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1.
Sci Total Environ ; 815: 152889, 2022 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-34998763

RESUMO

Surface sediments are both sinks and sources of chlorinated and brominated polycyclic aromatic hydrocarbons (Cl/Br-PAHs) in the environment. It is important to study the source of Cl/Br-PAHs in the surface sediment for controlling the ecological risk of Cl/Br-PAHs. Clues from the previous research suggested that atmospheric deposition may be one of the main sources of Cl/Br-PAHs in sediment. However, due to the lack of matched sediment and atmospheric Cl/Br-PAHs data, the contribution of atmospheric deposition to Cl/Br-PAHs in sediment has not been confirmed. This study investigated the characteristics of 37 Cl/Br-PAHs and validated the contribution of atmospheric sedimentation to Cl/Br-PAHs in sediment by a case study in the surface sediments of the Chaobai River, China. To the best of our knowledge, four Cl-PAHs and eleven Br-PAHs were found in the sediments for the first time. The total concentrations of 18 Cl-PAH species were 76-2301 pg/g, while those of Br-PAHs were 6-238 pg/g. The toxic equivalent quantities (TEQ) of the Cl-PAHs in surface sediments in the water conservation area and in the urban comparison area were 0.73 pg TEQ/g and 2.21 pg TEQ/g, respectively. The TEQ of the Br-PAHs in surface sediments in the water conservation area and in the urban comparison area were 2.85 × 10-2 pg TEQ/g and 6.6 × 10-2 pg TEQ/g, respectively. Based on the characteristics comparison and correlation analysis of Cl/Br-PAHs in both sediment and ambient air, it was initially confirmed the contribution of atmospheric deposition to Cl-PAHs in sediments. However, there was no conclusion of Br-PAHs in sediment similar to Cl-PAHs in sediment. It was inferred that the sources of Br-PAHs in sediment were different from Cl-PAHs in sediment.

2.
Sci Total Environ ; 806(Pt 3): 150691, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34600995

RESUMO

Thousands of organic pollutants are intentionally and unintentionally discharged into water bodies, adversely affecting the ecological environment and human health. Screening for organic pollutants that pose a potential risk in aquatic environments is essential for risk management. This review evaluates the processes, methods, and technologies used to screen such pollutants in the aquatic environment and discuss their advantages and disadvantages, in addition to the challenges and knowledge gaps in this field. Combining non-target screening, target screening, and suspect screening is often effective for compiling a list of potential risk compounds and enables the quantitative analysis of these compounds. Sample preparation technologies and pollutant detection technologies considerably affect the results of pollutant screening. The limited amount of chemical and toxicological information contained in databases hinders the screening of organic pollutants with potential risk. Machine learning, high-throughput methods, and other technologies will increase the accuracy and convenience of screening for high-risk pollutants. This review provides an important reference for screening these compounds in aquatic environments and can be used in future pollutant screening and risk management.


Assuntos
Poluentes Ambientais , Poluentes Químicos da Água , Humanos
3.
Water Res ; 207: 117787, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34731666

RESUMO

Hypobromous acid (HOBr), a highly reactive active species, can be formed and impact reaction processes with organic pollutants in source water during chlorination disinfection of the water containing bromide (Br-). In this study, we investigated the transformation kinetics of 10 parent polycyclic aromatic hydrocarbons (PAHs) and formation mechanisms of transformation products in the presence of Br- during chlorination. The results indicated that HOBr can accelerate the processes of electrophilic substitution (ES) and single electron transfer (ET) reactions in PAHs, and the second-order rate constants of HOBr are 102-103 times higher than those of hypochlorous acid (HOCl) with PAHs. HOBr was more conductive to induce ES reactions than HOCl. In water containing Br-, HOBr and HOCl dominate the reaction processes with PAHs, although other active bromine species may still affect reaction processes. In terms of transformation products, higher reactivity of HOBr results from faster formation of oxygenated PAHs (OPAHs) and halogenated PAHs (HPAHs) than HOCl. As an example of 3 model PAHs, anthracene transforms faster to its oxygenated products at a higher concentration, while pyrene and fluorene transform faster to halogenated products. These fundamental results were essential to understanding the transformation kinetics of PAHs and the formation of toxic disinfection by-products in the presence of Br-.

4.
Sci Total Environ ; 789: 147911, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34082210

RESUMO

In this study, we investigated the concentration distribution of parent polycyclic aromatic hydrocarbons (PAHs) and their derivatives in the effluents of 5 municipal wastewater treatment plants (WWTPs) in Beijing, China for eight months. We first identified the coexistence of PAHs, chlorinated PAHs (Cl-PAHs), brominated PAHs (Br-PAHs) and oxygenated PAHs (OPAHs) in the effluents of WWTPs. Three Cl-PAHs and 7 Br-PAHs were first found. The total concentrations of PAHs, Cl-PAHs, Br-PAHs and OPAHs ranged from 8.99-88.38, n.d.-5.70, n.d.-13.11 ng L-1 and 15.47-106.92 ng L-1, respectively. In terms of temporal distributions, the total concentrations of PAHs and OPAHs presented a decreasing trend from April to November and the total concentrations of Cl-PAHs and Br-PAHs fluctuated at lower levels. These results indicated that these compounds will be long-term discharged into the receiving river. In addition, Cl-PAHs, Br-PAHs and OPAHs were likely generated by transformations occurring during chlorination disinfection. For ecological risk assessment, risk quotients of 6 compounds, indeno[1,2,3-cd] pyrene, benzo[g,h,i]perylene, dibenz[a,h]anthracene, 6-bromobenzo[a]pyrene, 1,8-dibromopyrene and 1,6-dibromopyrene, were thought to indicate high ecological risk (fish). Furthermore, Cl-PAHs, Br-PAHs and OPAHs in the effluents of WWTPs can cause more serious environmental hazards than the corresponding PAHs.


Assuntos
Hidrocarbonetos Policíclicos Aromáticos , Poluentes Químicos da Água , Purificação da Água , Animais , Pequim , China , Monitoramento Ambiental , Hidrocarbonetos Policíclicos Aromáticos/análise , Medição de Risco , Poluentes Químicos da Água/análise
5.
J Hazard Mater ; 413: 125360, 2021 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-33611038

RESUMO

Recently, derivates of parent polycyclic aromatic hydrocarbons (PAHs) have aroused increasing concerns due to potential health problems they cause. In this study, we first found the coexistence of PAHs, chlorinated PAHs (Cl-PAHs), brominated PAHs (Br-PAHs) and oxygenated PAHs (OPAHs) in tap water. Twenty-six compounds including 13 PAHs, 5 Cl-PAHs, 5 Br-PAHs, and 3 OPAHs were detected. Total concentrations of PAHs (2.50-56.90 ng L-1) and OPAHs (n.d. to 80.34 ng L-1) were relatively higher than those of Cl-PAHs (0.30-11.28 ng L-1) and Br-PAHs (n.d. to 8.20 ng L-1). We calculated the 95th percentile incremental lifetime cancer risk (ILCR) values of PAHs and HPAHs. In all sampling sites, although no ILCR values for PAHs and HPAHs were higher than 1.00E-06, results still indicates there is still a low cancer risk existed. In addition, regional impact was established by combining ILCR values with population density. Predicted cancer incidence (PCI, people km-2) was calculated to evaluate regional impact more comprehensively. The results were different from previous hypothesis that sampling sites with high ILCR values may not necessarily present high regional impacts. After total PCI of each district was summed, all calculated districts of Beijing, China were at low regional impact.

6.
Ecotoxicol Environ Saf ; 181: 241-247, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31200196

RESUMO

The coexistence of parent polycyclic aromatic hydrocarbons (PPAHs) and halogenated PAHs (HPAHs) in drinking water has generated much concern recently. However, a method to simultaneously determine these compounds has not been developed. In this study, a method using solid-phase extraction combined with gas chromatography-mass spectrometry for determination of PPAHs and HPAHs in drinking water was established. Forty-two target compounds including 16 PPAHs and 26 HPAHs (16 chlorinated PAHs (Cl-HPAHs) and 10 brominated PAHs (Br-PAHs)) were selected to evaluate the performance. Our results indicate enriching compounds with a LC18 cartridge and eluting with dichloromethane is optimal with recovery of 74.88-119.4%. Method detection limits ranged from 0.34 to 3.37 ng L-1 when only using 1 L samples. The method accomplished the analysis of trace PPAHs and HPAHs. We found the coexistence of PPAHs and HPAHs including 12 PPAHs, 2 Cl-PAHs and 3 Br-PAHs in tap water samples. Maximum total concentration of PPAHs and HPAHs reached 33.69 ng L-1 and 3.04 ng L-1, respectively. Trace Br-PAHs were first detected in drinking water. 6-bromobenzene[a]pyrene was dominated among the HPAHs with a concentration from 2.30 to 2.69 ng L-1. The simultaneous occurrence of PPAHs and HPAHs in drinking water should receive more attention, and their formation mechanism should be further explored.


Assuntos
Água Potável/química , Cromatografia Gasosa-Espectrometria de Massas , Hidrocarbonetos Policíclicos Aromáticos/análise , Extração em Fase Sólida , Halogenação , Hidrocarbonetos Policíclicos Aromáticos/isolamento & purificação
7.
Adv Mater ; 30(49): e1805085, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30294817

RESUMO

Metal halide perovskite films are endowed with the nature of ions and polycrystallinity. Formamidinium iodide (FAI)-based perovskite films, which include large cations (FA) incorporated into the crystal lattice, are most likely to induce local defects due to the presence of the unreacted FAI species. Here, a diboron-assisted strategy is demonstrated to control the defects induced by the unreacted FAI both inside the grain boundaries and at the surface regions. The diboron compound (C12 H10 B2 O4 ) can selectively react with unreacted FAI, leading to reduced defect densities. Nonradiative recombination between a perovskite film and a hole-extraction layer is mitigated considerably after the introduction of the proposed approach and charge-carrier extraction is improved as well. A champion power conversion efficiency of 21.11% is therefore obtained with a stabilized power output of 20.83% at the maximum power point for planar perovskite solar cells. The optimized device also delivers negligible hysteresis effect under various scanning conditions. This approach paves a new way for mitigating defects and improving device performance.

8.
Nanoscale ; 10(1): 142-149, 2017 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-29159329

RESUMO

Plasmonic nanomaterials, along with their assemblies, provide numerous applications due to their profound optical properties. In this work, we report the self-assembly of Au@Ag core-shell nanocuboids (NCs) into staircase superstructures in both vertical and horizontal orientations through two-stage droplet evaporation. Each stair is composed of a uniform well-aligned monolayer of NCs. The gap distance between NCs can be greatly shrunk to boost the corresponding surface-enhanced Raman scattering (SERS) performance using an ethanol wash method. The SERS performance of the assembled NCs is calculated by finite-difference time-domain (FDTD) simulation, and studied against the step number using 4-mercaptobenzoic acid as a Raman reporter molecule. The increasing EF with the increase of layer number proves that the plasmon mode propagates well in our uniformly aligned assemblies.

9.
Nanoscale ; 9(35): 12830-12834, 2017 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-28702619

RESUMO

By utilizing the interaction between inorganic species and organic surfactants, the ordered layered mesostructures were generated for the synthesis of the one-dimensional oxide nanomaterials. The oxide nanomaterial products which evolved from the above layered structures were demonstrated as ultrathin (less than 2 nm) one-dimensional structures with superior catalytic performance. The synthetic method based on layered structures can be extended to prepare other one-dimensional oxide nanomaterials with the same ultrathin structures.

10.
Nanoscale ; 8(48): 19994-20000, 2016 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-27858031

RESUMO

A rational integration of 1D metallic nanotubes and oxide nanoparticles has been demonstrated as a viable strategy for the production of both highly stable and efficient anodes for lithium ion batteries. We encapsulated copper oxide (CuO) nanoparticles in ultra-long metallic copper nanotubes with engineered interspaces, and explored their electrochemical properties. Such a hierarchical architecture provides three important features: (i) a continuous nanoscale metallic Cu shell to minimize electronic/ionic transmitting impedance; (ii) a unique quasi-one-dimensional structure with a large aspect ratio to reduce self-aggregation; (iii) free space for volume expansion of CuO nanoparticles and stable solid-electrolyte interphase (SEI) formation. The anode materials with such hierarchical structures have high specific capacity (around 600 mA h g-1 at a current density of 0.1 A g-1), excellent cycling stability (over 94% capacity retention after 200 cycles) and superb reversible capacity of 175 mA h g-1 at a high charging rate of 15 A g-1.

11.
Sci Rep ; 5: 15630, 2015 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-26490441

RESUMO

Although the routes of de novo pyridoxal 5'-phosphate (PLP) biosynthesis have been well described, studies of the engineering of an intracellular PLP supply are limited, and the effects of cellular PLP levels on PLP-dependent enzyme-based whole-cell biocatalyst activity have not been described. To investigate the effects of PLP cofactor availability on whole-cell biocatalysis, the ribose 5-phosphate (R5P)-dependent pathway genes pdxS and pdxT of Bacillus subtilis were introduced into the lysine decarboxylase (CadA)-overexpressing Escherichia coli strain BL-CadA. This strain was then used as a whole-cell biocatalyst for cadaverine production from L-lysine. Co-expression strategies were evaluated, and the culture medium was optimised to improve the biocatalyst performance. As a result, the intracellular PLP concentration reached 1144 nmol/gDCW, and a specific cadaverine productivity of 25 g/gDCW/h was achieved; these values were 2.4-fold and 2.9-fold higher than those of unmodified BL-CadA, respectively. Additionally, the resulting strain AST3 showed a cadaverine titre (p = 0.143, α = 0.05) similar to that of the BL-CadA strain with the addition of 0.1 mM PLP. These approaches for improving intracellular PLP levels to enhance whole-cell lysine bioconversion activity show great promise for the engineering of a PLP cofactor to optimise whole-cell biocatalysis.


Assuntos
Biocatálise , Cadaverina/biossíntese , Engenharia Metabólica , Fosfato de Piridoxal/biossíntese , Bacillus subtilis/genética , Cadaverina/metabolismo , Carboxiliases/genética , Escherichia coli/genética , Fosfato de Piridoxal/química , Fosfato de Piridoxal/genética
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