Degradation of aniline in groundwater by persulfate with natural subsurface sediment as the activator

Aniline is reported as a toxic contaminant in the groundwater at some industrial sites. Persulfate oxidation is a promising method to degrade aniline. However, the lack of appropriate activation method limited its application in extensive engineering of groundwater remediation. This paper aims to evaluate the feasibility of aniline degradation in groundwater by persulfate with in-situ subsurface sediment as an activator. Our findings suggested that the Fe(II)-O complex in sediment interacted with persulfate to produce SO4 center dot, OH center dot and Fe(IV) as indicated by the radical scavenging studies. Interestingly, data further revealed that the presence of the sediments simultaneously induced a non-radical mechanism in the degradation process that oxidized aniline to form two aminophenol isomers and azoxybenzene (first detected), which possibly mineralized as indicated by the significant amount of TOC removal in 24 h. The stoichiometric efficiency of the treatment system was substantial in all evaluated conditions. It was notably enhanced by increasing either the initial amount of persulfate, aniline or mass of aquifer sediments. These results confirm that the persulfate without other high-cost activation technologies can be used for in-situ remediation of aniline contaminated groundwater as the sufficient subsurface sediment is an excellent activator and urge the reassessment when employing this technique for remediation purposes since each contaminant may demonstrate a different degradation mechanism.

Automated summary

The study found that aniline in groundwater can be effectively degraded by persulfate oxidation in the presence of subsurface sediment, producing various active species. Additionally, the sediments induce a non-radical mechanism, leading to the formation of two aminophenol isomers and azoxybenzene, which may be mineralized within 24 hours.