<p>This study employs density functional theory (DFT) to investigate the hydrolysis mechanism of the pesticide propanil and the adsorption behavior of both propanil and its major metabolite 3,4-dichloroaniline on the ionic liquid [Bmim]⁺BF₄⁻. The hydrolysis pathway proceeds through a tetrahedral intermediate, with the elimination step as the rate-determining step. Solvent-phase calculations reveal that water stabilizes intermediates and lowers activation barriers as compared to ionic liquid. Adsorption studies show that both propanil and 3,4-dichloroaniline form energetically favorable complexes with ionic liquid, with adsorption energies of − 14.79&#xa0;kcal/mol and − 13.18&#xa0;kcal/mol, respectively. Non-covalent interaction analyses using ESP, QTAIM, and RDG confirm the predominance of hydrogen bonding, dispersion, and electrostatic interactions in stabilizing the complexes. The recovery time for propanil and DCA was also calculated, indicating [Bmim]⁺BF₄⁻ functions as a reversible, reusable adsorbent medium. These findings suggest that [Bmim]⁺BF₄⁻ is a promising medium for the capture and removal of pesticide pollutants, with potential applications in environmental remediation.</p>