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J Contam Hydrol

Title:		Degradation studies of UV filter hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]-benzoate (DHHB) in aqueous solution
Author(s):		Santos AJM; da Silva J;
Address:		"Centro de Investigacao em Quimica da Universidade do Porto (CIQUP), Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto, Portugal. Electronic address: joelsantos24@hotmail.com. Centro de Investigacao em Quimica da Universidade do Porto (CIQUP), Departamento de Geociencias, Ambiente e Ordenamento do Territorio, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto, Portugal. Electronic address: jcsilva@fc.up.pt"
Journal Title:		J Contam Hydrol
Year:		2021
Volume:		20201130
Issue:
Page Number:		103740 -
DOI:		10.1016/j.jconhyd.2020.103740
ISSN/ISBN:		1873-6009 (Electronic) 0169-7722 (Linking)
Abstract:		"High performance liquid chromatography coupled with ultra-violet, diode array detection (HPLC-UV-DAD), was used to study the degradation reactions of ultraviolet (UV) filter hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]-benzoate (DHHB). Degradation by-products were detected and identified by means of liquid chromatography coupled with diode array detection and mass spectrometry (LC-DAD-MS). Environmentally-relevant characteristics, such as water pH, chlorine levels, water temperature and dissolved organic matter (DOM) concentration, were modulated and studied in order to determine their influence on the degradation reactions. Results show that DHHB degrades quite rapidly in typical drinking water disinfection conditions, displaying a kinetic rate constant of k(obs) = 0.0060 +/- 0.0002 s(-1) and a half-life period of merely t(1/2) = 116 +/- 4 s. As far as the non-volatile disinfection by-products (DBPs) are concerned, only the mono and dichlorinated forms of DHHB were detected in the degradation reactions. Regarding influential variables on DHHB degradation, the presence or absence of DOM in solution did not alter the trends that were found (degradation of DHHB is more significant at lower pH values and higher levels of active chlorine in solution). Chlorinated DBPs have also been found to predominate under higher pH values and lower levels of chlorine, whereas they were found to be unstable and further degradable, quite likely into smaller and more volatile compounds, when in lower pH and higher chlorine concentrations. As for the photo-degradation studies, DHHB was found to be extremely photo-stable, with only about 15% degradation rate detected during artificial irradiation periods of 6 h"
Keywords:		"Benzoates Chlorine Halogenation Kinetics Ultraviolet Rays Water *Water Pollutants, Chemical/analysis *Water Purification Dhhb Disinfection by-products UV filters Uvinul a plus;"
Notes:		"MedlineSantos, Albano Joel Moreira da Silva, Joaquim Carlos Gomes Esteves eng Netherlands 2020/12/04 J Contam Hydrol. 2021 Jan; 236:103740. doi: 10.1016/j.jconhyd.2020.103740. Epub 2020 Nov 30"