Photosensitized Degradation of Bisphenol A by Dissolved Organic Matter

Abstract

The direct and indirect photolysis of bisphenol A (BPA) was investigated using a solar simulator in the absence and presence of dissolved organic matter (DOM). BPA degradation by direct photolysis was significantly slower than its rate in the presence of DOM. In natural waters, the direct photolytic pathway would be even less important due to light screening effects. Surprisingly, differences in the rate of indirect BPA photolysis were relatively small between DOM samples. Two of the DOM samples represented terrestrial (Suwannee River fulvic acid) and autochthonous (Lake Fryxell) geochemical endmembers. The third DOM (Fulton County, Ohio) was derived from a temperate artificial wetland. We were unable to correlate BPA photoreactivity to the structural components of DOM or its extinction coefficient at 280 nm. The addition of methanol, a hydroxyl radical scavenger, to reaction solutions slowed but did not completely quench the indirect photolysis of BPA. This observation suggests that BPA photodegrades via multiple pathways involving other transients formed by the photolysis of DOM. Competitive experiments using 2,4,6-trimethylphenol also reduce the reaction rate of BPA by DOM and implythat other DOM-derived phototransients (e.g., excited triplet state DOM) are involved in the reaction. The reaction rate coefficients reported under solar-simulated irradiance in the presence of DOM are significantly faster than those reported for the microbial degradation of BPA. Thus, in natural surface waters photosensitized transformation of BPA by dissolved organic matter may be as important as biodegradation.

Occurrence and Fate of Selected Endocrine-Disrupting Chemicals in Water and Sediment from an Urban Lake

“…Previously, Chin et al (2004) found that direct photodegradation of BPA was very slow with an estimated halfmg kg -1 mg kg -1 Fig. 3 Linear adsorption isotherms of the EDCs in the lake sediment life of 235 h and that the presence of DOM significantly accelerated the degradation process (half-life 17.4-32.2 h).…”

Phototransformation of nitrobenzene in the Songhua River: Kinetics and photoproduct analysis

“…ROO), singlet oxygen ( 1 O 2 ), etc.) and other non-ROS transients (Chin et al, 2004). Nitrate and nitrite are other photosensitizers in natural waters and nitrate-induced photooxidation may be a significant transformation mechanism for trace organic chemicals in shallow, clear water bodies because it is important precursor in the photoproduction of .…”

Atmospheric HULIS enhance pollutant degradation by promoting the dark Fenton reaction

“…Humic substances have been seen to enhance the degradation of organic compounds by promoting photo-Fenton reactions [Fukushima and Tatsumi, 2001;Xu et al, 2006;Zhan et al, 2006], for example, enhancing the degree of pentachlorophenol degradation from 40% after 5 h of irradiation to more than 90% with added humic acid [Fukushima and Tatsumi, 2001]. Humic substances also produce various reactive oxygen species under photoirradiation [Sandvik et al, 2000], leading to accelerated pollutant oxidation [Sakkas et al, 2002;Chin et al, 2004;Zhan et al, 2006].…”