Characteristics in oxidative degradation by ozone for saturated hydrocarbons in soil contaminated with diesel fuel

Although alkanes are relatively less reactive to chemical oxidation compared to alkenes, the chemical oxidation of alkanes has not been adequately explored in the context of environmental remediation efforts. Laboratory-scale column experiments were therefore conducted with soil artificially contaminated by diesel fuel as a surrogate for alkanes of environmental relevance. Particular attention was paid to saturated hydrocarbons refractory to volatilization. Reaction conditions involve 1485 mg kg−1 of the initial concentration of diesel range organics (DRO) and a constant ozone concentration of 119 ± 6 mg l−1 at the flow rate of 50 ml min−1. The observed removal of DRO reached 94% over 14 h of continuous ozone injection. Ozone oxidation demonstrated effective removal of non-volatile DRO in the range of C12–C24. Each alkane compound displayed comparable degradation kinetics, suggesting virtually no selectivity of ozone reactions with alkanes in soil. A pseudo-first order kinetic model closely simulated the removal kinetics, yielding a reaction rate constant of 0.213 (±0.021) h−1 and a half-life of 3.3 (±0.3) h under the experimental conditions used in this study. An estimate of ozone demand was 32 mg of O3 (mg DRO)−1.