Charcoal Cloth Research Articles

261 Application of a new custom-made activated charcoal cloth patch in different real work conditions

261 Application of a new custom-made activated charcoal cloth patch in different real work conditions

An alternative method to assess permeation through disposable gloves

Previously, we have demonstrated the capability of activated charcoal cloth (ACC) to assess dermal exposure to VOCs. Here we investigated whether ACC patches can be used as an under-glove indicator to evaluate the ingress of toluene through disposable gloves in a controlled environment, and compared these results to the amount of toluene ingress determined from the standardized test methods for determining chemical permeation through PPE. In a test chamber, with plugs for air sampling, five to six ACC patches were placed on a mannequin hand underneath disposable gloves (latex, nitrile, neoprene, polymer laminate). Three work-exposure scenarios were simulated to assess toluene ingress through the different gloves: vapor exposure; spray exposure, and immersion. The standard permeation test, using a diffusion cell, was carried with glove material of the palm, with continuous contact conditions. In all of ACC test, the order of toluene ingress was latex > neoprene > nitrile > Barrier, but for the standardized testing, the order of the neoprene and nitrile was reversed, and nitrile had higher levels of toluene ingress. These results show the need to think beyond standard testing techniques for occupational exposure to hazardous substances, and the added value of “application style” testing.

Atrazine removal from water by activated charcoal cloths

Pollution control structures may be adapted to enhance the removal of nutrients and pesticides from water. Charcoal-like material is known to sorb organic compounds in solution, including atrazine, a herbicide used to control broadleaf weeds, which persists in soils and can migrate from soils to water bodies, ultimately affecting water quality. The primary goal of this study was to investigate if activated charcoal cloths (single-weave, SW; double-weave, DW; and knitted, KT) are more efficient to remove atrazine from aqueous solutions than a cloth without activated charcoal (control) currently used in pollution control structures. The approach consisted of sorption kinetics, flow-through, and desorption/degradation experiments using 50 and 1000 μg L-1 atrazine solutions. Results showed that within 30 min of contact time, the control sorbed from 22.6 to 36.1% of atrazine in solution; whereas the activated charcoal cloths sorbed from 76 to 99% of atrazine in solution (SW > KT > DW). The flow-through experiments showed that the SW sorbed 88.2, 76.1, and 52.2% of atrazine at the contact time of 0.75, 5, and 10 min, respectively. After 28 days of incubation, previously sorbed atrazine on the SW cloth did not degrade and <2.0% was desorbed. The results showed that activated charcoal cloths are a practical alternative for improving atrazine removal in water in pollution control structures.

Inhalation and dermal exposure to toluene among printing workers in a plastic bag factory

Purpose The purpose of this paper is to explore inhalation levels and dermal exposure to toluene among printing workers who wore no personal protective equipment; it is conducted in a plastic bag factory. Using a charcoal cloth pad (CCP) as a dermal sampler to assess skin permeation of liquid toluene is also investigated. Design/methodology/approach In total, 27 stationary air samples as well as urine and dermal samples were collected over 9 days from 11 printing workers. Six pieces of CCP were wrapped on each of the workers’ fingers for the dermal sample collection. Air samples were collected and analyzed according to NIOSH No. 1501, and 65 post-shift urine samples were collected and analyzed using gas chromatography equipped with headspace sampler (GC-HS/FID). Multiple linear regression was employed to analyze the association between the studied variables. Findings The mean (SD) urinary toluene (UTol) level was 13.42 (9.72) ug/L. Toluene on the CCP (TolCCP) was a meaningful predictor for UTol (p-value=0.027) with r and r2 values of 0.441 and 0.195, respectively. The r and r2 of the model using the toluene time-weighted average concentrations in air were 0.739 and 0.546, respectively. The absorbed dose of toluene determined from the TolCCP ranged from 1.05 to 91.94 mg, accounting for 12.3 percent of the threshold limit value (TLV). Originality/value Dermal exposure was insignificant when workers wore respirators, but when not, dermal absorption could contribute to the overall uptake and exposure above the TLV. Appropriate gloves should be assigned to the workers to reduce dermal exposure to toluene.

Integrated evaluation of solvent exposure in an occupational setting: air, dermal and bio-monitoring

The assessment of dermal exposure to volatile organic compounds (VOCs) is becoming increasingly important in industrial settings. The study aimed to evaluate the overall exposure (inhalation and dermal) of workers to VOCs, and to assess the suitability of activated charcoal cloth (ACC) patches for the evaluation of the contribution of dermal exposure (vs. inhalation exposure) to the whole body burden, as reflected by human biomonitoring.Inhalation exposure to toluene, acetone and styrene (passive 3 M organic vapour monitors, OVMs) and dermal exposure (ACC patches on the index finger, thumb and neck) were measured simultaneously in 37 subjects performing different tasks in a factory of thermoplastic panels. Systemic exposure was assessed in urine by quantification of mandelic acid (MA) and phenyl glyoxylic acid (PGA), as biomarkers for styrene, as well as acetone and hippuric acid (HA) as biomarkers for acetone and toluene, respectively.High styrene (range 30.66–302 mg/m3) and acetone (range 11–644 mg/m3) concentrations were found in the air of the workplace, while toluene was less abundantly present (range 0.05–2.6 mg/m3). On the ACC patches, considerable amounts of these VOCs were found. For employees manually handling styrene, dermal exposure on the index finger and thumb were substantially higher compared to the neck ACC patch. A good correlation between air and urinary levels of acetone exposure was found. MA and PGA levels in urine, markers for styrene exposure, were correlated with both air and dermal exposure.These data suggest that there is a substantial benefit from assessing dermal exposure in the work place in addition to the more conventional air monitoring and urinary biomonitoring.

A Method to Quantitatively Assess Dermal Exposure to Volatile Organic Compounds.

Assessing dermal exposure of workers to noxious chemicals becomes increasingly important in industrial settings. Among various chemicals, volatile organic compounds (VOCs) are widely used in industrialized countries, but still there are no validated methodologies able to accurately quantify skin exposure. In this study, we developed a sensitive methodology based on activated charcoal cloth (ACC) to quantitatively assess skin exposure to 181 VOCs. The majority of the VOCs (156) showed a constant desorption efficiency (DE) of ~100% over the studied concentration range. Seven VOCs showed a concentration dependency for the DEs, which we described by a Dubinin-Raduskevich desorption isotherm. For 18 compounds, the DEs were situated below 80% but showed to be constant over the concentration range. All tested VOCs showed a good storage stability on ACC, especially at -80°C storage. Only for n-pentane there was a decrease of ~40% when it was stored for a month. In a controlled environment test, ACC has shown to reflect well the increasing concentrations of VOCs in the air with a high linearity (R2 ≥ 0.812, except for gamma-butyrolactone where R2 = 0.570). In this study, we show that ACC is a suitable sampling material for quantitatively assessing dermal exposure to 181 VOCs in terms of sensitivity and DE. This method will allow more studies that are detailed on dermal exposure, which will lead to a better assessment of skin exposure in occupational settings.

Breakthrough behaviour of activated charcoal cloth samples against oxygen analogue of sulphur mustard

The breakthrough behaviour of activated charcoal cloth samples against an oxygen analogue (OA) of sulphur mustard has been studied using the modified Wheeler equation. Activated charcoal cloth samples having different surface area values in the range of 481 to 1290 m2/g were used for this purpose. Breakthrough behaviour was found to depend on the properties of the activated charcoal cloth, properties of the OA and the adsorption conditions. Activated charcoal cloth with a high surface area of 1290 m2/g, relatively large surface density of 160 g/m2 and coarser fiber structure exhibited better kinetic saturation capacity value, 0.19 g/g, against OA vapours when compared to others, thus confirming its potential use in foldable masks for protection against chemical warfare agents.

Protection efficacy of gloves against components of the solvent in a sprayed isocyanate coating utilizing a reciprocating permeation panel.

Determine protection effectiveness of 5-mil natural rubber latex (0.13-mm), 5-mil nitrile rubber (0.13-mm), and 13-mil butyl rubber (0.33-mm) glove materials against solvents present in a commonly used automotive clear coat formulation using a novel permeation panel. The latex and nitrile gloves were the type commonly used by local autobody spray painters. Glove materials were tested by spraying an automotive clear coat onto an automated reciprocating permeation panel (permeation panel II). Temperature, relative humidity, and spray conditions were controlled to optimize clear coat loading homogeneity as evaluated by gravimetric analysis. Solvent permeation was measured using charcoal cloth analyzed by the National Institute for Occupational Safety and Health 1501 method. Natural rubber latex allowed 3-5 times the permeation of solvents relative to nitrile rubber for all 10 solvents evaluated: ethyl benzene, 2-heptanone, 1-methoxy-2-propyl acetate, o-xylene, m-xylene, p-xylene, n-butyl acetate, methyl isobutyl ketone, petroleum distillates, and toluene. There is a distinct behavior in solvent permeation before and after the coating dry time. Solvent permeation increased steadily before coating dry time and remained fairly constant after coating dry time. Butyl was not permeated by any of the solvents under the conditions tested. Commonly used 5-mil thick (0.13-mm) latex and nitrile gloves were ineffective barriers to solvents found in a commonly used clear coat formulation. Conversely, 13-mil (0.33-mm) butyl gloves were found to be protective against all solvents in the clear coat formulation.

Impregnated charcoal cloth for the treatment of air polluted with hydrogen cyanide

Impregnated charcoal cloth was prepared by a novel single‐step method using water‐soluble salts such as copper nitrate, silver nitrate, and ammonium heptamolybdate. Impregnation was achieved by using simple, user‐friendly spraying technique. The obtained cloth samples were characterized by nitrogen adsorption technique. Kinetics of hydrogen cyanide adsorption were explored using charcoal cloth impregnated with copper(II), molybdenum(VI), and silver(I) salts. Modified Wheeler equation was used for analyzing adsorption kinetics, and the data were represented as kinetic saturation capacity and kinetic rate constant. Kinetic saturation capacity value was found to decrease from 0.01 to 0.003 g/g as the value of inlet concentration increased from 81 to 365 ppm. Kinetic rate constant value increased from 2018 to 5048 min−1 when the flow rate was increased from 400 to 1000 mL/min, whereas kinetic saturation capacity value was found to be invariant. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 715–720, 2013

Transport of a Solvent Mixture Across Two Glove Materials When Applied in a Paint Matrix

The transport of mixed paint solvents through natural rubber latex (4 mil) and nitrile rubber (5 mil) gloves was evaluated after spray application of the paint formulation directly on the glove surface. Glove materials and thicknesses were those selected by the majority of spray painters in the local automobile repair industry. A flat panel containing glove specimens mounted in multiple permeation cells permitted evaporation of solvents from the applied paint and incorporated a solid sorbent receiving medium for measuring glove membrane transport. The panel was sprayed in a paint booth to simulate use conditions. Charcoal cloth under the glove adsorbed transported solvents, which were quantified by gas chromatography. For each solvent component, results were expressed as mass transported through the glove relative to the mass applied, per unit area, during 30 min after spray application. The paint formulation contained ketones, acetates, and aromatics. Natural rubber latex allowed 6-10 times the transport of solvents relative to nitrile rubber for all eight solvent components: methyl ethyl ketone, toluene, styrene, ethyl benzene, xylene isomers, and 2-heptanone. m-Xylene showed the largest difference in transport between the two glove materials. This solvent also had the highest transport for each material. The results indicate that nitrile rubber gloves offer somewhat greater chemical resistance to all eight solvents studied compared with natural rubber latex gloves, regardless of the chemical properties of the individual solvent components. However, it must be emphasized that neither of the glove materials, in the thicknesses used in this study, provide adequate protection when exposed by direct spray painting. Simulation of realistic spray conditions may offer a source of useful information on the performance of chemical protective gloves because it accounts for solvent evaporation and the effect of paint polymerization after application on glove transport.

Natural biopolymer for preservation of microorganisms during sampling and storage

Stability of microbial cultures during sampling and storage is a vital issue in various fields of medicine, biotechnology, food science, and forensics. We have developed a unique bacterial preservation process involving a non-toxic, water-soluble acacia gum polymer that eliminates the need for refrigerated storage of samples. The main goal of this study is to characterize the efficacy of acacia gum polymer for preservation of pathogenic bacteria ( Bacillus anthracis and methicillin-resistant Staphylococcus aureus—MRSA) on different materials, used for swabbing and filtration: cotton, wool, polyester, rayon, charcoal cloth, and Whatman paper. Acacia gum polymer used for preservation of two pathogens has been shown to significantly protect bacteria during dehydration and storage in all tested samples at the range of temperatures (5–45 °C for MRSA and 40–90 °C for B. anthracis). Our results showed higher recovery as well as higher viability during the storage of both bacteria in all materials with acacia gum. Addition of acacia gum polymer to swabbing materials or filters will increase efficacy of sample collection and identification of pathogenic bacteria from locations such as hospitals or the environment. Proposed approach can also be used for long-term storage of culture collections, since acacia gum contributes to viability and stability of bacterial cultures.

The effect of volatile organic compounds and hypoxia on paper degradation

The possible effects of volatile organic compounds (VOCs) and of hypoxic conditions on the durability of library and archival collections have been investigated. There is growing evidence that particularly in micro-environments, there may be an important contribution of these indoor-generated pollutants to the degradation of paper. However, since the principal source of VOCs in repositories is the collections themselves, there are also significant possibilities for less stable papers, which are net VOC emitters, to promote the degradation of more stable papers, which may be net VOC absorbers.Using a range of model and real historic papers, the influence of acetic acid, formic acid, furfural, toluene, 1,4-diethylbenzene, iso-butylbenzol, 2-pentylfuran, paraformaldehyde, hexanal and vanillin was evaluated by adding them to samples degraded in closed vessels at elevated temperature. Possible protective effects of the use of activated charcoal cloth, oxygen removal, and of various chemisorbents were also investigated.The results strongly suggest that particularly VOCs with acidic or oxidisable functions can have a strong effect on degradation of cellulose. This is less pronounced in lignin-containing and acidic papers and more pronounced in papers with a small alkaline reserve. The removal of VOCs from the immediate environment can have a pronounced beneficial effect on papers emitting VOCs more intensively, in fact, the lifetime expectancy can be doubled.The results have immediate implications for storage of paper-based heritage in enclosures, but also for initiation of long-term VOC monitoring programmes in libraries and archives, where significant development is still needed.

Organophosphates in aircraft cabin and cockpit air—method development and measurements of contaminants

Methods for measurements and the potential for occupational exposure to organophosphates (OPs) originating from turbine and hydraulic oils among flying personnel in the aviation industry are described. Different sampling methods were applied, including active within-day methods for OPs and VOCs, newly developed passive long-term sample methods (deposition of OPs to wipe surface areas and to activated charcoal cloths), and measurements of OPs in high-efficiency particulate air (HEPA) recirculation filters (n = 6). In total, 95 and 72 within-day OP and VOC samples, respectively, have been collected during 47 flights in six different models of turbine jet engine, propeller and helicopter aircrafts (n = 40). In general, the OP air levels from the within-day samples were low. The most relevant OP in this regard originating from turbine and engine oils, tricresyl phosphate (TCP), was detected in only 4% of the samples (min-max <LOQ-0.29 µg m(-3)). TCP was however detected in 39% of the wipe samples (n = 56) and in all HEPA-filters. Other OPs, as dibutylphenyl phosphate (DBPP) and tri-n-butyl phosphate (TnBP) originating from hydraulic oils were more prominent in the samples, illustrated by determination of TnBP in all of the within-day samples collected from airplanes (n = 76, min-max 0.02-4.1 µg m(-3)). All samples were collected under normal flight conditions. However, the TCP concentration during ground testing in an airplane that had experienced leakage of turbine oil with subsequent contamination of the cabin and cockpit air, was an order of magnitude higher as compared to after engine replacement (p = 0.02).

An experimental wick-type solar still system: Design and construction

A tilted wick-type solar still was designed and constructed. Its practical aspects and performance are presented. Charcoal cloth was used as an absorber/evaporator material and for saline water transport. The distillation system consists of five main parts: (1) the still, (2) main reservoir, (3) constant head device, (4) distillate bottle, and (5) brine reservoir. Indoor and outdoor experimental testings were carried out to investigate the effect of input water flow rate and salinity on the still productivity together with the variation of the solar still efficiency with absorber temperature. The representative daily efficiency of the still was about 53% on clear days in summer. It has been concluded that, the charcoal cloth is a good material for use as an absorber/evaporator and also as a water transport medium. Increase of the input water mass flow rate leads to a reduction in the efficiency of the wick-type solar still. The still efficiency decreased linearly with increase of salinity of the input saline water e.g. it decreased, by indoor testing, from 37.7% to 20% as the NaCl salt concentration increased from 0% to 10% by weight.

Are bioploymers potential deodourising agents in wound management?

To investigate the odour-adsorbing properties of biopolymers, with a view to using the findings to develop a novel dressing with odour-adsorbing properties. The odour-adsorbing properties of a selection of biopolymers (aloe vera, tea tree oil, neem oil and manuka honey) and three commercially available dressings containing activated charcoal cloth (ACC) were quantitatively assessed using laboratory test equipment. An aloe vera-containing composite dressing, designed and developed by the authors, was also compared with the ACC dressings. Aloe vera was the most adsorbent of the biopolymers and a 40% dilution had comparable values to those of the ACC dressings. Furthermore, values for the novel composite dressing were similar to those of the ACC dressings. The novel composite dressing may be a potential alternative to ACC dressings, and has the added advantages of having antimicrobial properties as well as the ability to promote a moist wound environment. However, more research is needed.

Theoretical and experimental study of vapor deposition onto a dressed body part

AbstractWhen air‐permeable clothing is worn, vapor will penetrate to the inside of the clothing. The vapor can deposit onto the skin, thus, forming a potential health threat. In a previous article a model was presented, which describes the airflow around body parts, covered with clothing. This airflow profile is used to calculate the vapor deposition onto the skin. A test setup was developed to validate the deposition model. Cylinders are used as a representative for human body parts. They are covered by a layer of protective clothing and exposed to vapor of methylsalicylate. The amount of vapor which deposites onto the surface of the cylinder is determined by using charcoal cloth. The influence of the clothing air permeability, the wind speed, the diameter of the cylinder, and the distance between clothing and cylinder surface was investigated. The experimental results show reasonable to good agreement with the model. © 2008 American Institute of Chemical Engineers AIChE J, 2008

Development of a Biologically Relevant Dermal Sampler

There are currently no appropriate methods for measuring dermal exposure to volatile agents. To address this we have produced a prototype Institute of Occupational Medicine (IOM) dermal sampler consisting of an adsorbent sandwiched between a permeable membrane and an impervious backing. The concentration of solvent on the membrane surface may be estimated from the mass collected on the adsorbent and the known permeation rate through the membrane. We have developed the prototype IOM dermal sampler for measurement of toluene exposures. Evaluation of the prototype sampler was undertaken in two stages: laboratory performance in controlled exposure situations and two short-field evaluations, which included simultaneous measurement of inhalation exposure. In all cases we compared the prototype IOM dermal sampler with activated charcoal cloth (ACC). Laboratory trials were split into spray, pour and immersion tests. The data from these suggest that the sampler responds to concentration rather than the mass on the surface of the sampler. The field study showed that the prototype sampler was suitable for measuring dermal exposure. However, the mean permeation rate of the best membrane was 78 000 mug cm(-2) h(-1), which is higher than the permeation rate through skin. This high permeation rate created difficulties throughout the study, particularly as it allowed the adsorbent to become rapidly saturated. The prototype IOM dermal sampler is the first practical dermal exposure sampler to mimic uptake through the skin. The sampler gave reproducible results in the laboratory and field trials. Future work is required to identify a less permeable membrane, which has characteristics closer to that of human skin. Additionally, a higher capacity adsorbent would be desirable. We have demonstrated a major difference when calculating the total contribution to body burden via the dermal exposure pathway using the prototype IOM dermal sampler and ACC patches, 1.5% of the total body burden compared with 95%. The prototype IOM dermal sampler provides a more biologically relevant exposure metric than the alternatives.

A novel and convenient self-drying system for bacterial preservation

An effective microbial preservation technology for the long-term storage of viable prokaryotic cells is described. The method combines an almost instantaneous drying step with minimal stress to the cells during drying to maximize survival on rehydration. This is achieved by contact of a microlitre aliquot of a bacterial suspension with a novel, pre-dried activated charcoal cloth based matrix contained within a re-sealable system that can then be stored. The simple methodology completely circumvents the requirement for further drying or preparation. Using this method, a standard laboratory Escherichia coli strain was successfully revived following 390 days storage at 4, 20 and 30 °C. Data obtained yielded approximately 20%, 6% and 0.1% viable organisms at the aforementioned temperatures, respectively, following initial inoculations of 1.1 × 10 8/μl cells. While these figures represent a significant viability loss, there is sufficient recovery of microorganisms required for maintaining culture collections.

Dermal exposure assessment to benzene and toluene using charcoal cloth pads

Charcoal cloth pads have been used to assess volatile chemicals on the skin in a laboratory setting; however, they have not yet been applied to measure dermal exposure in occupational settings. This study aimed at evaluating whether charcoal pads can be used to assess dermal exposure to benzene and toluene in workers of a petrochemical plant. Inhalation and dermal exposure levels to benzene and toluene were assessed for workers of a petrochemical plant performing different jobs. Benzene uptake was assessed by determining S-phenylmercapturic acid in workers' urine samples. Dermal exposure levels on the charcoal pads were adjusted for ambient air levels of benzene and toluene by subtracting the amount of benzene or toluene measured in personal air from the amount of benzene or toluene measured on the charcoal pad. In general, measured external and internal exposure levels were low. The estimated contribution of the dermal route to internal benzene exposure levels was less than 0.06% for all jobs. Toluene personal air concentrations and benzene and toluene dermal exposure levels differed statistically significantly between job titles. For benzene, differences between jobs were larger for adjusted dermal exposures (maximum 17-fold, P = 0.02) than for inhalation exposures (maximum two-fold, P = 0.08). Also for toluene, although less clear, differences between jobs were larger for adjusted dermal exposures (maximum 23-fold, P = 0.01) as compared to inhalation exposures (maximum 10-fold, P = 0.01). Charcoal pads appeared to measure dermal exposures to benzene and toluene in addition to ambient air levels. Future studies applying charcoal cloth pads for the dermal exposure assessment at workplaces with higher dermal exposure to organic solvents may provide more insight into the biological relevance of dermal exposure levels measured by charcoal cloth pads. In addition, the design of the dermal sampler might be improved by configuring a dermal sampler, where part of the sampler is protected against direct contact and splashes, but still permeable for the gas phase. This design would most likely result in a better ability to correct for airborne concentrations at a given body location.

115 Carbohydrate‐based Wound Dressings with Elastase‐lowering Activity

The use of carbohydrate‐based wound dressings including cotton, xerogels, charcoal cloth, alginates, and hydrogels, for chronic wounds have afforded properties such as absorbency, ease of application and removal, bacterial protection, fluid balance, occlusion, and elasticity. An additional consideration is the use of the dressing to regulate proteolysis in the non‐healing wound. Elastase is a serine protease that has been associated with a variety of inflammatory diseases, and recently has been implicated as a destructive protease that impedes wound healing. The presence of elevated levels of elastase in non‐healing wounds has been associated with the degradation of important growth factors and fibronectin necessary for wound healing. Here we consider the design, preparation, and assessment of carbohydrate‐based wound dressings that either release protease inhibitors or act as sequestering agents to bind proteases such as elastase and thus reduce their high levels in the chronic wound. Carbohydrates ranging from small monosaccahrides up to large polysaccharides are crosslinked onto cotton wound dressings. The resulting carbohydrate conjugates of cotton cellulose possess unique properties advantageous for chronic wound treatment ranging from gelation and elasticity to elastase‐sequestering propertiesType in text here making sure it is in a single column format.