Yaghoub Hajizadeh , Mohsen Rezaei , Yousof Poureshgh, Marziyeh Vahid Dastjerdi, یعقوب حاج زاده,
Volume 10, Issue 2 (6-2014)
Abstract
AbstractBackground: Heavy metals in industrial wastewater especially chromium (VI) are considered as the main environmental pollutants.Methods: Electrochemical cell made of plexiglass with a volume of 1.95 lit was used. Iron and graphite electrodes, electricity conductor, each with dimensions of 0.1×3×10 cm (width×length×height) were designed and built. Tests were carried out in various conditions of pH, concentrations of input chromium (VI), different amounts of electrolytes, electric currents and retention times. Measurement of samples was performed using of diphenylhydrazine method.Findings: Maximum removal efficiency for iron and carbon electrodes at about 99.8% and 88.3% was observed, respectively. The lowest among of Cr+3 in efficiency wastewater of system was recorded about 0.05 mg/l for Fe electrode.Conclusion: The results showed that the operation of the electrochemical cell, efficiency removal of Cr (VI) by iron electrode in the same process conditions is more than carbon electrode. Generally, despite in this method removal efficiency of hexavalent chromium from synthetic wastewater is acceptable however consume a lot of electrical energy. Thus, electrochemical method is usable for the removal of heavy metals in industrial scale.
Mehri Seddigh, Fatemeh Sajjadfar, Hakimeh Teiri, Yaghoub Hajizadeh,
Volume 12, Issue 2 (7-2016)
Abstract
Background: Benzene, toluene, ethylbenzene, and xylene isomers (BTEX) are volatile organic compounds that are classified as suspected human carcinogens. These compounds are emitted into the atmosphere via evaporation of petroleum products and affect the health of staff, drivers, and surrounding residents. The aim of this study was to monitor BTEX concentrations in ambient air of filling stations and their surrounding areas, and compare them with the environmental and occupational standards.Methods: In this study, the air samples were collected from vicinity of fuel pumps and at a distance of 40 meters from them using a personal sampling pump with activated charcoal tubes. Then, the BTEX were extracted by CS2 solvent and analyzed using a gas chromatography-flame ionization detector (GC/FID). The aromatic hydrocarbon analysis method of the National Institute for Occupational Safety and Health (NIOSH) (method 1501) was used for sampling and analysis.Findings: The mean concentrations of benzene, toluene, ethylbenzene, and xylene isomers in the fuel stations, respectively, were 235.9, 415.2, 93.34, and 333.14 µg/m3 in the autumn, 200.1, 329.2, 73.3, and 321.4 µg/m3 in the winter, and 254.2, 432.5, 113.2, and 486.1 µg/m3 in the spring. The concentration of benzene in the filling station was much higher than the recommended standard for occupational exposure.Conclusion: The mean concentration of BTEX in the warm season was higher than cold season. Emission of the pollutants from CNG stations was much lower than gasoline and diesel stations. Concentrations measured at a distance of 40 meters from the stations were very low compared to that near the stations. Therefore, taking measures such as controlling of possible pumps and tanks leakage, and petrol vapor recovery during fuel transfer is necessary in order to protect the health of workers and bystanders.
