Sürdürülebilir Yeşil Kampüs Koleksiyonu / Sustainable Green Campus Collection
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Article Citation - WoS: 50Citation - Scopus: 55Determination of Henry's Law Constants of Organochlorine Pesticides in Deionized and Saline Water as a Function of Temperature(Elsevier Ltd., 2006) Çetin, Banu; Özer, Serdar; Sofuoğlu, Aysun; Odabaşı, MustafaThe Henry's law constant (H) is an important parameter that is required to estimate the air-water exchange of semi-volatile organic compounds. Henry's law constants for 17 banned/restricted/currently used organochlorine pesticides (OCPs) were experimentally determined using a gas-stripping technique in deionized and saline water (3%) over a temperature range of 5-35 °C. H values (at 25 °C) ranged between 0.066±0.037 Pa m3 mol-1 (endosulfan II) and 62.0±24.2 Pa m3 mol-1 (heptachlor) in deionized water while the range in saline water was 0.28±0.03 Pa m3 mol-1 (γ-HCH) and 135.2±31.3 Pa m3 mol-1 (heptachlor). The increase in dimensionless Henry's law constants (H′) for OCPs over the studied temperature range was between 3 (γ-HCH)-19 times (chlorpyrifos) and 3 (endosulfan II)-80 times (trans-nonachlor) in deionized and saline water, respectively. The calculated enthalpies of phase change (ΔHH) were within the ranges previously reported for OCPs and other organic compounds (23.8-100.2 kJ mol-1). The salting-out constant, ks, ranged between 0.04 (γ-HCH) and 1.80 L mol-1 (endosulfan II) indicating the importance of assessing the H values of OCPs in saline water to accurately determine their partitioning and fate in seawater.Article Determination of Henry's Law Constants of Organochlorine Pesticides in Deionized and Saline Water as a Function of Temperature(Elsevier Ltd., 2006) Çetin, Banu; Özer, Serdar; Sofuoğlu, Aysun; Odabaşı, MustafaThe publisher regrets that the second paragraph on p. 4545 was printed incorrectly. It now appears correctly, below. The presence of salts in aqueous solution affects the solubility of organic molecules, through the salting-out effect (Demou and Donaldson, 2002). The salting-out is defined as the decrease in aqueous solubility and increase in the activity coefficient observed for neutral non-polar compounds by dissolved inorganic salts. Ions in solution tightly bind several water molecules into hydration shells. This process (electrostriction), results in a reduction of the volume of the aqueous solution. A smaller aqueous volume results in less available water for cavity formation, and therefore less organic molecules are accommodated; their solubility decreases as a consequence (Schwarzenbach et al., 2002; Demou and Donaldson, 2002). The empirical relation for the effect of ionic strength on Henry’s law constant is described by Setschenow equation (Demou and Donaldson, 2002):Master Thesis Measurement of Henry's Law Constant of Organochlorinated Pesticides(Izmir Institute of Technology, 2005) Özer, Serdar; Sofuoğlu, AysunMost of the semi-volatile organic compounds, which are environmentally important, are subject to long range atmospheric transport due to their chemical and physical properties. Their vapor pressure, solubility and indirectly Henry.s law constants are the most important parameters defining their fate during transport of these compounds. Especially in the air-water exchange process, Henry.s law constant plays an important role. Therefore accurate and direct measurement of the Henry.s law constant are required for the most of the compound present in the environment. In this study 17 organochlorine pesticides. Henry.s law constants were measured by a dynamic equilibration method at 5, 15, 20, 25 and 35 a1C in deionized water. The variation in H with temperature was expressed using the van.t Hoff type Gibbs-Helmhotz equation. Calculated enthalpy of phase change for each compound, which helps to describe how sensitive is the partitioning between air and water, within the range of the values reported in the literature. In Gibbs-Helmhotz plots, H values of a compound in saline water were always higher than the H values of that compound in deionized water. Therefore, it was concluded that in the saline water, the air-water partition of these chemicals is shifted to air phase.