Identification,Occurrence,and Transformation Mechanism Of Tetrabromobisphenol A Derivatives In Contaminated Sites

Brominated flame retardants(BFRs)are currently one of the largest in production and most efficient organic flame retardants in the world.Tetrabromobisphenol A(TBBPA)accounts for approximately 60%of the total use of BFRs in the world.China is the main producer of TBBPA BFRs,with an annual production of over 180000 tons in2020.Tetrabromobisphenol A bis(2,3-dibromopropyl)ether(TBBPA-BDBPE),as the derivative of TBBPA with the highest bromine content,is mainly used as an additive flame retardant due to its excellent thermal and photo stability,and is widely used in the production of building materials,textiles,and electronic and electrical components.As an additive flame retardant,TBBPA-BDBPE is easy to be released into the environment during the lifetime of products,and transformed in different environmental media due to its non chemical bond connection with polymer components.TBBPA-BDBPE has been detected in various environmental samples such as air,sewage sludge,soil,river sediments,marine mollusks,and marine fish,and the detection concentration of TBBPA-BDBPE in some environmental media is much higher than that of TBBPA.The high concentration of TBBPA-BDBPE in environmental media increases the risk of exposure to organism.The occurrence characteristics and transformation process of potential new persistent organic pollutants TBBPA-BDBPE in the environment deserve further attention.In this paper,sediment,soil and water samples(15 sites,45 samples)collected in a river flowing through brominated flame retardant manufacturing zone were analyzed to determine TBBPA derivatives,byproducts,and transformation products.Non targeted screening was carried out for unknown TBBPA analogs in the environment,and 10unknown TBBPA analogs were identified.In addition,the occurrence of various unknown bromobisphenol A allyl ether analogs in the samples was further confirmed by using 11 synthesized analogs,which might be produced during the waste treatment process of the factories.Based on the previously synthesized and newly synthesized TBBPA analogs standards,qualitative and quantitative analysis was conducted on the occurrence characteristics of 25 substances,including TBBPA derivatives,byproducts,and transformation products in environmental samples.By characterizing the relevant unknown compounds in contaminated samples,the existence of multiple unknown TBBPA analogs compounds in environmental samples was further confirmed.It is speculated that TBBPA derivatives might be generated during waste treatment in brominated flame retardant manufacturing plant.The experimental results indicate that the detection concentration range of TBBPA derivatives and byproducts was from<MDL to 1.1×10~7ng/kg dw in all samples,with detection frequency from 0 to 100%.The concentration range of TBBPA-BDBPE transformation products in sediment and soil samples was from<MDL to 3.4×10~5ng/kg dw.The concentrations of TBBPA derivatives TBBPA-BDBPE and TBBPA-BAE in sediments and soil around brominated flame retardant manufacturing plants are higher than TBBPA,indicating that the impact of TBBPA derivatives on the environment cannot be ignored.In addition,through the use of synthetic standards,quantitative analysis of lower brominated bisphenol A analogs in environmental samples was carried out for the first time.It was found that the concentrations of lower brominated bisphenol A analogs(such as Tri BBPA-BAE,Tri BBPA-MAE-1,MBBPA-BAE,DBBPA(-1/2)-BAE,DBBPA(-1)-MAE and DBBPA(-2)-MAE-1/2 in sediment samples were higher than those in water samples,because their log Koc values were higher,and they were easier to be adsorbed on solid media when entering the environment.This study conducted a comprehensive investigation into the fate of TBBPA related substances based on the simultaneous determination of TBBPA derivatives,byproducts,and transformation products in real environments.To verify the transformation process of TBBPA-BDBPE in the environment,a photooxidation experiment of TBBPA-BDBPE was designed in the laboratory to explore the photooxidation transformation kinetics,products,and mechanisms of TBBPA-BDBPE in the waste treatment process of brominated flame retardant manufacturing plants.We selected a UV/base/persulfate(PS)silica gel medium aqueous solution system to study the photooxidation process of TBBPA-BDBPE,and found that TBBPA-BDBPE mainly undergoes ether bond cleavage,debromination,dehydroxylation,andβ-scission.The main products are TBBPA-MDBPE,TBBPA-MAE,TBBPA,Tri BBPA,DBBPA-1/2,BPA,Tri BBPA-MAE-1/2,TBBPA-MBHPE,TBBPA-MGE,TBBPA-MHPE,TBBPA-MDHPE,4-(2-hydroxyisopropyl)-2,6-dibromophenol,2,6-dibromophenol,and 2,6-dibromo-4-hydroxyphenol.Simulation experiments have confirmed that the novel TBBPA analogs discovered in the environment might be the transformation products of TBBPA derivatives,as well as byproducts generated during factory waste treatment processes and the photolysis of TBBPA derivatives in the environment.These unknown analogs may pose potential risks to humans and wildlife,especially in high levels of sediment and soil.These data provide new insights into the fate of TBBPA derivatives in environmental media.