Enhanced oriented oxidation of all alkanes through redistributing hydroxy radical by inactivating oxygen-containing functional groups in soil organic matter

To explore the effect of oxygen-containing functional groups in SOM on the oriented oxidation of all n-alkanes (OX-A) (C10 - C30), different proportions of NaOH (NaOH: protein I = 1:1 and 2:1) were used to pretreat two soils (S1 and S2). Then the crude oil (S1: 18,173 mg/kg; S2: 9853 mg/kg) was added to carry six groups of Fenton oxidation treatments. The results showed that when the content of C-O, O-H of phenol or alcohol, and O-H of carboxyl in the soil decreased, the two soils realized oriented oxidation of all n-alkanes under the low intensity of hydroxyl radical (•OH) (1.02 a.u.). The oriented oxidation of all n-alkanes group was as high as 4477.00 mg/kg (S1) and 2685.00 mg/kg (S2), respectively, which was 0.53–2.33 times of the other groups. In addition, after 1:1 regulation, the ability of •OH to capture oxygen-containing functional groups in SOM decreased, then the relative reactivity coefficient k of •OH to total petroleum hydrocarbons (TPH) increased to 2.01 and 1.81 (k > 1), which was 1.02–1.47 and 0.93–1.32 higher than the other five groups. The competition of SOM for oxidants was decreased by improving the reactivity of •OH with TPH. Thus, more •OH (S1: 48%, S2: 46%) transferred to efficiently oxidize TPH (S1: 310.60 mg/mmol, S2: 220.20 mg/mmol). In general, this study reduced the ineffective consumption of oxidants after developing inactivation, thereby the utilization efficiency of H2O2 was improved and the stability of petroleum-contaminated soil remediation was enhanced. [Display omitted] •The oxygen-containing functional groups could be inactivation by NaOH.•C-O, phenol or alcohol O-H, and carboxyl O-H could affect the H2O2 allocation.•The many •OH were favorable to achieve the oriented oxidation of all n-alkanes.•Decreasing SOM competition for oxidants could lead to low costs.