Remediation of a Laboratory Benzothiazoles‐Contaminated Aquifer Using Persulfate Activated by Iron‐Bearing Minerals in Porous Medium

Benzothiazoles (BTs), which are a class of toxic heterocyclic micropollutants, have been frequently detected in groundwater recently. Persulfate‐based in situ chemical oxidation (ISCO) is considered a promising remediation method for organic‐contaminated groundwater. In this study, batch experiments and 2‐dimensional tank experiments were performed to investigate the in situ oxidation of a BTs‐contaminated aquifer using a persulfate/iron‐bearing minerals system. The impact of three different minerals (pyrite, hematite, and magnetite) and the mass loading on the degradation of 2‐mercaptobenzothiazole (MBT), benzothiazole (BTH), and 2‐hydroxybenzothiazole (OBT) were evaluated. The temporal–spatial distribution of contaminants, injected persulfate, Fe 2+ , and geochemical parameters in an aquifer during the 100‐day remediation experiment are discussed in detail. The results indicate that MBT, BTH, and OBT can be effectively degraded in the presence of both persulfate and pyrite, all reaching removals of over 85% in 8 h. The removal of BTs benefits from increasing pyrite mass loading. ·SO 4 − and ·OH are the dominant reactive species involved in BTs degradation. In situ injection of persulfate into the lab‐scale aquifer led to 99%, 42%, and 20% reductions of total MBT, BTH, and OBT, respectively, during the tank experiment. The migration of BTs was intercepted, and their distribution area decreased significantly over time, confirming the long‐term effectiveness of the persulfate/pyrite in situ reactive zone for the treatment of BTs. The increase of ORP indicates the formation of an oxidizing condition in the subsurface. No significant disturbance to dissolved oxygen in groundwater occurred during the ISCO remediation. The outcomes of this study provide a basis for practical engineering remediation for groundwater contaminated with BTs.