formed HEC-silica selective layer. High content of C–O–Si bond formed via condensation reaction of HEC and TEOS endowed the selective layer with denser network structure and good rejection ability. Both insufficient and excessive hydrolysis led to a poor rejection ability of formed membrane. The optimized HEC-silica membrane possessed an average pore size of about 1.43 nm within the scope of nanofiltration membrane, a high pure water permeability coefficient of around 10.5 LMH/bar, and a medium rejection of 85.2% to 500 mg/l Na2SO4 aqueous solution at 5.0 bar. No changes in both chemical structure and separation performance occurred with the HEC-silica composite membrane after being soaked in aqueous H2SO4 solution of 4.9 wt% for 7 days, while evident structure destruction and serious performance degradation occurred with the compared polyamide-based commercial membrane NF270. Long-term soaking test using 15.0 wt% H2SO4 aqueous solution for 30 days also demonstrated that the acid resistance HEC silica membrane was comparable with those reported acid stable nanofiltration membranes. Furthermore, the HEC-silica membrane also maintained its water permeation and solute rejection abilities during a 30-day continuous filtration of aqueous solution of 4.9 wt% H2SO4 and 50 mg/l polyethylene glycol fraction (PEG2000). The good acid resistance of the HEC-silica composite membrane was attributed to its bulk cross-linked network structure composed of C–O–Si, Si–O–Si and C–C bonds.

Electrochemical Characterization of NdBa0.9Co2O5+δ SOFC Cathodes Prepared by Infiltration into Gd Doped Ceria Scaffolds

In this work, the electrocatalytic properties of novel cathodes prepared by infiltration of NdBa0.9Co2O5+δ (NBC) into porous Gd doped Ceria (GDC) scaffolds are investigated, and comparison is provided with La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) infiltrated GDC cathodes. For both formulations, symmetric cells are fabricated by blade coating and infiltration of aqueous nitrate precursor solutions until reaching 25% w/w load. The effects of the calcination temperature are explored between 750 °C and 950 °C for the NBC-GDC cathodes. Electrochemical impedance spectroscopy and polarization experiments are performed to study the electrocatalytic activity in the oxygen reduction reaction. Compared to LSCF-GDC, a remarkable improvement of the polarization resistance is found on the best performing NBC-GDC cathode between 500 °C and 700 °C (0.022 Ω cm2 vs 0.1 Ω cm2 at 700 °C). A shift in the rate determining step characterizes the performance of the NBC-GDC cathode above 650 °C, wherein the interfacial oxide ion transfer resistance prevails, while below 650 °C the surface exchange resistance dominates. Different stability behaviors are observed in ageing experiments up to 200 h: the NBC-GDC electrodes show constant ohmic resistance and moderate improvement of the polarization resistance at 700 °C and 550 °C, while the LSCF-GDC electrodes experience degradation.

Development of a combinatory filtration system for pollution and virus abatement by optimized nanoparticle deposition.

PM2.5, particulate matter less than 2.5 microns, is the leading contributor to air pollution which results in cardio-vascular and respiratory diseases. Recent studies also indicate a strong correlation between ambient air pollution and COVID-19 cases, which have affected the lives of billions of people globally. Abatement technologies such as ionic and other high efficiency filtration systems are expensive and unaffordable in communities with limited resources. The goal of this study was to develop a mask with an optimized nanoparticle coating which has a dual capability of particulate matter and virus filtration, while being affordable and safe for human use. The nanoparticles were selected for their filtration and virucidal capabilities. Particle filtration efficiency, tested with a wind tunnel and PM2.5 from incense sticks measured by laser particle detectors, improved by ~60% with nanoparticle coatings on KN95 and surgical masks. Virus filtration efficiency, tested using nebulized NaCl particles as a virus surrogate, improved by 95% with coated masks. The nanoparticle retention efficacy, tested by simulating a normal 8-hour workday, was well within the permissible exposure limits. This technology has several applications such as in personal protective equipment for virus protection, and in air-conditioning and car cabin filters for pollution abatement. In conclusion, the chosen combination of nanoparticles provides an effective and safe solution for both particulate matter and viral particle filtration.