Remediation of aged diesel contaminated soil by alkaline activated persulfate

The present work studies the efficiency of alkaline activated persulfate (PS) to remediate an aged diesel fuel contaminated soil from a train maintenance facility. The Total Petroleum Hydrocarbon (TPH) concentration in soil was approximately 5000mgkg−1 with a ratio of aliphatic:aromatic compounds of 70:30. Aromatic compounds were mainly naphtalenes and phenanthrenes. The experiments were performed in batch mode where different initial concentrations of persulfate (105mM, 210mM and 420mM) and activator:persulfate ratios (2 and 4) were evaluated, with NaOH used as activator. Runs were carried out during 56days. Complete TPH conversion was obtained with the highest concentration of PS and activator, whereas in the other runs the elimination of fuel ranged between 60 and 77%. Besides, the abatement of napthalenes and phenantrenes was faster than aliphatic reduction (i. e. after 4days of treatment, the conversions of the aromatic compounds were around 0.8 meanwhile the aliphatic abatements were 0.55) and no aromatic oxidation intermediates from naphtalenes or phenantrenes were detected. These results show that this technology is effective for the remediation of aged diesel in soil with alkaline pH. [Display omitted] •Aged diesel was effectively degraded in soil by alkali-activated persulfate (pH≥12).•A fast initial oxidation stage was noticed during the first 4days.•Total conversion of TPHs was found at 56days at 420mM of PS and NaOH:PS=4 (molar).•Aromatic fraction in aged diesel was more easily oxidized than aliphatic fraction.•No aromatic byproducts were obtained as oxidation intermediates.