Research on the volatility, phase transitions and thermodynamic stability of five organochlorine compounds

• Type: Article in International Scientific Journal
• Date: 2024

Authors

Almeida, RRP (Author) FCUP; Pinheiro, DA (Author) Other; Manuel J S Monte (Author) FCUP

Journal

Title: Chemosphere

Vol. 351

ISSN: 0045-6535

Publisher: Elsevier

Indexing

Scopus - 0 Citations

Other information

Authenticus ID: P-00Z-WN6

DOI: 10.1016/j.chemosphere.2024.141224

Abstract (EN): The present investigation describes the experimental evaluation of relevant physicochemical properties of five organochlorine compounds (OCs), including some that are related to their environmental mobility. The vapor pressures of (2,4¿-Dichlorodiphenyl)dichloroethane (2,4¿-DDD, CASN:53-19-0), 1,1-Dichloro-2,2-bis(4-chlorophenyl)ethane (4,4¿-DDD, CASN:72-54-8) and 2,2-Bis(4-chlorophenyl)acetic acid (4,4¿-DDA, CASN:83-05-6), as well as of the bactericide Nitrapyrin (CASN:1929-82-4) and of the rodenticide Crimidine (CASN:535-89-7) were determined at different temperatures. The Knudsen mass-loss effusion technique was employed to determine the sublimation vapor pressures of the referred compounds, apart from Crimidine. For the latter compound, a static method using a capacitance diaphragm manometer enabled the measurement of vapor pressures of both condensed (crystalline and liquid) phases. This technique was also used to measure the vapor pressures of the crystalline phase of Nitrapyrin over a larger temperature range, as well as its vaporization vapor pressures. The results of the standard molar enthalpies, entropies, and Gibbs energies of sublimation for all five compounds and of vaporization for Crimidine and Nitrapyrin, at reference temperatures, were derived. For these two compounds the phase diagram representations of the (p,T) results, in the vicinity of the triple point, were obtained. DSC analysis enabled the determination of the crystalline heat capacities of the five OCs studied and also of their temperatures and enthalpies of fusion. Gas-phase thermodynamic properties were estimated using quantum chemical calculations. The thermodynamic stability of the compounds studied was evaluated and compared in the crystalline and gaseous phases, at 298.15 K, in consideration with estimated results of the standard Gibbs energies of formation. Combined with other physical and chemical properties, the results derived from this study can be used to predict the mobility, and environmental fate of these pollutants. © 2024 Elsevier Ltd

Language: English

Type (Professor's evaluation): Scientific