The determination and role of peroxyacetil nitrate in photochemical processes in atmosphere.

Peroxyacetilnitrates (PAN) is the most characteristic photoxidant of a range of secondary pollutants formed by the photochemical reaction of hydrocarbons with nitrogen oxides in the atmosphere: it is phytotoxic and shows an increasing role in human health effects due to ambient air exposure, especially in presence of high ozone concentrations. Because of the similarity of the conditions required for their photochemical production PAN is observed in conjunction with elevated ozone concentrations. PAN has very low natural background concentrations so it is the very specific indicator of anthropogenic photochemical air pollution. In this paper we report PAN concentrations determined in Rome urban area during winter- and summer-period. PAN measurements were carried out by means of a gas-chromatograph equipped with an Electron Capture Detector (ECD) detector. For identifying the acute episodes of atmospheric photochemical pollutants the relationship between PAN and the variable Ox (=NO2+O3) which describes the oxidation process evolution is investigated. The role of Volatile Organic Compounds and PAN in the ozone formation is investigated as well the issue of taking in account the autovehicular emissions for checking the NOx fraction in fuel.

A preliminary investigation of total organic carbon variation in influent and effluent of Isfahan (Iran) water treatment plant, urban network and Fellman wells.

In this work a series of total organic carbon (TOC) analyses were carried out to analyse the influent and the effluent of a water treatment plant providing Isfahan city in Iran. Other analyses were focused on the determination of TOC in the urban network and Fellman wells (in Isfahan and Dehaghan cities), in order to compare the water quality soon after the treatment with that of circulating water in the city network. Since it supplies water treatment plant, TOC content of Zayandehrood River was also compared with the treated water. The obtained results revealed that there were significant differences between TOC content of effluent of water treatment plant and that of the urban network (made with eight different points). In this project all the samples were withdrawn during 2005. It is worth noting that the analyses were carried out with a high precision combustion-infrared method with a confidence limit lower than 0.05. The mean of TOC in Isfahan and Dehaghan Fellman wells were 0.7 and 2.6 mg.l(-1), respectively. The mean of TOC in influent of water treatment plant during June, July and September were 0.703, 1.148, 1.513 mg.l(-1) respectively which after treatment process reduced to about 0.7 mg.l(-1). In conclusion it can be said that during the summer with higher consumption of water and increase in vaporizing surface waters, we have accumulation of organic compounds and therefore we have increase in TOC content of various waters.

Optimization of cyanide elimination from an industrial wastewater on a pilot plant scale.

A pilot plant scale reactor was modelled and assembled to experimentally study the cyanide elimination process. The process was performed by using Ca(OCl)2, Cl2 and H2O2. The elimination was optimized at 25 degrees C for time of reaction, pH and amount of oxidant in a pilot plant scale reactor with synthetic solutions. Moreover some tests were carried out by using a real effluent deriving from a gold production industry.