Conventional Filtration Methods Research Articles

Spray-coated PDA-wrapped carboxylic CNT/PES membrane to augment fouling mitigation, organic removal, and membrane stability in electrochemical membrane filtration

This study introduces robust and conductive polydopamine (PDA)-wrapped carboxylic carbon nanotube (C-CNT)-coated polyethersulfone (PES) membrane for electrochemical membrane filtration to treat greywater. Self-polymerized dopamine was prepared directly under oxidative conditions on the CNT strands, followed by their immobilizations on the surface of the PES membrane through a novel spray-coating technique. The spraying coating technique improved both the durability of the coating layer and membrane permeability by 27 % higher than that prepared by the conventional vacuum filtration method. The spraying coating technique enhanced the electroactive properties of the PDA/C-CNT membrane so that the fouling rate was reduced more effectively than the C-CNT membrane or bare PES membrane. Fouling mitigation of the PDA/C-CNT membrane was attributed to the combined effect of electrostatic repulsions between the foulants and the conductive membrane surface along with degradation of organic compounds by electrochemical oxidation. The constant current density profile also confirmed the structural stability of the conductive layer on the membrane under both cathodic and anodic conditions. Furthermore, the fouling layer formed by membrane filtration was removed effectively by in-situ anodic cleaning. Over 80% of water permeability was recovered without losing the membrane integrity up to 3 consecutive anodic cleaning cycles.

Enhancing H2O2 production with a self-breathing gas diffusion electrode fabricated via ultrasonic impregnation and vacuum filtration

In this study, an electro-Fenton gas diffusion electrode featuring air self-respiration was fabricated by incorporating carbon nanotubes, carbon nitride, and polytetrafluoroethylene onto graphite felt. The fabrication process involved a synergistic approach of ultrasonic impregnation and vacuum filtration, establishing a gas–liquid-solid tri-phase interface both on the surface and within the electrode. This preparation method facilitates autonomous air intake, diffusing it to the tri-phase reaction interface, thereby eliminating the necessity for aeration and reducing operational costs. The optimal electrode preparation conditions were determined through Box-Behnken Design response surface experiments, leading to the enhancement of H2O2 production conditions. Under the optimized conditions, H2O2 accumulation reached 45.83 mg L−1 cm−2h−1, surpassing the performance achieved with conventional ultrasonic impregnation and vacuum filtration methods. Furthermore, the performance of self-breathing and the impact factors are explored. Finally, the electrode’s efficacy was demonstrated through the degradation of phenol and bisphenol A with concentrations of 100 mg L−1 exhibiting degradation rates of 92 % and 95 %, respectively, within 60 min.

Bio-based ionic liquid filter with enhanced electrostatic attraction for outside filtration and inside collection of viral aerosols

Hazardous biological pathogens in the air pose a significant public environmental health concern as infected individuals emit virus-laden aerosols (VLAs) during routine respiratory activities. Mask-wearing is a key preventive measure, but conventional filtration methods face challenges, particularly in high humidity conditions, where electrostatic charge decline increases the risk of infection. This study introduces a bio-based air filter comprising glycine ionic liquids (GILs) and malleable polymer composite (GILP) with high polarity and functional group density, which are wrapped around a melamine-formaldehyde (MF) resin skeleton, forming a conductive, porous GIL functionized ionic network air filter (GILP@MF). When subjected to low voltage, the GILP@MF composite efficiently captures VLAs including nanoscale virus particles through the enhanced electrostatic attraction, especially in facing high humidity bioaerosols exhaled by human body. The filtration/collection efficiency and quality factor can reach 98.3% and 0.264 Pa−1 at 0.1 m s−1, respectively. This innovative filter provides effective VLA protection and offers potential for non-invasive respiratory virus sampling, advancing medical diagnosis efforts.

Streamlined Synthesis of Clopidogrel Utilizing Magnetically Recyclable Fe3O4 Nanoparticles through the Strecker Reaction

Aim: The study explores the use of magnetite nanoparticles for eco-friendly α-aminonitrile synthesis via the Strecker reaction, aiming to provide a more efficient, cost-effective, and sustainable method. Methods: The research involves an extensive exploration of magnetite nanoparticles, belonging to the inverse spinel group, as catalysts for the Strecker reaction. The magnetic properties of Fe3O4 nanoparticles facilitate their easy removal from reaction masses using an external magnet, eliminating the need for conventional filtration or centrifugation methods. Trimethylsilyl cyanide (TMSCN) is utilized as a cyanide ion source, known for its efficiency and user-friendly characteristics, aiming to enhance the eco-friendliness of the synthesis. Results: Magnetite nanoparticles with FCC oxygen arrangement and Fe2+ and Fe3+ ions show potential applications in medical and organometallic chemistry. High saturation magnetization, low toxicity, and biocompatibility make them promising for drug delivery and MRI contrast agents. Conclusion: The research presents an environmentally friendly Strecker reaction method using Fe3O4 nanoparticles, offering a promising alternative to traditional methods for α-aminonitrile synthesis and demonstrating the potential of magnetite nanoparticles.

Investigating the sustainable performance of a nanoscale zerovalent iron permeable reactive barrier for removal of nitrate, sulfide, and arsenic

Abstract The quality of groundwater resources is at catastrophic risk. The proper performance of iron nanoparticles has made a permeable reactive barrier (PRB) an alternative to conventional filtration methods. The performance of nanozerovalent iron (nZVI) PRBs is limited by particle aggregation, instability, and phase separation, even at low iron concentrations. Therefore, the precipitation of reactive materials and a decrease in the longevity of PRB are fundamental challenges. A laboratory setup is used to compare the performance of bare nZVI and xanthan gum (XG)-nZVI + Mulch PRB to simultaneously remove nitrate, sulfide, and arsenic in groundwater. nZVI (average diameter of 35–55 nm) particles are used as reactive media. The objectives are (1) to develop a method for treating nitrate, sulfide, and arsenic simultaneously in groundwater using organic mulch and XG-nZVI; and (2) to evaluate the longevity performance of the XG-nZVI + Mulch and bare nanoparticles treatment system over 10 days. The results showed that the XG-nZVI + Mulch barrier's performance for eliminating NO3-, As, and S2− was generally improved compared to the bare nZVI barriers by 5.7, 19.2, and 10.9%, respectively. Finally, despite the need for long-term sustainability assessment, XG-nZVI PRB performance is impressive, and this stability promises to improve the longevity of nanoparticles while used in PRBs.

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.

Evaluation of BACTECTM FX Blood Culture System for Rapid Sterility Testing of Human Medicinal Solutions for Infusion

Human medicinal products for infusion should be tested for sterility at various stages of manufacturing including the final step before marketing. Conventional sterility methods recommended in pharmacopeia need a 14 days incubation period in order to get reliable analytical results. However, rapid alternative methods based on automated detection of microbial growth have the advantage of taking only 5 days for sterility testing of medicinal products which can be very important especially during pandemics and emergency conditions. The aim of the present study is to evaluate the microbial detection potential and capacity of the BACTEC FX system for the rapid sterility testing of Paracerol, a 10 mg/mL paracetamol containing pediatric medicine for infusion, and to specify time required for the detection of a variety of microorganisms. Accordingly, the results showed that there were no significant differences between the BACTEC and conventional membrane filtration methods for detecting contamination. All positive/negative controls and all samples intentionally contaminated with microorganisms were determined correctly by using both methods. BACTEC FX system detected all microorganisms including slow growers significantly faster than the membrane filtration method (p<0.05). This system can be considered as a rapid alternative over conventional sterility methods for the release of human medicinal products for infusion to the markets especially under emergency conditions. However, for each particular products, validation steps should be executed according to European Pharmacopoeia by using a broad range of microorganisms.

Miniature auto-perfusion bioreactor system with spiral microfluidic cell retention device.

Medium perfusion is critical in maintaining high cell concentration in cultures. The conventional membrane filtration method for medium exchange has been challenged by the fouling and clogging of the membrane filters in long-term cultures. In this study, we present a miniature auto-perfusion system that can be operated inside a common-size laboratory incubator. The system is equipped with a spiral microfluidic chip for cell retention to replace conventional membrane filters, which fundamentally overcomes the clogging and fouling problem. We showed that the system supported continuous perfusion culture of Chinese hamster ovary (CHO) cells in suspension up to 14 days without cell retention chip replacement. Compared to daily manual medium change, 25% higher CHO cell concentration can be maintained at an average auto-perfusion rate of 196 ml/day in spinner flask at 70 ml working volume (2.8 VVD). The auto-perfusion system also resulted in better cell quality at high concentrations, in terms of higher viability, more uniform and regular morphology, and fewer aggregates. We also demonstrated the potential application of the system for culturing mesenchymal stem cells on microcarriers. This miniature auto-perfusion system provides an excellent solution to maintain cell-favorable conditions and high cell concentration in small-scale cultures for research and clinical uses.

PM2.5 collected using cyclonic separation causes stronger biological responses than that collected using a conventional filtration method

Evaluation of the health effects of particulate matter with aerodynamic dias. ≤ 2.5 μm (PM2.5) should reflect realistic condition in ambient atmosphere. However, using conventional filtration methods, only extracts from PM2.5 collected on the filter can be analyzed and not the particle itself. Cyclonic separation is a technique that enables the direct analysis of the effects of the crude “powder form” of PM2.5 on respiratory health. Airway epithelial cells and antigen-presenting cells were exposed to PM2.5 collected during the same period using a conventional filtration method or cyclonic separation. PM2.5 collected using cyclonic separation led to a higher secretion of interleukins 6 and 8 (IL-6, IL-8) from airway epithelial cells, and IL-6, IL-1β, tumor necrosis factor-α (TNF-α) secretion, cluster of differentiation 86 (CD86), and dendritic and epithelial cells 205 (DEC205) expression on antigen-presenting cells, compared with the effects of filter-collected PM2.5. Furthermore, PM2.5 collected using cyclonic separation increased inflammatory cytokine levels and induced lung inflammation in vivo. These results suggest that crude PM2.5 collected using cyclonic separation causes stronger biological responses than filter-collected PM2.5. Hence, PM2.5 collected using cyclonic separation can be utilized for a reliable evaluation of the health effects of ambient PM2.5.

Scalable Manufacturing of MXene Films: Moving toward Industrialization

Industry-scale manufacturing techniques hold the key to the ultimate commercialization of MXene products. In Matter, Taylor, Gogotsi, and colleagues demonstrate a drop-casting method to prepare scalable and micro-patternable MXene films on hydrophobic substrates, highlighting the excellent potential for the commercial application in electromagnetic interference shielding.

Design and Validation of Passive Environmental DNA Samplers Using Granular Activated Carbon and Montmorillonite Clay

Environmental DNA (eDNA) analysis is gaining prominence as a tool for species and biodiversity monitoring in aquatic environments. eDNA shed by organisms is captured in grab samples, concentrated by filtration, extracted, and analyzed using molecular methods. Conventional capture and filtration methods are limited because (1) filtration does not capture all extracellular DNA, (2) eDNA can degrade during sample transport and storage, (3) filters often clog in turbid waters, reducing the eDNA captured, and (4) grab samples are time sensitive due to pulse eDNA inputs. To address these limitations, this work designs and validates Passive Environmental DNA Samplers (PEDS). PEDS consist of an adsorbent-filled sachet that is suspended in water to collect eDNA over time. Both extracellular and cellular DNA are captured, and the extracellular DNA is protected from degradation. The eDNA captured over time may be more representative than a grab sample. Two adsorbents, Montmorillonite Clay (MC) and Granular Activated Carbon (GAC), are tested. In laboratory experiments, MC-PEDS adsorbed five times more extracellular DNA and desorbed up to four times more than GAC-PEDS (despite high levels of eDNA loss during desorption). In microcosm and field experiments, GAC-PEDS captured over an order of magnitude more eDNA than MC-PEDS. Field results further validated PEDS as an effective eDNA capture method compared to conventional methods.

The Effect of Calcium Oxide and Aluminum Sulfate on Iron, Manganese and Color Removal at Peat Water Treatment

The availability of clean water is a basic need for human life. Peat water is well-known as acidic water (low pH), high content of Fe 2+ and Mn 2+ and colored that make it hard to remove by conventional filtration method. Treatment in batch and continuous methods by using Calcium Oxide (CaO) and aluminum sulfate Al 2 (SO 4 ) 3 ×18H 2 O result in significance reduce of iron and manganese. The batch method in particular, able to reduce iron from 3.5 ppm to 0.1 ppm (97%), manganese from 0.59 ppm to null (100%) and color from 130 TCU to 1.7 TCU. Turbidity also reduced from 33.8 NTU to 1.9 NTU whereas pH increase from 3.19 to 6.8. The continuous method in different circumstances shows iron removal from 3.35 ppm to 0.05 ppm (98.6%), manganese from 0.5 ppm to null (100%) whilst pH raised from 3.19 to 7.16 and turbidity decrease from 31.8 NTU to 1.14 NTU. Both results fulfill the water quality standard required by Permenkes No. 416/Menkes/1990

High‑throughput and continuous flow isolation of rare circulating tumor cells and clusters in gastric cancer from human whole blood samples using electromagnetic vibration‑based filtration.

Circulating tumor cells (CTCs) or CTC clusters are considered as suitable and relevant targets for liquid biopsy as they more accurately indicate cancer progression, the therapeutic effects of treatment and allows for monitoring of cancer metastasis in real-time. Among the various methods for isolating CTCs, size-based filtration is one of the most convenient methods. However, cell clogging makes the filtration process less efficient. In the present study, an electromagnetic vibration-based filtration (eVBF) device was developed that efficiently isolated rare CTCs and CTC clusters from clinical blood samples of patients with gastric cancer. Using human blood samples spiked with human gastric cancer cells, the parameters of this device such as vibrating amplitude and flow rate were optimized. Putative CTCs were detected using a conventional filtration method and the eVBF device from the peripheral blood samples of patients with gastric cancer. Continuous flow isolation of CTCs was evaluated by a simulated blood flow system. The eVBF device utilized the electromagnetic force to generate a periodic vibration that prevented the cell clogging and improved the filtering efficiency. The optimized eVBF device with the high-amplitude vibration exhibited a recovery efficiency of 80–90% from whole blood samples spiked with 100 or 1,000 gastric cancer cells per ml. Using the eVBF device, CTCs were detected in 100% of patients (10/10) with gastric cancer, and the positive detection rate of the eVBF device was 30% higher compared with the conventional filtration method. Furthermore, CTC clusters were detected in 40% (4/10) of CTC-positive patient samples, and the integrity of CTC clusters was preserved using the eVBF device. The eVBF device allowed for high-throughput (1 ml/min) and continuous flow isolation of CTCs without the addition of any antibodies, any chemical reagents or any pretreatment processes. Thus, the eVBF device provides an efficient tool for isolating rare CTCs and CTC clusters from patients with cancer, highlighting its potential for use in cancer diagnosis, treatment and cancer biology research.

Integration of photo-oxidation based on UV/Persulfate and adsorption processes for arsenic removal from aqueous solutions

This study aimed to evaluate the efficiency of integrating photo-oxidation process based on UV-persulfate and adsorption on arsenic (As) removal from aqueous environments. The effects of different parameters were studied on a laboratory scale by means of a cylindrical reactor containing a UV-C lamp (15 W). After passing the oxidized samples from the adsorption column, the oxidation and arsenic removal rates were measured using UV–visible spectrophotometer and inductively coupled plasma (ICP), respectively. Response surface methodology (RSM) based on Box Behnken design was applied to evaluate the effect of independent variables on the arsenic oxidation efficiency.The highest As removal efficiency (96%) was obtained in the oxidation phase under optimum pH 3, initial As concentration of 0.5 mg L−1, and persulfate concentration of 14 mM L−1. Moreover, in the adsorption phase, the optimal conditions were occurred for pH 6.5 and the equilibrium time of 75 min. The Langmuir isotherm was the best fitted model with an R2 value of 0.97 compared to Freundlich and Temkin isotherms. Oxidation of As (V) was determined through RSM based on Box Behnken design (R2>0.934).Use of UV-activated persulfates can greatly increase the As oxidation efficiency. This process has two advantages: transformation of toxic and dangerous form of arsenic into its low-risk one and better removal of As(V) than the conventional filtration methods.

Under-oil superhydrophilic salt particle filter for the efficient separation of water-in-oil emulsions.

In this study, a surfactant stabilized water-in-oil emulsion has been successfully separated by using only NaCl particles as a filter. This novel strategy is suitable for continuous filtration of a large quantity of water-in-oil emulsion with a volume of up to 1500 mL. Moreover, a filtration flux of up to 40 000 L m-2 h-1 is reported, which is around ten times higher than the conventional filtration methods.

Impact of Nonadsorbed Ionomer on Viscosity of Catalyst Inks for Polymer Electrolyte Fuel Cells

Abstract In a catalyst ink for polymer electrolyte fuel cells (PEFCs), some of the ionomer is adsorbed on the carbon-supported Pt catalyst (Pt/C), which enhances the ink stability, while the rest is dispersed in the solvent as a nonadsorbed ionomer. To clarify the effect of nonadsorbed ionomer on the ink viscosity, the amount of nonadsorbed ionomer in the catalyst ink was evaluated by small-angle neutron scattering (CV-SANS). At high-shear viscosity, the nonadsorbed ionomer was found to act as ionomer solution described by the Huggins equation. Moreover, comparison with the CV-SANS results revealed that the conventional filtration method overestimates the amount of nonadsorbed ionomer in a catalyst ink.

A general and facile method for preparation of large-scale reduced graphene oxide films with controlled structures

Graphene or reduced graphene oxide films (rGOFs) can be prepared by a number of methods including chemical vapor deposition (CVD), filtration, and spin-coating for a variety of applications. However, controlling their surface morphologies and microstructures to meet the requirements of specific applications is still a great challenge. Here, controlled microstructure of large-size rGOF with good electrical and thermal conductivities as well as high sorption ability is produced through a heating-assisted spray method. By simply tuning the heating temperature, the smooth surface and close-packed layered structure of rGOF can be changed to rough surface and porous structure. Impressively, the rapid preparation of rGOF with area as large as ∼216 cm2 in only 6 h has been successfully achieved, which is significant since normally it takes several days to prepare a rGOF with small area of ∼10 cm2 by using conventional filtration method. More importantly, our rGOFs show promising applications in oil sorption, supercapacitors, and thermally/electrically conductive films.

Recovering cellular biomass from fluids using chemical flocculation.

We developed an efficient, scalable and inexpensive method for recovering cellular biomass from complex fluid matrices that cannot be processed using conventional filtration methods. The method uses chemical flocculation with iron oxyhydroxides, is capable of recovering greater than 90% of cellular biomass from fluids with more than 103 cells ml-1 , and was validated using both mock communities and field samples. High quality DNA can be readily extracted from iron flocs using standard soil extraction kits. We applied chemical flocculation to fracing fluids from British Columbia, Canada and recovered a diversity of microbial taxa including abundant members of the Epsilon- and Deltaproteobacteria previously recovered from shale gas operations in the United States. Application of chemical flocculation presents new opportunities for scalable time-series monitoring and experimentation on complex fluid matrices including microbial community profiling and shotgun metagenomics over gas production well completion cycles.

Effects of bacterial pollution caused by a strong typhoon event and the restoration of a recreational beach: Transitions of fecal bacterial counts and bacterial flora in beach sand

To determine the effects of bacteria pollution associated with a strong typhoon event and to assess the restoration of the normal bacterial flora, we used conventional filtration methods and nextgeneration sequencing of 16S rRNA genes to analyze the transition of fecal and total bacterial counts in water and core sand samples collected from a recreational beach. Immediately after the typhoon event, Escherichia coli counts increased to 82 CFU/100 g in the surface beach sand. E. coli was detected through the surface to sand 85-cm deep at the land side point (10-m land side from the high-water line). However, E. coli disappeared within a month from the land side point. The composition of the bacterial flora in the beach sand at the land point was directly influenced by the typhoon event. Pseudomonas was the most prevalent genus throughout the sand layers (0–102-cm deep) during the typhoon event. After 3 months, the population of Pseudomonas significantly decreased, and the predominant genus in the surface layer was Kaistobacter, although Pseudomonas was the major genus in the 17- to 85-cm layer. When the beach conditions stabilized, the number of pollutant Pseudomonas among the 10 most abundant genera decreased to lower than the limit of detection. The bacterial population of the sand was subsequently restored to the most populous pre-event orders at the land point. A land-side beach, where users directly contact the sand, was significantly affected by bacterial pollution caused by a strong typhoon event. We show here that the normal bacterial flora of the surface sand was restored within 1 month.

Functional coupling between adenosine A1 receptors and G-proteins in rat and postmortem human brain membranes determined with conventional guanosine-5'-O-(3-[35S]thio)triphosphate ([35S]GTPγS) binding or [35S]GTPγS/immunoprecipitation assay.

Adenosine signaling plays a complex role in multiple physiological processes in the brain, and its dysfunction has been implicated in pathophysiology of neuropsychiatric diseases such as schizophrenia and affective disorders. In the present study, the coupling between adenosine A1 receptor and G-protein was assessed by means of two [35S]GTPγS binding assays, i.e., conventional filtration method and [35S]GTPγS binding/immunoprecipitation in rat and human brain membranes. The latter method provides information about adenosine A1 receptor-mediated Gαi-3 activation in rat as well as human brain membranes. On the other hand, adenosine-stimulated [35S]GTPγS binding determined with conventional assay derives from functional activation of Gαi/o proteins (not restricted only to Gαi-3) coupled to adenosine A1 receptors. The determination of adenosine concentrations in the samples used in the present study indicates the possibility that the assay mixture under our experimental conditions contains residual endogenous adenosine at nanomolar concentrations, which was also suggested by the results on the effects of adenosine receptor antagonists on basal [35S]GTPγS binding level. The effects of adenosine deaminase (ADA) on basal binding also support the presence of adenosine. Nevertheless, the varied patterns of ADA discouraged us from adding ADA into assay medium routinely. The concentration-dependent increases elicited by adenosine were determined in 40 subjects without any neuropsychiatric disorders. The increases in %Emax values determined by conventional assay according to aging and postmortem delay should be taken into account in future studies focusing on the effects of psychiatric disorders on adenosine A1 receptor/G-protein interaction in postmortem human brain tissue.