pISSN: 2008-5109
eISSN: 2008-5435
Editor-in-Chief:
Mohammadreza Monazzam Esmaeilpour, PhD.
Vol 6 No 1 (2014)
Published:
2015-10-15
Original Article(s)
-
The aim of this study was to investigate the removal of toluene from air through Nano-graphene modified by ionic liquid (NG-IL). The batch adsorption experiments in glass bottle of gas chromatography equipped with flame ionization detector (GC-FID) were used. Graphene ultrahigh-quality synthesized by substrate-free gas-phase method in a single step and graphene sheets were deposited with ionic- liquid by thermal adsorption in acetone blank solution. Various conditions including contact time, amount of adsorbent, adsorbate concentration, humidity, and temperature were studied and optimized. NG-IL adsorbent was used for the adsorption of toluene vapor from gaseous media and the effect of different conditions such as; toluene concentration, humidity, and temperature on the adsorption were investigated. The Langmuir adsorption isotherms were employed for toluene by NG-IL adsorbent. The adsorption capacity was decreased by raising the sorbent humidity above 50 percent. The toluene capture capacity for NG-IL was 126 mg/g. The results of SEM, XRD, and TEM showed that, the NG-IL have beneficial surfaces for toluene removal. NG-IL as a novel adsorbent has not previously been used for the adsorption of pollutants.
-
Heat stress is a common occupational health hazard at outdoor workplaces especially in a hot-humid climate. Overheating of the body can cause a number of problems, including heat rash, heat cramps, dizziness, heat exhaustion, and heat stroke. The present study aimed to assess heat stress indices including DI, WBGT, and SWreq/PHS, as a mean to estimate the heat load on the employees of a petrochemical industry. The study was conducted in Pardis Petrochemical Company. All of the ammonia-phase workers (10 men) working in the hot-humid condition were selected and other 11 men workers were chosen from the work sites without risk of heat stress. The physiological parameters such as heart rate, systolic and diastolic blood pressure and deep and skin temperatures and weather parameters, including: Discomfort Index, Wet Bulb Globe Temperature and Required Sweat Rate based on Predicted Heat Strain were measured simultaneously. All of the subjects in two groups as acclimated and unacclimated were monitored in two different weather and working conditions: the work-site and the rest-room. The mean values of the indices and the physiological parameters for both acclimated and unacclimated groups were significantly higher at the work-site than at the rest-room. For WBGT and DI indices, the highest correlation was found with heart rate (0.731, 0.725, respectively). However; the strongest linear relationship existed between SWreq/PHS and deep body temperature (0.766) among the under study heat stress indices. With regard to the data obtained, the SWreq/PHS index had the greatest correlation with deep body temperature, so, it can be served as a quick tool to evaluate heat stress for a petrochemical industry like Pardis and appraise the approximate amount of heat strain imposed to the employees.
-
The objective of this study was to evaluate the presence of perchloroethylene (PCE) and trichloroethylene (TCE) in dry cleaning shops in Tehran, Iran. PCE and TCE are two most prevalent solvents in dry-leaning shops. Air and effluent samples were collected in October to December 2011 from 10 dry-cleaning shops. Analyses were performed by head-space gas chromatography technique. Gas chromatography with FID detector is used for analysis. Mean PCE levels in the air of ten dry-cleanings ranged from 42.7 to 516 μgL-1 with maximum level of 960, PCE mean levels in the effluent ranged from 186.5 to 292.9 μgL-1 with maximum level of 326. Mean TCE levels in the air effluents ranged from 29.5 to 543.7 μgL-1 with maximum 964 and 25.5 to 29.75 μgL-1 with maximum level of 37 μgL-1 respectively. The survey of the PCE and TCE in dry-cleaning shops in Tehran shows that both air and effluent have been contaminated by PCE and TCE. These solvents have several negative health effects. Health education is essential for workers.
-
Acoustic experimental data of IRIB (Islamic Republic of Iran Broadcasting) server room was taken to measure the acoustic noise characteristics of frequency and Sound Pressure Level (SPL). The purposes of this paper are measuring the noise pollution and its evaluation through the regulations. The measurements were taken in two stages. The first one was taken at 10 points by Sound Investigator 2260 using ISO 3741: 1999(E) standard. The results indicate that IRIB server room is an acoustic noise polluted according to Iranian National Building Regulations. Measured data and its frequency analysis show that the high sound energy belongs to low frequencies in the server room. This is confirmed by the next stage of measurement. It was an hour long non-stop noise measurement in the server room to investigate noise exposure level by customers and employees. The Equivalent instant noise level on Aweighting network was 75 dBA. The results are valid for all of data centres, although this study is involved with a special case study. Two main factors are important in server room noise pollution scenario; the amount of sound absorbance in the space and environmental noise characteristics. Most surfaces in server rooms are hard and have low absorbance coefficient, therefore, the intensity of travelling sound increases. On the other hand, the main noise sources in any server room are fans which work usually on a narrowband with a fundamental frequency. So as the main features of server room acoustic noise are the same, the presented results can be generalized to any server room.
-
Noise is a common and widespread problem in workplaces. Noise can lead to hearing loss, hypertension, nervous and mental disorders, annoyance and stress, sleep disturbance, negative impact on productivity and working capacity. The undesirable effects of noise on an individual or group are called annoyance. Some personal and social characteristics can affect on annoyance. This study was aimed to assess the level of noise pollution in some hospitals in Qom, central Province of Iran and study its effects on nurses’ psychological and physiological responses. The sound levels were measured using a sound level meter and the noise annoyance was assessed through a valid and reliable questionnaire. The noise annoyance index was finally defined based on variables measured by the questionnaire and its correlation with equivalent sound level at different frequencies. Besides, the major noise sources in different wards of the hospitals, the relationship between noise annoyance and demographic and personal characteristics and the effects of noise on sleep disturbance were analyzed. Based on results the average noise level in some hospitals was higher than the national standard in Iran (45 dB (A)). Moreover, in some wards, nurses have experienced different ranges of noise annoyance with obvious signs of it. The finding also indicated that there was a significant relationship between sleep disturbance and noise annoyance (p<0.001). Nurses believed that the noise of patients’ families was the most annoying sound source. According to the annoyance index, noise pollution in hospitals can cause psychological effects on staff and be associated with annoyance.
-
ANSI/ASHRAE 110-95 protocol is a widely acceptable method to assess the performance of laboratory hoods. In this test, sulfur hexafluoride (SF6) is applied as a tracer gas to quantitatively evaluate the performance of laboratory hoods. The environmentally hostile characteristics of SF6 as well as its cost are the major concerns. In the present study, the substitution of ethylene with SF6 in the ASHRAE 110-95 test method was investigated. Both SF6 and ethylene were applied to a laboratory hood at different face velocities and injection flow rates according to the ASHRAE 110-95 method. Meanwhile, the exposure of a mannequin stationed at the front of hood was measured. The concentration of tracer gases was measured using direct reading instruments. Linear regression of the results was used to consider the substitution of ethylene with SF6.The occupational exposure of the proposed hood operator to SF6 and ethylene were 4.2-7.3 ppm and 0.1 to 0.57 ppm respectively. SF6 exposure was increased significantly (p<0.001) by increasing the injected level while ethylene exposure was decreased significantly (p<0.001). The linear correlation between the leakage levels of two tracer gases at the injected flow rate of 4 lit/min did not fit well with experimental data. Ethylene is not recommended as a substitution for SF6 in ASHRAE 110-95 hood performance test.
-
Infrastructure development being the major construction activity undertaken with the support of the Government to eradicate poor transport infrastructure, to cater to ever-increasing population, to reduce the usage of own vehicle and environmental impact thereof, the concept of mass rapid transit system came into existence. Among the various mass rapid transit system modes, Metro rail construction was picked up in several cities in India. The execution of metro rail involves many painstaking occupational and health issues for its employees and citizens. Simultaneous construction across the various locations along a particular corridor is adapted to provide efficient transportation to outer fringes of a city. This study was conducted in a construction organization involved in metro works in various corridors, to ascertain the priority corridor in a based on the environmental and occupational concerns in a particular city by using multiple attribute decision making approach. Results show environmental impacts varies among metro corridors. The contribution of the study will help clients, management and Government to frame safety policy to minimize effects on public health and employees.
-
The modeling of kinetic and isotherm curves acquired in adsorption of polycyclic aromatic hydrocarbons (PAHs) as a model compound (phenanthrene) on activated carbons in the organic solvent. All the runs were carried out in a batch system at atmospheric pressure, process temperature of 24±2°C, and using the 100 ml phenanthrene in cyclohexan. This experimental work was mainly focused on the study of how the variables properties such as adsorbent dosage, the initial phenanthrene concentration, contact time and pH of cyclohexane solutions influence the kinetic and isotherm of the adsorption process. The results indicated that pH did not play a key role in the process of phenanthrene adsorption. The considerable adsorption (8.34 mg/g) was reached at pH 7, adsorbent dosage of 0.3 g/100 ml and agitation time of 11 h on activated carbons. The impact of adsorbent dose on phenanthrene concentration was not important after 0.3 g/100 ml. The results also showed that adsorption capacity became notably greater with an increase in contact time and initial phenanthrene concentration. Another important finding was that adsorption processes and equilibrium data well fitted by pseudo-second-order kinetic (R2=0.99) and Fraundlich adsorption models (R2=0.99). It can be concluded that there was a significant positive correlation between adsorption processes and the Freundlich isotherm model but Langmuir theory showed only a weak association.
