Advanced sustainable processes via functionalized Fe–N co-doped fishbone biochar for the remediation of plasticizer di-(2-ethylhexyl) phthalate-contaminated marine sediment

Abstract

Sediments are important sinks for di-(2-ethylhexyl) phthalate (DEHP), a plasticizer, and thus, maintaining the sediment quality is essential for eliminating plasticizers in aqueous environments and recovering the sediment ecological functions. To mitigate the potential risks of endocrine-disrupting compounds, identifying an effective and eco-friendly degradation process of organic pollutants from sediments is important. However, sustainable and efficient utilization of slow pyrolysis for converting shark fishbone to generate shark fishbone biochar (SFBC) has rarely been explored. Herein, SFBC biomass was firstly produced by externally incorporating heteroatoms or iron oxide onto its surface in conjunction with peroxymonosulfate (PMS) to promote DEHP degradation and explore the associated benthic bacterial community composition from the sediment in the water column using the Fe-N-SFBC/PMS system. SFBC was pyrolyzed at 300–900 °C in aqueous sediment using a carbon-advanced oxidation process (CAOP) system based on PMS. SFBC was rationally modified via N or Fe–N doping as a radical precursor in the presence of PMS (1 × 10−5 M) for DEHP removal. The innovative SFBC/PMS, N-SFBC/PMS, and Fe-N-SFBC/PMS systems could remove 82%, 65%, and 90% of the DEHP at pH 3 in 60 min, respectively. The functionalized Fe3O4 and heteroatom (N) co-doped SFBC composite catalysts within a hydroxyapatite-based structure demonstrated the efficient action of PMS compared to pristine SFBC, which was attributed to its synergistic behavior, generating reactive radicals (SO4•–, HO•, and O2•–) and non-radicals (1O2) involved in DEHP decontamination. DEHP was significantly removed using the combined Fe-N-SFBC/PMS system, revealing that indigenous benthic microorganisms enhance their performance in DEHP-containing sediments. Further, DEHP-induced perturbation was particularly related to the Proteobacteria phylum, whereas Sulfurovum genus and Sulfurovum lithotrophicum species were observed. This study presents a sustainable method for practical, green marine sediment remediation via PMS-CAOP-induced processes using a novel Fe-N-SFBC composite material and biodegradation synergy.