Degradation Of Tetrabromobisphenol A Research Articles

The degradation of tetrabromobisphenol A by metal-free graphene oxide in the dark

Brominated flame retardants (BFRs) such as tetrabromobisphenol A (TBBPA) were widely detected in the environment. The ease of synthesis of graphene-based materials (GBMs) makes it an excellent metal-free carbon-based catalyst for the reductive debromination of TBBPA. Here we explore the complete debromination of TBBPA from the aqueous environment in the dark using metal-free graphene oxide (GO) and reduced GO (rGO). More importantly, radical scavenger experiments reveal the formation of superoxide radicals and singlet oxygen from the surface of GBMs leading to the debromination of TBBPA. GO shows an enhanced catalytic activity due to enriched O-functional groups on the surface than rGO, as observed by cyclic voltammetry and electrochemical impedance spectroscopy. In addition, the TBBPA degradation pathway was proposed with BPA as the end product and by-products were identified by mass spectroscopy. The complete TBBPA degradation was observed within 240 mins of reaction time (kobs = 8.6×10−3 min−1), which was significantly more efficient than the catalytic activity of other metal-based catalysts. Our study thus provides a new insight into the debromination mechanisms of TBBPA which would exhibit potential for future efficient catalyst development.

Visible light-induced photocatalytic degradation of tetrabromobisphenol A on platinized tungsten oxide

In this study, we investigated the degradation of the flame retardant tetrabromobisphenol A (TBBPA) using platinized tungsten oxide (Pt/WO3), synthesized via a simple photodeposition method, under visible light. The results of degradation experiments show a significant enhancement in TBBPA degradation upon surface platinization of WO3, with the degradation rate increasing by 13.4 times compared to bare WO3. The presence of Pt on the WO3 surface stores conduction band electrons, which facilitates the two-electron reduction of oxygen and enhances the production of valence band holes (hVB+) and hydroxyl radicals (●OH). Both hVB+ and ●OH are significantly involved in the degradation of TBBPA in the visible light-irradiated Pt/WO3 system. This was verified through fluorescence spectroscopy employing coumarin as a chemical probe and oxidizing species-quenching experiments. The analysis of degradation products and their toxicity assessment demonstrate that the toxicity of TBBPA-contaminated water is significantly reduced after Pt/WO3 photocatalysis. The degradation rate of TBBPA increased with increasing Pt/WO3 dosage, reached an optimum at a Pt content of 0.5 wt%, but decreased with increasing TBBPA concentration. The decrease in degradation efficiency of Pt/WO3 was minor, both in the presence of various anions and after repeated use. This study proposes that Pt/WO3 is a viable photocatalyst for the degradation of TBBPA in water under visible light.

Efficient removal of tetrabromobisphenol A in the Mn1Fe0.5Al0.5-LDO@BC/peroxymonosulfate water purification system

Tetrabromobisphenol A (TBBPA) brominated flame retardants in water posed threat to the ecological system due to its persistence and biomagnification. In this work, an efficient water purification system based on sulfate radical-based advanced oxidation processes (SR-AOPs) with Mn1Fe0.5Al0.5-LDO@BC as the core was constructed by adjusting the key preparation parameters, optimizing catalyst performance and exploring operating conditions. Under the optimal conditions of Mn1Fe0.5Al0.5-LDO@BC/PMS system (calcination temperature of 600 oC, 0.1 g/L Mn1Fe0.5Al0.5-LDO@BC, 0.15 mM PMS, pH value of 7–), 15 mg/L TBBPA was almost completely degraded within 30 min. Mn1Fe0.5Al0.5-LDO@BC/PMS water purification system exhibited resistance to inorganic anions and humic acid. In addition, Mn1Fe0.5Al0.5-LDO@BC reflected better cycle stability and ecological environmental protection. Electron paramagnetic resonance (EPR) and quenching experiments verified the existence of a large number of dominant active species in the water purification system, especially the contribution of O2•– and 1O2 to the degradation of TBBPA. Finally, the catalytic mechanism and possible degradation pathway of TBBPA were elucidated, and the toxicity of the intermediates was predicted. This work provided novel insights into the efficient purification of TBBPA brominated flame retardants in wastewater.

Fabrication of black phosphorus/CdS heterostructure with enhancement photocatalytic degradation activity for tetrabromobisphenol A and toxicity prediction of intermediates

Black phosphorus nanosheets (BPNs)/CdS heterostructure was successfully synthesized via hydrothermal method. The experimental results indicated that BPNs modified the surface of CdS nanoparticles uniformly. Meanwhile, the BPNs/CdS heterostructure exhibited a distinguished high rate of photocatalytic activity for Tetrabromobisphenol A (TBBPA) degradation under visible light irradiation (λ > 420 nm), the kinetic constant of TBBPA degradation reached 0.0261 min−1 was approximately 5.68 and 9.67 times higher than that of CdS and P25, respectively. Moreover, superoxide radical (•O2−) is the main active component in the degradation process of TBBPA (the relative contribution is 91.57%). The photocatalytic mechanism and intermediates of the TBBPA was clarified, and a suitable model and pathway for the degradation of TBBPA were proposed. The results indicated that the toxicities of some intermediates were higher than the parent pollutant. This research provided an efficient approach by a novel photocatalyst for the removal of TBBPA from wastewater, and the appraisal methods for the latent risks from the intermediates were reported in this paper.

One-step process for debromination and mineralization of tetrabromobisphenol a by a layered double oxide-supported sulfurized nanoscale zero-valent iron under ambient conditions

Tetrabromobisphenol A (TBBPA), currently the most widely used brominated flame retardant, has attracted significant attention. However, traditional methods for deep debromination or mineralization of TBBPA usually include multiple steps and require external oxidants. In this study, we report a complete degradation of TBBPA through a one-step process of only adding a layered double oxide-supported sulfurized nanoscale zero-valent iron (S-nZVI@LDO) under ambient conditions. TBBPA was rapidly removed by S-nZVI@LDO with an efficiency of 95.6 % (10 mg⋅L-1) within 12 h. The kinetic rate constant (0.0035 min−1) was greater when compared with traditional reductants. The produced Br- ion occupied 76.7 % of total Br content, and the concentration of total organic carbon decreased by over 50 %, suggesting a deep debromination and mineralization of TBBPA by S-nZVI@LDO. It is caused by the substantial improvement of electron transfer, O2 adsorption, and hydrophobicity of S-nZVI@LDO facilitating synchronous reductive debromination and O2 activation to produce ·O2– and ·OH, as approved by electrochemical test, O2-TPO analysis, EPR analysis, and density functional theory calculations. The enriched structural S(−II) and enhanced Fe(III)/Fe(II) redox cycling exerted vital roles in maintaining the reduction potential of the composite. The degradation pathways analysis confirmed that debromination-mineralization mechanisms dominated the complete degradation of TBBPA. This study demonstrates the feasibility of the one-step mineralization removal of TBBPA only using S-nZVI@LDO under ambient conditions and offers insight into external oxidant-free in-situ elimination of halogenated persistent organic pollutants in a natural environment.

Complete biodegradation of tetrabromobisphenol A through sequential anaerobic reductive dehalogenation and aerobic oxidation

Tetrabromobisphenol A (TBBPA), a common brominated flame retardant and a notorious pollutant in anaerobic environments, resists aerobic degradation but can undergo reductive dehalogenation to produce bisphenol A (BPA), an endocrine disruptor. Conversely, BPA is resistant to anaerobic biodegradation but susceptible to aerobic degradation. Microbial degradation of TBBPA via anoxic/oxic processes is scarcely documented. We established an anaerobic microcosm for TBBPA dehalogenation to BPA facilitated by humin. Dehalobacter species increased with a growth yield of 1.5 × 108 cells per μmol Br- released, suggesting their role in TBBPA dehalogenation. We innovatively achieved complete and sustainable biodegradation of TBBPA in sand/soil columns columns, synergizing TBBPA reductive dehalogenation by anaerobic functional microbiota and BPA aerobic oxidation by Sphingomonas sp. strain TTNP3. Over 42 days, 95.11 % of the injected TBBPA in three batches was debrominated to BPA. Following injection of strain TTNP3 cells, 85.57 % of BPA was aerobically degraded. Aerobic BPA degradation column experiments also indicated that aeration and cell colonization significantly increased degradation rates. This treatment strategy provides valuable technical insights for complete TBBPA biodegradation and analogous contaminants.

Insights into the influence of polystyrene microplastics on the bio-degradation behavior of tetrabromobisphenol A in soil

Soil contamination by emerging pollutants tetrabromobisphenol A (TBBPA) and microplastics has become a global environmental issue in recent years. However, little is known about the effect of microplastics on degradation of TBBPA in soil, especially aged microplastics. In this study, the effect of aged polystyrene (PS) microplastics on the degradation of TBBPA in soil and the mechanisms were investigated. The results suggested that the aged microplastics exhibited a stronger inhibitory effect on the degradation of TBBPA in soil than the pristine microplastics, and the degradation efficiency of TBBPA decreased by 21.57% at the aged microplastic content of 1%. This might be related to the higher TBBPA adsorption capacity of aged microplastics compared to pristine microplastics. Aged microplastics strongly altered TBBPA-contaminated soil properties, reduced oxidoreductase activity and affected microbial community composition. The decrease in soil oxidoreductase activity and relative abundance of functional microorganisms (e.g., Bacillus, Pseudarthrobacter and Sphingomonas) caused by aged microplastics interfered with metabolic pathways of TBBPA. This study indicated the importance the risk assessment and soil remediation for TBBPA-contaminated soil with aged microplastics.

Photocatalytic degradation of tetrabromobisphenol A by Z-scheme WO3/ZnIn2S4 heterojunction: Efficiency, mechanism and toxicity evaluation

Occurrence of brominated flame retardants especially tetrabromobisphenol A (TBBPA) in water bodies poses a serious threat to aquatic ecosystems. Heterogeneous photocatalysis is a versatile technology that can efficiently degrade organic contaminants. However, existing studies on photocatalytic degradation of TBBPA are all achieved under intense light irradiation and high initial concentrations of TBBPA, which are far from real environmental conditions and not conducive to practical application. In this study, series of Z-scheme heterojunctions of WO3/ZnIn2S4 photocatalysts were prepared and used for the high-efficiency photocatalytic degradation of TBBPA at lower light irradiation intensity (100 W) and lower TBBPA concentration (5.4 mg/L). Among them, WO3/ZnIn2S4-3 (molar ratio of 1:3) exhibited the highest photocatalytic activity due to the formation of Z-Scheme heterojunction which effectively facilitated the separation of photogenerated charges and endowed WO3/ZnIn2S4-3 higher redox ability. Thus, under light illumination, 91.6% degradation of TBBPA was achieved at an initial pH of 8.0 within 150 min, with a pseudo-first-order rate constant of 0.01572 min−1. Electron spin resonance spectroscopy and radical scavenger experiments confirmed that ·O2− radicals were the primary reactive oxygen species driving the TBBPA degradation. By applying LC-MS/MS, the degradation products were identified and possible degradation pathways were proposed. Finally, potential toxicity for PBBPA and generated intermediates were evaluated using luminescent bacteria, which revealed the toxicity of PBBPA was reduced effectively during the photocatalytic degradation process. Overall, the Z-scheme WO3/ZnIn2S4 photocatalyst provides a promising way for the application of photocatalytic technology in actual wastewater treatment.

Prussian blue analogues derived magnetic FeCo@GC material as high-performance metallic peroxymonosulfate activators to degrade tetrabromobisphenol A over a wide pH range.

Metal-organic frame (MOF) materials can effectively degrade organic pollutants, whereas the MOF is rapidly hydrolysed in water and has poor stability and low reusability. However, in the current advanced oxidation process (AOP) system, the removal effect of pollutants under alkaline condition is not ideal. In this study, a magnetic composite material derived from MOF was synthesised and used as a new catalyst for rapid degradation of tetrabromobisphenol A (TBBPA). Compared to precarbonisation, FeCo@GC formed a conductive graphite carbon skeleton, retained the complete rhombododecahedron structure, had a larger specific surface area and provided more active sites for peroxymonosulfate (PMS) activation. The target pollutant TBBPA (20 mg/L) was completely degraded within 30 min, and the mineralisation rate reached 40.98% in the FeCo@GC (150 mg/L) and PMS (1 mM) systems, owing to the synergistic interaction between Fe, Co and graphite carbon. The reactive oxygen species (ROS) involved in the reaction were determined to be SO4•-, ·OH, 1O2 and O2•- by electron paramagnetic resonance and free radical scavenging experiments, and the 1O2 played a dominant role. Based on the results of LC-MS analysis results, the main degradation pathways of TBBPA involve three mechanisms: the debromination reaction, hydroxylation and cleavage of the benzene ring. In addition, compared with previous AOP systems, FeCo@GC/PMS overcomes the disadvantage of poor degradation effect of TBPPA under alkaline conditions, has a wide range pH (3-11) application and has the best effect on TBBPA degradation under alkaline conditions. FeCo@GC has an excellent cycle performance, with a removal rate of re-calcined material of 88.52% after five cycles. Therefore, FeCo@GC can be used as a promising and efficient catalyst for removing environmental organic pollutants.

Efficient removal of tetrabromobisphenol A through persulfate activation by α-MnO2 nanofiber coated with graphene oxide

The development of efficient and environmentally friendly catalysts for activating persulfate is the focus of advanced oxidation treatment of organic contaminants. Manganese dioxide (MnO2), which has a multivalent nature and is a low-toxic natural stock, has the ability to immediately oxidize pollutants. In order to further improve its catalytic performance, the α-MnO2 nanofiber coated with graphene oxide (α-MnO2@GO) was prepared by one-step hydrothermal method, and worked as a peroxmonsulfate (PMS) activator for efficient degradation of tetrabromobisphenol A (TBBPA). The structure characterization results indicate that α-MnO2 nanofibers are successfully encapsulated by graphene and assembled into a three-dimensional layered structure. The factors affecting the catalytic degradation of TBBPA by this catalyst are investigated in detail. Under optimal conditions, the highest removal ratio of TBBPA could reach 100% after treatment of 20 min by α-MnO2@GO/PMS system, and a good mineralization efficiency of up to 79.50% is obtained. Electron paramagnetic resonance detection combined with quenching experiments showed that sulfate radical and hydroxyl radical played a role in the degradation of TBBPA. Based on X-ray photoelectron spectroscopy and free radical scavenging experiments, the peroxmonsulfate activation mechanism by α-MnO2@GO was proposed. Finally, based on the discovered intermediates, two potential TBBPA degradation routes using this catalyst were suggested. This study not only provides a new strategy for improving the catalytic activity of MnO2 but also sheds new insight into the application of eco-friendly natural stock for environmental remediation.

Efficient degradation of tetrabromobisphenol A using peroxymonosulfate oxidation activated by a novel nano-CuFe2O4@coconut shell biochar catalyst

In this study, a novel bimetallic complexation–curing nucleation–anaerobic calcination method was developed to synthesize a nano-CuFe2O4@coconut shell biochar (CuFe2O4@CSBC) catalyst to activate peroxymonosulfate for degradation of tetrabromobisphenol A (TBBPA). The reaction processes of the TBBPA on CuFe2O4@CSBC have been investigated using in situ characterization and metal leaching. The effects of initial reaction conditions and degradation mechanism were investigated. Greater than 99% degradation of TBBPA at 10 mg L−1 was achieved in 30 min under the condition of pH 11, a total organic carbon removal rate of up to 70.67% was achieved and the degradation efficiency was 90% after 5 cycles of CuFe2O4@CSBC use. The degradation was in a second-order reaction at a constant of 0.797 M−1 min−1 (R2 = 0.993). The degradation was attributed to the main active species (SO4·−≈·OH < 1O2), and the surface active site of CuFe2O4@CSBC was the key role. The degradation process involved three main degradation pathways. Path A: ·OH attacked the C–Br bonds (TBBPA→TriBBPA→DBBPA→MBBPA→BPA); Path B: Hydroxylation and decarboxylation; Path C: Dehydrocoupling of TBBPA. What's more, the practical application of the system was very positive, achieved >77% degradation in sewage and industrial wastewater.

Activation persulfate for efficient tetrabromobisphenol A degradation via carbon-based materials: Synergistic mechanism of doped N and Fe

In this study, a novel carbon-based material (Fe-N-PGWBC) utilizing the garden waste, melamine and FeSO4 as the precursor was successfully synthesized, efficiently activating peroxydisulfate (PDS) to degrade tetrabromobisphenol A (TBBPA). Under typical conditions (Fe-N-PGWBC dose of 100 mg·L−1, PDS of 0.2 mM and TBBPA of 10 mg·L−1), Fe-N-PGWBC/PDS system could achieve over 99% TBBPA removal (including adsorption and degradation) within 60 min, and the corresponding rate constant ks was 0.0724 min−1, which was almost 40.2 times higher than that of the pristine biochar. The extraction experiments implied that the excellent adsorption performance of Fe-N-PGWBC did not hinder the degradation of TBBPA. Abundant active sites (rich oxygen-containing functional groups, Fe-O and Fe3C) of Fe-N-PGWBC could effectively promote PDS decomposition to produce reactive oxygen species. The probe-based kinetic modelling methods verified that approximately 87.6% TBBPA was degraded by SO4·-, 12.2% TBBPA was degraded by 1O2, and 0.2% TBBPA was degraded by ·OH. Furthermore, based on the calculation of density functional theory and identification of products, TBBPA was mainly involved in three transformation pathways including hydroxylation, debromination and β-scission process. The study proposed a facile resource approach of garden waste and provided deeper understanding for the TBBPA degradation mechanisms in heterogeneous system.

Fe-Cu co-doped carbon-based catalyst activating peroxydisulfate for the degradation of tetrabromobisphenol A: The dominant role of superoxide radicals

Tetrabromobisphenol A (TBBPA) is highly biotoxic and difficult to remove, and there is an urgent need to provide an efficient method for addressing this environmental challenge. In this work, Fe3Cu2@NPC was prepared by calcination to activate peroxydisulfate (PDS) for the degradation of TBBPA. The results showed that TBBPA was completely removed within 20 min (kobs = 0.2476 min−1) and up to 90 % removal of total organic carbon (TOC) in the Fe3Cu2@NPC/PDS/TBBPA system. The cycling between Fe and Cu greatly promoted the degradation effect and had high degradation activity under neutral to alkaline conditions (pH = 7–11). Quenching experiments, EPR experiments, and steady-state concentration calculations show that TBBPA is degradated mainly by the free radical pathway, and the main active substance is O2−. The possible degradation paths of TBBPA mainly included debromination, dehydroxylation, and β-bond breakage. Fe3Cu2@NPC can be magnetically recycled and maintain high activity after reuse over four cycles.

Response of microbial community in the soil of halophyte after contamination with tetrabromobisphenol A.

Coastal wetlands are subjected to increasing tetrabromobisphenol A (TBBPA) pollution, whereas knowledge of TBBPA degradation in marine environments is lacking. The changes of bacterial communities in TBBPA-polluted soil covered with halophytes were investigated. TBBPA could be degraded in the halophyte-covered saline-alkali soil in a microcosm experiment. Higher TBBPA removal occurred in the soil of Kandelia obovata compared with soils covered with Suaeda australis and Phragmites australis within 56days of cultivation. The rhizosphere soils of S. australis, P. australis, and K. obovata mainly involved the classes of Bacteroidia, Gammaproteobacteria, Alphaproteobacteria, and Anaerolineae. Additionally, manganese oxidation, aerobic anoxygenic phototrophy, and fermentation functions were higher in the rhizosphere soil of K. obovata after TBBPA addition. This study supports that using suitable local halophytic plants is a promising approach for degrading TBBPA-contaminated coastal soil.

A Review on Tetrabromobisphenol A: Human Biomonitoring, Toxicity, Detection and Treatment in the Environment.

Tetrabromobisphenol A (TBBPA) is a known endocrine disruptor employed in a range of consumer products and has been predominantly found in different environments through industrial processes and in human samples. In this review, we aimed to summarize published scientific evidence on human biomonitoring, toxic effects and mode of action of TBBPA in humans. Interestingly, an overview of various pretreatment methods, emerging detection methods, and treatment methods was elucidated. Studies on exposure routes in humans, a combination of detection methods, adsorbent-based treatments and degradation of TBBPA are in the preliminary phase and have several limitations. Therefore, in-depth studies on these subjects should be considered to enhance the accurate body load of non-invasive matrix, external exposure levels, optimal design of combined detection techniques, and degrading technology of TBBPA. Overall, this review will improve the scientific comprehension of TBBPA in humans as well as the environment, and the breakthrough for treating waste products containing TBBPA.

Activation of iron based persulfate heterogeneous nano catalyst using plant extract for removal of tetrabromobisphenol A from soil

Contamination of tetrabromobisphenol A (TBBPA) in soils posed a high risk to human health and ecological systems. Iron based heterogeneous catalytic persulfate (PS) advanced oxidation technology has significant advantages in the degradation of TBBPA. However, how to effectively prepare iron-based materials for large-scale soil remediation was still controversial. Hence, the study aimed to determine whether plant extracts can effectively replace traditional chemical reagents to prepare iron nanoparticles (Fe NPs) for soil TBBPA degradation. In this study, Fe NPs synthesized from leaf extracts of Tung tree (T-Fe NPs), Aspen (A-Fe NPs), and Holly (H-Fe NPs), were applied in the activation of persulfate (PS) to remove TBBPA from soils. The main active substances in plant leaf extracts were 8 flavonoids, 6 polyphenolics, 4 polysaccharides, and 2 proteins, among which phenols played a crucial role in the formation of Fe NPs. The characterization by SEM, XRD, FTIR and XPS showed that the formed Fe NPs were amorphous structures with irregular spherical shape and mainly existed in the form of iron oxides and hydroxides. These three kinds of Fe NPs can effectively activate PS to degrade soil TBBPA, wherein, PS activation by T-Fe NPs showed the highest removal efficiency (82.07%), the fastest reaction rate (0.14 h−1), and the least affection on environmental factors. In conclusion, T-Fe NPs can effectively degrade TBBPA and have high application potential.

Rapid photocatalytic degradation of tetrabromobisphenol A using synergistic p-n/Z-scheme dual heterojunction of black phosphorus nanosheets/FeSe2/g-C3N4

Tetrabromobisphenol A (TBBPA), as a typical brominated flame retardant, has been confirmed to pose potential threats for human health and developed into a global pollutant. Graphitic carbon nitride (g-C3N4) is the most used catalyst for refractory organic pollutants removal, but the weak conductivity and quick recombination of photogenerated carries restrict its practical application. To improve the photocatalytic activity of pristine g-C3N4, a p-n/Z-scheme dual heterojunction photocatalyst (BFC) was designed and prepared by introducing black phosphorus nanosheets and FeSe2 into porous g-C3N4 (CN). Compared to traditional heterojunction catalysts, BFC not only can promote photogenerated carriers directed migration and effective separation, but also can retain higher redox potential for simultaneous generating O2− and OH, which are due to the synergistic effects of built-in electric field formation in p-n heterojunction and bandgap structure optimization by Z-scheme heterojunction. Above advantages promote BFC to achieve 100% TBBPA degradation efficiency in 40 min and 22.6% debromination efficiency in 60 min under visible light irradiation. The superfast reaction rate constant (0.143 min−1) is almost 10 times higher than that of pristine CN. This study proposes a facile design strategy to construct heterojunction photocatalysts and provides an alternative method to rapidly remove TBBPA in water.

Enhanced removal of tetrabromobisphenol A by Burkholderia cepacian Y17 immobilized on biochar

Biochar-immobilized bacteria have been widely used to remove organic pollutants; however, the enhanced effect of biochar-immobilized bacteria on tetrabromobisphenol A (TBBPA) removal has not been fully investigated and the removal mechanism remains unclear. In this study, a bacterial strain with high TBBPA degradation ability, Burkholderia cepacian Y17, was isolated from an e-waste disassembly area, immobilized with biochar, and used for the removal of TBBPA. Comparisons were performed of the factors affecting the immobilization and TBBPA removal efficiency, including the biochar preparation temperature, immobilization temperature, and pH. The highest 7-day TBBPA removal efficiency by immobilized bacteria was observed with the most suitable biochar preparation temperature (BC500) and an immobilization pH and temperature of 7 and 35 °C, respectively. The TBBPA removal efficiency reached 59.37%, which was increased by 30.23% and 15.88% compared to that of free and inactivated immobilized Y17, respectively. The suitable biochar preparation temperature BC500, immobilization temperature of 35 °C, and neutral pH of 7 increased the bacterial population and extracellular polymer concentration, which facilitated bacterial immobilization on biochar and promoted TBBPA removal. In this case, the high immobilized bacteria concentration (4.62 × 108 cfu∙g−1) and protein and polysaccharide contents (28.43 and 16.16 mg·g−1) contributed to the removal of TBBPA by facilitating TBBPA degradation. The main TBBPA degradation processes by BC500-immobilized Y17 involved debromination, β-scission, demethylation, O-methylation, hydroxylation, and hydroxyl oxidation. This study proposes a method for preparing immobilized bacteria for TBBPA removal and enriches the microbial degradation technology for TBBPA.

One-Step Synthesized Iron-Carbon Core-Shell Nanoparticles to Activate Persulfate for Effective Degradation of Tetrabromobisphenol A: Performance and Activation Mechanism.

Tetrabromobisphenol A (TBBPA), as an emerging endocrine disrupter, has been considered one of the persistent organic contaminants in water. It is urgently necessary to develop an efficient technique for the effective removal of TBBPA from water. Herein, a one-step hydrothermal synthesis route was employed to prepare a novel iron-carbon core-shell nanoparticle (Fe@MC) for effectively activating persulfate (PS) to degrade TBBPA. Morphological and structural characterization indicated that the prepared Fe@MC had a typical core-shell structure composed of a 5 nm thick graphene-like carbon shell and a multi-valence iron core. It can be seen that 94.9% of TBBPA (10 mg/L) could be degraded within 30 min at pH = 7. This excellent catalytic activity was attributed to the synergistic effect of the porous carbon shell and a multi-valence iron core. The porous carbon shell could effectively prevent the leaching of metal ions and facilitate PS activation due to its electron transfer capability. Furthermore, numerous micro-reaction zones could be formed on the surface of Fe@MC during the rapid TBBPA removal process. Radical quenching experiments and electron paramagnetic resonance (EPR) technology indicated that reactive oxygen species (ROS), including OH, SO4-, O2-, and 1O2, were involved in the TBBPA degradation process. Based on density functional theory (DFT) calculation, the carbon atoms linked by phenolic hydroxyl groups would be more vulnerable to attack by electron-rich groups; the central carbon was cracked and hydroxylated to generate short-chain aliphatic acids. The toxicity evaluation provides clear evidence for the promising application potential of our prepared material for the efficient removal of TBBPA from water.

Enhanced reductive degradation of tetrabromobisphenol A by biochar supported sulfidated nanoscale zero-valent iron: Selectivity and core reactivity

A core-shell structure of sulfidated nanoscale zero-valent iron deposited on biochar (S-nZVI/BC) was synthesized and the performance of S-nZVI/BC on tetrabromobisphenol A (TBBPA) degradation was investigated. Detailed characterizations indicated that controlling S content altered distribution of S species (i.e., S2-, S22-, and Sn2-) in shell and core and achieved higher hydrophobicity and lower electron-transfer resistance. S-nZVI/BC was highly reactive (∼4.3–11.3 times) and selective (∼78.9–152.6 times) over nZVI/BC for TBBPA degradation. Besides, BC improved reactivity and selectivity of S-nZVI by 0.17 and 1.35 times, respectively, deriving from increased electron-transfer, enhanced hydrophobicity, and more surface reduced S species. Thus, sulfidation and BC enhanced reactivity and selectivity of S-nZVI/BC by combining respective merits. Effects of initial TBBPA concentration, pH, and particles dosage on TBBPA degradation by S-nZVI/BC were also investigated. Remarkably, mechanism investigation revealed that core properties instead of shell dominated reactivity and TBBPA debromination mainly involved direct electron-transfer rather than atomic H.