Remediation of a Biodiesel Blend-Contaminated Soil with Activated Persulfate by Different Sources of Iron

摘要

The present work studies the remediation of a B20 (20 % biodiesel, 80 % diesel) biodiesel blend-contaminated soil (1,000 mg kg~(-1)) with persulfate activated by iron. Three different sources of iron (Fe(Ⅱ)), granular zerovalent iron (gZVI), and a slurry of nanopar-ticles of zerovalent iron (nZVI), without pH adjustment were tested. Besides, the effect of the addition of chelat-ing agents, such as trisodium citrate (SC), or citric acid (CiA), has been also studied. SC promotes pH under near-neutral conditions and reaction takes place at low rate at these experimental conditions. On the other hand, the use of CiA leads to an acidic pH and chelating agent is oxidized at higher rate than total petroleum hydrocarbons (TPH). Therefore, CiA addition does not seem to produce any improvement on the removal efficiency of TPH. Regarding the three different sources of iron used as activators, Fe(Ⅱ), gZVI and nZVI, in absence of chelating agent, under acidic pH and by adding the same amount of iron, the highest TPH conversion was obtained with ZVI (about 60 %), while a conversion of about 40 % was obtained with the addition of Fe(Ⅱ). The maximum TPH conversion value was achieved in shorter time using nZVI. Concerning the removal efficiency of each fraction of biodiesel abated, fatty acid methyl esters (FAME) were by far the easiest to oxidize, achieving 100 % of conversion, either by using Fe(Ⅱ) or nZVI activated persulfate.