Photochemical fate of solvent constituents of Corexit oil dispersants

WATER RESEARCH

卷:52

Article

Kover, Stephanie C.¹  Rosario-Ortiz, Fernando L.¹  Linden, Karl G.¹ 

[1] Univ Colorado, Boulder, CO 80309 USA

关键词: Hydroxyl radical;    Photolysis;    Propylene glycol;    Butoxyethanol;    Corexit;    Advanced oxidation process;   

DOI  :  10.1016/j.watres.2013.12.013

来源: Elsevier

【 摘 要 】

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 center dot) 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 (epsilon) and the HO center dot reaction rate constants (k(HO)center dot) of the individual compounds. Data illustrated that significant direct photolysis of either PG or 2-BE from sunlight is unlikely. The k(HO)center dot for PG and 2-BE were determined to be 6.15 x 10(8) M-1 s(-1) and 1.15 x 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 center dot concentrations, suggesting UV/H2O2 is a feasible possibility for the treatment of waters containing PG and 2-BE. (C) 2013 Elsevier Ltd. All rights reserved.

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