Green Fenton-like degradation of sulfamethoxazole using chlorogenic acid under neutral conditions: A mechanistic and environmental risk perspective

A green homogeneous Fenton-like system was developed using chlorogenic acid (CGA) to enhance the activation of H 2 O 2 by Fe(III) under neutral conditions for sulfamethoxazole (SMX) degradation. CGA enhanced Fe(III)/Fe(II) cycling and hydroxyl radical (HO • ) generation, achieving >99 % removal of 5 μM SMX within 60 min. Electron spin resonance and scavenging experiments identified HO • as the primary reactive species, with minor contributions from superoxide (O 2 •- ) and singlet oxygen ( 1 O 2 ). 15 degradation intermediates were detected and reasonably speculated degradation pathways were proposed. The system also showed broad-spectrum efficacy against 7 other emerging contaminants, tolerance to environmentally relevant pH, and moderate resistance to coexisting ions. Ecotoxicity predictions indicated reduced toxicity of transformation products. This work demonstrates a sustainable CGA-assisted Fenton-like strategy for antibiotic wastewater treatment. • CGA breaks acidic limits, enabling Fenton-like activity at pH 3–6.5. • CGA acts as dual chelator and Fe(III) reductant, accelerating iron cycling. • The system efficiently degraded 5 μM SMX in 60 mins and removed >80 % of 7 pollutants. • Reduced toxicity of degradation products lowers secondary pollution risks.