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The Role of Temperature in the Remediation of Petroleum Contaminants by Persulfate in Saline Environment

Saeed, Waleed *1; Shouakar-Stash, Orfan 1; Barker, Jim 1; Thmson, Neil 1; Mck, Rick 1
(1) University of Waterloo, Waterloo, ON, Canada.

In the past few decades, several aqueous oxidants have been employed (e.g. permanganate, persulfate) to remediate petroleum hydrocarbons. However, the majority of the research in this field has been focused primarily on the use of oxidants in treating fresh water at low groundwater temperature settings. In this study, bench top batch experiments were carried out to investigate the effectiveness of persulfate (PS) as an oxidation agent to remediate petroleum hydrocarbons in alternative settings (saline environments at high groundwater temperature). Benzene, Toluene, thylbenzenes, Xylenes (BTEX), Trimethylbenzenes (TMBs), and Naphthalene were the target investigated organic compounds during this project.

Three important aspects were examined during this laboratory study: 1) the evaluation of persulfate as a chemical oxidation agent; 2) the investigation of the effect of different temperature (10° versus 30° C) on the degradation rates by persulfate for selected organic contaminants; and 3) the determination of isotopic 13C fractionation factors associated with the chemical transformations of several organic contaminants.

The results showed the high potential of persulfate to remediate the target contaminants under certain conditions. The results also showed that both temperature and pH can play an important role in the reactivity of PS. For instant, the degradation rate of the target contaminants was seen to be dramatically increased by increasing the system temperature from 10° to 30° C. In contrast, lowering system pH resulted in a greater increase in the degradation rate of all compounds.

Due to their high concentration, benzene and toluene were the target investigated organic compounds during the compound-specific isotope analyses. The δ13C values were seen to get enriched gradually with time only in vials containing PS at 30° C. This showed the effect of temperature on the δ13C values and demonstrated insignificant change of δ13C by processes other than the chemical oxidation. Furthermore, significant enrichment values were only reported when PS was applied at (30° C). The enrichment of δ13C values were associated with the loss of concentrations of both compounds during degradation. This showed the potential of isotope analysis not only to be a sign of chemical degradation but also to approximate the magnitude of it.


AAPG Search and Discovery Article #90141©2012, GEO-2012, 10th Middle East Geosciences Conference and Exhibition, 4-7 March 2012, Manama, Bahrain