new method for sulfur components removal from sour gas through application of zinc and iron oxides nanoparticles

Use of zinc and iron oxide are common in the desulfurization process from natural gas. In this research, after determinations of the size and specifications through TEM and XRD for each of the metal oxides, two different size ratios were used, 0.66 for zinc oxide and 0.142 for iron oxide. Further, absorption of sulfur compounds in gas [hydrogen sulfide [H[2]S], carbonyl sulfide [COS], methyl mercaptan [C[1]H], ethyl mercaptan [C[2]SH], dimethyl sulfide [DMS], and carbon disulflde [CS[2]] were evaluated at 26°C, 15 psi. The separation and identification processes of the sulfur components were measured by gas chromatography with a chemical luminescence sulfur detector. Results show that particle size variation in zinc oxide increased the sulfur removal from H[2], C[1]SH and C[2]SH from 9.4% to 15.8%, but in the case of COS, DMS and CS, no significant sulfur removal was observed. Further, with reduction of iron oxide particle size [from 0.140 um to 20 nm], the sulfur removal rate increased from 37.9 to 63.1% in all of the natural gas components

Determination of trace elements concentration in wet and dry atmospheric deposition and surface soil in the largest industrial city, southwest of Iran

Dry and wet atmospheric depositions as well as urban surface soil samples were collected in eight different land use zones [during 2010] of the most important and largest industrial city, southwest Iran for determining Cadmium, Chromium, Lead and Zinc. The average of Cd, Cr, Pb and Zn concentrations in the study area for wet precipitation were 17.8 microg/L, 49.97 microg /L, 2.31 microg/L, and 0.53 microg/L, respectively. Also, the mean levels of mentioned elements were 0.144 mg/nr.day, 0.457 mg/m:.day, 0.091 mg/nr.day, and 0.0017 mg/ nr.day, respectively in dry deposition samples. Moreover, the average amounts of Pb, Zn, Cr, and Cd were recorded for soil samples as a value of 64.2 mg/kg, 197.3 mg/kg, 61.24 mg/kg and 0.73 mg/kg. As a result, the trend of metal concentrations in all media were similar and decreased as Zn> Pb> Cr> Cd. The high contamination levels of heavy metals indicate that they have been significantly impacted from anthropogenic activities [non-ferrous metal smelting, fossil fuel combustion, pit burning, gas flaring and traffic sources]. According to analysis results, the significantly positively correlations between Cd-Pb, Pb-Zn and Zn-Cd were shown in all three environments

Designing a traffic noise prediction model for highways in iranian megacities [case study: Ahvaz City]

One of the important factors in urban construction designs is noise prevention. According to results of this study [2011-2012], a suggested model is presented for traffic noise compatible to conditions in Ahvaz. Data was colleted to design a model from totally 112 measuring stations, 4 weekdays and 2 intervals as rush hours, yielding to a total number of 1344 traffic noise measurements [L] and the effective factors from traffic load, speed of vehicles, environmental and dimensional factors of roads. In the next step, based on desired overall structure, using analytical and experimental modeling strategies, several Regression multi-variables were tested on data in order to design a model. The model designed for Ahvaz consists of 9 inputs with high clarification coefficient [R[2]=0.92] and correlation coefficient [R= 0.95]. Due to precision and minuteness of designing as well as the number of inputs, the model can be a suitable one to define half- hour equal level for traffic noise and estimation of noise pollution in Ahvaz

Transferring of Hg concentration from ambient air to rain water and surface soil in an industrial urban area

Mercury is a dangerous and an extremely toxic element, which can transfer to the food chain. Presence of this element in the atmosphere particularly during the rainy seasons cause soil and environmental pollution, therefore this research will evaluate the transformation of mercury vapor from the atmosphere through precipitation into the soil. In the present study, mercury concentrations were determined during two seasons [winter and summer 2011] with 6 air, 14 rainwater and 6 soil, sampling stations. Collection, preparation and analysis of the air, rain, soil samples were based on NIOSH 6009, EPA1631 and EPA 7000 methods, respectively. Mercury concentration was determined by using cold vapor atomic absorption after sample preparation. The results show that the mean mercury vapour concentration in the air samples of Ahvaz city in winter and summer were 3.749 +/- 2.625 ng/m[3] and 2.379 +/- 0.984 ng/m[3], respectively. Further, the range of this pollutant in the air of studied area during the summer and winter seasons were 1.83-3.962 ng/m[3] and 1.394-5.00 microg/m[3], respectively. The highest value of Hg concentration in the rainwater sample was 0.77 +/- 0.0019 ppb and the mean concentration of mercury in the surface soil samples of the city was 0.511 microg/g in winter. Finally, Mercury comparison between results of air and soil samples as well as air and precipitation samples at the winter season [p<0.01] showed a significant relationship

biodegradation of crude oil by bacillus subtilis isolated from contaminated soil in hot weather areas

Using Environmental-friendly methods in order to remove or reduce oil pollutants and their derivations in the environment are developing. In this study, the biodegrading ability of Bacillus Subtilis .sp which has been separated from oil-polluted soil was examined. It was revealed that it can reduce surface tension of growth Medium and produce Bio-Surfactant at 37 and 20 Degrees centigrade. Also, it has the ability to biodegrade oil hydrocarbons. A reduction in surface tension from 58 Nm/m to 31.2 Nm/m at different percentages of crude oil at 37 degrees centigrade is one of the important results

Relationship between concentrations of heavy metals in wet precipitation and atmospheric PM[10] particles in Zanjan, Iran

In this article the heavy metal concentrations in atmospheric wet precipitation and its relationship with the particles [PM[10]] in the air of the city of Zanjan are reported. Two hundreds samples of rain water and snow were collected with 45 particle samples collected monthly. Heavy metals in wet and dry samples were determined by atomic absorption spectrophotometery. The use of enrichment factors and correlation coefficients allowed us to predict the major sources of these metals. The ranges of concentration of Pb, Zn, Cr and Cd in rain water [micro g/L] were 5.8-22.2, 29.26-70, 1.4-4 and 0.25-1.2, respectively. The results showed that the concentrations of Pb, Zn, Cr and Cd in wet precipitation and [PM[10]] in samples collected in southern parts of the city where the traffic load and industrial activities are very high [zone 4], were 22.2, 70, 1.2 and 4 [micro g/L] and 840, 16233, 32 and 54.8 [ng/m[3]], respectively. These values were higher than those measured in the other parts of the city. Most of the calculated enrichment factors higher than 10 were attributed to the traffic and industrial activities. The enrichment factor and correlation coefficient values showed that the heavy metals in the air of Zanjan originate from similar sources. The concentration of particulate matter in 30 air samples of total 45 samples were found to be higher than 50 micro g/m[3]. The average concentrations of Pb and Cd in the city center and near the industrial complexes were higher than World Health Organization standards

Asbestos concentrations and lung restrictive patterns

Asbestos applications were limited during past two decades in developed nations due to its debilitating health problems, while in developing countries it's various usages continues. The aim goals of present study were evaluation of asbestos concentrations in ambient outdoor and indoor air and occupational exposure, as well as exposure effects on pulmonary function. Sampling procedure was carried out during May and June 2010 at four outdoor and seven indoor air sampling stations. Ten persons were selected based on their exposure limits including high, moderate and low exposure. Also to assess pulmonary function of workers, 42 spirometry cases were tested. Samples were analyzed by SEM with EDXA. Obtained results revealed that average concentrations of asbestos fibers were 1.885 x 10 [-5] f/mL and 0.065 f/mL in outdoor and indoor air, respectively. Occupational exposure contents were between 1.5 x 10[-5] - 0.2 f/mL [based on exposure limits]. Spirometry tests showed that 28% of workers had impaired lung functions. Lung restrictive pattern in workers were 2% severe, 12% moderate and 14%. Results showed pattern of fibrous particles as actinolite> termolite> chrysotile in indoor air. Generally, it is clear that there is positive meaningful relationship between more than ten occupational ages and malfunction of lungs in studied workers due to asbestos effects