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The formation of polychlorinated dibenzo‐p‐dioxins (PCDDs), particularly 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD), is a significant environmental issue due to its toxicity and persistence. This study presents a comprehensive mechanistic investigation of silver chloride (AgCl) as a kinetic suppressor for dioxin formation, using density functional theory (B3LYP/def2‐TZVP). Seven AgCl–2,4,5‐trichlorophenol (TCP) complexes were identified, stabilized via σ‐ and π‐coordination motifs, with M2 being the most exergonic (–57.84 kJ mol −1 ). NBO charge analysis revealed Ag's role as a Lewis acid in mediating bond‐breaking and bond‐forming events. The mechanism involves two HCl eliminations, oxygen‐bridge formation, and final dioxin ring closure, with AgCl regenerated at the end. Gibbs free energy profiles show the process is exergonic across all temperatures (298–1200 K), but kinetically limited even at high temperatures (900–1200 K). The AgCl‐mediated pathway exhibits higher effective barriers (≥385 kJ mol −1 ) compared to CuCl‐mediated pathways (≈304–310 kJ mol −1 at 900 K), confirming AgCl's stronger suppression effect. The same mechanism applies to 2‐chlorophenol, but with reduced toxicity in non‐chlorinated dioxin products. These findings position AgCl as an effective kinetic suppressor for dioxin formation in post‐combustion systems.
Hussain et al. (Wed,) studied this question.