Search

Harmful and toxic gas sensing techniques are of vital importance for ecological environment. Abundant physical and chemical properties of metal-organic frameworks (MOFs) have been discovered gradually, such as luminescence, catalysis, and electrical conductivity, which make MOFs evolve into a kind of powerful sensing materials. Although many reported MOF-based sensors have been well reviewed, a comprehensive summary focused on the extremely toxic and harmful gas/vapor sensors is missing. In this review, from a different perspective, the major advances and applications of MOF-based sensors towards the very harmful and toxic analytes in the gas or vapor phase are reviewed, and the sensing mechanisms are also highlighted in detail. Finally, the critical challenges and prospects in this field are discussed from a macro point of view. It is expected that this review could offer a guidance of current state-of-art state on MOF-based hazardous gas/vapor sensors, and accelerates the further practical applications. • The main sensing principles of metal-organic frameworks-based gas sensors are summarized. • Applications of metal-organic frameworks in hazardous gas substances sensing are reviewed. • Challenges and future prospects of these metal-organic frameworks-based gas sensors are highlighted. [ABSTRACT FROM AUTHOR]

A surface enhanced Raman scattering (SERS) substrate, capable of extracting small amounts of organic species from surfaces of different types of materials with variable roughness, has been fabricated. The substrate consists of Ag NPs encapsulated in poly(vinyl alcohol) (PVA) hydrogels, commonly known as PVA “slime”. Unlike traditional SERS substrates, such as colloidal suspensions, the resulting PVA slime SERS substrate presents good viscoelasticity, allowing it to conform to the surface of various materials of arbitrary roughness. Surfaces of different materials, including sandpapers, cotton, metal, and wood, previously contaminated with nile blue A (NBA) were analyzed with the PVA slime SERS substrate. Limits of detection (LOD) as low as 100 ppb (0.79 ng in a total amount on an area of ∼3 cm2) were achieved for all surfaces tested. Pesticides and Sudan red III on the glass surface have also been detected, with a LOD of 1.6 ng per ∼3 cm2. [ABSTRACT FROM AUTHOR]

Abstract: The interaction of metronidazole (MTZ) and human serum albumin (HSA) was studied using the coupling system of on-line microdialysis sampling with flow-injection chemiluminescence detection (FI-MD-CL). The interested drug and HSA were mixed in different molar ratios in 0.067molL−1 phosphate buffer (pH 7.4) and incubated at 37°C in a water-bath. Then the microdialysis probe was put into the MTZ–HSA mixed solution and sampled at a perfusion rate of 5μLmin−1. The microdialysates was determined using flow-injection chemiluminescence. In vitro recovery (R) of MTZ under experimental conditions was approximately 25.2% with a R.S.D. of about 3.2%. The values estimated for the binding constant (K) and the number of the binding sites (n) were found to be 1.50×103 Lmol−1 and 1.89, respectively. The values of nK obtained using Scatchard analysis and Klotz plot were found to be quite similar. The method provided a reliable and simple technique for the study of drug–protein interaction. [Copyright &y& Elsevier]

A unique fluorescent sensing probe for UO22+ detection was fabricated with terbium-based metal organic frameworks via introducing specific recognition sites (denoted as Tb-TDPAT). The newly formed Tb-TDPAT presented remarkable detection sensitivity and selectivity towards UO22+, surpassing the need for complex post-modification methods. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) as a new class of zero-dimensional carbon-based nanomaterials that have gained growing interest and attention in many research areas. In addition to their comparable optical properties, CDs have the desired advantages of economy, low toxicity, excellent biocompatibility, simple synthetic routes and abundant carbon source. Since their discovery, CDs have been widely used in sensors, nanomedicine, bioimaging, and photo/electrocatalysis fields. To better understand the significant role of CDs in separation science, it becomes necessary to summarize the applications of CDs in sample preparation and chromatographic separation systematically. In this review, we aim to demonstrate the up-to-date advances of CDs with an emphasis on their properties, classification, synthetic methods and applications in sample preparation and chromatographic separation along with some perspectives on the current challenges and opportunities in this exciting and promising field. This review may open up some insights and inspiration for future research work. • Carbon dots (CDs) have emerged as a new carbon-based fluorescent nanomaterials. • Different types of synthesis strategies of CDs are introduced. • Applications of CDs in sample preparation are summarized in details. • Applications of CDs in chromatographic separation are also described. • The limit and future perspectives for CDs in chromatographic science are indicated. [ABSTRACT FROM AUTHOR]

A dual functional molecularly imprinted polymer (MIP) coated paper (MIP-CP) sensor was firstly proposed for rapid fluorescent (FL) and visual analysis of norfloxacin (NOR) in aqueous solutions. The sensor was fabricated via a sol-gel technique, and characterized by FTIR and SEM. The extraction capacity, selectivity, detection limit, and linear range of the MIP-CP sensor were studied by an FL spectrophotometer. The modified paper sensor showed good selectivity and high extraction capacity for NOR and its structural analogues. For FL analysis of NOR, the linear range and detection limit were found to be 10–100 ng/ml and 2.59 ng/ml, respectively. The visual determination of NOR (under UV light) based on the MIP-CP sensor was also explored, and the determination limit was found to be 0.1 μg/ml. Finally, the proposed methods were successfully applied to the direct determination of NOR in pharmaceutical preparations and cross-validated by UPLC. The MIP-CP sensor might be a potential platform for antibiotic determination due to its multifunction and good analytical performance. A dual functional molecularly imprinted polymer coated paper (MIP-CP) sensor was proposed for fluorescent and visual analysis of norfloxacin. Image 1 • A dual functional paper sensor was firstly fabricated via a sol-gel technique. • A simple fluorescence method was proposed for NOR detection. • A visual fluorescence method was established for NOR detection. [ABSTRACT FROM AUTHOR]

The poly[(9,9-dioctylfuorenyl-2,7-diyl)-alt-co-(1,4-benzo-{2,1′,3}-thiadiazole)] (PFBT) was carboxyl-functionalized to prepare polymer dots (C-PFBT Pdots), which served as a self-ECL emitter for producing an extraordinary ECL signal without any exogenous coreactants. The C-PFBT Pdots–modified electrode captured the substrate DNA and further hybridized with a ferrocene (Fc)-labeled DNA. The ECL emission of C-PFBT Pdots was quenched by Fc (a signal off state). After the DNAzyme was added, the DNAzyme-substrate hybrids were formed through hybridizing between DNAzyme and substrate and the Fc-labeled DNA was released. In the presence of target Pb2+, the DNAzyme-substrate hybrids could be specifically recognized and cleaved to release the DNAzyme and Pb2+. Ultimately, the released DNAzyme would further hybridize with the substrate for producing the DNAzyme-substrate hybrids and then were cleaved by the released Pb2+. As a result, the DNA walking machine was generated and the substantial Fc was away from C-PFBT Pdots to obtain a signal on state. Such a strategy achieved a sensitive detection of Pb2+ and the detection limit was as low as 0.17 pM. Moreover, making this ECL biosensor for an intracellular Pb2+ detecting, a convincing performance was achieved. The self-ECL emitter C-PFBT Pdots combining with the quencher Fc provided a new strategy and platform for constructing a coreactant-free ECL assay. [ABSTRACT FROM AUTHOR]

• A food safety screening method using a portable Raman spectrometer is described. • Adhesive tapes were examined and used as sampling media to recover analytes. • The tape lifting sampling efficiencies on different surfaces were explored. • Ag NPs were optimized for the best SERS performance. • Triazophos was successfully detected on fruit peels with high sensitivity. In this work, we report a simple and rapid surface-enhanced Raman scattering (SERS) method for the screening of pesticide residues on fruit peels using a portable Raman spectrometer. Adhesive tapes were used as the sampling media; the effectiveness of different tape brands was examined. Collection efficiencies were found to be 60.2 ± 7.6%, 54.3 ± 5.0%, and 52.3 ± 9.0% on glass, aluminum foil, and fruit peels, respectively. SERS was achieved by applying silver nanoparticles (Ag NPs) to the surface of the tape after analyte collection. Preparation of the Ag NPs was optimized for pesticide detection. The limit of detection of triazophos on apple peels was 25 ng/cm2 with the portable Raman spectrometer. Considering the least favorable conditions, the calculated detection limit was 0.0225 mg/kg, which is an order of magnitude less than the maximum residue limit (MRL, 0.2 mg/kg) in China. The method is sufficiently sensitive for use in field analysis. [ABSTRACT FROM AUTHOR]

Abstract Decision table (DT) in Rough Set was first proposed as a new chemometric approach for the optimization of synthesis strategy in this work. The fluorescence (FL) performance optimization of Mn-doped ZnS quantum dots was utilized as an example to illustrate the analysis procedure and verify the rationality of DT. Five condition attributes (namely synthesis conditions) were first reduced to be three through the analysis of FL intensity (decision attribute) and attribute reduction of the first DT. Two core attributes were confirmed: the volume ratio of ZnSO 4 and Na 2 S solution, the volume of MnCl 2 solution. It was then found that the latter was the most important condition attribute from attribute reduction of the second DT and the optimal synthesis strategy was obtained. The results were then verified by the use of single factor analysis and orthogonal experiment. Finally, it is concluded that the proposed method has the advantages of attribute reduction, core attribute determination and no requirement on evenly distributed conditions despite the need of certain mathematical knowledge. More importantly, it presents superiority for synthesis optimization when handling larger number of condition attributes due to attribute reduction. DT might be a new chemometric approach for the optimization of materials synthesis with multiple factors. Highlights • Decision table in Rough Set was first utilized to optimize synthesis strategy. • Decision table was compared with single factor analysis and orthogonal experiment. • The preparation of Mn-doped ZnS quantum dots was systematically discussed. [ABSTRACT FROM AUTHOR]

Detecting hexavalent chromium (Cr(VI)) is important for human health and environmental protection due to its high toxicity, carcinogenicity and persistence, but developing a sensor to selectively detect Cr(VI) remains challenging. Here, we proposed a selective fluorescent sensor for Cr(VI) detection using cetyltrimethylammonium chloride (CTAC) modified N-doped carbon dots (N-CDs–CTAC) synthesized via a post-modification strategy. Specifically, the introduced CTAC molecules could self-assemble into micelles for encapsulating fluorescent N-CDs, causing the aggregation of N-CD particles and then displaying enhanced fluorescence emission owing to the aggregation-induced emission effect. Moreover, the positively charged CTAC can interact with negatively charged Cr(VI) in the form of an anion (Cr2O72−), boosting the ability of the selective recognition of Cr(VI). Thus, a N-CDs–CTAC fluorescent probe was designed to selectively monitor Cr(VI) with an ultralow detection limit down to 40 nM, and was further used for Cr(VI) detection in real environmental samples. The fluorescence quenching mechanism of N-CDs–CTAC by Cr(VI) was attributed to dynamic quenching. The proposed assay opens an avenue for the selective detection of Cr(VI) in the environmental monitoring field. [ABSTRACT FROM AUTHOR]

[Display omitted] • Exceptional CIP degradation efficiency (>95 %) and minimal Co2+ leaching (<0.32 mg/L) were achieved. • The unique heterogeneous interior structure enhanced charge transfer and metal cycling. • SO 4 •− and 1O 2 were the primary reactive species responsible for CIP degradation. • Two degradation paths and the overall decrease of ecotoxicity after degradation were deduced. A dual-metal organic framework (MOF) heterostructure, ZIF-67@MIL-100(Fe), was successfully constructed and employed in a photo-assisted peroxymonosulfate (PMS) activation system for ciprofloxacin (CIP) degradation. The outer wrapping structure of MIL-100(Fe) effectively stabilizes ZIF-67, resulting in minimal Co2+ leaching (<0.32 mg/L). For CIP degradation (10 mg/L), the ZIF-67@MIL-100(Fe) exhibited superior catalytic performance (>95 %) with a rate constant of 0.0438 min−1, attributed to the synergistic interaction between the MIL-100(Fe) shell and ZIF-67 core. It was characterized to be more favorable for light absorption, charge separation, and migration than individual components, fostering redox cycles of Co(III)/Co(II) and Fe(III)/Fe(II). This photo-assisted PMS activation process involved both free radical and non-free radical pathways, with SO 4 •− and 1O 2 playing dominant roles in CIP degradation. Based on seven measured intermediates, two degradation pathways were derived: oxidation of the piperazine ring and hydroxylation. Toxicity Evaluation Software Tool (T.E.S.T.) analysis indicated an overall decrease in ecological toxicity following CIP degradation. Furthermore, the composite exhibited robust stability in five cyclic experiments and real aquatic environments, underscoring the photo-assisted ZIF-67@MIL-100(Fe) activated PMS process as a promising and environmentally friendly approach for eliminating antibiotics from contaminated water. [ABSTRACT FROM AUTHOR]

Sample preparation is a critical step in analytical chemistry, particularly in the consideration of analytes of interest from complex matrices. Due to this complexity, the presence of interferences and low concentrations of the analytes, direct analysis of matrices is not possible in most cases. So, to address this, sample preparation is necessary for removing possible interferences, and pre-concentrating the target analytes. Sorbent-based sorptive extraction/microextraction (SBSEME) is a versatile sample preparation method that has been widely applied for the processing of various samples. With a judicious choice of sorbents, SBSEME can provide benefits like simplicity, ease of operation, cost-effectiveness, high accessibility, moderate extraction time, and low-to-moderate consumption of solvents, and compatibility with different detection techniques. Among the many different materials that have been used in SBSEME as sorbents, two-dimensional materials (TDMs) like graphene and its derivatives (graphene oxide and reduced graphene oxide) have been attracting a lot of attention in recent years by those involved in the sample preparation field. TDMs have amenable characteristics like porous structures, high surface area, high adsorption capacity, ease of modification to further improve their properties, generally low toxicity, excellent biocompatibility, high physical, chemical and thermal stability, high elasticity and flexibility, and high resistance and thermal conductivity. To better investigate and understand the applicability of TDMs in sample preparation methods, it is important to survey recent progress and development of TDMs with reference to their synthesis and applications. To this end, in this review article, (a) TDMs, their features, synthesis and modification approaches are investigated; (b) different TDM composites are studied and evaluated; (c) the applications of TDMs and their composites in different extraction methods such as solid-phase extraction (SPE), dispersive SPE, magnetic SPE, micro-SPE, solid-phase microextraction, pipette-tip solid-phase extraction, stir bar sorptive extraction, and headspace sorptive extraction are described; (d) possible mechanisms of sorbent-analyte interactions as a vital aspect of extraction are also evaluated; and (e) current trends and future prospects in relation to synthesis and application of TDMs and their composites in extraction methods are assessed. The general conclusion that can be drawn from the review is that these versatile materials represent a fertile area of sample preparation research that will continue to be advanced further by analytical chemists. • Synthesis and modification approaches of TDMs and their composites are reviewed. • TDMs and their composites are surveyed and evaluated. • Applications of TDMs and their composites as extraction sorbents are studied. • Possible mechanisms of sorbent-analyte interactions are presented. • Current trends and future prospects of TDMs and their composites are discussed. [ABSTRACT FROM AUTHOR]

Phenotyping of bacteria with vibrational spectroscopy has caught much attention in bacteria-related research. It is known that many factors could affect this process. Among them, solution pH maintenance is crucial, yet its impact on the bacterial SERS spectra is surprisingly neglected. In this work, we focused on two situations related to pH maintenance: the effect of the same buffer on the SERS spectra of bacteria under different pH values, and the influence of different buffers on the SERS spectra of bacteria under the same pH value. Specifically, Britton-Robison (BR) buffer was used to evaluate the effect of pH value on bacteria SERS spectra thanks to its wide pH range. Four different buffers, namely BR buffer, acetate buffer, phosphate buffer, and carbonate buffer, were used to illustrate the impact of buffer types on SERS spectra of bacteria. The results showed that the intensity and number of characteristic peaks of the SERS spectra of Gram-negative (G −) bacteria changed more significantly than Gram-positive (G +) bacteria with the change of pH value. Furthermore, compared with phosphate buffer and carbonate buffer, BR buffer could bring more characteristic SERS bands with better reproducibility, but slightly inferior to acetate buffer. In conclusion, the influence of the pH and types of the buffer on the SERS spectra of bacteria are worthy of further discussion. [ABSTRACT FROM AUTHOR]

The adverse reactions caused by 6-thioguanine (6-TG) in anti-cancer treatment are closely related to the dose, leading to the urgent need for clinical monitoring of its concentration. In this work, a highly reproducible free-standing liquid membrane (FLM) surface-enhanced Raman spectroscopy (SERS) substrate was developed to detect 6-TG in human urine and serum quantitatively. Briefly, a prepared sample was adjusted to pH 2 and mixed with concentrated core–shell bimetallic nanoparticle (AgcoreAushell NP) suspension. The Au/Ag ratio of the AgcoreAushell NPs was optimized. Then the mixture was formed into an FLM using a custom mold. The relative standard deviation (RSD) of the experimental results can be stabilized below 10% (n ≥ 10). The R2 of the calibration curve in the range of 10 ~ 100 μg kg−1 was 0.988. In addition, the limit of detection (LOD) (3σ/k) of 6-TG was 5 μg kg−1. The FLM SERS platform has been successfully applied to the rapid and reliable analysis of 6-TG spiked in body fluids. [ABSTRACT FROM AUTHOR]

The use of lanthanide coordination materials (LnCMs) for photoluminescent sensing is the hot research area, due to their sharp fluorescent emission lines, large Stokes' shifts, and relatively long luminescent lifetime. However, the photoluminescent (PL) efficiencies, stabilities, as well as the sensing selectivity and sensitivities of LnCMs are subtle to interferences, which remains the major challenges that severely bottlenecked their applications. Since Ln(III) presents distinctively high coordination numbers, using auxiliary ligands to occupy the open metal sites have been recognized capable of substantially enhancing the stabilities and PL efficiencies of LnCMs. Moreover, the auxiliary ligands can promote the sensing selectivity and sensitivities via providing high-affinity binding sites and steric effects. Herein, the organic ligands that used for sensitizing Ln(III) are first summarized. Furthermore, the recent progresses of using auxiliary ligands in LnCMs for boosting the structural stabilities, PL efficiencies, as well as the sensing selectivity and sensitivities are discussed. Schematic diagram showing strategies via antenna effect on constructing robust lanthanide photoluminescent materials for chemical sensing. [Display omitted] • The characteristics of lanthanide ions have been described. • The conventional and novel ligands of lanthanide ions have been classified. • The strategies for constructing lanthanide coordination materials with using auxiliary ligands have been summarized. • The application of lanthanide coordination materials on photoluminescent sensing have been introduced. • The future application directions of lanthanide coordination materials have been analyzed. [ABSTRACT FROM AUTHOR]

Abstract: The study describes a flow injection on-line microdialysis system for in vivo monitoring of ergometrine maleate in rabbit blood with fluorescence detection. A flow-through microdialysis probe was used for intravenous sampling by pumping of the blood from the tested rabbit through the flow-through microdialysis probe located outside the living system at a flow rate of 15μlmin−1. The perfusion rate is 5μlmin−1. The ergometrine maleate in the dialysate was detected on-line with a flow injection fluorescence system after the ergometrine maleate administration (0.2mgkg−1, i.v.). The dialysate sample volume was about 15μl. The system was linearly related to the concentration of ergometrine maleate in the range 1–140ngml−1 (r =0.9989) with a detection limit 0.3ngml−1 (3σ). The pharmacokinetic parameters of ergometrine maleate were calculated utilizing the pharmacokinetic software ‘NDST-21’ by a one-compartmental open model. [Copyright &y& Elsevier]

Three-dimensional (3D) titanium dioxide – graphene aerogels (TA-TiO 2 -GA) with network architectures and in-situ growth of TiO 2 NPs onto its surface were facilely self-assembled via one-step hydrothermal treatment by employing tannic acid (TA). TA as the reducing agent and linker promoted a strong coupling between the graphene and TiO 2. The TA-TiO 2 -GA exhibited good photocatalytic performance and reusability in the degradation of typical organic contaminants: upon 3 h simulated solar irradiation, the removal rate of tetracycline, methylene blue and rhodamine B reached 43.2%, 77.8%, and 91.9%, respectively; nearly no deactivation of the TA-TiO 2 -GA was observed after reuse of over10 cycles. Mechanistic studies indicated that the synergy of adsorption and photocatalysis played an important role, and superoxide radical anions and hydroxyl radicals are the major reactive oxidative species. To conclude, this study provides a novel alternative to fabricate 3D TA-TiO 2 -GA which has great potential in solar light-driven environmental applications. [ABSTRACT FROM AUTHOR]

Realizing coordinated control of CO 2 and atmospheric pollutants in comprehensive transportation in large cities is an important way to promote sustainable urban development. Based on the LEAP framework, this study established a transport CO 2 and atmospheric pollutant emission analysis model for Chengdu from 2021 to 2040, set up three main scenarios for the study of carbon peaking trend and 12 sub-scenarios for the study of the synergistic effect of various emission reduction measures. In addition, the synergistic effects were analyzed by radar charts, grading charts of synergistic effects and the synergetic equivalence index. The results show that under the Green Scenario (GS) and the Strengthen Green Scenario (SGS), the CO 2 emissions from comprehensive transportation in Chengdu will peak at 26.774 × 106 t and 23.507 × 106 t in 2032 and 2029, respectively. The emissions of other atmospheric pollutants show a general downward trend. Under SGS, The measures that play the greatest role in reducing CO 2 , CO, VOCs, and NO x emissions by 2040 are NEV (New energy conversion of vehicles), Among them, the CO 2 emission reduction rate relative to BS scenario is 20.7%. While the measures that play the greatest role in reducing PM and SO 2 emissions are IES (Improvement of emission standards) and SRT (Strengthen railway transportation), respectively. Compared with other measures, the synergistic effect of SRT is the most highest. The emission reduction effect of NEV is most significant, with a synergistic effect level above level II. Under the joint regulation of multiple measures by GS and SGS, the synergistic equivalence index based on air quality standards has been effectively controlled, showing a downward trend. Overall, Chengdu faces challenges due to a large number of motor vehicles and air passenger throughput. Therefore, vigorously developing hydrogen vehicles and electric vehicles, strengthening railway construction in Chengdu, transferring the pressure of civil aviation and road transportation to railway, can make significant contributions to the pollution reduction and carbon reduction of Chengdu's transportation sector. [ABSTRACT FROM AUTHOR]

Tricresyl phosphate (TCP), a typical organic phosphorus flame retardant (OPFR), is an emerging pollutant that causes great concern in recent years due to its high neurotoxicity and reproductive toxicity, etc. Conventional analysis methods for TCP such as gas chromatography and liquid chromatography-tandem mass spectrometry exhibit high sensitivity and accuracy. However, these techniques generally suffer from certain limitations, such as high cost, bulky equipment, time-consuming and operator-dependent properties. Therefore, the establishment of fast and efficient analytical methods for TCP still remains a great challenge. A "turn on" fluorescence sensing strategy for the efficient detection of TCP was established, based on a unique molecular rotor probe of 9-(2,2-dicyanovinyl)-julolidine (DCVJ). The introduction of TCP led to a significant enhancement of the fluorescence intensity of DCVJ. The results show that twisted intramolecular charge transfer (TICT) process might play an important role for this enhancement of fluorescence response via dynamic light scattering measurements and fluorescence lifetime analysis. Further investigations demonstrate that the hydrophobic interaction and conjugation effect between DCVJ and TCP constrain the molecular rotation and vibration of DCVJ, thereby regulating the TICT process, which contribute to this intriguing "turn on" behavior. In view of this, a new sensing platform with excellent performance for TCP was established, which offers quick response time, high selectivity, wide linear range (20–1200 ng mL−1, 1600–8000 ng mL−1), and low detection limit (4.82 ng mL−1). The established new sensing platform for TCP demonstrates the advantages of simplicity, high efficiency, excellent sensitivity and selectivity. The obtained results are also superior to some other previously reported fluorescence methods. This work opens up a new perspective for the efficient detection of emerging OPFRs pollutants. [Display omitted] • A "turn on" fluorescence sensing strategy for TCP was firstly proposed. • The hydrophobic interaction and conjugate effect that limited TICT process contributed to the intriguing "turn on" mechanism. • The proposed sensing platform showed excellent analytical characteristics with high sensitivity, selectivity and simplicity. [ABSTRACT FROM AUTHOR]

[Display omitted] • The dual-emission ratiometric fluorescent probe was prepared by a facile hydrothermal synthesis method. • The quantification of Pb2+ was based on the efficient FRET between NCDs and AuNCs. • The sensor has good selectivity and anti-interference ability with satisfactory recovery in real water samples. • A paper-based sensor was fabricated for visual semi-quantitative detection by color change. Ratiometric fluorescent sensors could effectively eliminate the interference of spontaneous fluorescence or instrument fluctuation to improve the analysis sensitivity and accuracy. In this work, a dual-emission nitrogen-doped carbon dots/AuNCs (NCDs-AuNCs) nanohybrid was fabricated under mild conditions by the hydrothermal method, without additional coupling agents, which is facile and environmentally friendly. The prepared nanohybrid was employed for the sensitive detection of Pb2+. The sensor exhibited dual emission peaks at 460 and 625 nm with efficient fluorescence resonance energy transfer under a single excitation wavelength of 360 nm, in which the red fluorescence of AuNCs was enhanced and the blue fluorescence of NCDs was slightly quenched with the presence of Pb2+. The quantitative analysis of Pb2+ was performed upon the change of both fluorescence intensities. The sensor was successfully used for Pb2+ detection in real water samples with satisfactory spiking recoveries in a range of 91.0%–101.3% and low relatively standard deviations (RSDs < 3%), which exhibited good selectivity and anti-interference ability. In addition, a paper-based sensor was fabricated by immobilizing the nanohybrids on filter paper, which enables the visual semi-quantitative determination of Pb2+ by the naked eye through the color transition from blue to pink. The prepared NCDs-AuNCs nanohybrids showed great application potential in environmental water monitoring in an efficient and green way. [ABSTRACT FROM AUTHOR]

• Effect of co-HTC on hydrochar and nutrients from FW and WS blend were investigated. • High temperature and FW ratio decreased the hydrochar yield with low C retention. • High temperature and FW ratio enhanced the carbonization degree of hydrochar. • 10–60% of N and 82–94% of P were retained in hydrochar after co-HTC. The influence of co-hydrothermal carbonization (co-HTC) on the hydrochar properties and nutrients distribution derived from food waste (FW) and woody sawdust (WS) blend was assessed. The carbon retention, surface functional groups and morphology features involved in hydrochar were evaluated to study the interaction effects. Results suggested that hydrochar yield consistently decreased with increase of both FW ratio and HTC temperature. C retention from 260 °C hydrochar was low (approximately 65%), but more microsphere structures was formed due to the enhanced carbonization degree of hydrochar. Hydrochar obtained at high FW blend ratio and temperature resulted in weaken oxygen-containing groups like OH and C O with enhanced C C and C (O, N). 10.43–60.45% of N and 82–94% of P were retained in hydrochar. NH 4 +-N (6.63%–15.63%) and organic nitrogen (70.4%–87.7%) were identified as main N-containing species in liquid phase, while total P content (14–166 mg/L) depended more on FW ratio. [ABSTRACT FROM AUTHOR]

A novel method was developed for the sensitive and visual detection of p-phenylenediamine (PPD) via immobilizing the target specie PPD on dialdehyde cellulose membrane (DCM) followed by the reaction with salicylaldehyde. The obtained solid fluorescent membrane (S-PPD-DCM) emitted yellow fluorescence under 365 nm UV light. DCM was not only used as a solid matrix but also played a vital role in the enrichment of PPD. Experimental variables influencing the fluorescence signal were investigated and optimized. Under the optimum conditions, a detection limit of 5.35 μg L−1 was obtained and two linear ranges were observed at 10–100 and 100–1000 μg L−1, respectively. Moreover, the fluorescence of the resultant membrane can still be visualized by naked eye when PPD concentration was 50 μg L−1. The detection of PPD was hardly affected by the coexistence of 1 mg L−1 of o-phenylenediamine, m-phenylenediamine or p henylamine , exhibiting good selectivity. The developed method involved in a two-step Schiff base reaction and enhanced the fluorescence emission via blocking nonradiative intramolecular rotation decay of the excited molecules. It was applied to determine the PPD in spiked hair dye with satisfactory results. Image 1 • A novel method was developed for the sensitive and visual detection of PPD. • DCM as a solid matrix played a vital role in the enrichment of PPD. • The proposed method gave two linear ranges at 0.01–0.1 and 0.1–1 mg L−1, respectively. • The detection limit of PPD was calculated to be 5.35 μg L−1. • Detection mechanism was involved in two-step Schiff base reaction and AIE effect. [ABSTRACT FROM AUTHOR]

• The fabrication of a cotton-based water disinfection filter was proposed. • Ag NPs-C/CS has excellent bactericidal efficiency against B. subtilis and E. coil. • The filtration rate and the silver release can be manipulated with chitosan coating. • Ag NPs-C/CS was successfully applied to natural water disinfection. In this study, chitosan (CS) coated Ag nanoparticles (Ag NPs) embedded cotton fabric (Ag NPs-C/CS) was prepared by in-situ thermal reduction of AgNO 3 followed by a subsequent coating of porous CS membrane. The introduction of the CS membrane could prevent the excessive release of Ag into the treated water and allow more substantial Ag NPs loading, thereby significantly improving the bactericidal efficiency and stability. With 1.5 wt% of CS, the bactericidal efficiency against Bacillus subtilis and Escherichia coli of the functional material achieved 3.0 and 4.0 log reduction, respectively. Additionally, Ag NPs-C/CS was successfully applied for natural water disinfection, with silver content under 50 µg/L in the processed water. [ABSTRACT FROM AUTHOR]

2,4,6-trinitrotoluene (TNT) sensing on surfaces and in solution is an important issue in sensor fabrication for homeland security and environmental protection. Herein, Play-Doh, a modeling material popular for kids, was proposed as a versatile sensor for on-site fluorescent (FL), visual FL (VFL), and colorimetric detection of TNT both on surfaces and in solution after being doped with –NH 2 through a one-step approach. Play-Doh exhibits FL emission due to the main ingredient of flour. After –NH 2 doping, amino-Play-Doh (APD) was utilized to construct a FL sensor based on FL resonance energy transfer and inner filter effect for TNT detection. The advantage of APD was that no additional fluorophore was needed compared with the traditional sensors for FL and VFL analysis. The orange complex visible to the naked eye was also recorded for smartphone-based colorimetric detection of TNT. In both cases, the APD demonstrated good analytical performance for TNT. Finally, APD was successfully utilized for TNT sensing on fingerprints, luggage, and in environmental water samples, respectively. Play-Doh might be a potential sensor for future on-site detection of TNT owing to the merits of being cost-effective and versatile. Play-Doh, a modeling material popular for kids, was transformed into a versatile sensor for rapid on-site fluorescent (FL), visual FL, and colorimetric detection of TNT both on surfaces and in solution after being doped with –NH 2 through a one-step approach. Image 1 • Play-Doh was transformed into a versatile sensor for TNT sensing via a one-step method. • The proposed sensor could be used for rapid on-site fluorescent (FL), visual FL (VFL), and colorimetric assay, respectively. • TNT sensing on surfaces via visual method was first performed with the proposed sensor. • For FL and VFL analysis, no additional fluorophore was needed due to the flour in Play-Doh. [ABSTRACT FROM AUTHOR]

The availability of sensitive, reproducible, and broad spectral window range surface enhanced infrared absorption spectroscopy (SEIRAS) substrate is essential to the wide application of SEIRAS technique. Here, a facile method was proposed for the preparation of full mid-infrared range transmission surface-enhanced infrared absorption spectroscopy (T-SEIRAS) substrate, where silver nanoparticles (Ag NPs) was synthesized in situ by immersing copper foam into the silver nitrate solution with the help of hydroxylamine hydrochloride. The T-SEIRAS substrate was characterized with Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS). It was found that the spectral window of the substrate was from 600 to 4000 cm−1. The apparent signal enhancement factor of the T-SEIRAS substrate was found to be about 35 times with the utilization of 11-mercaptoundecanoic acid (MUA) as probe molecule. Finally, the T-SEIRAS spectrum of E. coli was successfully obtained. It is expected that this type of T-SEIRAS substrate could be used in inexpensive IR instruments for field sensing applications. • A cost-effective T-SEIRAS substrate for transmission IR analysis was proposed. • The substrate has extraordinary broad spectral window of 600–4000 cm−1. • The apparent signal enhancement of T-SEIRAS for MUA is 35 folds. • The T-SEIRAS spectra of E.coli were obtained. [ABSTRACT FROM AUTHOR]

Herein, a novel solid-phase microextraction (SPME)fiber based on hollow carbon nanobubbles was developed for the analysis of persistent organic pollutants. The hollow carbon nanobubbles (HCNBs), derived from the nanoscale zeoliticimidazolate framework (ZIF-8), not only possessed the ZIF-8-like microporous shell but also created an internal space for analytes storage. This architecture was beneficial to accelerating the mass transfer process and enhancing the enrichment capacity towards target analytes. As a result, the sensitivity of this HCNBs based SPME fiber toward analytes (e.g., BTEX, PAHs and PCBs) was 2–180 times higher compared with the commercial fibers (100 μm PDMS, 65 μm PDMS/DVB or 85 μm PA). In addition, owing to the size-selectivity of the microporous shell, the HCNBs-based SPME fiber showed high extraction ability towards target analytes with low molecule weight. Furthermore, the lifespan of the homemade fiber was evaluated to be more than 100 times attributing to the hard and stable carbon framework. Under optimal working conditions, analytical performance of the fiber towards PCBs with varying chlorination degrees showed a wide linear range (0.05–1000 ng L−1) and low LODs (0.0017–0.0042 ng L−1). Finally, the established method was successfully applied to the determinations of PCBs in three environmental water samples with good recoveries (84.5–117.1%). Image 1 • Hollow carbon nanobubbles (HCNBs) with ultrathin micropores shell were prepared and characterized. • The novel HCNBs-based SPME fiber was fabricated through layer-by-layer coating method. • The HCNBs-based SPME displayed higher extraction performance than the commercial fibers towards different analytes. • The HCNBs-based SPME exhibited size-selectivity and was successfully applied for PCBs detection in real water samples. [ABSTRACT FROM AUTHOR]

With the in-depth study of nanozymes, the specificity and catalytic activity of nanozymes still need to be improved for their diverse applications. Here, we report the preparation of Fe/C/Bi 2 O 3 by thermal activation of Fe-doped Bi MOFs (FeBi MOFs) under an air atmosphere. It is found that the Fe/C/Bi 2 O 3 has excellent peroxidase mimic activity due to the synergistic effect between two metals, while Fe is the crucial catalytic active site. The presence of abundant carboxyl groups gives it a high affinity for H 2 O 2 with a low K m of 0.076, which is about 49 times lower than that of HRP. The results of radical quenching and ESR experiments indicate that the main reactive oxygen species during TMB oxidation reaction are •OH and O 2 •–. By combining Fe/C/Bi 2 O 3 nanozymes with two natural enzymes, i.e., acetylcholinesterase (AChE) and choline oxidase (ChOx), a three-enzyme (Fe/C/Bi 2 O 3 , AChE, ChOx) cascade system is proposed for the colorimetric sensing of dichlorvos with a wide linear range from 0.60 to 100 μg L−1 and a low limit of quantitation of 0.60 μg L−1. This work not only provides a new strategy for the design and preparation of high activity Fe/C/Bi 2 O 3 nanozymes, but also demonstrats their potential use in environmental analysis. [Display omitted] • Fe/C/Bi 2 O 3 with uniform element distribution is prepared by thermal activation of FeBi MOFs. • Fe/C/Bi 2 O 3 has a strong affinity for H 2 O 2 substrates. • A sensitive and selective detection strategy for DDVP was proposed. [ABSTRACT FROM AUTHOR]

The accumulation of antibiotics in aquatic environments poses a serious threat to human health. Photocatalytic degradation is a promising method for removing antibiotics from water, but its practical implementation requires improvements in photocatalyst activity and recovery. Here, a novel graphite felt-supported MnS/Polypyrrole composite (MnS/PPy/GF) was constructed to achieve effective adsorption of antibiotics, stable loading of photocatalyst, and rapid separation of spatial charge. Systematic characterization of composition, structure and photoelectric properties indicated the efficient light absorption, charge separation and migration of the MnS/PPy/GF, which achieved 86.2% removal of antibiotic ciprofloxacin (CFX), higher than that of MnS/GF (73.7%) and PPy/GF (34.8%). The charge transfer-generated 1O 2 , energy transfer-generated 1O 2, and photogenerated h+ were identified as the dominant reactive species, which mainly attacked the piperazine ring in the photodegradation of CFX by MnS/PPy/GF. The •OH was confirmed to participate in the defluorination of CFX via hydroxylation substitution. The MnS/PPy/GF-based photocatalytic process could ultimately achieve the mineralization of CFX. The facile recyclability, robust stability, and excellent adaptability to actual aquatic environments further confirmed MnS/PPy/GF is a promising eco-friendly photocatalyst for antibiotic pollution control. [Display omitted] • A free-standing composite with superior photocatalytic activity was constructed. • Parameters governing ciprofloxacin (CFX) photocatalytic degradation were discussed. • The 1O 2 and h+ were the dominant reactive species for CFX photocatalytic degradation. • Piperazine ring opening and hydroxyldefluorination were the key degradation pathways. • Excellent adaptability of photocatalyst to actual aquatic environments were obtained. [ABSTRACT FROM AUTHOR]

We present for the first time a SERS based microbial sensor for assessing acute freshwater toxicity. The assay is based on indole, which is synthesized in many Gram-positive and Gram-negative bacteria by L-tryptophan via tryptophanase (TnaA). In the presence of external toxic substances in the microbial growth environment, microorganisms' respiratory and metabolic functions are inhibited at varying degrees, leading to a decrease in indole production. We used SERS to monitor the conversion of L-tryptophan to indole and thus assess the toxic effects of toxic chemicals on E. coli. Two other factors affecting bacterial metabolism were also explored: L-tryptophan concentration and its incubation time with E coli. Copper was chosen as a simulated toxicant to assess the method's effectiveness for acute toxicity in freshwater. The IC 50 of Cu2+ was found to be 2.028 mg/L, which showed a significant improvement in sensitivity compared to other methods. [Display omitted] • A SERS based biosensor method for water acute toxicity evaluation was firstly proposed. • The method is based on the indole producing capability of E coli bacteria. • Acute toxicity assessed using indole concentration change upon introducing toxic chemical. • The toxicity of model ion Cu2+ was determined with an IC 50 of 2.028 mg/L. The substances emerging in environmental water bodies are becoming increasingly complex, causing severe ecotoxicological problems. In addition, the intricate interaction among various chemicals in a water body makes it difficult to accurately evaluate the water quality by simply determining the specie and concentration of the chemicals. Thus, acute toxicity evaluation of water body presents significant importance in environmental monitoring, especially in emergency response. This work proposes a SERS approach for evaluating acute toxicity of fresh water for the first time, where indole, an interspecies signal molecule produced by E. coli strains during regulated spore formation, could be affected by toxic substances, was used as indicator. Several key factors that may affect the evaluation of acute toxicity in water were explored, including the concentration of exogenous L-tryptophan and the incubation time of E. coli with L-tryptophan. Finally, the established system was applied to the acute toxicity evaluation of model chemical Cu2+. The IC 50 was determined to be 2.028 mg L-1, better than the results reported in the literature. This study demonstrates the feasibility of using SERS-based microbial sensors to assess acute toxicity in water. [ABSTRACT FROM AUTHOR]

[Display omitted] • A highly efficient sensing strategy for TNBP was reported. • The CL mechanism for signal amplification of Ce4+/SO 3 2- system was investigated. • TNBP molecules induce the enhanced generation of HSO 3 • - radicals and amplified CL emission. Tributyl phosphate (TNBP) with remarkable biological neurotoxicity and genotoxicity is a typical organophosphate flame retardant (OPFR) emerging contaminant, which has been found frequently in water, atmosphere, and solid, etc. It is important to explore efficient sensing strategies for TNBP. Herein, a direct Ce4+/SO 3 2- chemiluminescence (CL) system for efficiently and sensitively detecting TNBP flame retardant has been developed. The CL mechanism was uncovered by exploring reactive oxygen species (ROS), the emitting species, and reaction products. The results demonstrate that TNBP molecules induce the enhanced generation of HSO 3 • - radicals in Ce4+/SO 3 2- system, and a large amount of SO 2 * are subsequently generated, which account for the amplified CL emission. In view of this, a novel CL sensor for TNBP is established, which shows the advantages of fast determination, great selectivity, wide linear range (50–10000 ng mL−1), low limit of detection (13.61 ng mL−1), and good precision (RSD < 4.67%, n = 13). This work further provides an interesting perspective for direct CL behavior of OPFRs, and paves the way for the real-time monitoring of emerging pollutants. [ABSTRACT FROM AUTHOR]

[Display omitted] • Magnetic activated carbon ballasted coagulation (MAC-BC) process was proposed. • Superior coagulation performance and enhanced antibiotic removal were achieved. • Response of floc properties to MAC ballasting was characterized in real-time. • MAC played a dominant role in antibiotic removal rather than the coagulant. • The mechanism of MAC ballasting to enhance antibiotic removal was deciphered. Removal of antibiotics from wastewater is extremely important for the reduction of antibiotic resistance-related risk and safe water reuse. Coagulation is a promising approach for this purpose, but its practical implementation requires further upgrades in coagulation performances and antibiotics targeting. Here, the magnetic activated carbon ballasted coagulation (MAC-BC) process was proposed to enhance the coagulation process and antibiotic sulfamethoxazole (SMX) removal. Response surface curves indicated that MAC played a dominant role in SMX removal rather than coagulant. The MAC ballasting promoted the removal of DOC and SMX in the coagulation process by 1.4 and 1.6 times, which was attributed to hydrogen bonding interaction, π-π electro-donor-accepter interaction, and surface complexation introduced by COOH/C–O, C C, and Fe–O/Al–O in the MAC flocs, respectively. MAC could serve as nuclei and readily bound to the hydrolyzed Al species, resulting in the formation of larger Al-species-induced primary clusters. The ratio of OH/Al on the surface of MAC-BC flocs was higher than that of the flocs generated in the single coagulation process. The higher binding ability with MAC addition facilitated the aggregation of primary clusters and increased the floc size by 1.3 times, which further accelerated floc settling and separation. The multiple functions of MAC ballasting enhanced the coagulation process and promoted SMX removal. This study opens a new avenue to upgrade traditional coagulation and adsorption processes. [ABSTRACT FROM AUTHOR]

In this study, a versatile dual-functional polydimethylsiloxane (PDMS) sponge Surface Enhanced Raman Scattering (SERS) substrate has been fabricated for the on-site detection of pesticide residues both on the surface and in solution with minimum or no sample pretreatment. The PDMS sponge was fabricated using white granulated sugar and soft white sugar as pore-forming reagents. Later, multiple rounds of Ag NP deposition were performed by incubating the PDMS sponge in the Ag NP solution with the help of 3-mercaptopropyltrimethoxysilane (APTMS). The highest SERS enhancement was achieved through 2 rounds of Ag NP deposition. Under optimum conditions, with Rhodamine 6G (R6G) as the probe molecule, the limit of detection (LOD) reached 2 femtomoles (20 μL at a concentration of 100 pM). The analytical performance for potential on-site applications of the substrate has been demonstrated with pesticide-spiked agricultural products taken as examples. Without sample pretreatment, the pesticide triazophos and methyl parathion were successfully detected by swabbing on the fruit surface with LODs of 0.79 ng and 1.58 ng, respectively. In addition, the lowest detected concentrations of triazophos and methyl parathion in fruit juice were found to be 100 ppb and 1 ppm. More importantly, the PDMS sponge SERS substrate can be safely stored for 36 days without affecting its SERS activity. [ABSTRACT FROM AUTHOR]

In this study, silver nanoparticle decorated chitosan (CS/Ag NP) cryogels were fabricated through a simple freeze-drying process for point-of-use (POU) water disinfection. The CS/Ag NP cryogels showed high porosity, good mechanical properties, an excellent water absorption capability, and most importantly, an efficient bactericidal feature. The absorption capacity for water was found to be 47 g/g, approximately 90% of which was recovered by simple squeezing. Three different sizes of Ag NPs were compared regarding their bactericidal capability against both Escherichia coli ( E. coli ) and Bacillus subtilis ( B. subtilis ). Under optimum conditions, a 3 log reduction of bacteria was observed by holding the bacteria suspension (10 8 colony forming units (cfu)/mL) in the cryogels for 5 min. Reduction was further increased to a 4 log when the contact time was doubled. The silver content in the cryogels was found to only be 7.5 mg/g. Furthermore, the total Ag in processed water was found to only be 22 μg/L, half of the safety limit set by China (< 50 μg/L). The bactericidal effectiveness of the material for real surface water samples was also demonstrated by treating water samples with different water quality matrices, including lake water and sewage water samples. In all three treated lake water samples, both the total bacteria and E. coli met the regulations for drinking water in China (< 100 cfu/mL for total bacteria and negative for E. coli ). CS/Ag NP cryogels can be used for drinking water disinfection during disaster relief and in contingency water supply applications. [ABSTRACT FROM AUTHOR]

• Industrial wastewater sourcing was first realized with multi-wavelength SERS. • The superiority of SERS in wastewater information capturing was confirmed by PCA. • 1D-CNN shows excellent performance in SERS signature extraction for sourcing. • The wastewater can be identified from unknown samples with 97.33% accuracy. The spectral fingerprint is a significant concept in nontarget screening of environmental samples to direct identification efforts to relevant and important features. Surface-enhanced Raman scattering (SERS) has long been recognized as an optical method that can provide fingerprint-like chemical information at the single-molecule level. Here, the advanced one-dimensional convolutional neural network (1D-CNN) approach was applied to accurately identify the SERS spectral signature of industrial wastewaters for source tracing. A total of 66,000 SERS spectra were acquired from wastewaters of 22 factories across 10 industrial categories at three excitation wavelengths after data augmentation. The dataset was used to train a 1D-CNN model consisting of three convolutional layers to achieve adequate feature extraction of SERS spectra. As a proof-of-concept, multimixed wastewater samples were used to simulate practical pollution scenarios and evaluate the application potential of the model. The SERS-1D-CNN platform can identify the amount and factory information of wastewaters in multimixed samples, which achieves a recognition accuracy rate of 97.33%. The results suggest that even in a complex and unknown water environment, the 1D-CNN model can accurately identify industrial wastewaters in precollected datasets, exhibiting excellent potential in pollution source tracing. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A dual-mode pyrene-based Zr-MOF was constructed to realize fluorescence "turn-on" in alkaline, and "turn-off" in acidic conditions. • The pyrene-based Zr-MOF fluorescence detection of alkaline pH liquid was established. • Detection method of pH film sensor by embedding the MOF particles into the PVA substrate was developed using smartphone detector. Rapid detection of on-the-spot water sample pH has become an urgent problem to resolve, and developing a method with the characters of fast, convenient and low-cost is significant. In this study, an amino functionalized pyrene-based Zr-MOF (NU-1000-NH 2) was synthesized by solvent-assisted ligand incorporation (SALI) method, in which the Zr 6 metal cluster, fluorescent pyrene-based H 4 TBAPy and p -aminobenzoic acid were acted as node, linker and modulator, respectively. The as-synthesized NU-1000-NH 2 possessed the pH-dependent fluorescence enhancement property at 450 nm emission under alkaline condition, thus a convenient fluorescence "turn-on" pH sensor was fabricated. Upon introduction of OH–, the carboxylate groups in NU-1000-NH 2 could react with it, and the deprotonation and gradual collapse of the NU-1000-NH 2 crystal were occurred, resulting in the release of the fluorescent H 4 TBAPy ligand and fluorescence enhancement. Moreover, to solve the difficulties of on-the-spot pH detection, the solid-phase pH film sensor was successfully constructed by embedding the NU-1000-NH 2 particles into the polyvinyl alcohol (PVA), combining with the RGB model and smartphone detector. The proposed fluorescent MOF-based pH sensor with dual-mode detection is expected to achieve on-the-spot pH monitoring in the field of environmental monitoring. [ABSTRACT FROM AUTHOR]

• Proposing comprehensive experiments investigating pH stress effect on nitrification. • Disclosing reactive inhibitory mechanism dominating in acid range. • Revealing hybrid pH stress effect with free ammonia. • Gaining a panoramic view understanding pH stress effect on nitrification. pH is a crucial factor of microbial nitrification, which often combines with high-strength ammonium to influence nitrogen removal pathway in wastewater treatment. However, the detailed inhibitory mechanisms of pH stress are not sufficiently disclosed yet. In this study, the pH stress effect on nitrification was comprehensively studied by a set of experiments which identified the reactivity of nitrification processes and activity of nitrifiers, the time dependence of inhibition effect and the hybrid pH stress effect with ammonium. The results revealed two distinct inhibitory mechanisms dominating in alkaline and acid ranges. In alkaline range (pH > 8), pH stress causes physiological damages on microorganisms which is named as microbial inhibition. It has the features of less recoverability of nitrifiers, time-dependent inhibition effect and low pH-tolerance of nitrite oxidation bacteria. Free ammonia enhanced microbial inhibition and greatly promoted nitrite accumulation. A novel reactive inhibition mechanism dominated in acid range (pH < 7) was disclosed. It only impedes ammonia oxidation process (AOP) but not impair microbial activity obviously and the effect is time-independent. The mechanism was clarified from H+ transport because AOP involved H+ production. The H+ transport was impeded under acid stress owing to the decrease of pH gradient across cell membrane. The two mechanisms formed a panoramic view of pH stress effect on nitrification advancing the understanding of nitrifier adaptability and nitritation regulation in wastewater treatment processes. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A UV-induced CL sensing platform based on PMS and luminol was established. • CL inhibition mechanism triggered by competitive consumption of ROS was proposed. • This CL sensor demonstrated excellent analytical performance with rapid determination, high selectivity and sensitivity. Organophosphate flame retardants (OPFRs) are emerging contaminants that cause great concern, and triphenyl phosphate (TPHP) with an extremely serious biotoxicity is a representative harmful OPFR. It remains a great challenge to develop real-time sensing strategy for TPHP. Herein, a UV-induced chemiluminescence (CL) sensing platform with potassium monopersulfate (PMS) as the source of reactive oxygen species (ROS) is established. Extraordinary CL emission can be generated due to the oxidation of luminol by ROS (e.g., SO 4 − and OH) from the UV-activated PMS. More importantly, the CL emission is greatly inhibited with the introduction of TPHP. Mechanism investigation for CL inhibition effect shows that, TPHP reacts with these ROS, leading to the obvious competitive consumption of ROS, and thus the oxidation degree of luminol is significantly impaired. Based on this, a new CL platform for the sensing of TPHP is fabricated, which demonstrates the advantages of simple operation, rapid determination, miniaturization potential, high selectivity and sensitivity, and grants the limit of detection down to 42.3 ng/L. This interesting work paves the way for the fast discrimination of emerging contaminants, and exhibits great prospects in real-time environmental monitoring. [ABSTRACT FROM AUTHOR]

Tricresyl phosphate (TCP), a notable emerging pollutant with a high bioconcentration factor and biotoxicity, is a typical representative of aryl-organophosphorus flame retardants. The electrochemical and chromatographic technologies used in conventional TCP detection have a variety of drawbacks. Hence, it is crucial to suggest an easy, accurate, and selective method for detecting TCP. In this study, we presented a brand-new method based on NH 2 -MIL-53(Al) nanoprobe for the direct luminescence assay of TCP. NH 2 -MIL-53(Al) possessed an excellent crystal structure and superior optical qualities. Notably, the introduction of TCP caused a considerable dampening of the photoluminescence signal of the nanoprobe. The fluorescence response based on static quenching was verified by fluorescence lifetime decay curves. The thermodynamic analysis further concluded that TCP and nanoprobe spontaneously produced non-fluorescent complexes due to hydrophobic interaction. The quenching efficiency (F 0 –F)/F 0 of the nanoprobe and the TCP concentration displayed good linearity in the scope of 0.3–3.0 μM (R2 = 0.996), and the LOD was 0.058 μM under the ideal detection conditions. More significantly, the technique was effectively used to identify TCP in lake and tap water (RSD ≤5.79%), which provided a fresh perspective on how to recognize OPFRs in environmental water. A novel fluorescence turn-off sensing platform of Al-based MOF for the determination of tricresyl phosphate (TCP) has been developed. [Display omitted] • The first work using fluorescence analysis to directly detect TCP was pioneered. • The method could identify TCP with high selectivity and a low LOD of 0.058 μM. • TCP and Al-MOF formed non-fluorescent complexes via hydrophobic interaction. [ABSTRACT FROM AUTHOR]

The development and construction of fluorescent sensors with high sensitivity for nitroaromatics explosives detection is of great significance for national security and public environmental issue. Herein, the mechanism of photoinduced electron transfer (PET) was utilized to design a newly amino-functionalized luminescent Zr-based metal-organic framework (NU-1000-NH 2) for ultra-sensitive fluorescent detection of nitroaromatic explosives, like 2,4,6-trinitrotoluene, 2,4-dinitrotoluene and 2-nitrotoluene. The amino constructed in cavities of NU-1000-NH 2 can be served as recognition site to capture and bind the nitroaromatic molecules. Thus the rational design of NU-1000-NH 2 has been proven an effective route to recognize the electron-deficient nitroaromatic explosives, causing fluorescence quenching of NU-1000-NH 2 due to the electron donor (–NH 2)–acceptor (-NO 2) interaction. Moreover, hydrogen-bonding effect of intermolecular N –H···O analyte between NU-1000-NH 2 and analytes was also found assisting for binding and recognizing of nitroaromatic explosives molecule. And the density functional theory (DFT) calculations were conducted to further investigate and quantitatively assess the molecule orbitals (MOs), interaction energies and electrostatic potential map, revealing the electron transfer process from conduction band (CB) of MOF to LUMO of nitro analytes and stronger interaction effect was obtained with more nitro groups of NEs. This study provided a feasible idea to design functionalized fluorescent MOFs for nitroaromatic explosives sensing based on PET and hydrogen-bonding effect. [Display omitted] • Fluorescence quenching mechanism of PET is successfully applied in the functionalized MOF design for fluorescent sensing. • DFT theoretical calculation is used to discuss molecule orbitals, hydrogen bonding and electrostatic interaction effect. • Interaction effect of host-guest hydrogen bonding could be evaluated by experiments and theoretical calculation. • Highly sensitive detection of Higher K sv and lower limits of detection (LODs) for multiple nitroaromatic explosives. [ABSTRACT FROM AUTHOR]

A novel fluorescence turn-off sensing strategy for I− ions detection was developed based on the internal filtering effect between CDs and iodide-induced aggregation His-AuNCs. [Display omitted] • An ultrasensitive sensing strategy for iodide detection was proposed. • His-AuNCs and iodide form ground-state complexes that block the CDs' fluorescence. • A new insight into I− ions determination with CDs/His-AuNCs is presented. In this work, a novel fluorescence turn-off sensing strategy for I− ions detection was developed. The fluorescence of CDs/His-AuNCs hybrid probes was effectively turned off by I− ions. It was attributed to the internal filtration effect between the fluorescence emission peak of CDs and the absorption spectrum of His-AuNCs enhanced by I− ions. Quantitative analysis of I− ions can be achieved by analyzing the fluorescence quenching degree of CDs/His-AuNCs. Under the optimal experimental conditions, it exhibited good linearity in two concentration ranges of I− ions: 0.1–5.0 μM and 5.0–60.0 μM (low detection limit = 34 nM). The established sensing platform has been successfully exploited for the detection of I− ions in practical water samples. This work provided new insight into the determination of anions using fluorescent nanoparticles. [ABSTRACT FROM AUTHOR]

More attention is being paid to the environmental analysis because of the increasingly serious environmental pollution. Due to the superiority of low interference, excellent sensitivity, rapidness, and simple construction, chemiluminescence (CL) has evolved into a powerful technique for pollution analysis. Recently, nanomaterials such as MOFs, BPQDs, CDs, MoS 2 , LDHs, and noble metal NPs, have been exploited to further amplify the CL radiation, owing to their wide surface area, unique photoelectric properties, and excellent reactivity. Much encouraging progress in environmental analysis utilizing nanomaterial-based CL has been made. However, a comprehensive summary concentrated on the application of nanomaterial-based CL for environmental analysis is still lacking. In this review, the recent advances of nanomaterial-based CL in environmental pollutant analysis for typical harmful substances are summarized during the last 5 years, including inorganic ions, ROS, antibiotics, and pesticides, etc. Ultimately, the key challenges and further prospects in this exciting area are also highlighted to promote the advancement of environmental analysis. • Main types and sensing principles of nanomaterials used in chemiluminescence systems are summarized. • Applications of nanomaterial-based chemiluminescence in environmental pollutant analysis are reviewed. • Key challenges and further prospects of this nanomaterial-based chemiluminescence are proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Surface modification of SERS nanomaterials can modulate the spectra of analytes and bring richer information. • Combining the modulated SERS spectra with multivariate analysis, structure similar fluoroquinolones antibiotics can be discriminated. • The SCA outperforms PCA in terms of spectral differentiation and identification. Surface-enhanced Raman spectroscopy (SERS) stands out in chemical analysis due to its rich molecular information, fast analysis speed, and high sensitivity. However, the differentiation of structural-similar chemicals is still challenging due to their similar SERS profiles. In this work, multivariate analysis (PCA and SCA) was combined with SERS for the differentiation and identification of highly similar chemicals using surface-modified SERS nanomaterials (MUO@Ag NPs), where three structural similar fluoroquinolone antibiotics (Norfloxacin, Ofloxacin, and Ciproflxacin) were used as examples. Due to their close molecular structure, the three chemicals showed very similar SERS spectra, with main feature located at 1394 cm−1. Introducing surface modification of the SERS substrate (MUO@Ag NPs) brought richer spectral information than the pristine ones. The performance of the two chemometric methods (PCA and SCA)was then compared using the MUO@Ag NPs as SERS substrate. SCA was found superior in identifying and differentiating these chemicals compared with widely adopted PCA analysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Cu-NCDs exhibited stronger fluorescence emission peaks benefiting from the Cu doping. • Selective and sensitive detection of Fe3+ and TC were achieved based on Cu-NCDs. • The total Fe in the detection system was realized by adding H 2 O 2 into the Cu-NCDs. • The Cu-NCDs were applied in the detection of Fe3+ and TC in real water samples. This paper synthesized carbon dots (Cu-NCDs) doped with nitrogen and copper, which could be used as a sensor for measurement of Fe3+ and tetracycline (TC). The average particle sizes of CDs and Cu-NCDs were determined as 3.9 nm and 4.8 nm, respectively. The presence of carbon, oxygen, nitrogen and Cu atoms was confirmed in the structure of Cu-NCDs. Both CDs and Cu-NCDs exhibited a strong fluorescence (FL) emission peak at 450 nm, but the doping of Cu and N makes the surface of Cu-NCDs positively charged, which enhances the fluorescence intensity. The carbon dots doped with copper had more significant optical effects than those doped with other metals, and the relative quantum yield (QY) of the Cu-NCDs was as high as 53.6%. Cu-NCDs can be used as multi-functional fluorescent probes to selectively detect Fe3+ and TC based on fluorescence quenching. The limit of detection of Fe3+ and TC separately was found as 1.189 µM and 0.416 µM. This probe is also suitable for the indirect determination of Fe2+ because the Fe2+ is oxidated to Fe3+ by H 2 O 2. The mechanisms of the quenching process for Fe3+ and TC were explored that is the complex process of dynamic quenching and static quenching based on internal filtration effect (IFE), respectively. The fabricated sensors were successfully applied to determine Fe3+ and TC in tap and lake water samples, suggesting a promising application in environment analysis. [ABSTRACT FROM AUTHOR]

Carbon emission trading, a market-incentive environmental regulation, plays a critical role in leading China towards the carbon peaking and carbon neutrality. To improve the national carbon emission trading in China, we analyze the effects of the policy in pilot provinces and pilot A-share listed firms from 2008 to 2016. Particularly, to explore the pilot policy's environmental and financial impacts, this paper applies a difference-in-difference method. After the robustness check, the results confirm the carbon emission trading pilot's significantly positive impact at both firm- and province-level regarding carbon emission reduction. Meanwhile, corporate innovation seems to partially mediate the relationship between the policy and corporate carbon emission reduction. Plus, the policy promotes firms' market-based financial performance but such impact on accounting-based financial performance is insignificant. Ultimately, the operational mechanism of the policy is proved to be effective. In this paper, industry- and firm-level carbon emissions databases are established via environmental extended input-output table, which fill the research gap of China's firm-level carbon emissions. To ensure the reliability of results, the list of covered firms is sorted out manually in accordance with the disclosed data of seven carbon trading markets. Our results are meaningful for avoid productivity reduction and mechanism re-design in the context of the national carbon emission trading launched in 2021. Specifically, encouraging firms to further improve their productivity and competitiveness by innovation could eventually achieve a win-win situation between economic performance and environmental merits in the long run. [ABSTRACT FROM AUTHOR]

[Display omitted] • A pumice-based solid visible light responsive photocatalyst PS@rGO@MnO 2 was successfully synthesized. • PS@rGO@MnO 2 has an effective removal effect on ciprofloxacin in natural surface water under sunlight. • The degradation mechanism and transformation pathway of ciprofloxacin, as well as the ecotoxicity of intermediate products were proposed. • PS@rGO@MnO 2 material has good stability and convenient recycling. The agglomeration and recycling of nano-photocatalytic materials are still a big problem restricting the practical application of photocatalytic technology. Natural porous pumice with adsorption capacity provides an innovative approach to this challenge. Herein, the pumice supported reduced graphene oxide and MnO 2 (PS@rGO@MnO 2) was designed as a visible-light-driven solid photocatalyst. The PS@rGO@MnO 2 possessed good photocatalytic performance, and the removal rate of ciprofloxacin (CFX) reached 80.00% with simulated solar irradiation for 6 h, and the degradation rate constant was 4.2 times that of blank pumice. The degradation rates of CFX in secondary effluent, lake water, and river water can reach 62.15%, 68.33%, and 67.63%, respectively. Hole (h+) and superoxide radical (O 2 −) are the main reactive oxygen species. The material test results revealed that the enhanced photocatalytic performance of PS@rGO@MnO 2 was due to the improvement of light utilization rate, the reduction of electron-hole pair recombination rate, and the improvement of charge separation efficiency and transfer efficiency. ECOSAR model predictions indicate that CFX can effectively reduce toxicity in photocatalytic reactions. The removal performance of actual natural water verified that the material was of great practical application potential. [ABSTRACT FROM AUTHOR]

An aggregation-induced emission copper nanoclusters fluorescence probe (TA-CuNCs@CTAB) was designed for the detection of tetracycline (TC) based on the turn-off fluorescence intensity. [Display omitted] • An aggregation-induced emission copper nanoclusters fluorescence probe (TA-CuNCs@CTAB) was designed. • TA-CuNCs@CTAB fluorescence probe can detect TC in environment samples with high accuracy and good selectivity. • The detection mechanism is the internal filtration effect (IFE) of TA-CuNCs@CTAB induced by TC. Copper nanoclusters (CuNCs) is a promising fluorescent material for water detection with unique fluorescence characteristics and low cost. To boost the fluorescence characteristics of CuNCs, cetyltrimethylammonium bromide (CTAB) modified material has the ability to improve the sensitivity, selectivity and sensing performance of the probe. Herein, fluorescence-enhanced copper nanoclusters (TA-CuNCs@CTAB) based on the tannic acid templated is designed due to the electrostatic interaction between CTAB and TA-CuNCs, the addition of CTAB induced the aggregation of TA-CuNCs, and the enhancement of fluorescence signal was achieved using the aggregation-induced emission (AIE) mechanism. As a new fluorescent probe (TA-CuNCs@CTAB) for tetracycline (TC) turn-off detection, it has satisfactory linearity in the two ranges of 5–50 μM and 50–130 μM, with a detection limit of 65 nM. The detection mechanism is that the internal filtration effect (IFE) of TA-CuNCs@CTAB induced by TC leads to a significant fluorescence quenching. Therefore, this method is used to detect TC in actual water samples, which is more convenient to operate, has high accuracy and good selectivity, and has a good application prospect in detecting TC. [ABSTRACT FROM AUTHOR]

SERS optrodes were used to “fish” aqueous drops from superhydrophobic surfaces. The technique led to an improvement of 2–3 orders of magnitude in the lowest detectable amount of the Raman probe nile blue A, reaching 25 fg (34 attomoles). Further tests run on samples containing pesticide revealed that 20 pg of triazophos could be clearly detected from a single drop. [ABSTRACT FROM AUTHOR]

This work reported an economical and sensitive fluorescence sensor for mercury (II) ions based on the cetyltrimethylammonium bromide-mediated nitrogen-doped carbon dots (NCDs). The NCDs, obtained by a solvothermal method, exhibit emission with low quantum yield (6%) that can be quenched by various ions such as Cu2+, Cr6+, Co2+, and Hg2+. After adding cetyltrimethylammonium bromide (CTAB), the two produced aggregation-induced fluorescence effect, coupled with electrostatic interaction, and the quantum yield increased to 32%. The spatial structure formed by CTAB/NCDs could selectively capture Hg2+ and make interact with the surface groups of NCDs to cause fluorescence quenching. The fluorescence intensity and Hg2+ concentration showed a linear response in the range of 0.15–1 mM and 0.16–10.24 μM (R2 = 0.998), and the detection limit was 85.71 nM. The fluorescent sensor was used to determine Hg2+ in environmental waters with satisfactory results. [Display omitted] • Structure property and fluorescence performance study of CATB modified carbon dots. • NCDs functionalized by CTAB have an aggregation-induced fluorescence effect. • The fluorescence intensity and quantum yield of CTAB modified NCDs were improved. • The sensor could selectively capture Hg2+ and be applied for practical detection. [ABSTRACT FROM AUTHOR]