Thermodynamics study of chlordecone solubility in water

Chlordecone, also known as Kepone, an organochlorine pesticide extensively employed in the French West Indies until 1993, presents a contemporary public health challenge due to its low solubility and historically substantial usage. In contrast to prior literature relying solely on computational modelling or structural analogy predictions, this study presents the first direct experimental determination of chlordecone’s thermodynamic solubility characteristics across the biologically and environmentally relevant temperature range of 4–90 °C, illustrating both quantitative and qualitative variations with temperature. At the reference temperature of 25 °C, the measured solubility is 10.69 mg L⁻1 (versus the historical 2.7 mg L⁻1), revealing significant variations between a theoretical and experimental approach. The compound’s melting point is experimentally determined to be 113 °C, accompanied by an enthalpy of fusion of 6.5 ± 0.8 kJ mol−1. The enthalpy of chlordecone dissolution in water is confirmed at 17 kJ mol−1 and the strong negative entropy change − 67 J K−1.mol-1 is found indicating a moderately evolving saturation process. The Apelblat and non-random-two-liquids (NTRL) model demonstrated efficacy in predicting chlordecone solubility, showing a high level of random arrangement due to hydrophobic properties of chlordecone. These findings contribute valuable insights into the thermodynamics governing chlordecone’s behaviour in aqueous environments, essential for comprehending its environmental impact, its effect on the population exposed to chlordecone and guiding mitigation strategies.