Solar-iron synergy driven degradation of p-chloroaniline in mine tailings via persulfate/percarbonate advanced oxidation: Mechanistic insights from DFT calculations and toxicity assessment

p-Chloroaniline (PCA), a persistent and toxic pollutant in mine tailings, necessitates cost-effective remediation strategies. This study evaluates the degradation of PCA by Fe 2+ /Fe 3+ -catalyzed sodium persulfate (SPS) and sodium percarbonate (SPC) oxidation enhanced by UVA-B irradiation. Among the systems tested, the UVA-B/Fe 2+ /SPS system achieved 96.2% PCA removal within 180 min, outperforming other configurations. Radical scavenging experiments and density functional theory (DFT) calculations suggested that SO 4 • − and •OH radicals were the primary reactive species in SPS systems, while •OH and O 2 ●- were identified as the major reactive species in SPC systems. DFT further revealed vulnerable sites on PCA for radical attack, supporting proposed degradation pathways. ECOSAR toxicity assessment revealed that although PCA acute toxicity decreased, certain intermediates (e.g., azo-compounds) retained high chronic toxicity, highlighting the importance of process optimization. This study provides novel insights into the degradation mechanisms of PCA, establishing a mechanistic foundation for designing solar-enhanced, iron-coupled advanced oxidation processes for industrial-scale remediation of halogenated aromatics in mining environments.