Quinone group modified sludge-based biochar as electron shuttle to enhance the biodegradation of naphthalene in petrochemical contaminated soil

In this study, an electron shuttle, anthraquinone-2,6-disulfonate (AQDS), was employed to construct quinone group modified sludge-based biochar (AQDS-SBC). The graft of quinone functional groups brought a higher level of aromatic structure and the effect of AQDS-SBC on the biodegradation of naphthalene was explored. The removal of naphthalene was improved by 80.67% with the addition of AQDS-SBC, and the degradation of naphthalene follows the pseudo-first-order kinetic. Furthermore, the results of electrochemical measurements suggested that the presence of quinone-like groups in AQDS-SBC as redox-active centers might play an important role in mediating extracellular electron transfer (EET), thereby accelerating the degradation of naphthalene. The microbial community analysis indicated that naphthalene-degrading bacteria (Phanerochaete chrysosporium and Pleurotus ostreatus) and EET-functional bacteria (Geobacter) were enriched in the presence of AQDS-SBC, which promoted the synergistic effect of multiple microorganisms and provided multiple modes of electron transfer to degrade naphthalene. In conclusion, this experiment verified that EET mediated by AQDS-SBC enhanced the degradation of naphthalene and provided a reference for the bioremediation of petrochemical-contaminated soil.