Photochemical processes involving the UV absorber benzophenone-4 (2-hydroxy-4-methoxybenzophenone-5-sulphonic acid) in aqueous solution: Reaction pathways and implications for surface waters

Abstract

processes involving the UV absorber benzophenone-4 (2-hydroxy-4-methoxybenzophenone-5-sulphonic acid) in aqueous solution. Reaction pathways and implications for surface waters. Wat. Res. 2013, 47, 5943-5953. DOI: 10.1016/j.waters.2013 You may download, copy and otherwise use the AAM for non-commercial purposes provided that your license is limited by the following restrictions:(1) You may use this AAM for non-commercial purposes only under the terms of the CC-BY-NC-ND license.(2) The integrity of the work and identification of the author, copyright owner, and publisher must be preserved in any copy. AbstractThe sunlight filter benzophenone-4 (BP-4) is present in surface waters as two prevailing forms, the singly deprotonated (HA − ) and the doubly deprotonated one (A 2− ), with pK a2 = 7.30±0.14 (µ±σ, by dissociation of the phenolic group). In freshwater environments, BP-4 would mainly undergo degradation by reaction with • OH and direct photolysis. The form HA − has a second-order reaction rate constant with • OH ( OH k • ) of (1.87±0.31)⋅10 10 M −1 s −1 and direct photolysis quantum yield Φ equal to (3.2±0.6)⋅10 −5 . The form A 2− has (8.46±0.24)⋅10 9 M −1 s −1 as the reaction rate constant with • OH and (7.0±1.3)⋅10 −5 as the photolysis quantum yield. The direct photolysis of HA − likely proceeds via homolytic breaking of the O-H bond of the phenolic group to give the corresponding phenoxy radical, as suggested by laser flash photolysis experiments. Photochemical modelling shows that because of more efficient direct photolysis (due to both higher sunlight absorption and higher photolysis quantum yield), the A 2− form can be degraded up to 3 times faster than HA − in surface waters. An exception is represented by low-DOC (dissolved organic carbon) conditions, where the • OH reaction dominates degradation and the transformation kinetics of HA − is faster compared to A 2− . The half-life time of BP-4 in mid-latitude summertime would be in the range of days to weeks, depending on the environmental conditions. BP-4 also reacts with Br 2 −• , and a rate constant

Hepatic oxidative stress biomarker responses in freshwater fish Carassius auratus exposed to four benzophenone UV filters

“…These findings demonstrate the apparent likelihood that BPs contained in PCPs might be emitted into the aquatic environment and persistent with a great potential for bioaccumulation through food chains (Gago-Ferrero et al, 2013). Thus, the occurrence (Liao and Kannan, 2014;Tsui et al, 2014), the degradation (Beel et al, 2013;Duirk et al, 2013;Yang and Ying, 2013;Ji et al, 2013;Laurentiis et al, 2013;Xiao et al, 2013) and, particularly the potential toxicities to humans and the ecosytems of these BP UV-filters have attracted widespread attention (Hofkamp et al, 2008;Downs et al, 2014;Paredes et al, 2014;Liu et al, 2015).…”

Indirect Photochemistry in Sunlit Surface Waters: Photoinduced Production of Reactive Transient Species

“…38, 77 Generally speaking, . OH tends to play an important role in the transformation of many emerging pollutants, such as pharmaceuticals and personal care products30, 38, 39 (although the easily oxidized acetaminophen is an important exception77), and it is strongly involved in the degradation of refractory compounds, including hydrocarbons such as toluene 78…”

“…In fact, in addition to thermal deactivation that can sometimes be very important, the main solutes that would scavenge the transients are DOM of mostly natural origin, inorganic carbon (especially bicarbonate and carbonate), bromide, and (in the case of 3 CDOM*) dissolved oxygen 25–27. Several components of surface waters can thus be involved in the formation and/or in the consumption of reactive transients, and important water chemistry parameters of photochemical significance are DOC (dissolved organic carbon, which is a measure of DOM), nitrate, nitrite, carbonate, bicarbonate, bromide, and dissolved oxygen 28–30…”

Photogeneration of reactive transient species upon irradiation of natural water samples: Formation quantum yields in different spectral intervals, and implications for the photochemistry of surface waters

“…Some processes induced by irradiated CDOM (e.g. the reaction of pollutants with 3 CDOM* and 1 O 2 ) are potentially more important in deep water bodies (De Laurentiis et al, 2013a), where the ability of CDOM photochemistry to be triggered by visible radiation is a major factor. In this context, the efficiency (quantum yield) by which irradiated CDOM produces different reactive transients as a function of the absorbed wavelength(s) has major importance.…”