CBr Bond Research Articles

Derivatives of Br-doped metal-organic framework for improved acetaldehyde adsorption-photocatalytic oxidation

Different Br-doped metal-organic frameworks (MOFs) derived (Brx@UiO-66) have been prepared by heat treatment using UiO-66 as the precursor. The experimental results showed that Br0.2@UiO-66 exhibited the best photocatalytic oxidation and adsorption performances toward acetaldehyde. In the dynamic system, the acetaldehyde removal rate and adsorption capacity of Br0.2@UiO-66 were 93.2 % and 230.59 mg/g, respectively. The improvement of the photocatalytic performance can be attributed to the presence of Br ions and CBr bonds, which facilitated the rapid separation of electrons and holes and the production of •O2−. In addition, Br0.2@UiO-66 had a better adsorption performance than 300UiO-66, mainly because of the increased Lewis acidity of the metal active sites due to Br doping. Radical capture experiments indicated that •O2− and e- were the primary active substances in acetaldehyde oxidation, and allowed establishing the possible mechanism of acetaldehyde oxidation. This work shows that MOFs can have high catalytic oxidation performances toward volatile organic compounds (VOCs) while retaining their adsorption capacity, and can be used for practical applications in the adsorption-catalytic integrated degradation of VOCs.

Free radical formation via BDE-209 thermolysis in the precalciner of a cement kiln: Simulation and DFT study

To deeply understand the formation mechanism of polybrominated dibenzo-p-dioxins/furans (PBDD/Fs) in the thermal disposal process of polybrominated diphenyl ether (PBDE)-containing waste, this paper studied the formation pathways of key intermediates (free radicals, FRs) in the formation process of PBDD/Fs. BDE-209, the most common PBDE in the environment, was selected as the object of study to analyze FR formation by simulating the key conditions such as temperature (850 °C) and Fe-based materials when PBDE-containing waste entering cement kiln precalciner. Electron paramagnetic resonance (EPR) spectroscopy and density functional theory (DFT) calculations were used to study the reaction. The result of simulation experiments revealed carbon-centered radicals, and DMPO-OH analysis further confirmed the generation of FRs. The findings confirmed previous calculations predicting the existence of radical intermediates during the formation of PBDD/Fs from BDE-209. DFT calculations revealed the existence of an inner ortho-position CBr bond in BDE-209. The priority order of the bond breaking of BDE-209 was ether bond, inner ortho-position CBr bond, and outside ortho-position CBr bond. BDE-209 can further form three kinds of FRs, namely, oxygen-centered radicals of single benzene rings, carbon-centered radicals of single benzene rings, and carbon-centered radicals of double benzene rings. The specific processes of FR formation were inferred: high-temperature homogeneous cleavage of chemical bonds, electron transfer, and chemisorption, where electron transfer and chemisorption may be more important pathways. The proposed inner ortho-position cleavage within BDE-209 provides new insights into the degradation of PBDEs and the formation of PBDD/Fs; the results regarding BDE-209 generation radicals further elucidate the synthesis mechanism of dioxins, which is important for controlling dioxin generation and emission during the treatment and disposal of waste containing PBDEs.

NHC-catalyzed [3 + 4] annulation between 2-dromoenal and aryl 1,2-diamine: Insights into mechanisms, chemo and stereoselectivities

We present a DFT study of the mechanisms, chemo- and stereoselectivities in the reaction of 2-bromoenal with aryl 1,2-diamine enabled by a chiral NHC. The catalytic reaction starts with NHC addition to 2-bromoenal, subsequent [1,2]-proton transfer results in the Breslow intermediate, which then undergoes sequential CBr bond breaking and [1,3]-proton transfer. The resulting acylazolium can transform to the [3 + 4] cycloadduct through subsequent CN bond formation, [1,3]-proton transfer and cyclization. Finally, elimination of catalyst provides 1,5-benzodiazepin-2-one. DFT results reveal that OAc− and HOAc play important roles respectively in the [1,2]- and [1,3]-proton transfer process. The CN bond formation step controls the enantioselectivity of the reaction, and preferably provides access to (R)-1,5-benzodiazepin-2-one. The computed enantioselectivity (97.5% ee) agrees well with experimental report (97% ee). Non-covalent NH···π, CH···N and CH···π interactions are the key factors for controlling the stereoselectivity. The NHC is demonstrated to play a role in CBr bond activation through reduce the electron density between the C and Br atoms, thus increases 2-bromoenal's electrophilicity and facilitates its subsequent reaction with diamines.

Oxygen vacancies enriched Bi2WO6 for enhanced decabromodiphenyl ether photodegradation via C-Br bond activation

CBr bond activation is a critical step in the degradation of organic halogenated pollutants. Herein, by introducing oxygen vacancies with different concentration gradients into Bi2WO6, the CBr bond in decabromodiphenyl ether (BDE209) is activated, so that BDE209 is successfully dehalogenated under visible light. The study shows that the degradation rate of BDE209 on Bi2WO6 is determined by both interface defects and crystallinity. Good crystallinity is conducive to the generation and separation of photogenerated electrons and holes, and an appropriate defect concentration can promote the C-Br activation of BDE209. In addition, through the tracking analysis of the degradation products of BDE209, the content of the meta-debromination products of BDE209 on Bi2WO6 is significantly higher than that of the ortho- and para-debromination products, indicating that the reduction reaction is a position selective multi-electron mechanism. The study shows that oxygen vacancy assisted debromination is an excellent strategy for photocatalytic treatment of halogenated flame retardant pollutants.

Dissolution and separation of non-metallic powder from printed circuit boards by using chloride solvent

Non-metallic components (NMC) in waste printed circuit boards (WPCBs) are made of the thermosetting epoxy resin and glass fiber, which has been a research concern in the waste recycling area. The recycling of thermosetting epoxy resin is a serious challenge due to their permanent cross-linked structure. An efficient approach to chemical recycling of epoxy resin for resource reutilization was developed in this research. ZnCl2/CH3COOH aqueous solution was selected as catalysts system to decompose epoxy resin under a mild reaction condition. The influence of reaction parameters such as reaction temperature, time, liquid-solid ratio and ZnCl2 amount on the decomposition efficiency of epoxy resin and reaction mechanism were investigated. The physical and chemical properties of NMC, reaction solvent and decomposed products were analyzed using scanning electron microscope(SEM), Fourier transform infrared spectroscopy (FT-IR) and Gas chromatography–mass spectrometry (GC–MS). Results showed that up to 81.85% of epoxy resin could be dissolved by using a temperature of 190 °C during 8 h with a mixture of acetic acid (15 wt%): ZnCl2 (5 g) 20 mL/g. Incompletely coordinated zinc ions enables the cleavage of CN, CBr and CO bonds in the thermosetting brominated epoxy resin, which was mainly converted to phenol, 2-Bromophenol and 2, 4-Dibromophenol with high resource value. And the functional groups of ethyl acetate and acetic acid maintained chemical structure before and after reaction. This research provided a practical approach to the dissolution and reutilization of NMC in WPCBs.

Solvent free, light induced 1,2-bromine shift reaction of α-bromo ketones

Photolysis of α-bromopropiophenones in acetonitrile results in formation of β-bromopropiophenones with good product selectivity, which can be coined as 1,2-Br shift reaction. The product selectivity increases when the reaction is done in neat or solid state, where only the 1,2-Br shift product is formed in some cases. The reaction is suggested to proceed by CBr bond homolysis to give a radical pair, followed by disproportionation and conjugate addition of HBr to the α,β-unsaturated ketone intermediate. When the unsaturated intermediate is stabilized by an extra conjugation, the reaction stops at the stage, in which the unsaturated ketone becomes a major product. The synthetic method described in this research fits in a category of eco-friendly organic synthesis nicely since the reaction does not use volatile organic solvents and any other additives such as acid, base or metal catalysts, etc. Besides, the method fits into perfect atom economy, which does not give any side products. The synthetic method should find much advantage over other alternative methods to obtain β-bromo carbonyl compounds.

Experimental and theoretical investigations on debromination pathways of polybrominated biphenyls (PBBs) under ultraviolet light

Polybrominated biphenyls (PBBs) are brominated flame retardants that are widely used in textiles and electronic products. Recently, many researches have been devoted to determining their concentrations in food and in the environment. Yet, their degradation behavior has been less investigated and is not well understood. Here, we have investigated the debromination pathways of PBBs by (UV) light in the case of 2,4,5-tribrominated biphenyl (PBB-29). Our investigation indicates that para-bromine substituent on PBB-29 was preferentially removed. By means of density functional theory (DFT), we found that the energies of the debromination products, the CBr bond length in the excited state (S1), the Mulliken charge of bromine in S1, and the lowest unoccupied molecular orbital (LUMO) in S1 correlated well with the debromination pathways of PBBs. Further, LUMO-based prediction of PBB debromination pathways in S1 suggests that the bromine substituent on all brominated positions (i.e. ortho-, meta- and para-) can be preferentially removed, as the debromination sequence is not based on the brominated position but on the specific brominated arrangement pattern. In addition, reductive debromination preferentially occurs on the benzene ring that has the highest number of bromine substituents. This study provided useful descriptors to predict the debromination pathways of PBBs, and the theoretical result greatly improve our understanding of photolytic debromination of PBBs.

Study on stepwise and concerted dissociation of CF2Br2 under electric field

The stepwise and concerted dissociation of ground state molecule under external fields is studied for the first time with density functional theory. The geometry, the orbit energies, the dissociation properties and the IR spectrum of CF2Br2 under external electrical fields (−0.015 a.u. to 0.065 a.u.) have been calculated at the B3PW91/6-311+G (2df) level. The potential energy surfaces along single and two CBr bonds under different external fields were obtained which indicate that the stepwise dissociation will happen under 0.055 a.u. and a generally repulsive pathway towards the concerted dissociation of ground state CF2Br2 exists under 0.065 a.u.(1 a.u. = 5.14225 × 1011 V·m−1).

Synergistic effect of ball-milled Al micro-scale particles with vitamin B12 on the degradation of 2,2′,4,4′-tetrabromodiphenyl ether in liquid system

2,2′,4,4′-Tetrabromodiphenyl ether (BDE47) is known as a recalcitrant bromated organic pollutant with the significant persistence, toxicity, and bioaccumulation. In this study, a synergistic effect of ball-milled Al particles with vitamin B12 on the degradation of BDE47 was found according to the coordinated catalytic reduction process. The micro-scale Al particles prepared by ball milling and vitamin B12 as common pharmaceutical composed a new combination reagent for hydrodebromination with low-cost and high reactivity. The degradation conditions were optimized by the addition of 2.0 g/L BM Al particles and 0.3 mM VB12 using the solvent of methanol/H2O (v:v = 40:60) at pH 4.0. More than 97% of 25 mg/L BDE47 was debrominated into lower-brominated diphenyl ethers in a sequential pattern and finally into diphenyl ethers within a 120-min reaction. UV/Visible spectra showed that vitamin B12 (Co(III)) was reduced to vitamin B12s (Co(II)) by the ball-milled Al particles, which possesses super nucleophilic property to associate the carbon atom on CBr bond and then facilitates the hydrodebromination process of brominated diphenyl ethers. The experimental results can provide basic understanding to identify a reaction process of vitamin B12/vitamin B12s for the enhanced reductive debromination of polybrominated diphenyl ethers by ball-milled Al particles, which would be possibly applied to treat soil washing solvent in the field of soil remediation.

Effects of monolayer Bi on the self-assembly of DBBA on Au(111)

The initial growth behaviors of nonplanar 10,10′-dibromo-9,9′-bianthryl (DBBA) molecules on the Au(111) substrates, which is either pristine or Bi-3 × √3-Au(111), at low deposition rates have been systematically investigated using low temperature scanning tunneling microscopy (LT-STM) and density functional theories (DFT) calculations. The effects of such substrates on the subsequent graphene nanoribbons (GNRs) formation are addressed. On clean Au(111), DBBA molecules self-assemble into highly ordered commensurate single-molecule chains along <112¯>Au at a coverage of 0.8 monolayer (ML), and collectively transit into long-range ordered commensurate double-molecule chains along <11¯0>Au but with many single-molecule vacancies at a coverage of 1.2 ML, revealing the delicate competing between intermolecular interactions and molecule-substrate interfacial interactions. The interfacial interactions are further tuned by introducing bismuth to form a Bi-3 × √3-Au(111)surface, where DBBA molecules self-assemble into an unique hexamer phase due to the enhanced intermolecular interactions via CH…π and halogen bonds. DFT calculations confirm the proposed molecular configuration change of single DBBA molecule when adsorbed on different substrates. The calculated difference in CBr bond gives further insight into why no GNRs formed on Bi-3 × √3-Au(111).

Dissociative ionization of CH2Br2 in 800 and 400 nm femtosecond laser fields

We experimentally demonstrate the dissociative ionization of CH2Br2 molecules irritated by 800 and 400nm femtosecond laser fields using time-of-flight mass spectra and dc-sliced ion imaging technology. Our results show that in both laser fields, CH2Br2 can ionize to CH2Br2+, then CH2Br2+ break one CBr bond to produce fragments CH2Br(+) and Br(+). The charge assignment is determined by the ionization energy of the fragments. Additionally, in 400nm laser fields, the CH2Br2+ can overpass a transition state to form an intermediate CH2BrBr+, then the intermediate break CBr bond to produce Br2 or Br2+ via elimination channel.

Inhibitory effect of the nucleophile in Ullmann condensation: Theoretical and experimental investigation

This article reports a study on amino acid chelated Cu(I) catalyzed coupling of benzylamine and bromobenzene. Experiments were conducted at 80°C with Cu(I) chelated to methionine, proline, hydroxyproline, tryptophan and tyrosine in dimethylsulfoxide (DMSO). In order to investigate kinetic effects, reaction time was restricted to 90min. Kinetically controlled product yields over amino acid ligated Cu(I) were in the order proline>hydroxyproline>methionine>tryptophan>tyrosine. Theoretical investigation of the reaction was carried out using density functional theory method, B3LYP/6-31+G(d,p) employing the solvation model SCRF=CPCM. The effective core potential of LANL2DZ was used to model copper and bromine. Geometry optimization of the structures of reactants, intermediates and activated complexes were carried out in the solvent DMSO. It was found that the reaction over amino acid Cu(I) complexes that gave low product yields are associated with high energy barriers for aryl halide bond activation. Further, the theoretical investigation revealed that benzylamine coordinates from nitrogen and phenyl ring and it hinders the pi-cordination of bromobenzene. Therefore, in order for the reaction to progress, formation of amioacid chelated copper bromobenzene complex and subsequent activation of CBr bond must occur before the coordination of benzylamine. As the stability of the aminoacid ligated copper benzyl amine complex is much higher than the stability of the corresponding bromobenzene complex, the resting state can be taken as the amine complex. Therefore, it is proposed that benzylamine must be replaced by bromobenzene in order for the formation of aminoacid chelated copper bromobenzene complex.

Piperidin-1-ylamidomethyltellurium derivatives: Synthesis and solid state structures

Oxidative insertion of low valent tellurium, Te(0) and Te(II), into the CBr bond of α-bromoacetylpiperidine proceeds readily under mild conditions and provides a direct synthetic route to stable, crystalline piperidin-1-ylamidomethyltellurium(IV) dibromides, (C5H10NCOCH2)2TeBr2, 1b and (C5H10NCOCH2)ArTeBr2 (Ar=2,4,6-Me3C6H2, 2b; 1-C10H7, 3b; 4-MeC6H4, 4b). While the bisulfite reduction of 1b affords a yellow coloured telluroether, (C5H10NCOCH2)2Te, 1 as an oil, that of the unsymmetrical diorganotellurium dibromides, (C5H10NCOCH2)ArTeBr2 leads to the isolation of the respective diarylditellurides, ArTeTeAr. The symmetrical telluroether, 1 adds dihalogens oxidatively to give piperidin-1-ylamidomethyltellurium(IV) dihalides, (C5H10NCOCH2)2TeX2 (X=Cl, 1a; Br, 1b and I, 1c;). All the new piperidin-1-ylamidomethyltellurium derivatives have been characterized by elemental and 1H, 13C, 125Te NMR spectral analyses. Single-crystal X-ray diffraction data for 1b and 1c indicated a butterfly molecular shape for the two halo analogues in which the six-member heterocyclic rings in the organic ligands retain the chair conformation of the independent piperidine molecule. The piperidin-1-yl appended organic ligand invariably results in the amido O atom being involved in an intramolecular Te O secondary bonding interaction and acts as a small-bite (C, O) chelating agent, at least in the solid state. Steric congestion around the six-coordinate Te(IV) atom and the partial positive charge on N owing to the resonating character of the NCO amido group prevents these atoms from participating in the intermolecular associative forces. Instead, the weak CH⋯O and CH⋯Br interactions take centre-stage in the solid state self-assembly.

Ruthenium complexes bearing a tridentate polypyridyl ligand with non-coordinating donor atoms: Construction of a specific coordination environment involving noncovalent interactions

We have prepared carbonyl (CO) ruthenium complexes which contained the tridentate polypyridyl type ligand (2,6-di(1,8-naphthyridin-2-yl)pyridine; dnp) with non-coordinating nitrogen atoms, for the development of specific reactions using noncovalent interactions. Similar to the aqua precursors that display intramolecular hydrogen bonds between the aqua and dnp ligands, a noncovalent interaction is formed between the terminal carbonyl ligand and non-coordinating nitrogen atoms of dnp; its strength depends on the identity of the axial ligand (triphenylphosphine or pyridine). Additionally, we investigated the reactivity of dnp-containing complexes bearing carbonyl ligands in both the equatorial and axial positions. As a result, it is suggested that the noncovalent interaction between dnp and CO ligands in positions equatorial to the dnp ligand is relatively strong, because the axial carbonyl ligand dissociates preferentially in ligand substitution reactions using organic solvents. Furthermore, in the ligand substitution reaction with a nitrile derivative, the coordination space constructed by the {Ru-dnp}2+ unit enables regulation of not only the ligand substitution reaction rate but also the identity of the donor atom. The present complex also leads to activation and cleavage of inert CCl and CBr bonds.

Characterization of non-classical C[sbnd]Br⋯π interactions in (E)-1,3-dibromo-5-(2-(ferrocenyl)vinyl)benzene and related derivatives of ferrocene

Amongst the halogens, the involvement of bromine atoms in various types of intermolecular interactions is comparatively the least studied. In this manuscript, we report the formation of CBr⋯π interactions, with the π-rings being the cyclopentadienyl (Cp) rings of a ferrocene molecule in a newly synthesized compound (E)-1,3-dibromo-5-(2-(ferrocenyl)vinyl)benzene. We have also performed a detailed quantitative analysis on CBr⋯π interactions observed in the synthesized molecule and in several related molecules found in the Cambridge Structure Database (CSD) showing the presence of these interactions. A topological analysis based upon QTAIM theory and electrostatic potential ESP mapped on the Hirshfeld surface of these molecules confirm that these interactions are better described as “halogen bonds” wherein the electropositive region (σ-hole) on the Br-atom interacts with the electronegative region over the Cp-ring of the ferrocene. Further, the electronegative region on the bromine atom (perpendicular to the CBr bond) was observed to be involved in the formation of highly directional CH⋯Br interactions with the ∠CBr⋯H close to 90°. Thus the bromine atom is acting as both a “halogen bond donor” and “hydrogen bond acceptor” in the crystal packing with the two interactions being mutually orthogonal.

Degradation products of profenofos as identified by high-field FTICR mass spectrometry: Isotopic fine structure approach

ABSTRACTThis study was performed to identify the degradation products of profenofos “a phenyl organothiophosphate insecticide” in raw water (RW) collected from the entry point of Metropolitan Water Works Authority “Bangkaen, Thailand” and ultrapure water (UPW) with and without TiO2 under simulated sunlight irradiation. Degradation of profenofos was followed with ultrahigh performance liquid chromatography (UHPLC) and follows pseudo first-order kinetic. Accordingly, high-field FTICR mass spectrometry coupled to an electrospray ionization source was used to reveal the degradation routes of profenofos and the isotopic fine structures (IFS) elucidations to approve the chemical structures of its degradation products. More degradation products were detected in UPW as compared to RW. Consequently, two main degradation pathways namely (i) interactive replacements of bromine and hydrogen by hydroxyl functional groups and (ii) rupture of PO, PS, CBr and CCl bonds were observed. None interactive replacement of chlorine by hydroxyl functional group was detected. Accordingly, mechanistical pathways of the main degradation products were established.

Photochemical functionalization of diazines: metal-free vinylation and phosphonylation

Under mild UVA irradiation, the CBr bond of bromodiazines can be activated to generate the corresponding radical intermediate. In the presence of alkynes, alkenylation reactions occurred to afford vinyl pyrimidine in moderate yields. Csp2-phosphorous bond can also be easily created in a photochemical version of the Arbuzov reaction. With UVA and a stoichiometric amount of trimethyl phosphite, the corresponding phosphonates were isolated in good to high yields. Very interesting selectivities were observed under these mild irradiation conditions. Functionalized substrates can be engaged and the resulting products could be further derivatized.

Gradation of proteins and cells attached to the surface of bio-inert zwitterionic polymer brush

A self-assembled monolayer (SAM) of a 2-bromoisobutyryl end group-carrying initiator for atom transfer radical polymerization (ATRP) was constructed on the surface of silicon wafer or glass substrates via a silane-coupling reaction. When the initiator SAM was irradiated with UV light at 254nm, the surface density of bromine atoms was reduced by the scission of CBr bonds as observed by XPS. With the surface-initiated ATRP of the zwitterionic vinyl monomer, carboxymethyl betaine (CMB), the surface density of PCMB brushes could be easily varied by changing the irradiation period of UV light prior to the polymerization. Furthermore, by using a UV-cut shutter sliding above the initiator SAM-modified substrate at a constant speed, the degree of bromine atom removal could be linearly varied along the direction of movement of the shutter. Consequently, the amount of both proteins adsorbed and cells adhered to the PCMB brush-covered substrate could easily be controlled by the gradation of the surface density of PCMB brushes, which suppressed protein adsorption and cell adhesion. Such a technique is very simple and useful for the regulation of the surface density of adsorbed proteins and adhered cells on an originally bio-inert surface.

Multi-photon dissociation dynamics of Freon 114B2 under UV radiation by femtosecond laser pulse

The ozone layer which absorbs harmful solar UV radiation is a necessary umbrella for human beings and biosphere. A large amount of alkyl halide including freon exhausted by human into the atmosphere poses a great threat to the ozone layer. Freon dissociates into the product of halogen radical, like Br and Cl, induced by UV sunlight radiation, which is found to be the main culprit for the destruction of atmospheric ozone. In this paper, time-of-flight (TOF) mass spectrometry and velocity map imaging technique are employed for investigating the multiphoton dissociation dynamics of Freon F114B2 (C2F4Br2) induced by femtosecond UV radiation at 267 nm. Fragment mass spectra of C2F4Br2 under UV radiation at 266 nm are obtained by TOF mass spectrometry. Three daughter ions C2F4Br+, C2F4+ and CF2Br+are discovered together with the parent ions C2F4Br2+. And three corresponding photodissociation mechanisms are concluded as follows: 1) C2F4Br2+C2F4Br++Br with single CBr bond breaking and direct production of Br radical; 2) C2F4Br2+C2F4++2Br with double CBr bonds breaking and production of two Br radical; 3) C2F4Br2+CF2Br++CF2Br with CC bond breaking. Velocity map images of the strongest daughter ion C2F4Br+with CBr breaking are measured by imaging apparatus. The kinetic energy distribution of C2F4Br+ ions is obtained from the measured velocity map images. And it can be well fitted by three Gaussian curves which describe normal distribution. It indicates that the production of the fragment C2F4Br+ stems from three different dissociation channels. Additional photodissociation dynamics is obtained by analyzing the angular distribution of the measured image. The values of anisotropy parameter are measured to be 0.1 (for the low energy channel), 0.8 (for the middle energy channel) and 1.4 (for the high energy channel) for the fragment C2F4Br+, respectively. The ratios of parallel transition to perpendicular transition are determined for three different channels. In addition, density functional theory calculations are also performed for further analysis and discussion. The optimized geometries of ground state and ionic state of C2F4Br2 are obtained and compared at the level of B3LYP/6-311G++(d, p). The calculated information about ionic states, including energy level and oscillator strength for the ionic excited states, are given.

Green mechanochemical oxidative decomposition of powdery decabromodiphenyl ether with persulfate

A method was developed for efficiently degrading powdery decabromodiphenyl ether (BDE209) by using mechanochemical (MC) activation of persulfate (PS). Characteristic Raman spectra of BDE209 corresponding to CBr and CO bonds were decreased in intensity and finally disappeared as the MC reaction proceeded. The BDE209 removal was influenced by the molar ratio of PS to BDE209, the mass ratio of milling ball to reaction mixtures, the ball size, and the ball rotation speed. Under optimal conditions, the new method could achieve a complete degradation, debromination and mineralization of BDE209 within 3h of milling. However, the degradation removal (or debromination efficiency) was decreased to only 51.7% (15.6%) and 67.8% (31.5%) for the use of CaO and peroxymonosulfate, respectively. The analyses of products demonstrated that once the degradation was initiated, BDE209 molecules were deeply debrominated and fully mineralized in the MC-PS system. The strong oxidizing ability of this system was due to the reactive sulfate radicals generated from the MC-enhanced activation of PS, which was confirmed with electron spin resonance spectroscopy. Because no toxic low brominated polybrominated diphenyl ethers were accumulated as byproducts, the proposed MC oxidative degradation method will have promising applications in the treatment of solid BDE209 at high concentrations.