The objective of this study was to promote desorption, degradation and switching of polycyclic aromatic hydrocarbons (PAHs) to powdered activated carbon, thus decreasing the bioaccessibility of PAHs (i.e., naphthalene, phenanthrene and pyrene) in three creosote contaminated sediments (Little Scioto, Ohio (LS); Gary, Indiana (GI) and Eagle Harbor, Washington (EH)) using sonication.
Firstly, sonication was shown to degrade these PAHs (naphthalene, phenanthrene and pyrene) in aqueous solution. Secondly, the application of ultrasound for remediation of naphthalene, phenanthrene, and pyrene in field-contaminated sediments reduced the amount of these PAHs by 23 %, 15 %, and 23 %, respectively after 60 min sonication time. In addition to sonodegradation, the fast desorbing fraction of pyrene, which has been related to bioaccessibility, was found to increase with sonication time of 20min, 40 min and 60 min followed by a decrease at 120 min. Sonolysis of particles facilitated the desorption of PAHs through localized turbulent liquid movement, microjets formation and particles fragmentation, exposing new surfaces to the aqueous phase, thus decreasing the slow desorbing fraction of phenanthrene and pyrene. This result suggested that ultrasound irradiation of natural sediment released the PAHs on the slow desorbing sites.
Lastly, the use of powdered activated carbon (PAC) amendment and sonication was employed to reduce the bioaccessibility of PAHs in these three creosote contaminated sediments. For these three sediments, sonochemically induced switching of phenanthrene and pyrene from sediment to PAC was more effective than mechanical mixing in decreasing the fast desorbing fraction (FFast) (i.e., % reduction in FFast; ultrasound: EH= 91 ± 3 %, GI = 67 ± 3 %, and LS = 67 ± 3 %, mixing: EH= 81 ± 3 %, GI = 42 ± 3 %, and LS = 53 ± 3 %). The enhancement effect observed for sediment treated with sonication was attributed to the facilitation of desorption of PAHs through localized turbulent liquid movement, microjets formation and particles fragmentation, exposing new surfaces to the aqueous phase.
|Commitee:||Chin, Yu-Ping, Lenhart, John, Nicholas, Basta|
|School:||The Ohio State University|
|School Location:||United States -- Ohio|
|Source:||DAI-B 78/11(E), Dissertation Abstracts International|
|Subjects:||Chemical engineering, Environmental engineering|
|Keywords:||Carbon amendment, Pah, Polycyclic aromatic hydrocarbon, Sonication, Sonolysis, Ultrasound|
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