Concentration Of Toluene In Air Research Articles

Evaluation of commercial biochar in South Korea for environmental application and carbon sequestration

AbstractThe performance of commercial wood chip (WC) and biosolid (BS) biochars available in bulk from carbonization processes in South Korea was examined via determination of sorption capacity from batch experiments and evaluation of carbon sequestration using biochar–mortar composites according to construction and environmental properties. Compared with rice straw (RS) biochar synthesized in a laboratory, the sorption capacities of WC and BC biochars are determined by the types of contaminants, the properties of the biochar, and sorption mechanisms. BS and WC biochars are competitive as sorbents for nitro explosives and chlorinated phenols. Characterization of biochar–mortar composites showed that 3–5 wt% biochar inclusion did not significantly change the composites' engineering properties, including flowability, compressive strength, and thermal conductivity. As the biochar content increased in the biochar–mortar composites, the benzene and toluene concentrations in air were accordingly reduced, suggesting that biochar inclusion may be favorable to remove volatile toxic contaminants that cause sick building syndrome. The toxicity characteristics leaching procedure (TCLP) and Micotox® bioassay tests showed that biochar–mortar composites were not toxic. These results suggest that BS and WC biochars in South Korea are competitive as sorbents for some organic contaminants and that biochar–mortar composites may be environmentally friendly carbon‐sequestering construction materials.

Toluene Safe concentration for Toll Gate Keepers at Kebon Jeruk, Jakarta indonesia

Toluene is one of the BTX compounds with a strong and distinctive aroma. When inhaled, this can affect the nervous system and body coordination and cause headaches. At constant exposure, toluene compounds can cause more serious health risks that can cause death. This study aims to determine the safe concentration of toluene in Kebun Jeruk toll gate officers, Jakarta. The population in this study were all 20 Kebun Jeruk toll gate keepers divided into two area points of toll gate 1 and toll gate 2. This study used manually calculated quantitative data analysis through safe concentration calculation in environmental toxicology concepts. Safe concentration data in Jakarta Kebon Jeruk toll gate keepers were obtained from experimental animals� body weight (W animals), body area (BSA animals), workers� characteristics including body weight (W), height (h), body surface area (BSA), breathing rate (BR) and working duration (t). In addition, data on the concentration of benzene (C), animal km, human km, NOAEL and the safe dose of toxin were also used. The concentration of toluene in air that enters the workers body through inhalation measured at two average points was 0.00125 mg/m3 (0.00033 ppm). The value obtained is still far below the toluene threshold value determined by the Minister of Manpower and Transmigration Regulation Number Per.13/Men/X/2011 of 2011. The calculated safe concentration of toluene shows a result of 0.0922 mg/m3 (0.0245 ppm) which is still in the safe category. This level must be maintained to assure its level does not increase. © 2019, Indian Journal of Public Health Research and Development. All rights reserved.

Promoting Effects of Ni for Toluene Catalytic Combustion Over CoNi/TiO2 Oxide Catalysts

AbstractThe supported CoNi/TiO2composite oxide catalysts were prepared by impregnation method. The physical and chemical properties of the prepared catalysts were studied by XRD, XPS and H2-TPR. The results show that the Co3O4, NiO and NiCo2O4species are formed in the CoNi/TiO2composite oxide catalysts. The interaction between the Co and Ni species can effectively enhance the properties of the CoNi/TiO2oxide catalysts. The introduction of Ni species can effectively enhance the surface hydroxyl oxygen species and adsorbed oxygen species content, and the Co3+species content can be enhanced on the surface of the prepared CoNi/TiO2composite oxide catalysts. The low temperature reducibility and toluene catalytic combustion activity of the CoNi/TiO2composite oxide catalysts can be improved by the Ni species. The toluene catalytic combustion activity of CoNi/TiO2composite catalysts can be obviously affected by the Co/Ni molar ratio. The CoNi/TiO2composite oxide catalyst, which has a Co/Ni molar ratio of 1.0, has the best toluene catalytic combustion activity and wide scope of the concentration of toluene. The toluene catalytic combustion conversion can exceed 99 % at 340 °C. That is to say, the toluene concentration in air can be decreased to 80 ppm from 8000 ppm.

Phenyl VOCs catalytic combustion on supported CoMn/AC oxide catalyst

Supported CoMn/AC composite oxide catalysts were prepared by a typical impregnation method at different calcination temperatures. The prepared CoMn/AC catalysts were characterized, and the catalytic activity of the prepared supported CoMn/AC oxide catalysts was also investigated by the catalytic combustion of phenyl volatile organic compounds (VOCs) (benzene, toluene, and ethylbenzene). XRD and XPS results indicated that MnCo2O4 and CoMn2O4 were the main crystal phase species in the prepared supported CoMn/AC oxide catalysts. The active components were observed to be highly dispersed and had small crystal sizes. The toluene catalytic combustion results demonstrated that the CAT350 catalyst had higher toluene catalytic combustion activity than the CTA250, CAT300, and CAT400 catalysts. The toluene catalytic combustion conversion of the CAT350 catalyst exceeded 93.5% at 235°C, with a decreased toluene concentration in air of less than 130ppm at 250°C. The order of toluene catalytic activity of the supported CoMn/AC oxide catalysts was as follows: CAT250<CAT300≈CAT400<CAT350. The catalytic combustion activity and stability of the CAT350 catalyst also increased with the increase in reaction temperature. The catalytic activity of the CAT350 catalyst was investigated to bring about the complete oxidation of benzene, ethylbenzene, and toluene. The combustibility of phenyl VOCs on the CAT350 catalyst was observed to follow the order benzene<ethylbenzene<toluene. Therefore, the differences in the phenyl VOC catalytic combustion performances of the supported CoMn/AC composite oxide catalysts can be attributed to the different physical chemistry properties of the phenyl VOC molecules and the catalyst.

Influence of Ce/Cu ratio on the performance of ordered mesoporous CeCu composite oxide catalysts

Abstract CeCu composite oxide catalysts were prepared by a hard-template method using different mole ratios of Ce/Cu (being designated as CeCu-HTx, where x is the Ce/Cu molar ratio). The prepared catalysts were characterized by XRD, TEM, AAS, XPS, and H2-TPR. The catalytic properties of the prepared CeCu composite oxide catalysts were also investigated by phenyl VOCs (benzene, toluene, xylene, and ethylbenzene) catalytic combustion in air. XRD results showed that the CuO species can fully dissolve into the CeO2 lattice to form CeCu solid solutions having the fluorite structure of crystal-phase CeO2. TEM and low-angle XRD results indicated that CeCu-HT3 had a well-ordered and developed mesoporous structure with uniform pore size, which is better than the CeCu-HT2 and CeCu-HT4. XPS and H2-TPR results showed that CeCu-HT3 had abundant active oxygen species and superior reducibility. CeCu-HT3 had higher toluene catalytic combustion activity than CeCu-HT2 and CeCu-HT4 in air. The minimum reaction temperature at which toluene conversion exceeded 90% on CeCu-HT3 was 225 °C. Toluene catalytic combustion conversion on CeCu-HT3 at 240 °C exceeded 99.3% with decreased toluene concentration in air to below 70 ppm. The phenyl VOCs catalytic combustion activity on the CeCu-HT3 catalyst follows the order ethylbenzene > toluene > xylene > benzene. The CeCu-HT3 catalyst shows high stability and efficiency for toluene catalytic combustion in air. And the CeCu-HT3 catalyst can be applied in purification treatments for air containing a wide range of toluene concentrations.

Toluene chemiresistor sensor based on nano-porous toluene-imprinted polymer

In this work, the application of molecularly imprinted polymer (MIP) as the recognition element of a chemiresistor sensor was introduced. Toluene-imprinted polymer and non-imprinted polymer (NIP) were synthesized and then mixed with carbon black powder in the presence of melted n-eicosane as the binder agent. The obtained composites were applied for the construction of chemiresistor sensors. The sensor, fabricated with toluene-imprinted polymer, showed a significant response towards toluene. Moreover, the response of the NIP-based (polymer synthesized without solvent) chemiresistor sensor was very small and negligible. The components of the MIP-based sensing composite were found to strongly influence the sensor sensitivity. Response surface experimental design methodology was applied to optimize the important parameters of the proposed sensor. Cross-sensitivity of the MIP-based chemiresistor sensor for different vapours was investigated and a satisfactory result was found for toluene vapour recognition. It was shown that the sensor response to toluene concentration in air was linear in the concentration range of 3.8 to 46.4 ppm. The detection limit and relative standard deviation (for five separate determinations) of the designed sensor were calculated equal to 0.8 ppm and 5.6%, respectively.

Effects of the structure of CeCu catalysts on the catalytic combustion of toluene in air

Abstract CeCu composite oxide catalysts were prepared by a hard-template method (CeCu-HT) and a complex method (CeCu-CA). The prepared CeCu composite oxide catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) analyses. The catalytic properties of the prepared CeCu composite oxide catalysts were also investigated by the catalytic combustion of toluene in air. XRD results showed that the synthesized CeCu composite oxide catalysts had different phase components and crystallinities but similar CeO 2 CuO solid solution phases. Low-angle XRD, TEM, and BET results indicated that the prepared CeCu-HT catalyst had a developed ordered mesoporous structure and a large specific surface area of 206.1 m 2 g −1 . Toluene catalytic combustion results indicated that the CeCu-HT catalyst had higher toluene catalytic combustion activity in air than the CeCu-CA catalyst. The minimum reaction temperature at which toluene conversion exceeded 90% for toluene catalytic combustion on the CeCu-HT catalyst was 225 °C. The toluene catalytic combustion conversion on the CeCu-HT catalyst at 240 °C exceeded 99.3% with decreased toluene concentration in air to below 70 ppm. On the other hand, the toluene catalytic combustion conversion on the CeCu-CA catalyst was only 92% even when the reaction temperature reached 280 °C. The differences between the toluene catalytic combustion performances of the CeCu composite oxide catalysts prepared by different methods can be attributed to their discrepant compositions and structures.

STUDY ON INDOOR VOCs CONCENTRATION REDUCTION PERFORMANCE OF THE ACTIVATED CARBON AND SORPTIVE BUILDING MATERIALS

The concentration of VOCs (Volatile Organic Compounds) in rooms depends not only on emission and ventilation rates, but also on sorption by the room surfaces. The use of sorptive building materials on room surfaces seems effective for decreasing VOCs concentrations that have the possibility of affecting human health. In this study, we evaluated the effects of sorptive building materials with respect to decreasing toluene concentrations in air using a small test chamber. Air containing a low concentration of toluene was supplied, and the decrease in toluene concentration was measured at the exhaust. We examined how the toluene concentration, the air exchange rate of the chamber, the loading factor of the sorptive materials, and the convective mass transfer rate influenced the sorptive performance, which was well reproduced experimentally with the CFD simulations.

작업장 특성에 따른 톨루엔 노출 근로자의 마뇨산 배출 특성

This study was carried out to investigate the correlation between toluene in air and hippuric acid in human urine, which is based in the results of the health check-in and measure of working environment, was investigated for five years. Toluene in air and hippuric acid in urine were checked 116 workers who exposed to toluene in five type of industry. The Mean concentration of toluene in air by type of industry and every year and sex distinction, had positive correlation.(p

Reduced exposure to organic solvents by use of water-based paint systems in car repair shops.

The objective of this study was to determine to what extent the substitution of solvent-based paint by water-based paint has reduced potential exposure to organic solvents for spray painters in car repair shops. Full-shift personal air sampling (n=79) was carried out over 3 consecutive days in eight car repair shops. Blood samples on the Monday morning (n=26) and at the end of the shift on the Wednesday (n=26), were analysed for organic solvents by headspace techniques. Toluene was the organic solvent detected at the highest geometric mean concentration in air samples when solvent-based paint systems were used (0.8 ppm), whereas xylene was found at the highest level when water-based systems were used (0.25 ppm). Toluene, isopropanol, acetone and butyl acetate were detected at higher concentrations when solvent-based paint was used than when water-based paint was employed. The additive factor, based on Norwegian limit values, was three-times higher for the painters using solvent-based paint (0.15) than for those using water-based paint (0.05). On Wednesday after shift the geometric mean of toluene in blood was significantly higher for the painters using solvent-based paint (0.044 microg/ml) than for the painters using water-based paint (0.007 microg/ml). There was a significant correlation between toluene in personal air samples and toluene in blood samples taken at the end of the shift on the same day. When solvent-based paint systems were used the additive factor for organic solvent exposure was three-times higher than when water-based systems were employed. The exposure levels of the organic solvents were well below the Norwegian limit values. The significant correlation between the toluene concentration in air and blood samples indicated that the uptake of organic solvents was correspondingly reduced. At the levels of organic solvents presently described the risk of acute and chronic health effects caused by organic solvents is low.

Estimating amounts of toluene inhaled by workers with protective mask using biological indicators of toluene

Personal air samplers were attached to workers wearing protective masks to determine the levels of toluene vapor in the breathing zone. Concentrations of toluene in exhaled air, blood and urine; and hippuric acid and o-cresol concentrations in the urine of the workers were determined. Subsequently, toluene concentrations in the air inhaled by workers with and without gas masks were estimated by single and multiple regression equations. Analysis of single regression equations revealed that, compared with toluene concentrations in air, masks decreased the concentrations of the four biological exposure indicators: toluene in exhaled air, urinary toluene, urinary hippuric acid and urinary o-cresol by about 29% in average. Analysis by multiple regression equations showed a decrease of 38% in four biological indicators. Since average exposure to toluene in the shop was relatively low, the workers wore the masks only during high concentrations of toluene; they were, however, exposed to direct inhalation when the masks were removed in lower concentrations.

Two cases of acute toluene intoxication.

Two patients exposed to high concentrations of toluene in air (greater than 7000 mg/m3) were found at the bottom of a small swimming pool under construction. Their symptoms were stupefaction, paresis, and amnesia. Patient A had been exposed for three hours and patient B for two hours. Ninety minutes after the exposure, the toluene blood concentration in patient A was 4.1 mg/l and in patient B 2.2 mg/l. Urinary ortho-cresol secretion was shown to be a good index of exposure to toluene. After high level exposure, urinary meta-cresol excretion may also be used to monitor toluene exposure.

Chronic toxicity and oncogenicity bioassay of inhaled toluene in fischer-344 rats

The chronic toxicity and oncogenicity of inhaled toluene were assessed in Fischer-344 rats. One hundred and twenty animals of each sex were exposed for 6 hours/day, 5 days/week, for up to 24 months at concentrations of toluene in air of 0, 30, 100, or 300 ppm. The calculated time-weighted average concentrations for the 24 months of exposure were 0.0, 30.1, 99.7, and 299.0 ppm, respectively. Interim sacrifices on randomly selected animals were conducted after 6, 12 and 18 months of exposure. All surviving rats were sacrificed at 24 months. A large battery of tissues and organs from all animals in the control and 300 ppm toluene group were examined for histopathology. All animals were examined for clinical changes throughout the course of the study and selected animals were used to determine ophthalmologic, hematologic, clinical blood chemistry or urinalysis effects. There were 140 unscheduled deaths over the 2-year study. Gross pathologic examination of rats dying during the course of the study, or that were sacrificed as scheduled, did not reveal any lesions attributable to toluene exposure. Histologically, a variety of proliferative, degenerative and inflammatory lesions were observed in the control and 300 ppm toluene-exposed group. These lesions were considered unrelated to toluene exposure. The results provide no evidence that toluene causes chronic toxicity or oncogenicity in Fischer-344 rats at these concentrations.

Hippuric acid and o-cresol in the urine of workers exposed to toluene.

Factory workers, 74 males and 56 females exposed predominantly to toluene up to 129 ppm, were examined for the urinary excretion of hippuric acid and o-cresol. The time-weighted averages (TWA) of toluene exposure were measured by personal sampling with carbon felt dosimeters. A preliminary study revealed that the concentrations of hippuric acid and o-cresol in urine increased during work and both reach their peaks at the end of the shift. Correlation coefficients between the TWA of toluene concentration in air and hippuric acid concentration in urine collected at the end of the shift were 0.803 for the 74 males, and 0.830 for the 56 females, while the counterpart correlation coefficients between toluene and o-cresol were 0.607 for the 74 males, and 0.627 for the 56 females, suggesting that hippuric acid is more reliable than o-cresol as an index of toluene exposure. In the urine samples (4 to 8 samples per subject) collected during 8-h worktime from 11 males and 13 females, the urinary levels of o-cresol increased as a function of exposure time in parallel with those of hippuric acid, and the correlation coefficients between o-cresol and hippuric acid were significant (r = 0.834 approximately 0.987; P less than 0.05) when the urine samples from the same subjects were examined. The comparison of the slopes of 24 regression lines between o-cresol and hippuric acid in urine revealed that the maximal slope was almost 8 times as large as the minimal one. From 8 female workers, five urine samples each were collected during 8-h worktime on two consecutive Mondays and analyzed for the two metabolites. The slopes of the regression lines between o-cresol and hippuric acid in the samples from the same subject were identical, regardless of variation in exposure intensity. The findings indicate that an individual difference exists in the pattern of toluene metabolism, and that the ratio between aliphatic and aromatic oxidation is presumably set congenitally. Possible toxicological significance is discussed.

Chronic occupational exposure to toluene.

Chronic occupational exposure to toluene was studied in a factory preparing tarpaulins. Seventy-eight workers were studied; 46 were exposed to various concentrations of toluene in air (20--200 ppm), 32 were unexposed workers in the same factory. In many cases the exposure had lasted for 10--20 years. The urinary hippuric acid excretion at the end of work shift showed good correlations to toluene concentrations in air, and it seems to be a good measure of exposure. The hippuric acid in urine samples collected overnight showed that elimination of toluene still occurs several hours after exposure. Most of the biological parameters measured showed no correlation to toluene exposure. The blood leukocyte count did not show slight positive correlations to toluene exposure, but even this parameter stayed inside the range of normal values. The occurrence of chronic diseases, drug using habits, and drinking and smoking habits did not show any correlations to toluene exposure.

The Analysis of Toluene for Benzene by an Ultraviolet Absorption of Vapor Mixtures and the Determination of Concentration of Toluene in Air by Use of the Rayleigh-Jeans Interference Refractometer*

A quantitative spectrographic method for the analysis of toluene for benzene is described, which is useful in the range of concentrations of benzene from 0.01 to 10 percent. The method is both convenient and highly specific. The use of the Rayleigh-Jeans interference refractometer in the control of concentration of toluene vapor in an exposure chamber suitable for toxicological investigations is described. The method employed is both rapid and accurate. At low concentrations, with the bubbler used, the control is within 5 percent of the amount present; at higher concentrations the control is within 10 percent.