title: Kinetics of tetrabromobisphenol A (TBBPA) reactions with H₂SO₄, HNO₃ and HCl: implication for hydrometallurgy of electronic wastes.
abstract: Hydrometallurgy is an acid leaching based process widely used for recovering precious metals from electronic wastes (e-wastes). The effects of acid leaching on the fate of brominated flame retardants (BFRs) in typical hydrometallurgical processes remain largely unknown. This study was aimed at evaluating the fate of tetrabromobisphenol A (TBBPA), a commonly used BFR, in three acid leaching reagents (i.e. H2SO4, HNO3, and HCl) commonly used in hydrometallurgy. It was found that the reactions of TBBPA with concentrated H2SO4 followed a pseudo-zero-order rate and the reaction rates declined rapidly as the concentrations of H2SO4 decreased. In contrast, TBBPA could be easily transformed in less concentrated HNO3 solutions (<21.7 wt%) and the reactions followed a pseudo-first-order rate. The reaction products identified by GC-MS indicated different transformation pathways of TBBPA in H2SO4 and HNO3. HCl or HCl/H2SO4 mixtures (3:1, v/v) did not appear to react with TBBPA, while aqua regia (3:1 HCl/HNO3, v/v) reacted violently with TBBPA and led to almost complete disappearance of TBBPA within a minute. It suggested that HNO3 significantly affected the fate of TBBPA and the use of HNO3 as leaching reagents in hydrometallurgy of e-wastes should be carefully evaluated. Collectively, our findings of distinct fate of TBBPA in different acid leaching reagents provided fundamental information for design of hydrometallurgical treatment of e-wastes to minimize acid reactions with BFRs within plastics matrix and to maximize acid leaching efficiency for metals recycling processes.
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Wushan, Guangzhou 510640, China.
authors.forename: Yin
authors.initials: Y
authors.lastname: Zhong
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Wushan, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Li
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Wushan, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Mao
authors.affiliation: Department of Environmental Sciences, Rutgers, The State University of New Jersey, 14 College Farm Road, New Brunswick 08901, NJ, USA.
authors.forename: Weilin
authors.initials: W
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Wushan, Guangzhou 510640, China. Electronic address: pinganp@gig.ac.cn.
authors.forename: Ping'an
authors.initials: P
authors.lastname: Peng
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Wushan, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Pei
authors.initials: P
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Wushan, Guangzhou 510640, China; Department of Chemistry, Guangdong Medical College, Dongguan 523808, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Mei
mesh_terms: D059029:Electronic Waste; D005411:Flame Retardants; D006851:Hydrochloric Acid / Q000737:chemistry*; D007700:Kinetics; D017942:Nitric Acid / Q000737:chemistry*; D011075:Polybrominated Biphenyls / Q000737:chemistry*; D013464:Sulfuric Acids / Q000737:chemistry*; D018505:Waste Management / Q000379:methods
chemical_list: D005411:Flame Retardants; D011075:Polybrominated Biphenyls; D013464:Sulfuric Acids; D017942:Nitric Acid; C020806:tetrabromobisphenol A; C033158:sulfuric acid; D006851:Hydrochloric Acid
keywords: Acid; Electronic wastes; Recycling; TBBPA; Transformation