EPA/600/JA-03/117
2003
Treatment of Methyl Tertiary-Butyl Ether (MTBE)-Contaminated Waters
with Fen ton's Reagent
Asim B. Ray, Ariamalar Selvakumar, and Anthony N. Tafuri
Urban Watershed Management Branch
United States Environmental Protection Agency
2890 Woodbridge Avenue
Edison, NJ 08837
ABSTRACT
Methyl tertiary-butyl ether (MTBE) has been commonly used as a fuel additive because
of its many favorable properties that allow it to improve fuel combustion and reduce resulting
concentrations of carbon monoxide and unburnt hydrocarbons. Unfortunately, increased
production and use have led to its introduction into the environment. Of particular concern is its
introduction into drinking water supplies. Accordingly, research studies have been initiated to
investigate the treatment of MTBE-contaminated soil and water. In this study, experiments were
conducted to demonstrate the effectiveness of Fenton's reagent (H2O2:Fe+2) to treat MTBE-
contaminated groundwater. The concentration of MTBE was reduced from an initial
concentration of 1,300 Fg/L (14.77 F moles) to the regulatory level of 20 Fg/L (0.23 F moles) at
a H2O2:Fe+2 molar ratio of 1:1, with 10 minutes of contact time and an optimum pH of 5. The
byproducts, acetone and tertiary butyl alcohol, always present in MTBE in trace amounts, were
not removed even after 60 minutes of reaction time.
INTRODUCTION
Several oxygenates have been used in the United States since the 1970s as octane-
enhancing replacements for tetraethyl lead. These include ethanol, methanol, ethyl tertiary-butyl
ether (ETBE), and tertiary-butyl alcohol (TEA) as well as methyl tertiary-butyl ether (MTBE).
MTBE is the most commonly used fuel oxygenate because of its many favorable properties,
including low production cost, ease of production, high octane rating, and favorable transfer and
blending characteristics (Ainsworth, 1992; Shelly and Fouhy, 1994). The addition of MTBE to
gasoline improves fuel combustion and reduces the resulting concentrations of carbon monoxide
and unburnt hydrocarbons. The use of MTBE in gasoline at levels in excess of 10% by volume
began in November 1992 when the requirements of the 1990 Clean Air Act Amendments
(CAAA) mandated the use of oxygenated gasoline during the winter to help meet standards for
carbon monoxide emissions. Furthermore, since January 1995, the CAAA also required nine
metropolitan areas that have the most severe ozone pollution to use, year-round, reformulated
gasoline that contains fuel oxygenates. Accordingly, MTBE was added to about 30% of the
gasoline nationwide at an average concentration of about 11% by volume (USEPA, 1994). Since
1993, MTBE has been the second most produced organic chemical manufactured in the United
States (USEPA, 1998).
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The increased production and physical properties of MTBE have led to its introduction
into the environment. MTBE can enter the environment in several ways: leaks from above- and
below ground storage and conveyance facilities, incomplete combustion in internal combustion
engines, spillage and evaporation during the manufacture and transportation of MTBE and
gasoline containing MTBE, and watercraft exhaust (especially from two-cycle engines). MTBE
has been detected both in groundwater (Squillace et al., 1996) and stormwater (Delzer et al.,
1996). Of the 60 volatile organic compounds (VOCs) analyzed in samples of shallow ambient
groundwater collected from eight urban areas during 1993 to 1994, as a part of the United States
Geological Survey's National Water-Quality Assessment Program, MTBE was the second most,
after trichloromethane, frequently detected compound.
Both the physical and chemical properties of MTBE control its fate in the environment.
MTBE is a liquid with a molecular weight of 88 and a boiling point of 55°C under atmospheric
pressure. It is soluble in all common solvents and is highly soluble in water (~50 g/L or 575 F
moles). Therefore, MTBE is highly mobile, undergoing little or no retardation as it travels
through a groundwater system. MTBE, through co-solvent effects, increases the solubility of
other petroleum derivatives, such as benzene, toluene, ethyl benzene, and total xylenes (Schrimer
and Barker, 1998). It is resistant to biological degradation with a half-life of 10,000 days (27
years). Laboratory studies have shown that MTBE is recalcitrant to all forms of aerobic as well
as anaerobic biodegradation, key components in the natural attenuation process (Vance, 1998).
The U.S. Environmental Protection Agency has tentatively classified MTBE as a possible
human carcinogen and has issued a drinking water advisory, based on taste and odor thresholds,
of 20 (ig/L (0.23 F moles) (USEPA, 1997).
Treatment of MTBE
A number of techniques have been investigated for the remediation of MTBE from
aqueous media. Because of MTBE's low Henry's law constant and high water solubility, air
stripping (a routine practice for the removal of volatile organic compounds from groundwater) is
unsatisfactory for MTBE removal. In addition, the process produces contaminated air
byproducts that require further treatment.
Biodegradation of MTBE has also been explored. In a study by Eweis et al. (1997), a
culture capable of degrading MTBE, both as a fixed film on a solid matrix and in liquid culture,
was isolated from a bio-filter from the County Sanitation District of Los Angeles County Joint
Water Pollution Control Plant in Carson, California. Another aerobic microbe consortium
capable of biodegrading MTBE was isolated from two waste air bio-trickling filters
(Fortin and Discusses, 1999). Further studies are, however, needed to assess the feasibility of
biodegradation of MTBE-contaminated aqueous media. Natural attenuation of MTBE, although
intrinsically feasible, is a very slow process (Schrimer and Barker, 1998) and may not be suitable
for situations where immediate corrective action is required.
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In a study by Tornatore et al. (2000a), both granulated activated carbon (GAC) and
synthetic adsorbents (Ambersorb 563 and Ambersorb 572- Rohm and Haas) were evaluated for
their ability to remove MTBE from drinking water. Because of its electrophilic nature, MTBE is
weakly adsorbed by GAC and consequently requires larger quantities of GAC for removals
equivalent to other organic pollutants such as trichloroethylene (TCE). Montgomery Watson
(1996) observed that using activated carbon to remove MTBE from aqueous streams is about 21
times more expensive than removing the same mass of TCE. Although the synthetic adsorbents
performed better than activated carbon, they are 5 to 10 times more expensive than GAC.
Consequently, the use of GAC or other synthetic adsorbents is not practical for the treatment of
large volumes of MTBE-contaminated water.
Chemical oxidation is an efficient technique for the remediation of organic compounds.
It is the most practical and effective way to convert, in aqueous media, organic compounds such
as MTBE into innocuous carbon dioxide and water. The relevant oxidation techniques can be
broadly sub-divided into:
• chemical oxidizing agents;
• chemical oxidizing agents with a catalyst;
• irradiation; and
• irradiation with a chemical oxidizing agent.
Chang and Young (1998) evaluated the chlorination (sodium hypochlorite) of MTBE-
contaminated water at pH 4 and 7 and found that even after 24 hours of contact, there was no
significant reduction in MTBE concentration. The same authors also found that using hydrogen
peroxide or UV radiation alone did not result in a significant reduction in MTBE.
Farooq et al. (1993) used a high energy electron beam to disinfect wastewaters
containing raw sewage. The disinfection mechanism involved the generation of the hydroxyl
radical (OH*) by the photolysis of water:
H2O + hv ° OH* + H
The hydroxyl radical is one of the most powerful oxidizing chemicals known. Tornatore et al.
(2000b) used this technique in their studies on the reduction of MTBE in water from deep water
wells. Greater than 99% reduction of MTBE was achieved with initial concentrations of 170 and
196 (ig/L (1.96 and 2.25 F moles) and a pH between 7.7 and 8.8. The MTBE reduction was
found to be dose-dependent and the major byproducts tert-butyl formate (TBF) and TBA were
present in small quantities.
Barreto et al. (1995) investigated the photo-catalytic degradation of MTBE. Several
reaction products including TBF, TBA, acetone, and acetic and formic acids, in addition to
gaseous COi, were identified. A small quantity of a-hydroperoxy methyl-tert-butyl ether was
tentatively identified. An exposure of 4 hours was needed to completely degrade an aqueous
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solution containing MTBE at a concentration of 88 mg/L (1.012 F moles). Complete elimination
of TBF, TEA, and acetone required 10 hours of reaction time.
The reaction of aqueous MTBE with the hydroxyl radical generated by UV/H2O2 was
investigated by Carter et al. (2000). Results indicated that the rate of destruction of MTBE is
influenced by the initial concentrations of both hydrogen peroxide and MTBE. In all cases, the
decay of MTBE was found to follow first-order reaction kinetics with a pseudo first-order rate
constant, ki. The value of ki increased as the concentration of MTBE decreased. Byproducts of
the UV/H2O2 degradation of MTBE were found to be TBF, TEA, methyl acetate, acetone, a per-
oxy compound, formaldehyde, alkanes, and acetic and formic acids (Stefan et al., 2000). A 4-
hour reaction time was required to remove 86.9 mg/L (1 milli mole) of MTBE, and after 10
hours, approximately 85% of the initial organic carbon was mineralized.
Fenton's Reagent
Many metals have special oxygen transfer properties which improve the utility of H2O2.
By far, the most common of these is iron which, when used in a prescribed manner, results in the
generation of highly reactive OHC The reactivity of this system was first observed in 1894 by its
f\
inventor H. J.H Fenton. The chemistry involved in the generation of OH by the Fenton's reagent
can be summarized by the following equations:
Fe+2+ H2O2 ° Fe+3 + OH! + OHC
Fe+3 + H2O2 ° Fe+2 + OOHC+ H+
The procedure requires:
• adjusting the wastewater to a pH of 3 to 5;
• adding the iron catalyst (as a solution of FeSO/i); and
• adding the H2O2 slowly.
Fenton's reagent is used to treat a variety of industrial wastes containing a range of toxic
organic compounds (phenols, formaldehyde, BTEX, and complex wastes derived from dyestuffs,
pesticides, wood preservatives, plastic additives, and rubber chemicals). The process may be
applied to wastewaters, sludges, or contaminated soils, with the effects being:
• organic pollutant destruction;
• toxicity reduction;
• biodegradability improvement;
• BOD/COD removal; and
• odor and color removal.
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OBJECTIVE
The overall objective of this study was to determine the optimum conditions for using the
OH* radical to treat MTBE-contaminated waters frequently found at "hot spots" such as fueling
depots, petro-chemical facilities, parking lots and garages, and gasoline stations. These
contaminated streams are often carried by stormwater runoff via combined and separate
stormwater sewers to drinking water sources. Because of the potential contamination and the
volume of water involved, a fast, efficient, and cost-effective technology is needed. Early
studies (Barreto etal, 1995; Carter etal., 2000; Stefan etal., 2000; Ray and Selvakumar, 2000)
suggest that OH* radicals generated by Fenton's reagent are capable of treating MTBE
contaminated waters quickly and effectively. However, major byproducts such as TEA, TBF,
and acetone, and small quantities of 2-methyl-l-propene (isobutylene) have been identified in
some studies (Ray and Selvakumar, 2000). Because of the potential end-use of these waters, the
MTBE content must be at or below 20 Fg/L (0.23 F moles ) and free from major byproducts.
Therefore, a secondary objective of the study was to monitor, over time, the concentrations of
the reported major byproducts of the treatment as well as their subsequent degradation by the
OH* radical.
EXPERIMENTAL DESIGN
Reagents and Materials
All chemicals used in the study were of American Chemical Society analytical grade or
better.
Apparatus
A 3-necked septum-fitted flask (1.5-L capacity) with various attachments (Exhibit 1) was
used for this study. Using a syringe, reagents were introduced into the center neck; pH samples
and other samples for analysis were withdrawn through the outer necks. A magnetic bar was
used to agitate the liquid reagent mixture. Gas samples were collected through the gas sampling
port.
Analytical Methods
• MTBE and its degradation products were analyzed by USEPA Method 624. The
GC/Mass system used consisted of a HP 5890 Series II GC with a Model 5971A
mass spectrometer.
• Organic acids (formic and acetic) were analyzed by USEPA Method 300 using a
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Dionex DX-100 ion chromatograph equipped with a column (AS4-A) for
separation.
• H2O2 was analyzed by a HACH (Model 5000) scanning spectrometer at a
wavelength of 276 nm. Hydrogen peroxide strongly absorbs at this wavelength;
neither NaHSOs nor any other analyte of interest has any absorption at this
wavelength.
• The CO2 that evolved was analyzed by gas chromatography using a thermal
conductivity detector. The volume of gases collected was measured by a gas
burette as shown in Exhibit 1.
• All calibrations were carried out with a five-point calibration procedure.
Experimental Procedure
A total of twelve experiments was performed to determine the optimum pH, Fe+2 to H2O2
ratio, and contact time for the degradation of MTBE without major byproducts. Reaction
stoichiometry of these tests was based on the assumption that complete mineralization of MTBE
takes place according to the equation:
C5Hi2O + 15H2O20 5CO2 + 21H2O
In all cases the total volume of the reactants was 1 L. One liter of deionized water was added to
the flask and purged with oxygen-free nitrogen gas to remove all air and any dissolved oxygen
from the system. Predetermined quantities of MTBE, FeSC>4 solution, and H2O2, from stock
solutions, were sequentially added to the flask. Prior to the addition of H2O2, the pH of the
reaction medium was adjusted by either a dilute sulfuric acid or sodium hydroxide solution.
Liquid samples for analyses were withdrawn from the flask every five minutes over a period of 1
hour. Excess NaHSO:, solution was added to the collected samples to remove any residual H2O2
and to prevent further reaction. The samples were then cooled to 4°C and analyzed for MTBE
and byproducts. The quantity of H2O2, CO2, and O2 was determined at the beginning and end of
each experiment. All H2O2 and pH measurements were conducted before the addition of
NaHSO3 solution.
The initial concentration of MTBE, in most cases, was approximately 1,300 Fg/L (14.77
(j, moles). Because of an earlier observation that MTBE reduction by the Fenton's reagent
appeared to depend on the H2O2:Fe+2 molar ratio (Ray and Selvakumar, 2000), the ratio of these
chemicals was also varied in the study. The quantity of H2O2 used in all cases was the same; i.e.,
twice the amount specified in the above equation. All reactions were carried out at three
different pH values of 3, 5, and 7. The reaction conditions are summarized in Exhibit 2.
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Reasons for this approach are as follows:
• Contaminated groundwater often contains organic matter which can consume
H2O2 and thereby affect the concentration of H2O2 in the Fenton's reagent.
Hence,
the effect of varying the H2O2:Fe+2 ratio of the efficiency of Fenton's reagent in
removing MTBE was investigated.
• Although Fenton's reagent works best in strongly acidic media (pH 2 to 4), it is
somewhat impractical to lower the groundwater pH to such a low value. Because
of this, additional tests were performed at more natural pH values of 5 and 7.
As previously mentioned, a total of twelve tests were conducted; however, details of only those
tests in which significant amounts of MTBE reduction occurred are discussed.
RESULTS
Test Series A (H2O2:Fe+2 = 0.1:1)
In Test Series A, it was observed that the reaction of MTBE with Fenton's reagent was
pH dependent. At pH ~3, the MTBE concentration was reduced by 75% after 20 minutes of
reaction time. At the end of one hour, the initial MTBE concentration was reduced by 82% from
1,367 to 251 Fg/L (15.53 to 2.85 F moles). The byproducts, at the end of one hour, were acetone
(33.64 Fg/L or 0.58 F moles), TEA (7.4 Fg/L or 0.10 F moles), and TBF (10.2 Fg/L or 0.10 F
moles). Although both formate and acetate ions were detected after 10 minutes of reaction they
disappeared after 30 minutes. The highest concentration of formate ions (286.2 Fg/L or 6.36 F
moles) and acetate ions (404.15 Fg/L or 6.85 F moles) were observed at 20 and 30 minutes,
respectively. In addition to the above compounds, 58.96 Fg (1.34 F moles) of CC>2 gas were
produced. The pH of the mixture also decreased from the initial value of 2.9 to a final value of
2.4. No residual H2O2 was detected at the end of the reaction. These results are shown in
Exhibits 3 and 4. No significant change in MTBE concentration, however, was observed when
the reaction was carried out either at pH 5 or 7.
Test Series B (H2O2:Fe+2 = 1:1)
In contrast to Test Series A, Test Series B exhibited a rapid reduction in MTBE
concentration at pH 5. MTBE concentration was reduced by 99% within five minutes of
reaction. After 10 minutes, no detectable amount of MTBE was found. These results are shown
in Exhibit 5 and graphically represented in Exhibit 6. No significant change in MTBE
concentration occurred when the oxidation reaction was carried out at pH 3 and 7.
Test Series C and D (H2O2:Fe+2 = 10:1 and 100:1)
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In Test Series C and D, no significant change in MTBE concentration occurred at any of
the three pH values of 3, 5, and 7.
DISCUSSION
This study demonstrated that Fenton's reagent was successful in reducing MTBE
concentration in water from approximately 1,300 Fg/L (14.77 F moles) to the proposed
regulatory level of 20 Fg/L (0.23 F moles) or lower without generating significant amounts of
undesirable byproducts. This reduction was achieved with a contact time of 10 minutes or less.
The reaction was found to be dependent both on the pH of the reaction medium and on the ratio
of H2O2:Fe+2 in the Fenton's reagent.
These findings are in contrast to some of the earlier studies. Wagler and Malley (1994)
found that pH had only a minor role in UV/H2O2 treatment of MTBE in low-alkalinity
groundwater. Yeh and Novak (1995) found that the oxidation process using Fenton's reagent is
influenced by pH, H2O2 concentration, and the presence of Fe+2, but is independent of the iron
concentration. This disagreement is probably due to the different methods used to generate OH*
radicals. In the UV/H2O2 process, the OH* radical is generated by the photocatalysis of H2O2
(H2O2 + hv ° 2 OH*) and hence is independent of the pH of the medium.
A drop in pH of the reaction medium during the progress of the reaction was also
reported in the photocatalytic degradation of MTBE in TiO2 slurries (Barreto etaL, 1995). This
drop in pH, which agrees with the results of this study, was attributed to the formation of formic
and acetic acid byproducts.
Observations of Barreto etal. (1995) that the oxidation of MTBE by H2O2 and Fe+2 iron
is independent of iron concentration are also in contrast to previous findings (Ray and
Selvakumar, 2000) and the findings of the present study. Optimum conditions for generating the
OH* radical by Fenton's reagent requires not only acid conditions but also a molar ratio of
H2O2:Fe+ of 1:1 (Fischer and Fisher). The most rapid oxidation of MTBE was achieved in this
study using Fenton's reagent with a 1:1 ratio of H2O2:Fe+2. However, the inability of Fenton's
reagent to oxidize MTBE with this molar ratio at pH 3 requires further study, especially in view
of the fact that Fenton's reagent with a 0.1 to 1 ratio of H2O2:Fe+2 was able to achieve a
substantial and fairly rapid reduction of MTBE at pH ~3 (Exhibit 3).
Of the byproducts studied (Exhibits 4 and 6), only the concentration of acetone remained
almost constant during the 60-minute time periods of the reaction. Both formate and acetate ions
reached their peak concentrations at 20 and 25 minutes of the reaction, respectively, and
disappeared shortly thereafter. TEA and TBF, although in small concentrations, persisted after
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60 minutes of reaction. Incomplete mineralization of these byproducts is probably due to the
lack of the necessary amount of H2O2 since no residual amount of it was found at the end of the
reaction. During the reaction, a total volume of 186.56 Fg/L (4.24 F moles) of COz gas evolved.
Results of this study indicate that any significant change in MTBE concentration is
always accompanied by the evolution of a substantial quantity of C(>2 gas, formation of acetone
and TBF, and loss of TEA (almost always present as an impurity in MTBE). Conversely, in all
cases where no significant change in MTBE concentration occurred, no change in the
concentrations of the original impurities (acetone, TBF, and TBA) present in MTBE nor any
evolution of CO2 was observed. The byproducts, acetone and TBA could not be removed even
after 60 minutes of reaction time. Other byproducts such as formates and acetates, although
originally absent, appeared after 10 minutes of reaction but disappeared after 40 minutes.
CONCLUSION
Fenton's reagent can be used to remediate, at ambient temperature, MTBE-contaminated
groundwater. MTBE concentration was reduced from an initial concentration of 1,300 Fg/L
(14.77 F moles) to the regulatory limit of 20 Fg/L (0.23 F moles) or less. This study established
that this can be achieved by Fenton's reagent under the following conditions:
• H2C>2:Fe+2 molar ratio of 1:1 in Fenton's reagent
• Reaction pH of 5
• Contact time less than 10 minutes
Evolution of CC>2 confirmed mineralization of MTBE and other byproducts. A drop in
pH and evolution of C(>2 can be used as an indication of the progress of the mineralization of
MTBE.
REFERENCES
Ainsworth, S. 1992. Oxygenates Seen as Hot Market by Industry. Chemical Engineering
News, Vol. 70, pp. 26-30.
Barreto, R.D., K.A. Gray, and K. Anders. 1995. Photo-catalytic Degradation of Methyl-tert-
Butyl Ether in TiO2 Slurries: A Proposed Reaction Scheme. Water Res., Vol. 29, No.5 pp. 1243-
1248.
Carter, S.R, I. Stefan Mihaela, J.R Bolton, and A. Safarzadeh-Amiri. 2000. UV/H2O2
Treatment of Methyl-tert-Butyl Ether in Contaminated Waters. Environ. Sci. Technol., Vol. 34,
pp. 659-662.
Chang, P. and T. Young. 1998. Reactivity and By-products of Methyl Tertiary Butyl Ether
-------
Resulting from Water Treatment Processes. Report to the California State Legislature under
S.B. 521, Volume V. University of California, Davis. Civil and Environmental Engineering.
Delzer, G.C., J.S. Zogorski, TJ. Lopes, and R.L. Bosshart. 1996. Occurrence of the gasoline
oxygenate MTBE and BTEX compounds in urban storm water in the United States, 1991-95.
U.S. Geological Survey Water Resource Investigations Report No. 96-4145.
Eweis, J. B., D.P.Y. Chang, E.D. Scroder, K.M. Scow, R.L. Morton, and R.C. Caballero. 1997.
Meeting the Challenge of MTBE Biodegradation. Air & Waste Management Association's 90
Annual Meeting & Exhibition, June 8-13, Toronto, Ontario, Canada.
,th
Farooq, S., C.N. Kurucz, T.D. Waite, and WJ. Cooper. 1993. Disinfection of Waste waters:
High-Energy Electron Vs. Gamma Irradiation. Water Res., Vol. 27, No.7. pp. 1177-1184.
Fischer, L.F. and M. Fisher. Reagents for Organic Synthesis. John Wiley and Sons.
Fortin, N.Y. and M.A. Discusses. 1999. Treatment of Methyl-tert-Butyl Ether Vapors in
Biotrickling Filters. 1. Reactor Startup, Steady-State Performance, and Culture Characteristics.
Environ. Sci. Technol, Vol. 33, pp. 2980-2986.
Montgomery Watson. 1996. Treatment Alternatives for MTBE in Ground Water. Applied
Research Department. Technology Transfer Note No. 11.
Ray, A.B. and A. Selvakumar. 2000. Treatment of MTBE Using Fenton's Reagent.
Remediation, Vol. 10, No. 3, pp. 3-13.
Schrimer, M., and J.F. Barker. 1998. A Study of long-term MTBE attenuation in the
Borden aquifer, Ontario, Canada. Ground Water Monitoring and Remediation, Vol. 8, No. 2, pp.
113-112.
Shelly, S. and K. Fouhy. 1994. The Drive for Cleaner Burning Fuel. Chemical Engineering,
Vol. 101, No. l,pp. 61-63.
Squillace, P.J., J.S. Zogorski, W.G. Wiber, and C.V Price. 1996. Preliminary Assessment of
the Occurrence and Possible Sources of MTBE in Groundwater in the United States, 1993-1994.
Environ. Sci. Technol, Vol. 30, pp. 1721-1730.
Stefan M.I., J. Mack, and J.R. Bolton. 2000. Degradation Pathways During the Treatment of
Methyl-tert- Butyl Ether by the UV/H2O2 Process. Environ. Sci. Technol, Vol. 34, pp. 650-658.
Tornatore, P.M., S.E. Powers, W.J. Cooper, and E.G. Isacoff. 2000a. Synthetic Adsorbents
Show Promise for Removing MTBE from Drinking Water. Water Online. June 28.
10
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Tornatore, P.M., S.E. Powers, WJ. Cooper, and E.G. Isacoff. 2000b. High Energy Electron
Injection System Destroys MTBE in Drinking Water. Water Online. July 28.
USEPA. 1994. Health Risk Perspectives on Fuel Oxygenates. EPA/600/R-94/217. Office of
Research and Development, Washington, D.C.
USEPA. 1997. "Drinking Water Advisory: Consumer Acceptability Advice and Health Effects
Analysis on Methyl tertiary-Butyl Ether (MTBE)." EPA 822-F-97-008. Office of Water,
Washington, D.C. December.
USEPA. 1998. MTBE Fact Sheet #3. Use and Distribution of MTBE and Ethanol. EPA/510-F-
97-016. Office of Solid Waste and Emergency Response.
Vance, D.B. 1998. MTBE: Character in Question. Environmental Technology.
January/February.
Wagler, J.L. and J.P. Malley. 1994. J. N. Engl. Water Works Assoc., Vol. 108, pp. 236.
Yeh, C.K. and J.T. Novak. 1995. The effect of hydrogen peroxide on the degradation of methyl
and ethyl tert-butyl ether in soils. Water Environment Research, Vol. 67, No. 5, pp. 828-834.
11
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About the Authors
Dr. Asim B. Ray is a Technical Scientist with the Senior Environmental Employee Program
with the USEPA, National Risk Management Research Laboratory, Water Supply and Water
Resources Division, Urban Watershed Management Branch, 2890 Woodbridge Avenue, Edison,
NJ 08837. Dr. Ariamalar Selvakumar and Mr. Anthony Tafuri are Environmental Engineer and
Senior Environmental Engineer, respectively, with the same Branch.
Disclaimer
Although the research described in this article has been funded wholly by the USEPA through
Contract No. 68-C7-0008, it has not been subjected to the Agency's peer review. Therefore, it
does not necessarily reflect the views of the Agency. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use.
12
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Exhibit 1. Schematic Diagram of Experimental Apparatus
Gas Samp'.if) j Port.
° ' °°xp^Sw!un'1'j
—-^ ik\, I jh.
13
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Exhibit 2. Test Conditions for MTBE Degradation
Test
Designation
A
B
C
D
H2O2:Fe+ (molar ratio)
0.1:1
1:1
10:1
100:1
pH
3,5,7
3,5,7
3,5,7
3,5,7
14
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Exhibit 3. Test Series A: H2O2:Fe = 0.1:1; pH 2.9 to 2.4
Time
(minutes)
0
5
10
15
20
25
30
35
40
45
50
55
60
MTBE
(F moles)
15.53
NA
3.61
NA
3.77
3.41
3.17
3.16
2.85
2.88
3.23
3.39
2.85
Acetone
(F moles)
0.19
0.42
0.47
0.56
0.56
0.55
0.51
0.51
0.46
0.47
0.56
0.57
0.48
TEA
(F moles)
0.49
0.63
0.21
0.39
0.30
0.22
0.20
0.20
0.18
0.19
0.20
0.22
0.01
TBF
(F moles)
0.05
0.08
0.01
0.05
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
Formate
(F moles)
ND
ND
2.22
0.67
6.36
4.36
4.53
1.51
ND
ND
ND
ND
ND
Acetate
(F moles)
ND
ND
3.05
3.56
1.59
5.08
6.85
ND
ND
ND
ND
ND
ND
At the end of the reaction 1.34 F moles of CC>2 gas was collected.
NA = not analyzed.
ND = not detected.
Note: Testing at pH 5 and 7 showed no significant change in MTBE concentrations.
15
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-------
+2
Exhibit 5. Test Series B: H2O2:Fe = 1:1; pH 5.2 to 3.3
Time
(minutes)
0
5
10
15
20
25
30
35
40
45
50
55
60
MTBE
(F moles)
15.10
0.19
0
0
0
0
0
0
0
0
0
0
0
Acetone
(F moles)
0
4.10
4.78
4.31
4.50
4.93
4.60
4.66
5.22
5.28
5.38
4.31
4.74
TEA
(F moles)
3.08
1.69
1.16
0.91
0.68
0.54
0.62
0.55
0.55
0.50
0.50
0.38
0.27
TBF
(F moles)
0
1.86
1.41
1.11
0.89
0.54
0.70
0.70
0.66
0.62
0.51
0.43
0.29
Formate
(F moles)
ND
ND
5.24
8.00
12.84
4.36
ND
ND
ND
ND
ND
ND
ND
Acetate
(F moles)
ND
ND
ND
2.98
5.36
12.14
9.19
7.12
3.76
ND
ND
ND
ND
ND = not detected.
After 60 minutes of reaction 4.24 F moles of COz evolved.
Note: Testing at pH 3 and 7 showed no significant change in MTBE concentrations.
17
-------
Concentration in micromoles
00
oo
CD
5'
3
c
CD"
CO
O
cn
o
M
BT
Sj
p^-
p\
0
=
era
re
H
03
H
03
O
a
n
n
o
=
o
re
=
o
=
H
§'
re
re
<*!
p*
C/5
re
S"
VI
03
------- |