Effective oxidation of crude oil in soils by consuming less hydroxyl radical with target iron

Abstract

To achieve similar oxidative efficiency of long-, medium-, and short-chain alkanes in soils, the mechanism of efficient oxidation of crude oil in soils by consuming less hydroxyl radical (OH) with target iron were investigated. The two contaminated soils (initial total petroleum hydrocarbons (TPH): 9274 mg/kg (S1); 9941 mg/kg (S2)) were subjected to targeted oxidation with target iron (targeted oxidation). The results showed that similar removal efficiencies (25 ± 5%) of each alkane (C14–C24, C26, C28–C30) with 5.6–15.0 of octanol coefficient by unit OH consumption was achieved after targeted oxidation. Under less consumption of OH, considerable removal of TPH (5969 mg/kg; 64%) after targeted oxidation was about 5 times that of the nontargeted oxidation control. The organic functional groups on target iron will combine with each alkane to form targets, which altered the way of OH accessing to all the long-, medium- and short-chain alkanes. A possible explanation of the similar efficiency targeted oxidation of each alkane was achieved by consuming less OH (1.77 ± 0.5 × 10−2 a.u.) was that the TPH in soils can be oxidized as soon as the OH produced in the vicinity of the target, resulting in OH scarcely waste.