Photodegradation Of Novel Brominated Flame Retardants And Phthalates Esters

New brominated flame retardants?NBFRs?and Phthalates esters?PAEs?represent two important groups of industrial additive chemicals.Following massive applications,they are widely present in various environmental media and biological systems.They were also reported to exhibit various biological effects and ecological risks.Photodegradation has been demonstrated to be important in affecting the environmental fate of pollutants such as NBFRs and PAEs.In this study,two NBFR and fourteen PAE chemicals were selected for the investigation of their photodegradation kinetics and products under different conditions.Factors including wavelength and solvent type were studied for their effect on degradation kinetics and possible degradation products were characterized.Two highly brominated FRs,Tris?2,3-dibromopropyl?Isocyanurate?TDBP-TAZTO?and Decabromodiphenyl ethane?DBDPE?,were selected for the study.The res?Lts indicated that the degradation kinetics was affected by UV irradiation wavelength,intensity,solvent type,as well as the structural characteristics.The study found that increasing the light intensity can greatly stim?Late the degradation of TDBP-TAZTO and DBDPE.Meanwhile,the res?Lts show that TDBP-TAZTO and DBDPE have different absorbances for different wavelengths of light,and UV-B promotes degradation significantly compared to UV-A.The influence of the solvent on the degradation is very obvious.Whether it is TDBP-TAZTO or DBDPE,its half-life(t_1/2)in the No-solvent is far greater than other reaction media,and the THF promotion effect is greater than Me OH.It is spec?Lated that it is related to the hydrogen-donating ability of the organic solvent.The greater the hydrogen-donating ability,the more obvious the promotion of degradation.TDBP-TAZTO exhibited degradation half-lives(t_1/2)of 23.5–6931 min under various UV irradiation conditions and 91.2 days under natural sunlight.Its degradation was much slower than that of DBDPE which exhibited t_1/2 of 0.8–101.9 min under UV and 41.3 min under natural sunlight.It shows that the degradation rate of TDBP-TAZTO is significantly slower than that of DBDPE,presumably related to the structure of the substance,the degradation of NBFRs is faster with increasing number of bromine substituents.Through the identification of degradation products,it was found that a variety of degradation products are generated during the degradation process and the main degradation pathways include dehydrobromination,hydroxylation or oxygenation.Fourteen well-known PAEs were studied to explore their photodegradation process and degradation kinetics in indoor dust.Their degradation all followed pseudo-first-order kinetic reactions.The degradation rate constants decreased along with the increase of initial concentrations.Similar to NBFRs,light intensity has a significant effect on the degradation of PAEs,and the degradation of PAEs was faster under high-intensity irradiation.Characterization of degradation products suggested that phthalate monoesters?Mono-PAEs?were produced as the main photodegradation products.However,additional products co?ld also be present,which requires further investigations.