Peracetic acid activation by CO2-derived peat moss biochar for remediation of PAH-contaminated marine sediments: Catalytic performance and microbial responses

This study presents a catalytic remediation strategy for polycyclic aromatic hydrocarbon (PAH)-contaminated marine sediments using peracetic acid (PAA) activated by CO 2 -derived Sphagnum peat moss biochar (SPMBC). Under optimized conditions (pH 3, 3.33 g L⁻ 1 SPMBC, and ∑[PAHs]: [PAA] = 1:1), the SPMBC/PAA system removed approximately 96% of total PAHs within 60 min. The degradation of PAHs followed a ring-dependent trend, with removal efficiencies of 96%, 89%, 94%, 96%, and 98% for 2-, 3-, 4-, 5-, and 6-ring compounds, respectively. Mechanistic investigation showed that PAA activation involved coupled radical and nonradical pathways, including HO• and 1 O 2 , likely associated with interfacial electron transfer and defect-rich carbon structures on SPMBC. Microbial community analysis based on high-throughput 16S rRNA gene sequencing revealed regulated compositional restructuring without major disturbance of dominant phyla, while predicted functions associated with carbon, nitrogen, and sulfur cycling remained largely stable. The results demonstrate that waste-derived SPMBC is an efficient activator for PAA-based sediment remediation and that the treatment process remains microbiologically compatible. This work highlights the potential of combining waste-derived carbon catalysts with advanced oxidation technology for sustainable management of contaminated marine sediments. • CO 2 -derived Sphagnum peat moss biochar effectively activated peracetic acid for PAH removal from marine sediments. • The SPMBC/PAA system achieved approximately 96% PAH removal within 60 min under optimized conditions. • PAH degradation proceeded through coupled radical and nonradical pathways involving HO• and 1 O 2 . • Interfacial electron transfer and defect-rich carbon domains contributed to efficient PAA activation. • Catalytic treatment induced regulated microbial restructuring while largely preserving dominant phyla and key metabolic functions.