جستجوی مقالات مرتبط با کلیدواژه "اتیل بنزن و زایلن" در نشریات گروه "پزشکی"

BTEX compounds are one of the most important chemical air pollutants in the oil industry, which have adverse health effects on the employees of this industry. This research was conducted with the aim of evaluating and measuring the concentration of BTEX compounds and their possible effects on the respiratory parameters of the employees of Abadan Oil Refining Company.

In this study, 80 workers were examined. Sampling of the respiratory area of the exposed workers was performed according to the NIOSH method 1501 using an active personal sampling pump of SKC UK company, model 44-224 MTX and using SKC activated carbon absorbent tubes(model 226-01) and the measurement of respiratory parameters was done by a microlab spirometry device made in Italy by MIR company.

The results showed that the average concentration of toluene, ethylbenzene and xylene compounds in the respiratory area of the exposed workers is lower than the standard limit, but the average concentration of benzene compound is above the limit. The results showed that there is no significant difference between the respiratory parameters of the two groups of employees, and there is a direct and significant relationship between the average respiratory parameters of FEV1 and FVC in the two groups of employees, and there is no significant relationship between the respiratory parameters and demographic characteristics in the two groups. It didn't happen.

Considering that the average concentration of benzene compound is higher than the permissible limit of the recommended standards, to control it, it is necessary to take necessary measures to reduce the concentration and remove this compound through technical engineering and management controls, periodic inspections. 

Among the volatile organic compounds, benzene, toluene, ethylbenzene and xylene compounds (BTEX) are important as air pollutants that have harmful effect for health even at very low concentrations. The main source of these compounds is the exhaust gases from vehicles exhaust. The purpose of this study was to measure BTEX compounds in outdoor and indoor environment of 4 high schools located in two districts of Isfahan and Chadegan city. Samples of air from inside and outside the schools were collected by individual sampling pumps using active carbon tubes. Then BTEX compounds were extracted by solvent CS2 and measured by mass spectrometric gas chromatography (GC-MS). Findings: The average concentration of BTEX compounds in Isfahan city was higher than Chadegan. Also, the concentration of BTEX compounds in Isfahan region 2 (Imam Hossein Square) was higher than Zone 1 (Chahar Bagh Khaju) and the highest and lowest concentrations among the BTEX components were respectively in relation to toluene and ethylbenzene. There was not significant difference between Indoor/Outdoor ratio in two regions. There was no significant relationship between the indoor and outdoor concentrations of BTEX compounds in two cities and two regions, which shows that the indoor environment is contaminated by internal resources. Based on the results, the city of Isfahan was more polluted then Chadegan. Also, region 2 in Isfahan was more polluted than region 1. So that the pollution is more related to external sources such as traffic. Keywords

Benzene, Toluene, Ethylbenzene and Xylenes (BTEX) are important parts of the volatile organic compounds (VOCs) family, which are widely used in many industries. These have been classified as carcinogenic compounds and the neurotoxic effects of BTEX have been reported; so, a screening evaluation of workplace air quality for determining BTEX may seem necessary.
In order to measure the workplace concentrations of BTEX in the hydrometallurgical process, six sampling stations were selected. Volatile organic compounds were analyzed using the method 1501 of the National Institute for Occupational Safety and Health (NIOSH). Activated carbon was used for sampling and samples were analyzed by gas chromatography with flame ionization detection (GC-FID).
The highest measured levels were observed for ethylbenzene at sampling station 1 (0.8 ppm). The concentration of benzene in this sampling location was 0.05 ppm. The highest toluene concentration was reported at sampling station 4 (0.15 ppm) and the lowest toluene concentration was 0.02 ppm at sampling station 6.
Indoor air quality in workplaces can be affected by the presence of BTEX. The results of measurements of BTEX showed low concentration levels of these compounds in the studied workplace.

The removal of ethylbenzene and xylene at a concentration of 10 mg/l from aqueous solutions by single- and multi-walled carbon nanotubes (SWCNT and MWCNT, respectively) and hybrid carbon nanotubes (HCNT) was evaluated at a nanomaterials dose of 1 g/l, a contact time of 10 minutes, and a pH 7. Synthetic samples were analyzed by gas chromatography/mass spectrometry (GC/MS). In order to analyze the data, design of experiment (DOE) was applied. The equilibrium amounts (qe) (mg/g) using SWCNT (ethylbenzene: 9.97 mg/g and xylene: 10 mg/g) were higher than using MWCNT and HCNT. Xylene was adsorbed more than ethylbenzene due to its better water solubility and lower molecular weight. It is concluded that recycling by heating at 105 ± 2ºC, used for the first time in this study, cause better adsorption performance for carbon nanotubes. In addition, the SWCNTs can effectively adsorb ethylbenzene and xylene from water and can thus be used as efficient adsorbents to purify waters and wastewaters polluted by petrochemicals.

The BTEX chemicals (Benzene, Toluene, Ethyl benzene, and Xylene) are volatile monoaromatic hydrocarbons. Motor vehicles and fuels are examples for major sources of these environmental pollutants emission. They have harmful health effects. To reduce their health influences, monitoring their concentrations and controlling these pollutants in ambient air is indispensable. The aim of this study was to survey 24 hour variations of BTEX concentration in the ambient air of Tehran, Iran. In this cross sectional study, round-the clock concentration variations of these compounds in the atmosphere of Tehran metropolitan city were surveyed. Two air quality monitoring stations, Aghdasieh and Ray, in two different locations in the city were applied. Twenty four hour sampling was carried out by an online sampler on a monthly basis. The mean concentration of benzene (63.24±11.19 ppb), ethyl benzene (38.23±9.08) and xylene (14.13±3.29), in Ray was higher than Aghdasieh (16.57±5.86, 5.08±1.67 and 5.96±1.89, respectively) and the mean concentration of toluene in Aghdasieh (9.11±1.16) was higher than Ray (7.6±1.78). The results showed correlations among the concentrations of pollutants in each station in most cases and between two stations (p< 0.05). According to the results, despite of the different concentrations of pollutants for two studied stations; a similar trend of daily concentration changes was seen in the stations. This similar trend can be useful in 24 h concentrations prediction of BTEX in ambient air for different places.