Fabrication and regeneration of MnCoOx-PDA@PPS catalytic filter materials for low-temperature selective catalytic reduction of NO with NH3

Nature-based solutions (NBSs), such as green roofs, are among the most effective ways to manage urban stormwater, improve building energy efficiency, and adapt to climate change. However, conventional green roofs confront several restrictions related to stormwater drainage, retention capacity, irrigation demand, and pressure on urban water networks during dry periods. This study proposes and experimentally validates a novel system applicable to green roofs and other NBS, including streetside planting systems and vegetated sports grounds. The novelty of the proposed system lies in a double-layer design, the integration of filters within soil substrate to enhance short-term stormwater retention and controlled drainage, and passive subsurface capillary irrigation with cords to improve irrigation efficiency. Infiltration tests showed that filter hydraulic conductivity strongly depends on pore size, with measured infiltration rates ranging from 0.01 mm/min (ceramic, 0.1 μm) to 20 mm/min (polypropylene, 50 μm). The results showed that filter material and pore size significantly influence infiltration behaviour and short-term storage capacity. When integrated with the soil substrate, the combined system exhibited infiltration rates of 0.8–2.0 mm/min, decreasing as hydraulic head declined. Capillary rise experiments demonstrated a maximum vertical rise of 32 cm and horizontal rise of 39 cm for polyester cords (6 mm width), confirming the feasibility of passive subsurface irrigation through stored runoff reuse without external energy. The experiments were conducted at a laboratory scale (25 × 25 cm) as a proof-of-concept validation. Finally, the study results demonstrate the feasibility of the proposed system as a multifunctional NBS solution that enhances stormwater retention while enabling passive irrigation using retained runoff.

We present a DNA extraction protocol for atmospheric bioaerosol samples collected on glass-fiber filters widely used in air quality monitoring. The protocol produces high-quality molecules suitable for third-generation sequencing and other applications. The initial protocol was developed and applied in a Bioaerosol campaign performed in Finland and Lithuania in 2021 using low-volume air samplers, which posed stringent requirements to the method sensitivity. The protocol included a phenol-chloroform step for DNA purification, thus involving aggressive reagents; it was also quite time consuming and laborious. The present study advances this protocol to exclude the use of hazardous chemicals by using the SPRI paramagnetic bead technology for DNA purification and compares it to several commercial extraction methods. Despite trailing in efficiency to the initial method, the new development proved to be more efficient than several column-based commercial kits. The updated protocol was effective for a relatively high mass ratio of biological material to filter material: 70 nanograms of potential DNA on the filter to one milligram of filter fiber, as detected with the initial phenol-chloroform-based method. However, the new approach was not effective for a mass ratio lower than 15 nanograms of potential DNA per milligram of the filter material. The applicability of the new protocol for preparation of samples for the 3rd generation sequencing was confirmed by subsequent processing of the samples with the Oxford Nanopore (ONT) GridION sequencer.

Climate-driven increases in wildfire activity threaten urban air quality both through long-range smoke transport from rural fires and direct exposure as the wildland–urban interface expands. Filters installed in Heating Ventilation and Air Conditioning (HVAC) systems represent a critical first barrier for limiting indoor exposure to smoke-derived particulate matter. In this study, we evaluated the smoke filtration performance of more than seventeen commercially available HVAC filter media spanning efficiency ratings from 10 to 15 (Minimum Efficiency Reporting Value, MERV) using pine needle combustion aerosols as a wildfire smoke proxy, quantifying size-resolved filtration efficiency, pressure drop, and temporal performance changes. The results show that charged polymer media across all tested MERV classes exhibited pronounced and rapid losses in smoke removal efficiency under exposure, despite minimal changes in airflow resistance. In contrast, mechanical media demonstrated greater stability in filtration efficiency over time but experienced considerable increases in pressure drop. Scanning electron microscopy revealed distinct smoke deposition morphologies on filter fibers, providing insight into mechanisms underlying performance degradation. Collectively, these findings indicate that filtration performance under wildfire smoke conditions is not adequately captured by current standards based on inorganic test aerosols. The results underscore the importance of advancing filter material evaluation and developing smoke-relevant testing approaches to better support indoor air quality, energy-aware building operation, and urban resilience under climate-driven wildfire smoke exposure.

The regeneration of air filter materials can extend the service life of filters, and also reduce resource waste and air pollution caused by replacements, which directly lower carbon emissions. This paper focuses on reduced graphene oxide (rGO) filter materials, investigating the effects of ultrasonic cleaning utilizing water, lemon acid, and a cleaning agent. Regeneration performances were also tested and discussed and analyzed. Results show the synergistic effect of the cleaning agent and ultrasonic cleaning yields the most optimal regeneration performance. Compared to the water and lemon acid, filtration efficiency of rGO materials for PM10, PM2.5, and PM1.0 increased by 2.0%~12.15% and 0.42%~7.13%, 0.04%~5.67% and 0.03%~2.35%, and 0.02%~3.47% and 0.16%~2.02%, respectively. Filtration efficiency recovery rates for PM10, PM2.5, and PM1.0 using the cleaning agent exceeded 70%. Counting filtration efficiency exhibited significant changes for particle sizes from 0.265 to 1.0 μm. The resistance after water cleaning was higher than that of cleaning agent cleaning and lemon acid cleaning. After 10 cleaning cycles, the cleaning agent exhibited QF values that were 0.0012 Pa-1, 0.0003 Pa-1, and 0.0001 Pa-1 higher for PM10, PM2.5, and PM1.0, respectively, compared to the water, and 0.0007 Pa-1, 0.0001 Pa-1, and 0.0001 Pa-1 higher compared to the lemon acid. It provides data references for the efficient regeneration of rGO materials and promotes the green application of air filter materials.

Fabrication and properties of air filter materials with fluffy multi-scale micro/nano bimodal fibers via multi-nozzle solution blow spinning

Affinity capture of nanoplastics and their thermogravimetric quantification on plasma polymer coated filters.

The increasing number of motorcycles in Indonesia contributes to air pollution, including exposure to particulate matter and ultrafine particles that may affect human health (Schraufnagel, 2020; Masruroh, 2015). This study developed and evaluated ORFIL, a natural air filter made from cocopeat (coconut husk waste) and rice straw, to reduce motorcycle exhaust emissions. The filter material was prepared by dehydrating 70 g cocopeat and 70 g straw for 48 hours, grinding each into coarse powder, mixing them, and packing the mixture inside a factory filter frame using tulle fabric as a retaining layer. Emission performance was tested on one motorcycle (motorcycle X) by comparing the factory-installed foam filter and ORFIL using measured exhaust parameters (CO, HC, CO₂, and O₂). The ORFIL filter produced lower emissions than the factory filter: CO decreased from 0.04% to 0.027%, HC decreased from 19 ppm to 15 ppm, and CO₂ decreased from 0.6% to 0.48%, while O₂ increased from 20.41% to 22.2%. These results indicate that cocopeat and rice straw have practical potential as low-cost natural filter media, consistent with prior findings on coconut fiber and straw-based filtering materials (Lay & Pasang, 2003; Wahyuningrum et al., 2014; Surjosatyo, 2020).

This study investigates the use of carbon nanotubes (CNTs) in the development of a filter capable of capturing toxic and carcinogenic compounds found in cigarette smoke dispersed in the environment. The aim is to contribute to the reduction in passive exposure to these substances, with potential benefits for public health and air quality. Carbon nanotubes were selected for their exceptional adsorption properties, attributed to their high specific surface area and porous structure. The material’s adsorptive performance was evaluated based on the quantity used, to determine the optimal mass that ensures the best filtering capacity. To test the system, an experimental setup was assembled to simulate real-world smoke emission conditions. Filters containing CNTs were subjected to gravimetric analysis to measure the amount of retained substances, and to gas chromatography to identify the adsorbed chemical compounds. The results confirm the potential of carbon nanotubes as an advanced filtering material, paving the way for robust solutions to mitigate the environmental impact of secondhand smoke. The results indicate that CNT-based filters, particularly those containing 0.06 g of material, are highly effective in retaining several toxic components of cigarette smoke, including nicotine. This configuration achieves a strong reduction in harmful organic species while using a moderate amount of adsorbent, suggesting a promising selectivity of CNTs toward the most hazardous molecules.

This study focused on evaluating the effectiveness of different filter media including activated carbon, Pyrolox and Greensand in improving water quality based on key parameters such as color, turbidity, dissolved oxygen, total dissolved solids, pH, hardness, and sludge density index. Preliminary results showed that each filter material had its own advantages. Specifically, activated carbon showed superior performance in removing color (8.3 TCU–9.233 TCU) and turbidity (0.5 NTU–0.767 NTU), while Pyrolox showed the highest efficiency in reducing dissolved oxygen in the range of 4.657–6.85 mg/L. Notably, Greensand was recorded as the best filter material in reducing sludge density index (3.52 ± 0.252), an extremely important factor for membrane filtration systems. The study also found that these filter media had no significant impact on pH, total dissolved solids and hardness of water. In addition, another important finding is that the use of filters with smaller pore sizes significantly improves color removal efficiency. These findings provide valuable data for the selection and optimization of water treatment systems to meet diverse water quality requirements in preparation for reverse osmosis desalination.

Abstract Carbon monoxide (CO) in cigarette smoke poses significant human health risks, and merely reducing tar content cannot achieve tobacco harm reduction. Developing innovative filter materials that effectively convert CO at 60–70°C (cigarette combustion temperature) is crucial. Carbon nanotubes (CNTs) are promising carriers for low‐temperature CO catalytic oxidation due to their high conductivity, large specific surface area, excellent thermal stabilit, and spatial confinement effect. This paper systematically reviews research progress on CNT‐based metal catalysts for this purpose. It describes synthesis methods of supported catalysts (active components dispersed on CNT outer surfaces) and confined catalysts (active components encapsulated in CNT hollow interiors). Compared with graphene oxide‐based and activated carbon‐based catalysts, CNT‐based ones exhibit superior low‐temperature catalytic activity. Key factors regulating performance (active component particle size, oxidation state, CNT surface functional groups, interfacial electronic interactions, hydrophilicity/hydrophobicity) and reaction mechanisms (L‐H, M‐K, E‐R) are elucidated, providing theoretical and technical support for tobacco harm reduction and industrial application of low‐temperature CO catalysis.

Air pollution has emerged as one of the most pressing environmental challenges, primarily driven by rapid industrialization and climate-related phenomena. Within this context, nanofiber-based filter materials offering high particle capture efficiency and low pressure drop (ΔP) play a crucial role in ensuring access to clean air. In this study, nanofibrous filter surfaces based on thermoplastic polyurethane (TPU) were fabricated via the melt-blowing (MB) technique a solvent-free and high-throughput production method. The experimental design was structured using a Taguchi L9 orthogonal array, considering three processing parameters at three levels each: feeding rate (1, 5, and 10 rpm), die (nozzle) temperature (220, 240, and 260 °C), and air pressure (1, 2, and 3 bar). The morphological characteristics of the produced nanofibers were examined through scanning electron microscopy (SEM). Their AFDs, filtration efficiencies, pressure drops (ΔP), air permeabilities, and quality factors (QFs) were systematically compared. The sample produced under the optimal conditions -1 rpm feeding rate, 260 °C die temperature, and 3 bar air pressure- demonstrated the best performance, achieving a filtration efficiency of 82.12% and a ΔP of 95 Pa, with an average fiber diameter (AFD) of 423 ± 47 nm. Moreover, this optimal sample was subjected to mechanical strain levels of 5%, 10%, and 20%, and successfully preserved its functional integrity, maintaining a filtration efficiency of 71.44% even at 20% elongation. These findings highlight the potential of the melt-blown process as an environmentally friendly, rapid, scalable, and solvent-free method to produce high-performance TPU based nanofibrous air filters.

Zeolites enriched with such “biocidal” metals as silver, copper and zinc exhibit antimicrobial activity and can be used as disinfectant filter materials and fillers. Zeolite enrichment is carried out by exchanging cations of “biocidal” metals with compensating cations under various conditions, as a result of which not only the cationic composition but also the porous structure of the zeolite changes. Enrichment of heulandite-bearing tuff from the Dzegwi-Tedzami deposit (Eastern Georgia) with Cu2+ and Zn2+ ions was carried out by treatment in solutions of the copper and zinc chlorides (“liquid” ion exchange) and by the “solid-state” ion exchange method. It has been found that “liquid” ion exchange is more effective for enriching heulandite with zinc, and as a result of ion exchange, the crystal structure of heulandite is preserved, but changes in the chemical composition of the zeolite affect its porosity. Filling of micropores with water molecules does not depend on the presence of copper and zinc ions, whereas as a result of enrichment the number of water molecules adsorbed in large pores increases significantly. The volume of micropores calculated from the low-temperature (77 K) nitrogen adsorption-desorption isotherms and the specific surface area calculated using the Brunauer-Emmett-Teller model increase as a result of enrichment. Analysis of the mesopore system using the Barret-Joyner-Halenda model shows that the average mesopore diameter increases slightly (from 17.2 to 21.5 nm), while as a result of “liquid” ion exchange, the volume of mesopores with a diameter of less than 180 nm decreases and pores with a diameter of 4 nm become predominant, whereas as a result of “solid” ion exchange, the volume of mesopores increases, and their distribution by pore size depends on the nature of the absorbed metal.

In this study, the physicochemical properties of domestic washing machine graywater were determined, and the treatment performance of granular activated carbon (GAC) was evaluated in a laboratory setting. Graywater samples were collected using different washing programs and analyzed for key parameters such as pH, electrical conductivity, suspended solids, chemical oxygen demand (COD), surfactants, total phosphate, and total nitrogen. Adsorption experiments conducted at different GAC doses (0.5–4 g/L) and contact times of 30–120 minutes revealed that the optimum conditions were 4 g/L GAC and 120 minutes of contact time. Under these conditions, COD removal was 32% and surfactant removal was 38%. Kinetic analyses showed a high fit to the pseudo-second-order model (R²=0.98), and isotherm studies revealed that the Freundlich model reflects heterogeneous surface properties. In conclusion, the low removal rates obtained with GAC indicate that the current method is inadequate for the treatment of washing machine graywater and that the design and use of more effective new filter materials are needed.

Accurate analysis of trace elements in particulate matter (PM) emitted by brake systems critically depends on the filter selection and handling processes, which can significantly impact analytical results due to contamination and elemental interference from filter elemental composition. This study systematically evaluated two widely used filter types, EMFAB (borosilicate glass microfiber reinforced with PTFE) and Teflon (PTFE), for their suitability in the trace element determination of brake-wear PM10 collected using a tribometer set-up. A total of twenty-three PM10 samples were analyzed, encompassing two different friction materials, to thoroughly assess the performance and analytical implications of each filter type. Filters were tested for their chemical background, handling practicality and potential contamination risk through extensive elemental analysis by inductively coupled plasma–optical emission spectrometry (ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS). Additionally, morphological characterization of both filter types was conducted via scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) to elucidate structural features affecting particle capture and subsequent analytical performance. Significant differences emerged between the two filters regarding elemental interferences: EMFAB filters exhibited substantial background contribution, particularly for alkali and alkaline earth metals (Ca, Na, Mg and K), complicating accurate quantification at trace levels. Conversely, Teflon filters demonstrated considerably lower background but required careful manipulation due to their structural fragility and the necessity to remove supporting rings, potentially introducing analytical variability. Statistical analysis confirmed that the filter material significantly affects elemental quantification, particularly when the collected PM10 mass is limited, highlighting the importance of careful filter selection and handling procedures. Recommendations for optimal analytical practices are provided to minimize contamination risks and enhance reliability in trace element analysis of PM10 emissions. These findings contribute to refining analytical methodologies essential for accurate environmental monitoring and regulatory assessments of vehicular non-exhaust emissions.

The purpose of the work was to study the possibility of using sorbents of plant origin (native and chemically modified wood sawdust of various species) as filter materials for the neutralization of wastewater containing polychlorinated biphenyls (PCBs). Native samples of sawdust from Scots pine (Pinus sylvestris) and linden (Tilia europaea) wood with a particle size of 0.75–2.00 mm, as well as Siberian cedar (Pinus sibirica) shells with a particle size of 0.55–0.75 mm, which are waste wood processing, have been studied as an alternative to active carbons (AC). The sorption properties of lignocellulose-containing sorbents were studied in a static mode using the example of sorption of both the sum of PCBs and groups of PCB congeners from aqueous media. The concentration of PCBs in model aqueous solutions before and after sorption was determined by gas chromatography with flame ionization detection. It has been shown that 100% recovery of PCBs is achieved in 4 days when using pine sawdust (comparable to activated carbon), and in 7 days in the presence of pine nut shells. The use of pine sawdust is more effective for removing highly chlorinated PCBs from water, while AC is preferable for the extraction of di- and trichlorinated biphenyls. For the sorbent based on linden sawdust, the degree of PCB recovery reached 94% only after 14 days. It has been established that chemical modification of natural sorbents with a 5N HNO3 solution increases the degree of PCB extraction by linden sawdust. It has been proven that the PCB extraction efficiency remains up to 91–97% upon repeated use of the studied sorbents without their corresponding regeneration. When studying the desorption of PCBs after accumulation over a certain period (from 1 to 14 days) in the composition of sorbents, it was found that the degree of desorption of PCBs from AC was 10%, from pine nut shells – 30%, from native and chemically modified pine and linden sawdust - 46 and 65% respectively. Linden wood sawdust with a particle size of 0.75–2.00 mm can be recommended as a sorption material most suitable for implementing the “sorption-desorption” cycle of PCBs.

Well water often contains elevated levels of iron, manganese, hydrogen sulfide, hardness salts, nitrates, sulfates, and chlorides. In some regions, the total dissolved solids content is also significantly high. Modern membrane technologies such as reverse osmosis and nanofiltration offer effective solutions for reducing mineral content, removing nitrates, and producing water suitable for both drinking and industrial use. However, prior to membrane treatment, it is critical to remove iron, manganese, and hydrogen sulfide, as these compounds contribute to the formation of inorganic fouling on membrane surfaces, which leads to premature membrane failure. An optimal approach involves pretreatment with pressure filters using catalytic filtration media, followed by antiscalant dosing before the membrane system. While catalytic media have been used in water treatment for many years, most manufacturers do not provide clear and practical guidelines for their use under varying conditions. Calculations were performed for the selection and configuration of filters with catalytic materials Greensand Plus® and Filter Ox®. Optimal parameters and operational stages of the filters were established. The impact of down flow and up flow regeneration on the quality of treated water, filter cycle duration, and filtration rate was investigated. Pilot tests were conducted on a unit with a capacity of 1.0 m³/h using well water from the city of Irpin Ukraine. Test results demonstrated the advantages of up flow regeneration over down flow regeneration, as well as the superiority of the Greensand Plus® filtering material. The results obtained enable the use of catalytic materials prior to membrane technologies to prevent fouling.

The pursuit of sustainable livestock farming and environmentally responsible agricultural practices has spurred the development of innovative and affordable wastewater treatment technologies. This study investigates new biological treatment approaches that integrate the complementary processes of filtration, biosorption, and biodegradation to enhance eco-friendly wastewater management. A novel treatment concept was developed, representing a modern modification of the biosorption method that combines the oxidation of organic pollutants with ammonium reduction by an immobilized biocenosis, achieved through controlled aeration zones within a single bioreactor. An experimental facility was constructed and implemented at Feldman EcoPark (Kharkiv region, Ukraine) to serve the wastewater treatment needs of a contact zoo and animal rehabilitation center. The installation consists of a drainage treatment column with filter materials and a bioreactor - rotating biological contactor (RBC) containing microbial communities immobilized on inert carriers. Operational testing demonstrated high treatment efficiency, achieving up to 97.1% reduction in chemical oxygen demand (COD) and 85.6% removal of nitrogen compounds. Among the tested methods, biosorption proved particularly advantageous due to its cost-effectiveness, operational simplicity, and adaptability. The study also evaluated recycled polymers, including post-consumer PET, polycarbonate, and LDPE, as sustainable functional materials supporting filtration and microbial growth in wastewater treatment systems.

In India, crop land has become increasingly reliant on groundwater, causing groundwater decline. Rainwater harvesting (RWH) for the aquifer is one potential alternative to addressing the groundwater issue. This is mirrored in a rise in water supply expansion plans. Which includes RWH as a key building component. Assessing the overall impact of these construction projects is crucial to achieving a beneficial net effect on groundwater both economically and within the watershed. As a result, the focus of this analysis is on the meteorological effects of RWH on recharge in rural regions, at both the local (individual structure) and watershed levels. There is relatively limited field data on the claimed positive outcomes at the small scale, and a variety of proposed adverse effects have been identified at the watershed scale. The watershed level is now largely overlooked in field studies and is typically only addressed through modelling. Modelling is seen as a potential method for augmenting constrained data sets, and situation studies will be used to examine possible dangers. Unfortunately, many previous RWH model simulations had a specific scope or were based on insufficient information. To be coupled with increased data gathering, different modelling tools must be established. New opportunities can include growing use of spatial data and improved analytical techniques. In contrast, several test items are suggested to evaluate the meteorological and other impacts of RWH as part of water harvesting at the local and district levels. Additionally, with the Earth acting as a natural filtering material, it will enrich the rainwater with minerals, resulting in water that exhibits freshwater qualities.

Introduction. The current state of filtering technology has been defined by the growing requirements for the purity of technical fluids, the enhanced durability of filter elements, and the advances of modern nanotechnology, particularly with respect to magnetic properties.Problem Statement. The incorporation of nanomagnetic components based on iron oxides has had the potentialto fundamentally transform the structure and functional parameters of porous materials used in filter devices. However, no technology has yet enabled the adjustment of these parameters under the influence of a magneticfield.Materials and Methods. The materials employed are porous structures based on polyurethane foams saturated with nanocomposites of divalent and trivalent iron oxides. Experimental methods have included measurements of magnetic induction and the throughput capacity of porous elements, while theoretical methods have involved the analysis of magnetic forces and the application of hydrodynamic equations for channel flows.Results. Porous filter materials infused with magnetic nanocomponents consisting of mixed divalent and trivalent ferric oxides have demonstrated structural changes under the influence of a magnetic field. The proposed system of electromagnetic control for filters filled with magnetic nanocomposites has allowed the adjustment of their structural parameters. When the magnetic field induction has been varied from 0 to 0.2×10–³ T, the filter bandwidth increases 1.7—1.9 times, corresponding to a change in the average pore diameter by a factor of 1.24—1.17. This principle has enabled both the increase of filter throughput as clogging occurs and the adjustment of pore sizes to selectively retain harmful components of predetermined dimensions.Conclusions. The study has confirmed the feasibility of regulating the structural parameters of porous filteringmaterials by incorporating magnetic nanocomponents. Electromagnetic control has made it possible to achieveadjustable filter capacity tailored to specifi c operational requirements.