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Nitrated polycyclic aromatic hydrocarbons (NPAHs) are widespread organic pollutants that possess carcinogenic and mutagenic properties, so they may pose a risk to the environment and human health. In this study, the concentrations of 15 NPAHs and 16 polycyclic aromatic hydrocarbons (PAHs) in 30 surface water samples and 26 sediment samples were measured in 2018 from the Taige Canal, one of the main rivers flowing into Taihu Lake, China. The total NPAH concentrations in water and sediment ranged from 14.7 to 235 ng/L and 22.9 to 96.5 ng/g dw, respectively. 9-nitrophenanthrene (nd-76.3 ng/L) was the dominant compound in surface water, while 2+3-nitrofluoranthene (1.73-18.1 ng/g dw) dominated in sediment. Among PAHs, concentration ranging from 1,097 to 2,981 ng/L and 1,089 to 4,489 ng/g dw in surface water and sediment, respectively. There was a strong positive correlation between the log octanol-water partition coefficient (K

Because polycyclic aromatic compounds (PACs) are persistent, universal, and toxic pollutants, understanding the potential source and ecological risk thereof in lakes is critical to the safety of the aquatic environment. Here, a total of 25 sedimentary samples were collected from Lake Taihu, China, in 2018. The total concentrations of 16 parent polycyclic aromatic hydrocarbons (PAHs), 15 nitrated PAHs (NPAHs), nine oxygenated PAHs (OPAHs), and five hydroxy-PAHs (OH-PAHs) ranged from 294 to 1243, 3.0 to 54.5, 188 to 1897, and 8.3 to 51.7 ng/g dw, with the most abundant compounds being fluoranthene, 1,8-dinitropyrene, 6H-Benzo[cd]pyren-6-one, and 2-phenylphenol, respectively. The spatial distribution of PACs in sediments of Lake Taihu showed elevated concentrations from east to west due to economic development and transportation. The positive correlations between most paired PAHs indicate that these compounds likely originated from similar sources. The total organic carbon and organic matter contents affected the distribution characteristics of PACs in sediments. Diagnostic ratios, principal component analysis-multiple linear regression (PCA-MLR), and positive matrix factorization (PMF) were integrated to identify the sources. PACs had various sources including combustion, petroleum leakage, traffic emissions, hydroxyl metabolism, and other oxidation pathways in sediments of Lake Taihu. The PMF (R

The occurrence of nitrated polycyclic aromatic hydrocarbons (NPAHs) in sediments has been widely reported, but research on NPAH bioavailability is lacking. In this study, a self-made zeolite imidazolate framework-8/hexagonal boron nitride (ZIF-8/h-BN) solid-phase microextraction (SPME) fiber and commercial Tenax are compared as efficient tools to predict the bioavailability of NPAHs in sediments with bioassays using Cipangopaludina chinensis. During the process of SPME, the NPAH concentrations on the ZIF-8/h-BN fibers reached extraction equilibrium after 72 h. The fiber extraction of NPAHs in sediments was well-fitted by the pseudo first-order kinetic model with a rate constant of 2 × 10

Owing to their bioavailability and toxicity, the dissolved polycyclic aromatic hydrocarbons (PAHs-d) loaded in rivers are harmful to both inland and marine ecosystems. Thus, exploring the changes in PAHs-d levels and sources is important for controlling PAHs pollution. In this study, the concentration of PAHs-d in the mainstream of the Yangtze River during dry and wet seasons was investigated and the source was analyzed using the positive matrix factorization (PMF) model to assess the response of PAHs-d to hydrological and anthropogenic activities changes. The concentration of PAHs-d in the wet season (166.2 ± 52.51 ng/L) was significantly higher than that in the dry season (89.05 ± 20.89 ng/L) (ANOVA, P 0.001), and the sampling sites with high pollution were mainly distributed in the downstream urban agglomeration. Herein, 2-3 rings were identified to play a dominant role in the composition of PAHs-d. Compared with the dry season, the proportion of the low molecular weight (LMW) PAHs-d were relatively depleted and the high molecular weight (HMW) PAHs-d were accumulated in the wet season. Coal and coke combustion were identified as the main sources of PAHs-d (65.9% in the dry season and 59.2% in the wet season), followed by vehicle emissions, petroleum sources, and biomass combustion. Owing to the change in energy consumption structure and climate characteristics, the sources of PAHs-d displayed seasonal variation and spatial heterogeneity. Further, flow was identified as the most important factor affecting PAHs-d in the hydrological parameters. Increases of flow, pH, and SPM decreased the proportion of LMW PAHs-d, and increased that of HMW PAHs-d. The increase in anthropogenic activities intensified the residual levels of 2-3rings and 5-6 rings in water, but had no significant impact on the levels of 4 rings.

Nitro-polycyclic aromatic hydrocarbons have been detected in various environmental media. However, determination in sediment matrix is challenging due to the lack of a suitable method. In this study, a reliable method for determining 15 nitro-polycyclic aromatic hydrocarbons in sediments was developed based on accelerated solvent extraction and solid-phase microextraction coupled with gas chromatography-tandem mass spectrometry. The accelerated solvent extraction and solid-phase microextraction are sample pre-treatment techniques that have advantages, such as rapid operation and minimal sample volume. Initially, the solid-phase microextraction was optimized using five commercial fibers and from that 65 μm polydimethylsiloxane/divinylbenzene fiber was selected as the best fiber. Further, the accelerated solvent extraction conditions were optimized by Taguchi experimental design, such as extraction temperature (120℃), extraction solvent (dichloromethane), number of cycles (two), static extraction period (4 min), and rinse volume (90%). The method parameters, such as limits of quantitation, and intraday and interday accuracy and precision, were in the range of 0.067-1.57 ng/g, 75.2-115.2%, 69.9-115.4%, and 1.0-16.5%, respectively. Upon meeting all the quality criteria, the method was applied successfully to analyze real sediment samples. Therefore, our study creates a new prospect for the future application of direct immersion solid-phase microextraction in sediment analysis.

Visible light driven plasmonic Ag/Ag

In this study, three kinds of Zeolite imidazolate framework-8 (ZIF-8), synthesized by solvothermal, stirring and ball-milling method, were fabricated on the stainless steel wire via sol-gel technique. These fibers were used as solid phase microextraction (SPME) coating materials and applied for analyzing 16 polycyclic aromatic hydrocarbons (PAHs) and 11 nitro polycyclic aromatic hydrocarbons (NPAHs) in environmental water samples by gas chromatography-tandem mass spectrometry (GC–MS). The optimal pH, ionic strength, extraction time, extraction temperature, desorption temperature and desorption time were 6.0, without salt addition, 45 min, 35 °C, 260 °C and 5 min, respectively. The extraction mechanism of the ZIF-8 fiber might be the hydrophobicity, molecular penetration and π-π stacking interactions. Under the optimized conditions, the as-proposed fiber provides a wide linearity range from 10 to 20,000 ng L−1 and a low detection limit of 0.3–27.0 ng L−1 for PAHs and NPAHs analysis. The single fiber and fiber to fiber relative standard deviations were observed in the range of 3.0%–13.9% and 3.5%–12.3%, respectively. The method shows great potential in environmental analysis field.

Developing sheet-on-sheet (2D/2D) heterostructure with built-in electric field (BIEF) is effective in boosting the performance of photocatalysts for emerging contaminants degradation. Herein, the 2D/2D microtopography and (-)TiO

Nitrated polycyclic aromatic hydrocarbons (NPAHs) have toxic potentials that are higher than those of their corresponding parent polycyclic aromatic hydrocarbons (PAHs) and thus have received increasing attention in recent years. In this study, the occurrence, distribution, source, and human health risk assessment of 15 NPAHs and 16 PAHs were investigated in the surface water from 20 sampling sites of Lake Taihu during the dry, normal, and flood seasons of 2018. The ΣPAH concentrations ranged from 255 to 7298 ng/L and the ΣNPAH concentrations ranged from not-detected (ND) to 212 ng/L. Among the target analytes, 2-nitrofluorene (2-nFlu) was the predominant NPAH, with a detection frequency ranging from 85% to 90% and a maximum concentration of 56.2 ng/L. The three-ringed and four-ringed NPAHs and PAHs comprised the majority of the detected compounds. In terms of seasonal variation, the highest levels of the ΣNPAHs and ΣPAHs were in the dry season and flood season, respectively. Diagnostic ratio analysis indicated that the prime source of NPAHs was direct combustion, whereas in the case of PAHs the contribution was predominantly from a mixed pattern including pollution from unburned petroleum and petroleum combustion. The human health risk of NPAHs and PAHs was evaluated using a lifetime carcinogenic risk assessment model. The carcinogenic risk level of the targets ranged from 2.09 × 10−7 to 5.75 × 10−5 and some surface water samples posed a potential health risk.

We report a simple strategy to synthesize the Ag3PO4 nanopolyhedrons with regular morphology and uniform size under mild conditions. The photocatalytic properties of the composite were optimized by adjusting the content of Ag nanoparticles. The as-prepared photocatalysts were characterized and the photocatalytic performances were evaluated by the degradation of acenaphthylene (ANY) under visible-light illumination. The surface plasmon resonance (SPR) of appropriate Ag nanoparticles was generated on surface under visible light irradiation, which enhanced the absorption and utilization of visible light. At the same time, the conductivity of Ag promoted the separation and transfer of photogenerated carriers, provided active sites for the reaction, and enhanced the photocatalytic degradation efficiency through the generation of active species. As a result, the optimized composite exhibited enhanced visible-light photocatalytic activity of 0.03512 min−1 and higher removal rate of 97.3% for ANY (4 times and 1.8 times higher than that of pristine Ag3PO4, respectively), more photogenerated active species (h+ and •O2–) and relatively high stability (4 times of cycle experiments). In addition, the possible degradation pathway of ANY was proposed. The work of this paper has a crucial guiding significance for the working principle and design direction of silver semiconductor composite photocatalysts with surface plasmon effect.

Developing sheet-on-sheet (2D/2D) heterostructure with built-in electric field (BIEF) is effective in boosting the performance of photocatalysts for emerging contaminants degradation. Herein, the 2D/2D microtopography and (-)TiO2/(+)Bi2MoO6 BIEF were precisely integrated into hierarchical nanosheets, which can provide the basis and driving force for charge transfer both in in-plane and interface of heterojunction. The prepared photocatalyst (TiO2/Bi2MoO6) showed high-efficiency and stable performance for photocatalytic amoxicillin (AMX) degradation, which was 18.2 and 5.7 times higher than TiO2 and Bi2MoO6, respectively. More importantly, TiO2/Bi2MoO6 showed more efficient photocatalytic activity and photogenerated charge separation than TiO2@Bi2MoO6 (different morphology). Besides, four possible pathways of AMX degradation were proposed depending on Gaussian calculations and intermediates analysis by GC-MS and HPLC-TOFMS. This work sheds light on the design and construction of unique 2D/2D heterostructure photocatalysts for AMX degradation.

A novel ternary Ag/Ag 2 CO 3 /BiVO 4 plasmonic heterojunction photocatalyst was successfully fabricated by a precipitation method over BiVO 4 , followed by light reduction. The obtained composites were characterized by various measurements and the photocatalytic performances of the as-prepared composites were assessed by the degradation of tetracycline (TC) under visible-light illumination. The ternary plasmonic heterojunction photocatalyst exhibits higher and wider absorption in the visible and ultraviolet regions than the pure BiVO 4 and it displays superior performance in the degradation of tetracycline. The highest efficiency of Ag/Ag 2 CO 3 /BiVO 4 photocatalyst to degrade TC is up to 94.9% at 150 min. On the basis of the obtained experimental results, the probable photocatalytic mechanism of the enhanced activity is discussed. The degradation of tetracycline is not only influenced by OH, but also caused by valence-band holes (h + ). Therefore, the improved photocatalytic activity of Ag/Ag 2 CO 3 /BiVO 4 is due to the enhanced absorbance under the visible light, the facilitated charge transfer and the inhibited recombination of electron-hole pairs. The likely degradation pathway was proposed on the basis of the intermediate products detected by GC–MS. Moreover, the surface plasmon resonance and the electric field enhancement were simulated by the three dimensional finite difference time domain (FDTD) method.

The development of stable, efficient photocatalyst for environmental antibiotics degradation is great significant and remains a major challenge. Herein, zero dimensional Co3O4 nanodots are grown in situ onto two dimensional TiO2 nanosheets, successfully producing a Z-scheme heterojunction Co3O4/TiO2 photocatalyst for the photocatalytic degradation of enrofloxacin. The synthesized nanohybrid exhibits superior photodegradation performance (0.0269 min−1 for enrofloxacin) and excellent stability (four cycles). The matched energy bands allow the formation of the Z-scheme heterojunction, and the built-in electric field provides the reaction driving force. The formed Z-scheme heterojunction can simultaneously inhibit photoinduced electron-hole recombination, boost photoinduced charge carrier transfer, and produce more active electrons and holes, therefore generating more active species for eventual photocatalytic degradation. In addition, a the possible enrofloxacin degradation pathway was proposed based on simulated calculations and GC MS analysis. This work can inspire further design and construction of Z-scheme heterojunction photocatalysts.

Although reductive soil disinfestation (RSD) is an effective method for suppressing Fusarium oxysporum, there is limited information on the relationships among types of organic matter, disinfestation efficiencies (DEs), and changes in soil functional microorganisms during the RSD process. Hence, we performed laboratory experiments using nine different organic materials and used quantitative real-time PCR and MiSeq pyrosequencing to investigate the suppression of F. oxysporum and changes in soil microbial communities during the RSD process. The results showed that the RSD treatments using different organic matters significantly decreased F. oxysporum populations in the soil, but DEs of the RSD treatments were dramatically different. Contents of easily oxidized organic carbon (EOC) in these plant residuals (sugarcane leaf, banana leaf, alfalfa, rice husk, wheat bran, reed, and sugarcane residue) had a significant positive correlation with the DEs and that in all of the organic matters had a significant positive correlation with total organic acid contents. The C/N values of these plant residuals had a significant negative correlation with DEs. Furthermore, the soil bacterial community during the alfalfa RSD process was significantly changed. In the early stage of the RSD treatment, relative abundances of Coprococcus (Firmicutes), UC-Clostridiaceae (Firmicutes), and Klebsiella (Proteobacteria) increased significantly and had a significant positive correlation with organic acids. In contrast, relative abundances of UC-Cytophagaceae (Bacteroidetes) and UC-Xanthomonadaceae (Proteobacteria) decreased significantly. In the later stage of the RSD treatment, the number of Opitutus (Verrucomicrobia) and UC-Clostridiales (Firmicutes) increased significantly. During the entire RSD process, relative abundances of decomposers of less-degradable organic carbon, such as UC-Chitinophagaceae (Bacteroidetes), Clostridium (Firmicutes), UC-Ruminococcaceae (Firmicutes), Pseudoxanthomonas (Proteobacteria), and Flavisolibacter (Bacteroidetes), were always higher than their initial relative abundance values. Overall, types of organic matter with lower C/N could induce higher DEs; organic matters with higher EOC could stimulate organic acid producers to produce more toxic organic acids and consequently induce higher DEs during the RSD process. Dominant functional microorganisms found during the alfalfa RSD treatment belonged to Firmicutes, Proteobacteria, and Bacteroidetes.

The role of illumination and cathode is important to improve the efficiency of photoelectro-Fenton (PEF) system. In this study, cathodes with black carbon-poly tetra fluoro ethylene (BC-PTFE) for increase the concentration of hydrogen peroxide in PEF. A new PEF system using EIEL and BC-PTFE air-diffusion cathode was established. The electrode performance was tested and the influence factors, degradation kinetics, intermediates, pathway and mechanism of the model compound methyl orange (MO) were studied. The capacities of concentration decays and total organic carbon (TOC) removals were compared between different electrochemical advanced oxidation processes. The experimental conditions were optimized for a current density of 20 mA cm−2 with 0.5 mM Fe2+ and 100 mg L−1 MO at 20 °C and pH 3.0 in an 8 L reservoir. The higher MO concentration was, the smaller pseudo-first-order kinetic constants of concentration decays and TOC removals were. Intermediate products were identified by gas chromatography-mass spectrometry and ion-exclusion high performance liquid chromatograph in EIEL-PEF. Combined with frontier electron density, the degradation pathway was deduced as follows: destruction of azo bond, substitution of •OH, dehydrogenation and oxidation, opening-ring and mineralization. In EIEL-PEF, the concentration of oxalic acid and oxamic acid reached the maximum value 9.2 and 1.5 mg L−1 at 60 and 90 min, respectively. The photolysis of N-intermediates produced NH4+-N was released in more proportion than NO3−-N and oxamic acid-N. The study indicated that PEF system has the potential to remove organic pollutants in aquatic environments.

It is important to establish an available analytical method for polycyclic aromatic hydrocarbons (PAHs), nitrated PAHs (nitro-PAHs), oxygenated forms of PAHs (oxy-PAHs), and hydroxy-PAHs (OH-PAHs) in sediment samples due to the fact that they co-exist in various environmental mediates, particularly in sediment. In this study, an analytical method has been developed and validated for the quantification of PAHs, nitro-PAHs, oxy-PAHs, and OH-PAHs in sediment samples. The sediment samples were extracted by accelerated solvent extraction and cleaned up with SPE alumina-n combining with aminopropyl cartridges. The extracts were further fractionated by using different solvents. The fractionated extracts were analyzed via gas chromatography of single and triple quadrupole mass spectrometry in the electron ionization and negative ion chemical ionization with selective ion monitoring and selective reaction monitoring mode and liquid chromatography-triple quadrupole mass spectrometry. Each group of analytes was determined by different instrument modes such as GC-EI-SIM for PAHs, GC-NICI-SRM for nitro-PAHs, GC-EI-SRM for the oxy-PAHs and LC-ESI-MS/MS for OH-PAHs. A total of 44 analytes (16 PAHs, 14 nitro-PAHs, 9 oxy-PAHs, and 5 OH-PAHs) and 6 deuterated surrogates were performed. Most of recovery percentage varied from 52.8% up to 114.1% for the targeted analytes verified at three concentration levels (100 ng/g, 400 ng/g and 1000 ng/g for PAHs and 10 ng/g, 50 ng/g and 400 ng/g for their derivatives). The repeatability determined by the relative standard deviation percentage of triplicate trials was less than 10% for most analytes. The limit of detection ranged from 0.01 to 0.02 ng/g for PAHs, 0.002–0.067 ng/g for nitro-PAHs, 0.01–0.1 ng/g for oxy-PAHs, and 0.003–0.006 ng/g for OH-PAHs. Most of the compounds were detectable in the sediments collected from a local River, which illustrates the developed method could be a practical and suitable technique for detection of PAHs and their derivatives in real sediment samples.

A solid-phase microextraction coupled with gas chromatography and mass spectrometry method has been developed for the determination of ten nitrated polycyclic aromatic hydrocarbons in water samples. Five different kinds of commerical fibers were used to compare the extraction efficiency, including 65 μm polydimethylsiloxane/divinylbenzene, 100 μm polydimethylsiloxane, 30 μm polydimethylsiloxane, 7 μm polydimethylsiloxane, and 85 μm polyacrylate fibers. Five factors were also selected to optimize conditions, including extraction temperature, time, stirring speed, salt concentration, and headspace volume. Taguchi design was applied to design the experiments and obtain the best parameters. The results show that 65 μm polydimethylsiloxane/divinylbenzene fiber directly immersed into aqueous solution for 35 min at 55°C with a constant stirring rate of 1150 rpm were the optimal conditions. Under these conditions, the limits of quantification were 0.007-0.063 μg/L, and the relative standard deviation based on six replicates ranged from 2.8 to 9.5%. The spiked recoveries ranged from 69.1 to 110.1%. Intra- and inter day relative standard deviations at three concentration levels were less than 12%, and the recoveries were 66.4-111.5%. The proposed method is reliable for analyzing nitrated polycyclic aromatic hydrocarbons in different water samples.

The novel microwave catalyst MgFe2O4-SiC was synthesized via sol-gel method, to remove azo dye Direct Black BN (DB BN) through adsorption and microwave-induced catalytic reaction. Microwave-induced catalytic degradation of DB BN, including adsorption behavior and its influencing factors of DB BN on MgFe2O4-SiC were investigated. According to the obtained results, it indicated that the pseudo-second-order kinetics model was suitable for the adsorption of DB BN onto MgFe2O4-SiC. Besides, the consequence of adsorption isotherm depicted that the adsorption of DB BN was in accordance with the Langmuir isotherm, which verified that the singer layer adsorption of MgFe2O4-SiC was dominant than the multi-layer one. The excellent adsorption capacities of MgFe2O4-SiC were kept in the range of initial pH from 3 to 7. In addition, it could be concluded that the degradation rate of DB BN decreased over ten percent after the adsorption equilibrium had been attained, and the results from the result of comparative experiments manifested that the adsorption process was not conducive to the process of microwave-induced catalytic degradation. The degradation intermediates and products of DB BN were identified and determined by GC-MS and LC-MS. Furthermore, combined with the catalytic mechanism of MgFe2O4-SiC, the proposed degradation pathways of DB BN were the involution of microwave-induced $OH and holes in this catalytic system the breakage of azo bond, hydroxyl substitution, hydroxyl addition, nitration reaction, deamination reaction, desorbate reaction, dehydroxy group and ring-opening reaction.

A series of ternary Ag/AgCl/BiVO4 photocatalysts with different UV light reduction time were synthesized. All the samples were investigated and characterized by XRD, XPS, SEM, PL and so on. The results of UV–Vis DRS and PL demonstrated that the ternary photocatalysts exhibited higher absorption in visible light region. And from the XRD patterns, it could be inferred that with the increase of illumination time, the content of metallic Ag on the surface of ternary photocatalysts increased. In the ternary photocatalyst system, Ag nanoparticles acted as the electron mediator and induced the surface plasmon resonance to facilite the photocatalytic activity of as-obtained ternary photocatalysts. During the photocatalytic degradation of oxytetracycline hydrochloride, the 1 h-Ag/AgCl/BiVO4 photocatalyst showed the best degradation activity, and the main active species participating in the reaction were holes and superoxide radicals. According to the experimental results, the 1 h-Ag/AgCl/BiVO4 photocatalyst exhibited excellent stability and effectively degraded OTC under a wide pH range condition or co-existing ions. The experimental results provided a scientific basis for the practical application of the 1 h-Ag/AgCl/BiVO4 photocatalyst, especially for the treatment of antibiotics in the water.