TY - JOUR

T1 - Photodegradation of the UV filter ethylhexyl methoxycinnamate under ultraviolet light

T2 - identification and in silico assessment of photo-transformation products in the context of grey water reuse

AU - Jentzsch, Franziska

AU - Olsson, Oliver

AU - Westphal, Janin

AU - Reich, Marco

AU - Leder, Christoph

AU - Kümmerer, Klaus

PY - 2016/12/1

Y1 - 2016/12/1

N2 - To prevent water shortages in the future and to reduce domestic water consumption, decentralized grey water (GW) reuse has become increasingly important. This water has, however, to be free of pollutants. Conventional treatment of GW does not fully eliminate micropollutants such as the UV filter substance ethylhexyl methoxycinnamate (EHMC). EHMC, which is commonly used in sunscreens and personal care products, is an endocrine disruptor and shows potential to bioaccumulation, which is also reflected in its low water solubility. Photolysis has been proposed as an alternative treatment method for other micropollutants, but it is not clear yet whether it can also be used to eliminate EHMC. One goal of this study was to better understand the basic pathways involved in this process. It aimed to identify photo-transformation products (photo-TPs) by using, in the test conditions, an initial concentration of EHMC higher than those expected in the environment. Acetonitrile (ACN) was added in low concentrations to the aqueous solution to overcome the low aquatic solubility of EHMC. The influence of this co-solvent on the degradation kinetics was studied. The photolysis experiments were carried out using a medium pressure mercury lamp, which emits UV light in the range of 200–400 nm. The quantum yield of the photolysis of EHMC was 0.0042 and 0.0023 mol·Einstein − 1 (for 0.2 and 0.5% ACN (v/v), respectively), and the relative and absolute UV photon fluxes were determined. HPLC was used to monitor the elimination kinetics of EHMC, which followed first-order kinetics. The results of LC-MS n analyses revealed that beside others, several oxidized and hydroxylized EHMC isomers were formed as photo-TPs in aqueous solution. Using a set of in silico quantitative structure-activity relationship (QSAR) models, this study also offered new insights concerning the environmental fate and toxicity of the TPs of EHMC.

AB - To prevent water shortages in the future and to reduce domestic water consumption, decentralized grey water (GW) reuse has become increasingly important. This water has, however, to be free of pollutants. Conventional treatment of GW does not fully eliminate micropollutants such as the UV filter substance ethylhexyl methoxycinnamate (EHMC). EHMC, which is commonly used in sunscreens and personal care products, is an endocrine disruptor and shows potential to bioaccumulation, which is also reflected in its low water solubility. Photolysis has been proposed as an alternative treatment method for other micropollutants, but it is not clear yet whether it can also be used to eliminate EHMC. One goal of this study was to better understand the basic pathways involved in this process. It aimed to identify photo-transformation products (photo-TPs) by using, in the test conditions, an initial concentration of EHMC higher than those expected in the environment. Acetonitrile (ACN) was added in low concentrations to the aqueous solution to overcome the low aquatic solubility of EHMC. The influence of this co-solvent on the degradation kinetics was studied. The photolysis experiments were carried out using a medium pressure mercury lamp, which emits UV light in the range of 200–400 nm. The quantum yield of the photolysis of EHMC was 0.0042 and 0.0023 mol·Einstein − 1 (for 0.2 and 0.5% ACN (v/v), respectively), and the relative and absolute UV photon fluxes were determined. HPLC was used to monitor the elimination kinetics of EHMC, which followed first-order kinetics. The results of LC-MS n analyses revealed that beside others, several oxidized and hydroxylized EHMC isomers were formed as photo-TPs in aqueous solution. Using a set of in silico quantitative structure-activity relationship (QSAR) models, this study also offered new insights concerning the environmental fate and toxicity of the TPs of EHMC.

KW - Chemistry

KW - Grey water

KW - Personal care products

KW - Photolysis

KW - Quantitative structure-activity relationship

KW - UV treatment

KW - Sustainability Science

KW - Transformation

UR - http://www.scopus.com/inward/record.url?scp=84994043917&partnerID=8YFLogxK

U2 - 10.1016/j.scitotenv.2016.08.017

DO - 10.1016/j.scitotenv.2016.08.017

M3 - Journal articles

C2 - 27531468

VL - 572

SP - 1092

EP - 1100

JO - The Science of The Total Environment

JF - The Science of The Total Environment

SN - 0048-9697

ER -