Tetrabromobisphenol A Removal Research Articles

Selective solvothermal extraction of tetrabromobisphenol A to promote plastic recycling

Removal of brominated flame retardants (BFRs) is imperative for increasing the recycling rate of hazardous plastic waste. In mechanical recycling, BFRs should be removed without damaging the surrounding polymer matrix, but economically viable processes under mild conditions are still rare. In this study, tetrabromobisphenol A (TBBPA) was solvothermally extracted from a compounded high-impact polystyrene (HIPS, 2500 ppm Br) model sample in an autoclave using mixtures of water, isopropanol (IPA) and NaOH as solvents. Removal of total elemental bromine was analyzed with X-ray fluorescence (XRF), whereas the removal of TBBPA and other plastic additives was evaluated with direct insertion probe mass spectrometry (DIP-MS). IPA/NaOH extraction provided efficient bromine removal, but it also extracted plenty of other plastic additives, including phenolic stabilizers Irganox 1076 and Cyasorb UV-2908. The inclusion of water in the IPA/NaOH mixture shifted the extraction selectivity towards TBBPA, leaving most of the other additives unaffected. Furthermore, H2O/IPA/NaOH was found to be equally effective in removing TBBPA from the samples with bromine concentrations an order of magnitude higher (25,000 ppm). Yet, larger plastic particle size hindered the extraction efficiency. 1H NMR and size exclusion chromatography confirmed that the HIPS matrix was left unaffected after all the studied extractions. Additionally, DIP-MS was found to be a valuable characterization method for assessing the removal and decomposition of various additives from solid plastic samples with minimal sample preparation. Overall, the results presented herein offer a target-selective extraction processes under relatively mild conditions for further advancing the mechanical recycling of plastics.

Strong enhancement on tetrabromobisphenol A removal in natural water matrix by adding cysteine into Cu(II)/peroxymonosulfate system over the wide pH range of 4–12: Efficiency and mechanism

Although Cu(II) can trigger peroxymonosulfate (PMS) oxidation of pollutants, it is only effective under alkaline environments and is susceptible to interference by aqueous matrix components. In this study, cysteine, a natural thiol and amino acid, was found to greatly improve the performance of tetrabromobisphenol A (TBBPA) elimination in the Cu(II)/PMS system across a broad pH range of 4.0–12.0. The cysteine/Cu(II)/PMS system achieved a 94.34 % elimination of TBBPA within 10 min at pH 7.0, which had a 7.55-fold increase in efficiency relative to the Cu(II)/PMS system, and superior to the previously-reported hydroxylamine and gallic acid-enhanced Cu(II)/PMS systems. Cu(III)-(cysteine)2, as opposed to radicals, was the main reactive species leading to the removal of TBBPA, contributing at least 91.53 %. Cysteine first coordinated with Cu(II) through sulfhydryl groups (−SH) and rapidly converted Cu(II)-(cysteine)2 to Cu(I)-(cysteine)2, then Cu(III)-(cysteine)2 was formed finally by the further oxidation of PMS on Cu(I)-(cysteine)2. This enhancement was further extended to other thiols including cysteamine, β-mercaptoethanol and mercaptosuccinic acid. Four potential degradation pathways of TBBPA were inferred from the determined nine degradation intermediates. A marked decline in the toxicity of the reaction solutions was observed after the elimination of TBBPA. Furthermore, the cysteine/Cu(II)/PMS system shown high anti-interference performance with common cations and anions (Ca(II), Mg(II), NO3–, SO42–, HCO3– and Cl–), humic acid and actual water samples. Overall, this study provided a promising approach to extend the working pH range of Cu(II)/PMS system and its anti-interference capability with actual water matrix, which was favorable for its potential utilization in water treatment.

S-Fe/Co@GC reduction-oxidation sequential reaction system for the high-efficiency mineralization of tetrabromobisphenol a in water

The lipophilic, bioaccumulative, persistent nature of Tetrabromobisphenol A (TBBPA) contributes to its widespread detection in various environmental media, posing significant negative implications for the living environment and human health. In this study, a reduction system and a reduction-oxidation sequential reaction system were developed using a magnetic core-shell bimetallic amendment (S-Fe/Co@GC) to investigate the degradation and mineralization properties of TBBPA. Additionally, the degradation mechanism and degradation pathway of TBBPA in various systems were analyzed. In the sole S-Fe/Co@GC reduction system, sulfurized nano-zero-valent iron (S-Fe) and Co0 exhibited remarkable reductive capabilities towards TBBPA. The reaction of S-Fe/Co@GC gradually facilitated the debromination of TBBPA, ultimately leading to its conversion into bisphenol A. The reaction process demonstrated the synergistic effect among S-Fe, Co0, and graphite carbon, leading to a remarkable enhancement in the reduction performance of the material. Consequently, TBBPA removal efficiency reached 97.5% within a time frame of 10 h. In the reduction-oxidation sequential reaction system, the debromination of TBBPA during the reduction stage enhanced the subsequent oxidation stage's total organic carbon (TOC) removal rate. During the oxidation stage (0.03 mmol of PMS added at 30 min), TBBPA underwent attack by sulfate radical (SO4·-), hydroxyl radical (·OH), superoxide radical (O2·-), and singlet oxygen (1O2), leading to cleavage and opening of its structure. This process resulted in the conversion of TBBPA into short-chain fatty acids, ultimately mineralizing it into CO2 and H2O. Thus, this degradation pathway mitigated potential environmental risk associated with intermediates. The final TOC removal rate significantly increased to 72.7% when the dose of composite material was set at 1.0 g/L, surpassing that achieved by the conventional advanced oxidation system. Hence, the S-Fe/Co@GC reduction-oxidation sequential reaction system provides a new strategy for treating high-concentration TBBPA-contaminated water.

Enhanced removal of tetrabromobisphenolA (TBBPA) from e-waste by Fe–S nanoparticles and Fe–S/CuS nanocomposite with response surface methodology (RSM)

TetrabromobisphenolA is a well-known member of the brominated flame retardant group and is widely used as a highly effective fire-retardant additive in electronic and electrical equipment. TBBPA is commonly found in various environmental sources and can be harmful to human health. This study presents a simple approach to preparing a magnetic nanocomposite, offering a straightforward method that results in consistent quality and low resource consumption. The nanocomposite has a high surface-to-volume ratio for the removal of tetrabromobisphenolA. Various characterization techniques, including XRD, FTIR, EDX, FESEM, VSM, TEM, and BET analyses were used to characterize the Fe–S nanoparticles and Fe–S/CuS. The results showed that Fe–S/CuS nanocomposite successfully removed over 97% of the initial TBBPA (15 mg L−1) under optimized conditions determined by RSM, such as a contact time of 15 min, pH of 7, Fe–S/CuS nanocomposite dosage of 0.69 g L−1, and salt concentration of 0.10%. The RSM analysis provided a second-order polynomial model with a confidence level of 93% (F = 29.58; p < 0.0001) to predict the TBBPA removal efficiency at various concentrations. In the adsorption kinetic studies, the second-order kinetic model provided the best fit for the experimental data. Additionally, Fe–S/CuS nanocomposite shows great potential for practical applications and environmental remediation efforts, making it a valuable asset for real-sample use in environmental settings.

Ultrasonic preparation of fluorinated functionalised magnetic covalent organic frameworks for adsorption and removal of tetrabromobisphenol A

Tetrabromobisphenol A (TBBPA) was a widely used brominated flame retardant, and had attracted widespread attention from researchers due to its potential adverse effects on ecosystems and human health. Therefore, to eliminate the negative effects of TBBPA, methods for the adsorption and removal of TBBPA are urgently needed. In this work, the fluorine-functionalised magnetic covalent organic frameworks (Fe3O4@TFAPT-TFPA@COF) were first prepared through a simple and rapid ultrasound method to efficiently adsorpt and remove TBBPA. Firstly, a pre-modification strategy was used to modify fluorine functional groups onto amine monomers via superacid catalyzed trimerization. Then, amine and aldehyde monomers undergo Schiff base reaction smoothly to form a COF layer coated on the surface of Fe3O4 nanoparticles. The characterisation results indicated that the prepared Fe3O4@TFAPT-TFPA@COF had a high surface area, porosity, crystallinity and abundant F-containing binding sites. Additionally, the adsorption process of prepared Fe3O4@TFAPT-TFPA@COF complied with pseudo-second-order kinetics and the Langmuir adsorption model. It had a large adsorption capacity (107.5 mg g−1), could effectively remove tetrabromobisphenol A within 4 minutes and had excellent regeneration ability within eighth repetitions. Finally, tetrabromobisphenol A was efficiently removed by a small separation column loaded with Fe3O4@TFAPT-TFPA@COF, achieving levels below the detection limit (< 0.05 mg L−1) and providing practical application value for the real-time removal of TBBPA. The main mechanisms promoting the excellent adsorption performance of TBBPA were through halogen bonds, electrostatic interactions, π-π stacking, and hydrogen bonding interactions, providing potential reference value for the adsorption ability and mechanism of TBBPA in other applications.

Highly efficient removal of TBBPA and ATE by photocatalytic degradation with green synthesized NiO@CuHCF p-n heterojunction: Optimizations, kinetics, and mechanistic insights

Because of their incorrect disposal and persistence in environmental media, two frequently used brominated flame retardants (BFRs), tetrabromobisphenol A (TBBPA) and allyl 2,4,6-tribormorphenul ether (ATE) pose serious health concerns. A green technique was used to synthesize the NiO@CuHCF nanohybrids, and their ability to degrade target BFRs was examined. The optimal removal circumstances included a dose of 10 mg of nanocatalyst, a pH of 9, and 10 mg L−1. In 120 minutes, TBBPA and ATE were practically completely eradicated followed by first-order kinetics. High surface area, visible light active band gap, low recombination rate, robust cross-linking with contaminants, and catalytic free radical generation are some of the unique features of NiO@CuHCF. Under 120 minutes, the NiO@CuHCF was able to achieve an ideal elimination rate of 91–97 % and a debromination rate of over 75.4–82.3 %. After 8 cycles, the composite demonstrated excellent catalytic performance and minimal catalyst loss, demonstrating its stability and reusability. In comparison to parent nanoparticles, the investigation revealed that NiO-modified CuHCF exhibited higher degrading efficiency. To evaluate the catalytic efficacy of NiO@CuHCF, the actual sample was also analyzed. The hypothesis that the degradation efficiency of leachate BFRs was lower than that of controlled ones was rejected due to the potential leaching of extra analyte. Major reaction products or intermediates were discovered using HPLC and GC-MS, which also suggested a possible degradation pathway. NiO@CuHCF nanohybrid is a promising nanomaterial for the photodegradation of BFRs and other pollutants from environmental matrices, with further research and development enhancing their practical implementation.

Efficient Adsorption Removal of Tetrabromobisphenol A from Water by Using a Magnetic Composite Fe3O4/GO/ZIF-67

Tetrabromobisphenol A (TBBPA) is a kind of widely used brominated flame retardant (BFR), which is proven to be harmful to ecological systems and public health. It is very important to remove TBBPA from the environment. In our study, a magnetic composite named Fe3O4/GO/ZIF-67 was synthesized by a coprecipitation method and applied in the highly efficient adsorption of TBBPA from water. Static adsorption experiments demonstrated that the adsorption capacity could reach 232 mg·g−1 within 120 min, which is much higher than those reported in the other literature. The experimental results show that the adsorption of TBBPA on Fe3O4/GO/ZIF-67 followed Langmuir and pseudo-second-order kinetic adsorption models. The main mechanisms for these adsorptions were identified as hydrogen bonds between OH groups in TBBPA and COOHs of Fe3O4/GO/ZIF-67, and π-π stacking between Fe3O4/GO/ZIF-67 and TBBPA. This study provides a method with great promise for the design and synthesis of better adsorbents for the removal of TBBPA from the water environment.

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.

Nitrogen-doped carbon enhances Fe0 activation for efficient tetrabromobisphenol a decontamination and its removal mechanism

Biomass derived N-doped carbon-encapsulated nano zero-valent iron (NC@Fe0) was successfully used to activate hydrogen peroxide (H2O2) for efficient oxidation of tetrabromobisphenol A (TBBPA). The as-prepared NC@Fe0 exhibited high H2O2 activation performance, with a TBBPA removal efficiency of 95.9 % and an oxidation rate constant of 0.031 min−1. The quenching experiments and electrochemical tests showed that the overall contributions of nonradical pathways were over 83.0 %, via synergistic production of singlet oxygen (1O2) and an electron transfer process (ETP). Specifically, the N group on NC@Fe0 greatly enhanced 1O2 production, while formation of surface complexes (OVs-H2O2) was responsible for the ETP mechanism. High Performance Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometer (HPLC-Q-TOF MS/MS) and Toxicity Estimation Software Tool (T.E.S.T) clearly demonstrated that products were mainly generated via debromination and β-scission, where the products were less toxic than the parent. During practical wastewater, in both lake water and domestic wastewaters, NC@Fe0/H2O2 removed over 91.0 % of TBBPA. This study highlighted the considerable contribution of nonradicals in contaminant removal and enriched our understandings of a green activator for future environmental remediations.

Electrochemical detoxification of tetrabromobisphenol A-contaminated water using Ti/SnO2-Sb/PbO2-Ce anodic membrane

Degradation of refractory organics has been limited by their low mass-transport rates in conventional flow-by operated electrochemical reactors. This study explores for the first time the development of porous titanium (Ti)-based metal oxide anodic membrane for efficient flow-through degradation of recalcitrant tetrabromobisphenol A (TBBPA). For this purpose, a duplexed Ti/SnO2-Sb/PbO2-Ce anodic membrane was successfully prepared by sol-gel and electrodeposition methods. Ti/SnO2-Sb/PbO2-Ce exhibited improved mechanical and electrochemical stability, larger electrochemical surface area, higher oxygen evolution potential and lower charge transfer resistance, as compared to its mono-layered rival (Ti/SnO2-Sb). The switching from flow-by to flow-through operation resulted in an increased mass transfer rate constant and narrowed diffusion layer thickness of Ti/SnO2-Sb/PbO2-Ce. In the flow-through mode, Ti/SnO2-Sb/PbO2-Ce enabled the complete TBBPA removal at a relatively low electric energy (0.11 kWh m−3). The TBBPA removal was ascribed to the direct anodic oxidation and indirect anodic oxidation incurred by absorbed HO, free HO and 1O2. The intermediate products, which were arisen from the attack of TBBPA by these reactive species, were identified. We further estimated their acute toxicities and bioaccumulation factors. This research proposed a robust electrochemical filtration approach for detoxification of TBBPA-contaminated water.

Enhanced extraction of brominated flame retardants from e-waste plastics

Acrylonitrile butadiene styrene (ABS) is a high utility engineering thermoplastic, abundantly present in waste electronic and electrical goods. The demand for this plastic resin increases continuously with rapid industrial growth across the world. During the recycling of e-waste plastics, it is a common occurrence to find brominated flame retardants, such as Tetrabromobisphenol A (TBBPA) in the plastic. These flame retardants are intentionally added to the plastics as additives. Three processes were investigated to find the optimum solvent/antisolvent combinations, process parameters for the efficient recovery of TBBPA free plastics: microwave assisted extraction (MAE), ultrasound assisted extraction (UAE), and dissolution reprecipitation (DR). Rigorous solvent screening was carried out for both TBBPA and ABS using Hansen Solubility Parameters (HSP), and their interactions with the solvents were investigated with a molecular based Conductor like Screening Model for Realistic Solvents (COSMO-RS) software platform. A 4:1 (v/v) solvent mixture of 1-propanol and heptane was found to be ideal for the solid–liquid extraction process. The optimal extraction conditions (Temperature = 110 – 130 °C, time = 60 to 70 min solid/liquid ratio of 0.025) in MAE were predicted using machine learning based Support Vector Regression (SVR) technique. MAE was found to be superior to UAE and DR processes in terms of quantity and quality of recovered plastics. The maximum extraction efficiencies for TBBPA removal were achieved with MAE, UAE, and DR processes at 95.81%, 93.92%, and 98.15%, respectively. However, the DR process had a relatively lower plastic recovery.

Convenient green synthesis of Cu/Fe nanoparticles using pomegranate peel extracts and their performance for tetrabromobisphenol A removal.

In this work, pomegranate peel extracts were used as the green reducing agent to synthesize Cu/Fe nanoparticles (P-Cu/Fe nanoparticles) and removed tetrabromobisphenol A (TBBPA) in aqueous solution. P-Cu/Fe nanoparticles were amorphous and irregularly spherical. The surfaces of nanoparticles contained Fe0, Fe3+ oxides (hydroxides), and Cu0. The bioactive molecules from pomegranate peel were extremely important for the synthesis of nanoparticles. P-Cu/Fe nanoparticles had excellent removal performance for TBBPA, and 98.6% of TBBPA (5mg L-1) was removed within 60min. The removal reaction of TBBPA by P-Cu/Fe nanoparticles was well-fitted with the pseudo-first-order kinetic model. The Cu loading was critical for TBBPA removal with an optimum value of 1.0 wt%. A weakly acidic condition (pH 5) was more favorable for the removal of TBBPA. The removal efficiency of TBBPA increased with the rise of temperature and decreased with increasing initial TBBPA concentration. The activation energy (Ea) was 54.09kJmol-1, indicating that the removal of TBBPA by P-Cu/Fe nanoparticles was mainly surface-controlled. Reductive degradation was the main mechanism of TBBPA removal by P-Cu/Fe nanoparticles. In conclusion, green synthesized P-Cu/Fe nanoparticles using pomegranate peel waste show great potential for the remediation of TBBPA in aqueous solution.

Preparation of a Molecularly Imprinted Silica Nanoparticles Embedded Microfiltration Membrane for Selective Separation of Tetrabromobisphenol A from Water.

The ubiquitous presence of tetrabromobisphenol A (TBBPA) in aquatic environments has caused severe environmental and public health concerns; it is therefore of great significance to develop effective techniques to remove this compound from contaminated waters. Herein, a TBBPA imprinted membrane was successfully fabricated via incorporating imprinted silica nanoparticles (SiO2 NPs). The TBBPA imprinted layer was synthesized on the 3-(methacryloyloxy) propyltrimethoxysilane (KH-570) modified SiO2 NPs via surface imprinting. Eluted TBBPA molecularly imprinted nanoparticles (E-TBBPA-MINs) were incorporated onto a polyvinylidene difluoride (PVDF) microfiltration membrane via vacuum-assisted filtration. The obtained E-TBBPA-MINs embedded membrane (E-TBBPA-MIM) showed appreciable permeation selectivity toward the structurally analogous to TBBPA (i.e., 6.74, 5.24 and 6.31 of the permselectivity factors for p-tert-butylphenol (BP), bisphenol A (BPA) and 4,4'-dihydroxybiphenyl (DDBP), respectively), far superior to the non-imprinted membrane (i.e., 1.47, 1.17 and 1.56 for BP, BPA and DDBP, respectively). The permselectivity mechanism of E-TBBPA-MIM could be attributed to the specific chemical adsorption and spatial complementation of TBBPA molecules by the imprinted cavities. The resulting E-TBBPA-MIM exhibited good stability after five adsorption/desorption cycles. The findings of this study validated the feasibility of developing nanoparticles embedded molecularly imprinted membrane for efficient separation and removal of TBBPA from water.

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.

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.

Micro surface modification of Zn/Cu-foam electrode for debromination of tetrabromobisphenol A

Copper nanoparticles (Cu NPs) modified zinc electrode (Cu-Zn/Cu-foam) is successfully prepared via cathodic electrodeposition followed by a galvanic-exchange procedure and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), Tafel curve and galvanostatic electrolysis. With the reconstruction of Zn through the formation of Cu NPs on the surface, the corrosion current and active surface area are increased, and the activity on the electrochemical reduction of tetrabromobisphenol A (TBBPA) is activated. The TBBPA (10 mmol/L) is almost degraded within 1 h, and the yield of the complete debromination product bisphenol A (BPA) reaches 92 % in 3 h. Furthermore, the surface of used Cu-Zn/Cu-foam electrode become more uniform and CuZn5 is formed, which enabled the stable electro-catalytic activity on the electro-reduction of TBBPA even after ten cycles. Then the degradation mechanism is proposed. The micro galvanic reconstruction of Zn offers a promising strategy for the removal of TBBPA in aquatic environment.

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.

Visible photocatalytic degradation of tetrabromobisphenol A by CuO-modified Ce2O3: Mechanisms and DFT studies

The widespread use of brominated flame retardants poses serious hazards to environment and health. In this study, CuO/Ce2O3 nanocomposites were synthesized by a coprecipitation method. Various characterization methods and density functional theory (DFT) calculations were used to analyze the composition and surface structure of material. Under visible light, the prototypical pollutant, namely, tetrabromobisphenol A (TBBPA) exhibited the highest degradation efficiency of 80.46% after 120 min with a CuO/Ce2O3 ratio of 1:20. The photocatalytic degradation mechanism of TBBPA in the CuO/Ce2O3 system was comprehensively investigated. Radical scavenging experiments showed that h+ is the primary active substance in TBBPA photodegradation, and·OH and·O2− are secondary contributors. Moreover, the Fukui index was used to predict the active site, and DFT methods were used to calculate the degradation mechanism of TBBPA. Combined gas chromatography/mass spectrometry and high-performance liquid chromatography-mass spectrometry showed that the possible degradation pathways of TBBPA were determined to be debromination, C–C bond breaking, and ring-opening. Ecotoxicity evaluation showed that degradation products have significantly lower acute toxicity than TBBPA. The excellent reusability and stability of CuO/Ce2O3 indicate that this system can be successfully applied in water treatment, which is of great significance for the environmentally-friendly removal of TBBPA.