Decoding Coumaphos: Tracing its journey in the lithosphere via degradation mechanisms and assessing sorption proficiency through kinetics study

Abstract

The fate of Coumaphos in the environment was evaluated through meticulous emulation and analysis of the intricate pedospheric matrices. The fate-determinative investigations entailed a meticulous examination of Coumaphos's behavior, encompassing adsorption and desorption characteristics and its decomposition rate via hydrolysis, photolysis, and intrinsic biological degradation in soil. The interactions between Coumaphos molecules and soils were found to be robust, with physiosorption being the predominant mode of interaction. Thermodynamic analysis, based on the negative values of Gibbs free energy (−23,569 to −15,798 kJ/mol), indicated exothermic and spontaneous adsorption processes. The highest adsorption capacity (K_d(ads) = 34.97 μg/mL) was observed in soils with a notable organic matter content (1.99%), exhibiting a C-type isotherm that was confirmed through linear and Freundlich models. Analytical techniques such as ultraviolet-visible spectrophotometry and gas chromatography-mass spectrometry were employed to determine the fate of Coumaphos in soil matrices. The minimum half-lives of Coumaphos in hydrolysis, biodegradation, and photolysis experiments were 203, 52, and 69 days, respectively. These findings highlight the strong affinity of Coumaphos for the selected agricultural soils, indicating limited potential for transformation. Moreover, findings highlight the potential for further optimization of these degradative routes to devise practical strategies for environmental remediation utilizing natural processes.