Photochemical fate of solvent constituents of Corexit oil dispersants.
In 2010, an estimated 1.87 million gallons (7079 cubic meters) of chemical dispersants were applied to open ocean waters in the Gulf of Mexico as part of the response to the Deepwater Horizon blowout. This unprecedented volume of dispersant application highlighted the importance of dispersant chemical formulations, raising questions of dispersant fate and transport in the open ocean and spurring research into formulation improvements. The research presented here elucidates the contribution of photolytic processes to the degradation of two solvent constituents of these dispersant mixtures: propylene glycol (PG) and 2-butoxyethanol (2-BE). A series of photodegradation experiments were conducted to determine the contribution of direct photolysis and indirect photolysis via hydroxyl radical (HO) to compound degradation. Experiments were performed using both deep UV light sources (low pressure (LP) and medium pressure (MP) mercury vapor ultraviolet (UV) lamps) and a solar simulator. Sample matrices included ultrapure water, nitrate amended water, hydrogen peroxide (H2O2) spiked water, Gulf of Mexico seawater, and a surface water from Boulder, CO. Experiments included determination of the molar absorption coefficients (ε) and the HO reaction rate constants (kHO) of the individual compounds. Data illustrated that significant direct photolysis of either PG or 2-BE from sunlight is unlikely. The kHO for PG and 2-BE were determined to be 6.15 × 10(8) M(-1) s(-1) and 1.15 × 10(9) M(-1) s(-1), respectively. Solar simulation and UV experiments indicate that in natural systems, neither PG nor 2-BE is expected to undergo significant, rapid degradation due to direct or indirect photolysis. PG and 2-BE are effectively degraded through indirect photolysis in the presence of high HO concentrations, suggesting UV/H2O2 is a feasible possibility for the treatment of waters containing PG and 2-BE.
Civil, Environmental and Architectural Engineering, University of Colorado at Boulder, 428 UCB, ECOT 441, Boulder, CO 80309-0428, USA.
Stephanie C
SC
Kover
Civil, Environmental and Architectural Engineering, University of Colorado at Boulder, 428 UCB, ECOT 441, Boulder, CO 80309-0428, USA.
Fernando L
FL
Rosario-Ortiz
Civil, Environmental and Architectural Engineering, University of Colorado at Boulder, 428 UCB, ECOT 441, Boulder, CO 80309-0428, USA. Electronic address: karl.linden@colorado.edu.
Karl G
KG
Linden
D000327:Adsorption; D001673:Biodegradation, Environmental; D005026:Ethylene Glycols / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry; D008055:Lipids / Q000737:chemistry*; D010782:Photolysis; D019946:Propylene Glycol / Q000737:chemistry*; D012623:Seawater; D012997:Solvents / Q000737:chemistry*; D013472:Sunlight; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000737:chemistry
D005026:Ethylene Glycols; D008055:Lipids; D012997:Solvents; D014874:Water Pollutants, Chemical; C470995:corexit 9500; D017665:Hydroxyl Radical; C021984:corexit 9527; D019946:Propylene Glycol; D006861:Hydrogen Peroxide; C017096:n-butoxyethanol
Advanced oxidation process; Butoxyethanol; Corexit; Hydroxyl radical; Photolysis; Propylene glycol