Activated Carbon Fiber Filter Research Articles

Purification performance of modified polyacrylonitrile fiber-activated carbon fiber filter for heavy metal ions.

A heavy metal ion adsorbent (HFPANF) with high surface area was obtained from polyacrylonitrile fibers with fibrillation and alkali hydrolysis, and an activated carbon fiber filter was prepared by using HFPANF as the binder. The surface area of polyacrylonitrile was 48.64 m2/g due to fibrillation, which also led to the carboxyl content of the HFPANF up to 3.4mmol/g. Batch adsorption experiments on Cu2+ and Pb2+ showed that the adsorption capacities of HFPANF for Cu2+ and Pb2+ were 47.5mg/g and 54.3mg/g. The adsorption kinetics showed that the adsorption reached equilibrium at 90min and that the adsorption followed the pseudo-second order model. It indicates that the adsorption process is chemisorption. HFPANF formed a single tooth chelate with Cu and a double tooth chelate with Pb. HFPANF-ACF filter was prepared by wet molding technique. When the HFPANF content was 30%, the filter reached a compressive strength of 15.37MPa and its maximum flux was 180 L/h. 2.5mg/L of Cu and Pb were used for dynamic adsorption experiments and the heavy metal removal rate was still above 95% after filtering 600 L. The pressure drop of HFPANF-ACF filter was much smaller compared with that of GAC filter due to the combined effect of fibrillated nanofibers and ACF, which can improve the filtration efficiency of the filter.

Development of a novel type activated carbon fiber filter for indoor air purification

A novel type of activated carbon fiber filter was developed for indoor air purification. The filter is equipped with electrodes for thermo-electrical regeneration at the point of saturation. The electrodes are arranged in such a way that the filter forms a pleated structure with an electrode in the tip of each pleat. This allows for a uniform temperature distribution on the filter surface during the regeneration process and the pleated structure reduces the overall pressure drop across the filter. The latter was validated by Computational Fluid Dynamics, using Darcy-Forchheimer parameters derived in previous work. The CFD model was further used to perform a virtual sensitivity study in search for the optimal ACF filter design by varying the pleat length, pleat height and filter thickness. Finally, adsorption and desorption properties were investigated with acetaldehyde and toluene as model compounds. Freundlich and Langmuir adsorption parameters, derived in previous work were successfully validated with a Multiphysics model.

Determination of the Optimum Removal Efficiency of Fine Particulate Matter Using Activated Carbon Fiber (ACF).

In Korea, concentrations of particulate matter (PM10) are significantly higher in urban railway tunnels (178.1 μg/m3) than in metropolitan areas (49 μg/m3). In railway tunnels in Korea, it was maintained at 3–4 times higher concentration than general atmosphere and platform. Dust generated by trains is scattered at high speed in these tunnels, making filtration difficult; therefore, the development of filters that can be maintained in tunnels is required. In the present study, we examined PM adsorption in the laboratory scale using activated carbon fiber (ACF), which has high adsorption and capacity. The ACF depth, velocity of flow, and fine PM concentration in the tunnel were the experimental variables. We compared PM concentrations before and after the filter experiments, and calculated removal efficiency to determine the optimal conditions. Comprehensive examination of the experimental variables and differential pressure showed that the optimal conditions for an ACF specimen were a wind speed of 3.0 m/s and the ACF depth of 400 mm. The average removal efficiency of PM10 was 55.5%, and that of PM2.5 was 36.6%. The reproducibility tests showed that the ACF filter could be washed and reused and is suitable for various places because it is easily maintained.

One-Pot Decoration of Cupric Oxide on Activated Carbon Fibers Mediated by Polydopamine for Bacterial Growth Inhibition.

Despite the widespread application of activated carbon fiber (ACF) filters in air cleaning owing to their high surface area and low price, they have certain limitations in that they facilitate bacterial growth upon prolonged use as ACF filters can provide favorable conditions for bacterial survival. The deposition of cupric oxide (CuO) on ACFs can be an effective way of resolving this problem because CuO can inhibit the proliferation of bacteria owing to its antimicrobial properties. However, finding a new method that allows the simple and uniform coating of CuO on ACF filters is challenging. Here, we demonstrate one-pot CuO deposition mediated by polydopamine (PD) to realize an ACF filter with antimicrobial activity. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) analyses reveal that CuO and PD are uniformly deposited on the ACF surface. The amount of CuO formed on the ACFs is measured by thermogravimetric analysis (TGA). Finally, the changes in surface area, pressure drop, and antimicrobial activity after coating PD-CuO on the ACFs are evaluated. The use of PD-CuO on the ACFs effectively suppresses the growth of bacteria and enhances the mechanical properties without significantly sacrificing the original characteristics of the ACF filter.

Activated carbon fiber filters could reduce the risk of surgical smoke exposure during laparoscopic surgery: application of volatile organic compounds.

Generation of smoke is inevitable during surgical procedures. Some volatile organic compounds (VOCs) in surgical smoke are known to be strong carcinogens. We used a prototype of a multi-layered complex filter in an attempt to eliminate VOCs. From June 2015 to July 2015, 20 patients underwent transperitoneal laparoscopic nephrectomy for renal cell carcinoma. Smoke (pre-filter) was collected 20min after the electrocautery device was first used during the surgery, by the direct collection method, with a 5-L Tedlar® gas-sampling bag. Twenty and 120min after the filter was applied, smoke (post-filter) was again collected using the same method. The sample was analyzed by gas chromatography and mass spectrography. The cancer risk and hazard quotient were analyzed based on US Environmental Protection Agency guidelines. Twenty patients with a median age of 54.5 (30-80) years were enrolled in the study. Eighteen VOCs were detected using the Japanese indoor air standards mix analysis. The total elimination rate of the VOCs was 86.49 ± 2.83%. The post-filter (120min) cancer risk (mean ± standard deviation) reduced to a negligible level for benzene, ethylbenzene, and styrene except 1,2-dichloroethane. The post-filter (120min) hazard quotient for each compound decreased to levels posing a negligible risk for acetone, hexane, benzene, toluene, p-xylene, o-xylene, and styrene. Strong carcinogens, such as 1,2-dichloroethane, benzene, and ethylbenzene, were eliminated by more than 85% by using this activated carbon fiber filter and the risks from these compounds decreased to an almost negligible level. We suggest using every measure, including these filters, to protect the health of operating room personnel.

A novel electrostatic precipitator-type small air purifier with a carbon fiber ionizer and an activated carbon fiber filter

We developed and investigated the air cleaning performance of a novel electrostatic precipitator (ESP)-type small air purifier with a carbon brush ionizer and an activated carbon fiber (ACF) filter. This version had a high particle charging rate and a low ozone emission rate. Applying a negative voltage of 10kV to the carbon brush ionizer increased the single-pass particle collection efficiency of 0.3-μm particles from 17.8% to 47.1%. The flow rate was maintained at 362L/min, and the efficiency increased to 64.2% as we applied a negative voltage to the collection stage and increased the voltage to 10kV. This was relatively low when compared to a market-leading commercial HEPA filter-type small air purifier (80.7%). However, our novel purifier showed a particle clean air delivery rate (CADR) of 0.31m3/min, approximately a 1.7 times higher than that for the commercial purifier (0.18m3/min) due to its high flow rate and low pressure drop. We measured the gas removal efficiency in a 1-m3 test chamber with acetic acid, acetaldehyde, and ammonia; after 30min of operation, the results were 97.9%, 92.4%, and 87.8% for the novel purifier and 95.2%, 65.4%, and 57.9% for the commercial purifier, respectively. The ozone concentration was measured in a closed test chamber (30.4m3) over 15h of continuous operation, and it showed a maximum value of 2.5 ppb, much lower than the current standard for ESPs (50 ppb).

Air Cleaning Performance of a Novel Electrostatic Air Purifier Using an Activated Carbon Fiber Filter for Passenger Cars

We developed a novel electrostatic air purifier using a carbon fiber brush charger combined with a metallic collection rod and an activated carbon fiber (ACF) sheet to improve the indoor air quality of passenger vehicles. The ACF sheet was used to apply electrostatic forces to move charged particles toward a collection rod and simultaneously adsorb gas. The cylindrical air purifier (diameter: 100 mm, length: 190 mm) was composed of a conductive brush charger and an electrostatic collection rod for particle removal, as well as an ACF filter for gas removal. The flow rate of the device was approximately 209–360 L/min. The novel purifier was tested in a 1-m3 chamber with particles 0.3 μ m in diameter and three gases: ammonia, acetic acid, and acetaldehyde. The gas cleaning performance of the purifier was compared with that of a commercial purifier with a high-efficiency particulate air (HEPA) filter, activated carbon pellets, and alumina balls. The clean air delivery rate (CADR) of the novel electrostatic air cleaner was 0.219 m3/min, 35% higher than that of the HEPA filter. The CADRs of the ESP air cleaner for the test gases were 0.25, 0.19, and 0.19 m3/min, respectively, indicating that the novel ESP air cleaner reduced the gases 308%, 204%, and 327%, respectively, faster than the commercial purifier.

Enhanced Antimicrobial Activity on Non-Conducting and Conducting Air Filters by Using Air Ions and Grapefruit Seed Extract

ABSTRACTThe application of grapefruit seed extract (GSE) and air ions to filters was investigated with the goal of collecting indoor bioaerosols. GSE exhibits antimicrobial activity because it contains flavonoids such as naringin. Air ions are usually generated by electric ionizers and can inactivate bacteria, viruses, and fungi. In this study, GSE particles were coated onto three different filters: polypropylene (PP), activated carbon fiber (ACF), and metal foam (MF). Ions were supplied to the filter surface using an ionizer. The rate of surface inactivation of Staphylococcus aureus was measured. When only GSE was applied to the filters, the inactivation rate was about 60%; when air ions were applied, the rate was about 70–80%. When both GSE and ions were applied simultaneously, the inactivation rate increased to 80–90%. The physical collection efficiencies of the as-purchased filters were in the following order: PP > ACF > MF. However, when ions were supplied to the filters, the collection efficiencies increased to over 98% for each filter. The inactivation rate of the ACF filter was the highest (92.5%). Therefore, we conclude that the ACF filter is the most efficient of these three filters for inactivating S. aureus.

Loading of fibrous filter media and newly designed filter configurations by salt particles: An experimental study

Various fibrous filter media, including surface filter media, depth filter media, woven and nonwoven filter media, were tested and particle loading capacity was calculated using bench‐scale setup via a new estimation approach which was proposed and experimentally verified with Novick‐Kozeny model. Multi‐element structured arrays (MESAs) developed by our research group were evaluated as well for particle loading capacity and filter lifetime on 24″ × 24″ full scale test rig (based on ASHRAE 52.2 Standard). Effects of varying filter media type, filter depth, pleat count and MESAs' element count on salt particle loading performance were experimentally investigated. The experimental studies showed that nonwoven activated carbon fiber filter media have allowed significantly higher salt particle loading capacity and longer useful lifetime compared to woven or nanofiber entrapped media. Furthermore, MESAs were able to significantly enhance loading capacity for salt particles and useful lifetime due to higher filtration area and lower filtration velocity. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3739–3750, 2016

1061 Activated carbon fiber filter could reduce the risk of surgical smoke exposure during the laparoscopic surgery

1061 Activated carbon fiber filter could reduce the risk of surgical smoke exposure during the laparoscopic surgery

An amperometric nitric oxide sensor with fast response and ppb-level concentration detection relevant to asthma monitoring

A MEMS-based amperometric nitric oxide (NO) gas sensor is reported in this paper. The sensor is designed to detect NO gas for the purpose of asthma monitoring. The unique property of this sensor lies in the combination of a microporous high-surface area electrode that is coated with Nafion™, together with a liquid electrolyte. The sensor is able to detect gas concentrations of the order of parts-per-billion (ppb) and has a measured NO sensitivity of 0.045nA/ppb and an operating range between 25 and 65% relative humidity. The settling time of the sensor is measured to 8s. The selectivity to interfering gases such as ammonia (NH3) and carbon monoxide (CO) was high when placing an activated carbon fiber filter above the sensor. The ppb-level detection capability of this sensor combined with its relatively fast response, high selectivity to CO and NH3 makes the sensor potentially applicable in gas monitoring for asthma detection.

Adsorption of volatile organic compounds using activated carbon fiber filter in the automobiles

The adsorption of volatile organic compounds (VOCs) was carried out using an activated carbon fiber (ACF) filter in an automobile. The adsorption capacities of formaldehyde, toluene, and benzene on an ACF filter were far better than those of a polypropylene (PP) mat filter and combined (PP+activated carbon) mat filter by batch adsorption in a gas bag. In a continuous flow of air containing toluene vapor through an ACF packed bed, the breakpoint time was very long, the length of the unused bed was short, and sharp S -type breakthrough curve was plotted soon after breakpoint, showing a narrow mass transfer zone of toluene on the ACF. The adsorption amount of toluene on the ACF filter was proportional to the specific surface area of the ACF; however, the development of mesopores 2-5 nm in size on the ACF was very effective with regard to the adsorption of toluene. The ACF air clarifier filter is strongly recommended to remove VOCs in newly produced automobiles.

Development and evaluation of antimicrobial activated carbon fiber filters using Sophora flavescens nanoparticles

Activated carbon fiber (ACF) filters have a wide range of applications, including air purification, dehumidification, and water purification, due to their large specific surface area, high adsorption capacity and rate, and specific surface reactivity. However, when airborne microorganisms such as bacteria and fungi adhere to the carbon substrate, ACF filters can become a source of microbial contamination, and their filter efficacy declines. Antimicrobial treatments are a promising means of preventing ACF bio-contamination. In this study, we demonstrate the use of Sophora flavescens in antimicrobial nanoparticles coated onto ACF filters. The particles were prepared using an aerosol process consisting of nebulization–thermal drying and particle deposition. The extract from S. flavescens is an effective, natural antimicrobial agent that exhibits antibacterial activity against various pathogens. The efficiency of Staphylococcus epidermidis inactivation increased with the concentration of S. flavescens nanoparticles in the ACF filter coating. The gas adsorption efficiency of the coated antimicrobial ACF filters was also evaluated using toluene. The toluene-removal capacity of the ACF filters remained unchanged while the antimicrobial activity was over 90% for some nanoparticle concentrations. Our results provide a scientific basis for controlling both bioaerosol and gaseous pollutants using antimicrobial ACF filters coated with S. flavescens nanoparticles.

Reducing the inhibitory effect of cigarette smoke on the activity of oral peroxidase by the addition of berberine in cigarette filter

This study was carried out to evaluate the effect of cigarette smoke (CS) on the activity of oral peroxidase (OPO) after berberine was added to the cigarette filter. Activated carbon fiber (ACF) was chosen to load berberine as a part of the cellulose acetate (CA) filter to obtain the modified B-ACF cigarette filter. Then the effects of CS from the testing cigarettes on the activity of OPO were investigated in vitro by the 2-nitrobenzoic acid assay, and the smoke chemistry was also analyzed, especially the content of hydrogen cyanide (HCN) in the CS. The results indicated that the loss of activity of OPO in B-ACF filter cigarette group decreased by 20% and 25%, compared with those of ACF and CA filter cigarette groups, respectively. The relative residual activity of OPO in B-ACF filter group was increased with the increase of berberine in the filter compared with the CA filter group. It could be observed that the reduction in HCN might be related to the berberine in the cigarette filter, reducing the inhibition of CS on the activity of OPO.

Improved Removal of Indoor Volatile Organic Compounds by Activated Carbon Fiber Filters Calcined with Copper Oxide Catalyst

AbstractHeating, ventilating, and air‐conditioning (HVAC) systems ensure indoor air quality and provide a comfortable environment. However, the conventional HVAC systems only provide indoor ventilation and adjust temperature and humidity. This work removes indoor volatile organic compounds (VOCs) using a feasible and novel air‐cleaning for an HVAC system, to remove indoor VOCs. An activated carbon‐fiber (ACF) filter calcined with copper oxide (CuO) catalyst, called a CuO/ACF catalyst filter, was the developed kit. Formaldehyde, a major VOC, was chosen as the target pollutant. Experiments were performed to confirm the filtration ability of the CuO/ACF catalyst filter in removing formaldehyde in a stainless‐steel chamber equipped with a simplified HVAC system. Total air exchange rate (ACH) was controlled at 0.5 and 1.0 h−1, the fresh ACH was 0.15 and 0.30 h−1, and relative humidity (RH) was set at 30 and 70%. A first‐order decay of formaldehyde existed in the controlled chamber when the two pretreated CuO/ACF catalyst filters were employed. Experimental results demonstrate that the CuO/ACF catalyst filters removed formaldehyde effectively. The decay constant was 0.425 and 0.618 h−1 for 0.5 and 2.0 ppm formaldehyde, respectively. Moreover, the formaldehyde decay rate increased as total ACH, fresh ACH, RH, and the Cu(NO3)2 concentration for calcination of CuO/ACF catalyst filter increased.

Antimicrobial Effect of Silver Particles on Bacterial Contamination of Activated Carbon Fibers

Even though activated carbon fiber (ACF) filters have been widely used in air cleaning for the removal of hazardous gaseous pollutants, because of their extended surface area and high adsorption capacity, bacteria may breed on the ACF filters as a result of their good biocompatibility; ACF filters can themselves become a source of bioaerosols. In this study, silver particles were coated onto an ACF filter, using an electroless deposition method and their efficacy for bioaerosol removal was tested. First, various surface analyses, including scanning electron microscopy, inductively coupled plasma and X-ray diffraction were carried out to characterize the prepared ACF filters. Filtration and antimicrobial tests were then performed on the filters. The results showed that the silver-deposited ACF filters were effective for the removal of bioaerosols by inhibition of the survival of microorganisms, whereas pristine ACF filters were not. Two bacteria, Bacillus subtilis and Escherichia coli, were completely inhibited within 10 and 60 min, respectively. Electroless silver deposition did not influence the physical characteristics of ACF filters such as pressure drop and filtration efficiency. The gas adsorptive ability of the silver-deposited ACF filter, as represented by the micropore specific surface area, decreased by about 20% compared to the pristine filter because of the blockage of the ACF micropores by silver particles. Therefore, the amount of silver particles on the ACF filters needs to be optimized to avoid excessive reduction of their adsorptive characteristics and to show effective antimicrobial activity.

Physical and chemical forms of radionuclides of 38S, 38Cl, 39Cl, and 82Br, produced at a high-energy proton accelerator facility

High-energy protons and neutrons produce various radionuclides in the air, mainly through the nuclear spallation of atmospheric elements. Air samples were collected from the EP-2 tunnel of the KEK 12 GeV proton synchrotron facility with a filter pack, which consisted of a membrane filter for aerosols, a Na2CO3-impregnated filter for acidic gases, and an activated carbon fiber filter for non-acidic gases. Sulfur-38 was found on the membrane and Na2CO3-impregnated filters, 38Cl and 39Cl were on the membrane, Na2CO3-impregnated, and ACF filters, and 82Br was only on the ACF filter. The results on the relative abundances of aerosol and gaseous acidic components have indicated that 38Cl produced by thermal neutron capture, which is the main reaction for 38Cl production in the EP-2 tunnel air, are likely not to be present as aerosol or acidic gas. This was similar to the case of 82Br produced by thermal neutron capture.

Removal Characteristics of Gaseous Sulfur-Containing Compounds by Pulsed Corona Plasma

Pulsed corona plasma was employed to treat the gases containing hydrogen sulfide, methyl mercaptan (MM), and dimethyl sulfide (DMS), respectively. For the plasma oxidation only, the removal efficiencies of hydrogen sulfide, MM, and DMS were approximated to be 90%, 69%, and 52% when the discharge power was 5.6 W. But all the removal efficiencies were over 98% when an activated carbon fiber (ACF) filter was used downstream from the plasma reactor. In addition, the decomposition reaction mechanism was discussed and a competitive reaction kinetics model was proposed to describe the plasma decomposition reaction kinetics. The ACF filter appeared to be co-beneficial in the improvement of removal efficiency, reduction of energy consumption, and the abatement of ozone or other byproducts. The energy consumption was about 3 W·h/m3 for hydrogen sulfide to obtain about 90% of the removal efficiency by plasma oxidation only, but it can be reduced below 1.2 W·h/m3 in the present of the ACF filter.

Simultaneous Monitoring Method of Polycyclic Aromatic Hydrocarbons and Persistent Organic Pollutants in the Atmosphere Using Activated Carbon Fiber Filter Paper

In order to simultaneously monitor the concentrations of PAHs and POPs in the atmosphere, an activated carbon fiber filter paper (ACFP) was used as the adsorbing material in this study. The pressurized liquid extraction method (PLE method) was used to extract PAHs and POPs collected on the ACFP. Toluene was an effective solvent to extract them from ACFP using the PLE method, but some of PAHs, such as benzo(a)pyrene, benzo(g,h,i)perylene, dibenzo(a,h)anthracene and indeno(1,2,3-cd)pyrene, were hardly extracted. These PAHs were adsorbed on the particulate matter in the atmosphere. In general, these forms of particulate matter could be collected using a quartz fiber paper (QFP); these PAHs were efficiently extracted from the QFP using the PLE method with toluene. In this study, the collecting method of the PAHs was modified by using QFP overlapped in front of the ACFP. Atmospheric monitoring of PAHs and POPs in Niigata area was performed using this method, and most of the target compounds were detected. However, some of the POPs, such as aldrin, endrin, mirex, could not be detected. The POPs, such as hexachlorobenzene, alpha-hexachlorocyclohexane and chlordanes, and most of the PAHs were detected from all of the samples collected throughout the monitoring period. It was confirmed that these methods were effective to simultaneously monitor the concentrations of the PAHs and POPs in the atmosphere.

Pore formation in carbon-coated ceramic fiber filter media

Resin-coated ceramic fiber filter media were prepared from chopped ceramic fibers and phenolic resin. The coated resin was converted to activated carbon by pyrolysis in N 2 followed by activation in a mixture of steam (75%)–N 2 flow at 750–900 °C. The BET area and pore structure of the ceramic fiber-supported activated carbon (FAC) were studied as a function of burn-off and compared with published data of activated carbon fiber (ACF) derived from phenolic fabrics. The observed BET area curve of FAC has a similar trend to that of ACF, i.e., increase of BET area occurs parabolically with increasing burn-off, with the difference that the BET area of the FAC is about 20% lower than that of the ACF at the same burn-off. It is also found that FAC has a relatively wide pore size distribution than ACF. These discrepancies are presumed because of the difference in the steam concentration of the activating agent. The breakthrough experiments on toluene were performed to compare the absorption efficiency of FAC and ACF filters prepared in this study. Assuming that the shape of the breakthrough curves for toluene achieved by the FAC and ACF filters does not change and breakthrough time is simply proportional to the activated carbon content of each filter, both FAC and ACF filters containing 1 g of activated carbon show similar estimated breakthrough time.