Filtration Purification Research Articles

INVESTIGATION OF THE EFFECT OF AN IMPREGNATING AGENT ON THE SORPTION CHARACTERISTICS OF A CARBON-SILICON SORBENT

Efforts to control the spread of airborne respiratory pathogens in enclosed public spaces have become particularly relevant due to the COVID-19 pandemic. One of the control methods is the use of bactericidal filters for ventilation air purification systems in enclosed public spaces in order to effectively remove pathogenic microorganisms from the air environment. The impregnated sorbents developed in this work are used as a filter material. The purpose of the work is investigation of the effect of an impregnating agent on the sorption characteristics of a carbon-silicon sorbent used as the basis of bactericidal filters for air purification. Methodology. It has been established that carbonation makes it possible to obtain more durable carbon sorbents with a high specific surface area. According to the results of X-ray dispersion analysis, carbonized rice husk contains 86.57% carbon and 1.75% silicon. Results and discussion. The effect of the carbonization process on the specific surface area and specific volume of the initial sorbent has been studied. The specific surface area was measured and the pore size of impregnated carbon-silicon sorbents was measured. The study of the effect of impregnating agents on the sorption characteristics of a carbon-silicon sorbent showed that an increase in the concentration of chlorhexidine and tannin in the composition leads to an increase in the specific surface area and specific pore volume of sorbents. Conclusion. It was found that the impregnation of a carbon sorbent leads to an increase in the specific surface area from 320 g/m2 to 350 g/m 2, the specific pore volume from 0.1256 cm3/g to 0.1399 cm3/g.

A high-flux, photocatalytic wood-derived filter for high-efficiency water purification

Wastewater purification has evolved into a global problem in the face of increasing scarcity of freshwater resources. Photocatalysis technology possesses prominent advantages in treating pollutants in water because of its low cost and mild reaction conditions, which provides an effective way to treat multiple pollutants and reduce membrane fouling. Herein, we combine photocatalysis technology with filtration technology via in situ reduction Bi0 with Bi2SiO5 strategy incorporating a carbonized wood filter to synthesize carbon/Bi2SiO5@Bi bi-functional composite. Thus, simultaneous filtration and photocatalytic degradation of Rhodamine B and tetracycline were achieved. After filtrating for 30 min, the degradation rate of RhB and TC were 94.23 % and 81.39 %, respectively. Especially, the flux of RhB and TC were up to 2162.16 L m−2 h−1 and 1811.32 L m−2 h−1. In addition, the composite filter also has good recyclability and reusability, after 5 cycles, the degradation efficiency of RhB remains at 91 %. This study utilized photocatalytic technology combined with membrane filtration technology to successfully solve the contradiction between catalytic efficiency and water flux, which realized rapid and dynamic removal of organic pollutants from water. Besides, the use of carbonized wood-based materials provides a potential biomass technology for the preparation of bifunctional photocatalytic filters.

SO2 removal performance and breakthrough prediction of activated carbon-based chemical filters for electronics cleanroom air purification

Electronic cleanrooms have strict control requirements for SO2 concentration due its significant influence on product yield, and application of chemical filters is the main measure of SO2 control. In this study, 8 activated carbon (AC)-based chemical filters were collected and tested for their SO2 purification performance and resistance. These filters had very similar initial efficiencies (all >95 %) but large differences in 20 % breakthrough adsorption capacity (49–294 g at 9 ppm and 0.35 m/s). The adsorption capacity is found to be positively correlated with pleat density, which is a main structural parameter of pleated chemical filter. Meanwhile, the filter resistance (9.3–34 Pa at 0.35 m/s) demonstrates a decreasing and then increasing trend with increasing pleat density. This indicated the existence of an optimal range of pleat numbers that can be used to achieve a balance between resistance and adsorption capacity. A comprehensive performance evaluation index (Z′-index) is proposed for assessing the integrated resistant and adsorption capacity performance of chemical filters (19–210 g/W for 8 samples). A lumped parameter model was proposed for predicting the breakthrough curves at low concentration based on the traditional semi-empirical breakthrough models. The prediction deviation of the breakthrough curve at real cleanroom scenario (2 ppb) is less than 15 %. In addition, a rapid filter life prediction method based on filter design parameters is developed from the lumped parameter model. This work helps the understanding of the impact of filter structure parameters on performance and facilitate the development of high-performance chemical filters for SO2 contaminant control in electronic cleanrooms.

Polylactic acid-based composite filter with multi-gradient structure developed for high-efficiency particulate matter filtration and NH3 purification

Particulate matter (PM), ammonia (NH3) and other polluted gases emitted from animal feeding operations have emerged as significant risks to workers, surrounding residents, and the regional environment. Therefore, the development of air filters capable of simultaneously filtering PM and adsorbing toxic gases is particularly important. In this study, a three-layer gradient structure nanofiber filter was prepared by electrospinning technology, consisting of fluorinated Polylactic acid (PLA)/SiO2 as the outer layer, PLA nanofibers as the middle layer, and PLA/UiO-66-NH2 as the inner layer. This gradient structure of composite filter featured gradually decreasing pore sizes, exhibited optimal air filtration performance compared to PLA filter and commercial glass fiber filter. At 5.3 cm/s flow rate, the composite nanofiber filter achieved high filtration efficiency (99.15 % for PM0.5) and low pressure drop (89.65 Pa). Furthermore, the composite nanofiber filter exhibited highest dust holding capacity, indicating longer service life. It also featured excellent self-cleaning capabilities, allowing for reuse after simple water rinsing. Additionally, the results of ammonia (NH3) adsorption tests demonstrated the prepared composite filter’s highest adsorption capacity for NH3. Therefore, this work enhanced the application potential of high-performance air filters in the removal of PM pollution and hazardous gases.

3D hydrophobic wood membrane with micro-nano baffle structure for multifunctional air purification filters: “Kill three eagles with one arrow”

Air pollution has presented an imminent threat to the world. Multifunctional filters with high filtration efficiency, low pressure drop, moisture resistance, antibacterial properties, and renewability are urgently needed to be developed. In this study, multifunctional wood filters are innovatively designed with a baffle structure combining macroscopic structural design and microscopic in-situ synthesis of silver nanoparticles (Ag NPs). The filter has excellent particle removal efficiency (PM0.3, 98.5 %), exceptional volatile organic compounds (VOCs) adsorption efficiency (98.4 % for formaldehyde and 91.7 % for xylene), high sterilization efficiency (99.99 %) and excellent regeneration ability (performance recovery to 98 % of the initial). Furthermore, personal protective masks were assembled by the prepared filters, whose process of replacing element is as simple as replacement of electric mosquito incense tablets. This innovative filter holds promise for applications such as daily protection, sudden accidents and prevention and control of respiratory infectious diseases. We envision that the functionally modified Ag NPs wood filters with a multilayer structure offer a comprehensive solution for more effective air purification in polluted environment.

Justification of the Locations of Differential Pressure Sensors for Coarse and Fine Filter Elements Installed one Inside the Other in a Single Gas Filter Housing

Statement of the problem. The relevant task of ensuring the uninterrupted operation of modern gas pressure reduction systems is to develop and comprehensively substantiate the possibility of using two-stage filters for natural gas purification in gas reduction points and theoretically substantiate the method for calculating the pressure drop in cylindrical filter elements (CFE). Results. It is proved that when gas flows in the upper cross section of the filter, the pressure drop will be less than in lower cross sections, including the pressure drop in the lowest cross section. This leads to a larger amount of leaking gas, to a larger mass of impurities settling in the lower part of the filter elements of cylindrical coarse and fine cleaning and to a greater degree of their clogging. Therefore, it is recommended to place gas pressure sensors in the lower part of the internal volume of the coarse and fine-cleaned CFE, so that the flow direction of the coarse and finely purified gas washing the sensors at the location of the hole for measuring statistical pressure is tangential to the side surface of the sensor tube. Then the flow direction of the roughly and finely purified gas entering the holes of the sensors is carried out at an angle of 90° and the pressure gauges measure the static pressure. Conclusions. The locations of pressure drop sensors on coarse and fine filter elements installed one inside the other in a single gas filter housing are substantiated. The proposed arrangement of differential pressure sensors will significantly increase the possibility of receiving an earlier signal about the degree of clogging of the gas filter at the control room, as well as have a significant amount of time for timely removal of blockages formed in the coarse cleaning CFE and replacement of fine cleaning CFE.

Stable colour conversion layer with enhanced conversion efficiency by incorporating nanoparticles for micro-LED display application

Due to their promising optical performance, micro-light emitting diodes (micro-LEDs) based on colour conversion layer (CCL) have garnered significant attention as the next-generation display technology. However, fabricating CCL with excellent conversion efficiency (CE) with minimal blue light leakage for miniaturized sub-pixel designing is still in its infancy. Herein, we have demonstrated CCL of a thickness (<3.5 μm) based on an organic-inorganic hybrid system incorporated with Titanium dioxide (TiO2) and Zinc Oxide (ZnO) Nanoparticles (NPs) with high CE. The inclusion of the NPs enhances the absorption of blue light within the CCL. We further combined the CCL with a colour purification filter to mitigate blue light leakage, which recycles blue light and suppresses blue light loss, resulting in improved CE. Specifically, we achieved a CE of 83.80 % for the green CCL and 66.97 % for the red CCL. Subsequently, full-colour arrays with a pixel size of 4 μm × 4 μm were successfully patterned and fabricated based on reduced thickness and improved optical performance using NP-doped CCL. This paves the way for cost-effective higher-resolution micro-LED displays for various applications.

The Prediction of Failure in the Gas Filtration System in Low-Pressure Carburising Furnaces

Predictive maintenance is one of the key aspects of Industry 4.0. The article presents the results of experimental tests of nitrogen purification filters in the installation of a low-pressure, metal processing device. The aim of the research was to develop a predictive algorithm for making decisions regarding the replacement of used filters, based on flow analysis and measurement of the pressure difference in front of and behind the tested filter. For the purposes of the research, a special test stand was constructed, which made it possible to determine the operating characteristics of three selected filters. Based on the tests carried out, the limit characteristics of the parameters measured were determined, identifying the need to replace filters in the gas installation.

Analytical model and comprehensive index construction of indoor air purification effect based on dynamic characteristics and energy efficiency

Meeting environmental regulation requirements while improving energy usage efficiency are crucial endeavors to achieve decarbonization and indoor environmental regulation. In this study, experimental testing, data analysis, and modeling are performed for the dynamic purification process of indoor PM2.5 (fine particulate matter) in the context of regulating the indoor environment of buildings. The results show that indoor PM2.5 levels are dynamically matched to the outdoor environment state and the requirements of environmental control. An analytical model of the effect of PM2.5 purification is constructed, which can accurately reflect the dynamic changes in the PM2.5 mass concentration during the indoor air purification process considering the outdoor PM2.5 concentration and the purification efficiency of the purification filters and purification systems, thus supporting the prediction of purification outcomes and accurately constraining the actual indoor air quality purification process. Meanwhile, an indoor air quality control index (IAQCI) is established based on the purification effect and purification energy efficiency under various combinations of air filters and purification systems. This approach is used to quantitatively assess the dual control of energy efficiency and environmental regulation, as well as the purification effect and efficiency of indoor purification schemes based on outdoor dynamic PM2.5 conditions.This study provides a set of innovative and feasible research methods for realizing comprehensive indoor environmental performance evaluations of buildings.

Heavy Metal Ion Adsorbent in Aqueous Solution: A Review on Chitosan and Chitosan Composites

One prominent contributor to environmental degradation is the presence of heavy metal ions, which are commonly introduced into ecosystems through diverse channels, including mining operations, paint manufacturing, battery production, and agricultural practises. The unprocessed waste from these industries typically undergoes direct discharge into rivers and seas, thereby adversely influencing the potable water supply and marine ecosystem. This results in the accumulation of heavy metals within living organisms and subsequent environmental degradation that poses a significant risk to human health, as their prolonged consumption can harm various organs and the nervous system. Therefore, the United States Environmental Protection Agency (US-EPA) and the World Health Organisation (WHO) have established stringent regulations regarding the allowable levels of heavy metal intake, particularly concerning potable water consumption. The imperative lies in surmounting this challenge by discovering the optimal technique for extracting heavy metals. This paper examines the primary methods of eliminating heavy metal ions using chitosan-based materials. Specifically, the methods under scrutiny include electrocoagulation (E.C.), bioremediation, ion-exchange, membrane filtration (purification), and adsorption. Adsorption, as a highly efficient method, presents itself as a viable strategy for the remediation of dyes in textile wastewater due to its advantageous characteristics. Notably, this approach obviates the need for extensive spatial requirements and exhibits a commendably swift treatment duration. Chitosan exhibits promising adsorptive characteristics owing to its advantageous physical attributes, including crystalline structure, porous nature, and particle dimensions, all of which synergistically enhance the adsorption capacity of chitosan. Research findings indicate that the adsorption characteristics of chitosan are subject to variation contingent upon the distinct heavy metal ions under consideration and the specific experimental parameters employed. Hence, optimising these parameters becomes imperative to attain enhanced chitosan adsorption capabilities for heavy metal ion removal.

Experimental study on enhancing electrostatic charging of nonwoven filter media through novel electrode configurations

The COVID-19 pandemic has underscored the urgent need for efficient particle filtration to tackle public health challenges. This study compares the electrostatic charging capabilities of two types of electrodes: conventional Metal Lamellar Electrodes (MLE) and Modified Lamellar Plate Electrodes (MLPE) with PMMA insulation, in their role of charging nonwoven polypropylene filter media. Experimental analysis unequivocally demonstrates the superiority of MLPE in promoting effective electrostatic charge, as influenced by applied high voltage and inter-electrode distance, resulting in a significant enhancement in fine particle filtration. Numerical simulations of the electric field conducted using the COMSOL software and employing the Finite Element Method (FEM) validate these findings. FEM discretizes the domain into small finite elements and applies Laplace's equation in charge-free regions, providing a comprehensive understanding of the behavior of dual-electrode corona discharge systems. These simulations indicate higher field intensities for MLPE compared to MLE.By integrating experimental and numerical analyses, this study sheds light on the potential benefits of MLPE for air filtration systems, offering a noteworthy advancement in the control of airborne infections and reduction of environmental health risks. This research lays the groundwork for the development of more efficient and durable filtration systems, meeting the increasing demands for public health protection.The findings of this study suggest that the adoption of MLPE could significantly contribute to improving indoor air quality and mitigating the transmission of respiratory diseases. MLPE may also find utility in industrial filtration and air purification in sensitive work environments. Ultimately, this research sets the stage for the development of more efficient and sustainable filtration systems, addressing the growing needs for public health protection.

Ведение ВХР с применением реагентов ВТИАМИН на ТЭЦ с сезонным режимом работы

The main equipment of the thermal power plant (TPP) includes a E-120-7.0-500GM steam boiler produced by LLC “Belenergomash – BZEM” with a single-stage evaporation circuit. The operating mode of the thermal power plant has seasonal characteristics. During the period of February to the end of August the equipment is stopped as a reserve. Dosing of AMINAT PK-3 does not provide the required pH level in steam and feed water, so the reagent for water-chemical regime and preservation has been substituted with VTIAMIN KR-33. The complex reagent VTIAMIN KR-33 ensures both the maintenance of the required quality indicators of the coolant along the path and promotes the formation of a protective barrier film on the internal heating surfaces. To check water-chemical regime, the existing automatic chemical control system has been updated. Panels have been installed for automatic chemical control of pH value, electrical conductivity of direct and H-cationized samples. The filter material has been replaced and the mechanical filters have been connected. The first stage of the filter has been replaced, the second stage of the filter and final purification filters Н-OH have been installed. The authors have demonstrated the possibility to use boilers with seasonal operating modes and measuring the electrical conductivity of cooled water and steam samples as a chemical control of water chemistry. It is found out that dosing the VTIAMIN KR-33 reagent with periodic dosing of the VTIAMIN D-8 reagent into the boiler water prevent the precipitation of hardness salts and other impurities coming with the return condensate. Analysis of the indicators of the water chemistry regime at the thermal power plant when dosing the VTIAMIN KR-33 reagent at two points has shown that the pH value of the feed water is in the range of 8,8–9,0 and the indicators of the water chemistry regime in terms of the content of iron, silicic acid and sodium are also within the norm limits. The composition of the reagents is selected. Flexibility of water chemistry management is ensured. It has been shown that the dosage of the amine-containing reagent VTIAMIN neutralizes the negative effects of aggressive gases (carbon dioxide and oxygen) due to their binding and the formation of a protective film of the magnetite-amine type on heating surfaces. Introduction of the water chemical regime when the equipment is stopped as a reserve does not require additional preservation measures.

Ultrafast dyeing wastewater purification by high-performance and reusable lignin-derived activated porous carbon filter

Achieving ultrafast purification during filtration while maintaining high adsorption capacity and low-cost filter production is a critical challenge that must be addressed immediately to promote large-scale water filter applications, particularly in remote areas without wastewater purification plants. Herein, low-cost, renewable lignin was used as a carbon source precursor to produce a high-performance, reusable activated porous carbon filter for ultrafast dye wastewater purification. Lignin-derived active porous carbon (LAPC) can achieve a high specific surface area (2276 m2/g) by using a lower amount of KOH (a mass ratio of 0.4 KOH to precursor) during the activation process, which not only meets the requirements of water transport and dye adsorption, but also reduces manufacturing costs. Owing to the pore-filling effect and electrostatic interaction, the LAPC particles displayed a high removal capacity of 1800 mg/g in the static adsorption, higher than most of the reported porous carbon. Furthermore, LAPC filters assembled from a flow of LAPC particles achieve significant dye removal (99.82 % in 30 s) during the dynamic adsorption process. Both anionic and cationic dyes can be removed and clean water can be produced simultaneously by simple dynamic filtration. Moreover, the LAPC filter could be reused for wastewater purification with a high removal efficiency (more than 95 % after 7 cycles of regeneration and use). This continuous operation, strong absorption versatility, and high efficiency of LAPC filter device for complex hybrid dyes system make it have a bright prospect in industrial dyeing wastewater treatment fields.

Nitrogen plasma treated cotton fabrics coated with SiO2 followed by RGO deposition for water purification process

Experimental investigations have been carried out to modify the surface properties of Cotton fabrics using low temperature DC glow discharge nitrogen plasma. Plasma treatment is an eco-friendly, dry and clean process over wet chemical methods and does not suffer from any environmental and health concerns [1]. The important plasma parameters such as power and working pressure are kept constant with various treatment times (5, 15, 30, and 60 mins). The plasma-treated cotton fabrics are optimized by XRD, FTIR, and SEM. A comparative study has been done for the untreated and different treated fibers. Pure SiO2 is coated on untreated and nitrogen plasma treated cotton fabrics by sputtering method. The samples are coated for different sputtering times (10 and 30 min). Finally, Reduced Graphene Oxide (RGO) is coated on plasma treated SiO2 deposited fabrics. RGO is prepared by modified hummers methods [2]. Our results provide a way to develop a filter for water purification.

Multi-plug Filtration Purification Combined with High-Performance Liquid Chromatography-Tandem Mass Spectrometry for the Simultaneous Determination of Pesticides, Veterinary Drugs, Mycotoxins, and Persistent Organic Pollutants in Livestock and Poultry Meat

Multi-plug Filtration Purification Combined with High-Performance Liquid Chromatography-Tandem Mass Spectrometry for the Simultaneous Determination of Pesticides, Veterinary Drugs, Mycotoxins, and Persistent Organic Pollutants in Livestock and Poultry Meat

Harnessing the potential of zinc oxide nanoparticles from Strychnos potatorum seeds impregnated with activated carbon for an effective removal of fluoride in deep soil water

Abstract Fluoride (F−) contamination in global water sources is a growing concern, prompting the need for innovative solutions. This explores a novel method using zinc oxide nanoparticle-activated carbon (ZnO-NP/AC) composite for efficient fluoride removal from deep soil water, aiming to evaluate its effectiveness in attracting fluoride contaminants. The focus is on treatment of water sample collected from Dharmapuri, Tamil Nadu, using green synthesis method for ZnO-NP/AC column filter. Employed an exclusive column adsorption method, investigated on physiochemical parameters in water before and after running the column. Fluoride concentration and TDS where significantly harnessed in water after running the green synthesis composite column filter. Characterization of green synthesized nanoparticles of Strychnos potatorum seed powder synthesis with ZnO NPs. Green synthesis successes were confirmed in two ways; one way is UV-visible spectrophotometer technique in depth quantity peak and another one is graphically peak from SEM, density and crystalline structure in XRD techniques. Column composite with S.potatorum ZnO-AC NPs has removed fluoride efficiently (80.5%) at range of 20 g/L for a contact time of 60 minutes, surpassing World health organization (WHO) guidelines for safe drinking water. In conclusion ZnO-AC NPs composite is a sustainable and cost-effective method for effective removal of fluoride contaminants from deep soil water, addressing a pressing global issue.

Molecular mechanism of Fe3+ binding inhibition to Vibrio metschnikovii ferric ion-binding protein, FbpA, by rosmarinic acid and its hydrolysate, danshensu.

Global warming has increased the growth of pathogenic Vibrio bacteria, which can cause foodborne illnesses and death. Vibrio bacteria require iron for growth and survival. They utilize a ferric ion-binding protein (FbpA) to bind and transport Fe3+ into the cell. FbpA from Vibrio metschnikovii (Vm) is a potential target for inhibiting its growth. Rosmarinic acid (RA) can block the binding of VmFbpA to Fe3+ ; however, the molecular mechanism of Fe3+ binding and RA inhibition to VmFbpA is unclear. In this study, we used x-ray crystallography to determine the Fe3+ -binding mode of VmFbpA and the mechanism of RA inhibition. The structures revealed that in the Fe3+ bound form, Fe3+ was coordinated to VmFbpA by two Tyr residues, two HCO3 - ions, and two water molecules in a six-coordinated geometry. In contrast, in the inhibitor bound form, RA was initially bound to VmFbpA following gel filtration purification, but it was hydrolyzed to danshensu (DSS), which occupied the binding site as shown in an electron density map and reverse phase chromatography (RPC) analysis. Both RA and DSS exhibited a stronger binding affinity to VmFbpA, higher Fe3+ reduction capacity, and more potent bacteriostatic effect on V. metschnikovii compared with caffeic acid (CA), another hydrolysis product of RA. These results provide insight into the mechanism of iron acquisition by V. metschnikovii and inhibition by RA and DSS. Our findings offer clues on the development of effective strategies to prevent Vibrio infections.

Impacts of reduced graphene oxide modified air purification filters on removal of particulate matter from Ambient Air

Impacts of reduced graphene oxide modified air purification filters on removal of particulate matter from Ambient Air

A bio-based nanofibre hydrogel filter for sustainable water purification

A bio-based nanofibre hydrogel filter for sustainable water purification

One step cleanup of 160 pesticides and veterinary drugs in aquatic products using melamine-based automatic pressure filtration purification method combined with HPLC-MS/MS

A 15-channel pressure filtration purification method was presented for high throughput sample preparation of aquatic products. A cost-effective device was constructed and melamine sponge was selected as the cleanup sorbent. Upon interfacing with HPLC-MS/MS, the analytical procedure demonstrated its suitability for quantifying 160 pesticides and veterinary drug residues in aquatic products such as fish, shrimp, and crab. The method achieved sample recoveries ranging from 61.3 to 124.9 %. The detection limits were established between 0.5 and 1.0 μg/kg, while the quantitation limits were confirmed to be within the range of 1.0–2.0 μg/kg. The method was applied to quantify the pesticide and veterinary drug residues in mostly consumed aquatic products from five coastal provinces in China. The results showed significant differences between different aquatic products in the concentrations of pesticide and veterinary drug residues, implying the necessity of supervision for the accurate determination of pesticides and veterinary drugs.