Ethanol washing of PAH-contaminated soil and Fenton oxidation of washing solution

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  • AbstractAs a means to remediate soil contaminated by polycyclicaromatic hydrocarbons, we investigated a combined pro-cess involving ethanol washing followed by a Fenton oxi-dation reaction. Artificial loamy soil was contaminated withvarious representative polycyclic aromatic hydrocarbons(i.e., fluorene, anthracene, pyrene, benzo(b)fluoranthene, orbenzo(a)pyrene) at concentrations ten times higher thanregulatory soil standards of The Netherlands or Canada,and then washed four times in ethanol, which reduced theconcentration of polycyclic aromatic hydrocarbon contam-ination to below the regulatory standard. Fenton oxidationof ethanol solutions containing anthracene, benzo(a)py-rene, pyrene, acenaphthylene, acenaphthene, benz(a)an-thracene, benzo(j)fluoranthene, or indeno(1,2,3-cd)pyreneshowed a removal efficiency of 73.3%99.0%; by contrast,solutions containing naphthalene, fluorene, fluoranthene,phenanthrene, or benzo(b)fluoranthene showed a removalefficiency of 9.6%27.6%. Since each of the nonremediatedpolycyclic aromatic hydrocarbons, excluding benzo(b)fluo-ranthene, are easily biodegradable, these results indicatethat the proposed treatment can be successfully applied topolycyclic aromatic hydrocarbon-contaminated soil thatdoes not contain high concentrations of benzo(b)fluo-ranthene. The main reaction products resulting from Fenton oxidation of ethanol solutions containinganthracene or benz(a)anthracene were anthraquinon orbenz(a)anthracene-7,12-dione, respectively; while 1,8-naphthalic anhydride was produced by solutions of ace-naphthylene and acenaphthene, and 9-fluorenone by a flu-orene solution.

    Key words PAH-contaminated soil Ethanol soil washing Fenton oxidation Reaction product identification


    Polycyclic aromatic hydrocarbons (PAHs), which containmore than two benzene rings, are refractory organic com-pounds commonly produced by incomplete combustion of fossil fuels.1 Some PAHs with more than four benzene rings have accumulated in soil due to their strong microbialresistance.2

    Clean-up processes for PAH-contaminated soil havebeen studied extensively over the last two decades, most ofthem being bioremediation processes based on microbialdegradation.39 Unfortunately, however, these processes are not only time-consuming, but are of limited value; theyhave almost no degradational effect on four-ring or greaterPAHs.2

    With the aim of developing a means to accelerate PAH decomposition prior to microbial degradation, achemicalbiological treatment has been applied, i.e., anadvanced oxidative process with Fentons reagent,10,11

    although practical application is difficult owing to the highcosts of the chemicals required.

    Soil washing has been applied to PAH- and heavy metal-contaminated soil because of its simplicity, low capital andoperating costs, easy maintenance requirements, and rela-tively good removal efficiency. On the other hand, furthertreatment of the washing solution (i.e., water, surfactant,and solvent) is needed; hence, this is only a partial remedy.

    According to a U.S. EPA report, highly PAH-contaminated soil (301400mgPAH/kg) was washed andbiodegraded by the Biogenesis system.12 Compressed air-hot water (90C) was used in this system, and a re-moval efficiency of 65%73% was obtained. After aerobicbiodegradation of the washed water, the total PAH removalefficiency was 85%88%. In spite of long-term biodegrada-tion (120 days), the treated soil could not meet the soil stan-dards of The Netherlands or Canada. Table 1 shows the soilstandards of The Netherlands and Canada.

    In the process of Fenton treatment, a Fenton reactionproduces an OH radical (HO) in such a way that oxidationof refractory organics and an organic radical occurs.13,14

    J Mater Cycles Waste Manag (2000) 2:2430 Springer-Verlag 2000

    Byung-Dae Lee Masaaki Hosomi

    Ethanol washing of PAH-contaminated soil and Fenton oxidation of washingsolution

    Received: June 9, 1998 / Accepted: March 24, 1999


    B.-D. Lee (*) M. HosomiDepartment of Chemical Engineering, Tokyo University ofAgriculture and Technology, 2-24-16 Naka, Koganei, Tokyo 184-8588,JapanTel. +81-42-388-7070; Fax +81-42-381-4201e-mail:

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  • 25

    With the above treatment history of PAH-contaminatedsoil in mind, we now describe a new, combined ethanol-washing/Fenton-oxidation process which is used for thispurpose. That is, we report on the applicability of ethanolwashing of artificial soil contaminated with represen-tative PAHs, and also on further degradation treatment ofPAH-containing washing solutions by a Fenton oxidationprocess. In addition, for various PAHs we identify the mainoxidation product generated in the Fenton reaction inethanol.



    The following materials were used for PAHs: special grade naphthalene (NAP) (95%, Waco); acenaphthylene(ACEL) (98%, AccuStandard); acenaphthene (ACE)(97%, Aldrich); fluorene (FLU) (95%, Waco); fluoranthene(FLUT) (95%, Waco); 9-fluorenone (FLUO) (99%, Waco);phenanthrene (PHE) (98%, Aldrich); anthracene (ANT)(99%, Aldrich); anthraquinone (ANTQU) (97%, Aldrich);pyrene (PYN) (98%, Waco); benz(a)anthracene (BAA)(99%, Aldrich); benz(a)anthracene-7,12-dione (BAADI)(97%, Aldrich); benzo(b)fluoranthene (BBFT) (99%,Aldrich); benzo(j)fluoranthene (BJFT) (98%,