ABSTRACT
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
ABSTRACT
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