Biodegradation of potential diesel oxygenate additives: dibutyl maleate (DBM), and tripropylene glycol methyl ether (TGME).
The addition of oxygen-bearing compounds to diesel fuel considerably reduces particulate emissions. TGME and DBM have been identified as possible diesel additives based on their physicochemical characteristics and performance in engine tests. Although these compounds will reduce particulate emissions, their potential environmental impacts are unknown. As a means of characterizing their persistence in environmental media such as soil and groundwater, we conducted a series of biodegradation tests of DBM and TGME. Benzene and methyl tertiary butyl ether (MTBE) were also tested as reference compounds. Primary degradation of DBM fully occurred within 3 days, while TGME presented a lag phase of approximately 8 days and was not completely degraded by day 28. Benzene primary degradation occurred completely by day 3 and MTBE did not degrade at all. The total mineralized fractions of DBM and TGME achieved constant values as a function of time of approximately 65% and approximately 40%, respectively. Transport predictions show that, released to the environment, DBM and TGME would concentrate mostly in soils and waters with minimal impact to air. From an environmental standpoint, these results combined with the transport predictions indicate that DBM is a better choice than TGME as a diesel additive.
Marchetti
Alfredo A
AA
Environmental Science Division, Lawrence Livermore National Laboratory, 7000 East Avenue, L-396, Livermore, CA 94550, USA. marchetti1@llnl.gov
Knize
Mark G
MG
Chiarappa-Zucca
Marina L
ML
Pletcher
Ronald J
RJ
Layton
David W
DW
D001420:Bacteria, Aerobic; D001554:Benzene / Q000378:metabolism; D001673:Biodegradation, Environmental; D002245:Carbon Dioxide / Q000032:analysis; D005742:Gasoline / Q000032:analysis*; D008298:Maleates / Q000378:metabolism*; D008738:Methyl Ethers / Q000737:chemistry / Q000378:metabolism*; D011409:Propylene Glycols / Q000737:chemistry / Q000378:metabolism*; D012015:Reference Standards; D012722:Sewage / Q000382:microbiology; D012989:Soil Pollutants / Q000032:analysis; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000032:analysis
D005742:Gasoline; D008298:Maleates; D008738:Methyl Ethers; D011409:Propylene Glycols; D012722:Sewage; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D002245:Carbon Dioxide; C048074:dibutyl maleate; D001554:Benzene