Search

Sulfidated zerovalent iron (S-ZVI) has been extensively used for reducing pollutants. In this study, the oxidation process in the reductive removal of p-nitrophenol (PNP) by S-ZVI was confirmed under anaerobic conditions. We revealed that a PNP oxidation process involving •OH resulted from the H2O2 activation by surface-bound Fe(II) in S-ZVI, in which H2O2 was generated via a surface-mediated reaction between water and FeS2. Only the PNP reduction process occurred for ZVI. Herein, efficient PNP degradation by S-ZVI resulted from two functions: reduction into p-aminophenol due to enhanced electron transfer and PNP oxidation into p-benzoquinone by •OH radicals from the interaction of surface-bound Fe(II) and in situ generated H2O2, the contributions of the oxidation and reduction processes to PNP degradation over S-ZVI were 10 and 90%, respectively. Sulfur in S-ZVI suppressed the pH increase in the reaction media and produced more surface-bound Fe(II) than ZVI for •OH generation via the heterogeneous Fenton reaction process. Since different degradation pathways could lead to different effects on the water environment, such as toxicity, our findings suggest that the oxidizing process induced by S-ZVI during groundwater decontamination should be considered.

Sulfidation can greatly improve the efficiency of utilization of reducing equivalents for contaminant removal; however, whether this method benefits Fenton-like reactions or not and the possible mechanism are not well understood. In this study, we revealed that surface sulfidation can greatly promote the heterogeneous Fenton activity of β-FeOOH (Fe

Due to the extremely low concentration, complex composition and easy to be converted into each other in water and air of water-soluble volatile organic compounds (VOCs), it is a great challenge to the traditional detection technology, pollution control and traceability, etc. Therefore, developing a convenient, swift and on-site detection method for simultaneous quantification of multiple VOCs is highly anticipated. In this paper, a multifunctional sensor array with adsorption and sensing of VOCs has been constructed by four fluorescence channels of small-sized Eu@Uio-66 and Tb@Uio-66. Due to the obvious cross-reactive characteristics between 4 fluorescence channels and VOCs, the sensor array could detect 8 VOCs simultaneously with all detection limits as low as ppb level. In addition, the detection results of sensor array for actual water samples coexisting with multiple VOCs confirmed that it has strong anti-interference performance and could be used for simultaneous detection of multiple VOCs in real water. The construction of sensor array with VOC adsorption function not only helps to reduce the detection limit of VOCs benefiting from the pre-concentration of materials, but also has significant value to reduce the harmfulness of pollutants. Predictably, this work is of great significance for VOC traceability, analysis of ecotoxicological effects and monitoring of pollution distribution characteristics.

Aniline has attracted much concern for its long degradation half-life and huge toxicity to the environment and human beings. Therefore, the development of a multi-functional device for visual detection and efficient removal of aniline was highly anticipated. In our work, the small-size Eu@UiO-66(COOH) was obtained by post-synthesis modification (PSM), and then the film-based fluorescent sensor was prepared by crosslinking reaction. The films not only showed incredible mechanical stability and potential for large-scale preparation, but also have excellent fluorescence response to aniline in solutions and gas phase. As the concentration of aniline increased, the fluorescence of films gradually increased at 350 nm, while the fluorescence gradually quenching at 620 nm, and the detection limits (LOD) of aniline in water and air were 0.27 ppb and 0.086 ppb, respectively. In addition, the adsorption performance of the film for aniline has also been confirmed and the maximum adsorption capacity was 32.6 mg/g, which is a strong guarantee for the realization of ultra-trace detection and toxicity reduction of aniline. In summary, the multi-functional film sensor has been designed for ultra-trace detection and efficient removal of aniline in solutions and gas phase, and have significant value for pollutant treatment, ecological restoration and early prevention.

Sulfur quantum dots are promising alternatives for traditional heavy metal-containing quantum dots due to their benign chemical properties and low cytotoxicity. Herein, cysteine-decorated sulfur dots were prepared from facile modification of pristine sulfur dots and can be acted as a chemosensor for the fluorometric and colorimetric dual-channel detection of cobalt (Co2+) with high sensitivity and selectivity. Visual colors of the as-prepared chemosensor in the presence of Co2+ changed from blue to colorless under UV light and also can transform from colorless to yellow under sunlight based on the photoinduced electron transfer effect. The detection limit of cysteine-decorated sulfur dots toward Co2+ was determined as low as 0.16 μM with a wide detection range, which is lower than the permitted guideline level by Department of Environmental Protection for drinking water (1.7 μM). Furthermore, portable paper sensor-based cysteine-decorated sulfur dots were fabricated for Co2+ detection and showed superior detection ability. Aided by a common smartphone as detector, the rapid, on-site and accurate quantification of Co2+ in real water samples can be accomplished. Our research has provided a novel chemosensor based on sulfur dots for dual-channel detection of Co2+, which would expand applications of sulfur dots in environmental monitoring, diseases diagnosis, cell imaging, light-emitting diodes, etc. Cysteine-decorated sulfur dots were acted as a chemosensor for fluorometric and colorimetric dual channel detection of Co2+ based on the photoinduced electron transfer effect.

As(iii) pollution has caused increasing concern due to its significant impact in environmental safety and human health. Carbon dots (CDs)-MnO2 nanocomposites were prepared and characterized for As(iii) detection. The intense blue fluorescence of CDs can be greatly quenched by functionalization with MnO2 nanosheets due to the existence of the fluorescence resonance energy transfer (FRET) effect. CDs-MnO2 nanocomposites were then used as a fluorescence sensor for As(iii) detection with high detection sensitivity and selectivity. The redox reaction between As(iii) and MnO2 nanosheets can induce the decomposition of MnO2 and termination of the FRET process. Then the blue fluorescence originating from CDs can be recovered. The detection limit of CDs-MnO2 nanocomposites toward As(iii) was calculated to be 16.8 nM (1.40 ppb) in a linear concentration range of 0-200 nM. CDs-MnO2 nanocomposites were also found to possess highly selective ability toward As(iii) detection. In addition, the spiked and recovery test also confirmed the practicality and reliability of CDs-MnO2 nanocomposites toward As(iii) detection in real water samples, such as groundwater etc. Our research has provided a reliable tool and strategy for visual detection of As(iii) with outstanding sensing ability.

The threat of tetracycline antibiotics to the environment and human health is attracting widespread attention. The development of morphological analysis and quantitative techniques of multiple tetracyclines is of great significance for the evaluation of biochemical toxicity, wide-spectrum antibacterial property and degradation cycle between different tetracyclines. In this study, the white fluorescent Eu/Tb@CDs was synthesized and applied successfully to the identification and detection of the most widely used tetracycline antibiotics (tetracycline (TC), oxytetracycline (OC), chlortetracycline (CC) and doxycycline (DC)) with detection limits all below 1 nM. For the actual water samples with coexistence of the above 4 tetracyclines, their simultaneous morphology identification and accurate quantitative detection can also be realized through simple spectrometric measurement. In addition, the selective and competitive experiments have been carried out on the pollutants widely present in water, and the results have also confirmed that other pollutants could not interfere with the detection of the above 4 tetracyclines. It is undeniable that this work will conveniently and visually reveal the existence information and geographical distribution characteristics of different tetracycline antibiotics in the environment and their action mechanism on organisms.

In Fenton or Fenton-like processes, the key step is to catalyze H

Simple and rapid sensing of polycyclic aromatic hydrocarbons (PAHs) remains a great technical challenge due to their chemical stability and structural similarity. Here, a simple, sensitive and cost-effective sensing strategy is proposed to detect multiple PAHs by utilizing the inner filter effect (IFE) and a reusable fluorescent sensor array consisting of four polyvinyl alcohol (PVA) composite carbon quantum dots (CDs) film sensors. The CDs/PVA films have a wide and tunable excitation range, which provide sufficient spectral overlap with PAHs and ensure the efficient occurrence of IFE. Under different excitations, the diverse UV absorption capacities of PAHs resulted in diverse spectral responses, enabling a unique chemical fingerprint for each PAH. Upon multivariate pattern recognition analysis, the array rendered high-throughput discrimination and sensitive quantification of 16 priority PAHs with 100% classification accuracy and detection limit as low as 57 nM. Moreover, the rapid and accurate screening of multiple environmental samples were also realized with the results consistent with high-performance liquid chromatography. This IFE-based reusable array is readily prepared, green and feasible, which exhibits great potential in environmental analysis and brings an advanced strategy to high-throughput sensing of more pollutants with similar structures and lack of recognition sites.

Perovskites (the general formula of ABO3) with versatile substrates can serve as desirable catalysts to initiate advanced oxidation processes (AOPs) for environmental remediation. However, the knowledge regarding the active centers remains piecemeal and unclear, such as how the redox metal centers of B site, inert metals of A site, oxygen vacancies, and direct oxidation of catalysts govern the chemical degradation of aqueous pollutants. This study aimed to identify principal alternations in physicochemical and electrical properties of ABO3-based perovskites modified with partial/overall substitution at A/B sites and synthesized at different conditions. In order to probe varied catalytic activity of these catalysts, ofloxacin (OFX) was used as a model micro-pollutant. Results showed that the OFX degradation by activation of peroxymonosulfate (PMS) with LaFeO3 perovskite was favored by the Sr substitution at A site, Cu substitution at B site, and increasing calcination temperature. Evolution of 1O2, •OH and SO4•- have proven for efficient OFX oxidation, as evidenced by results from in-situ electron paramagnetic resonance (EPR) analyses and quenching tests. Specifically, the introduction of Sr at A site can facilitate PMS self-decomposition to produce more 1O2 due to the increased abundance of surface oxygen vacancies. In contrast, the Cu substitution at B site improved the surface oxygen vacancies, as well as the electrical conductivity, which can further accelerate •OH and SO4•- generation for the OFX degradation. This study provides deeper insights into the underlying mechanisms governing the catalytic activity of perovskites. These findings build a basis for better decontamination of hazardous environmental organic pollutants.

The impact of surfactant on biomass adaptation and microbial community response in sewage treatment was studied by anaerobic membrane bioreactor (AnMBR). An increase in abundance and reduction in diversity for Firmicutes and Bacteroidetes but a decrease in distribution for Proteobacteria were observed when surfactant was present in sewage. A significant change at genus level in the microbial diversity and distribution for Firmicutes and Bacteroidetes was confirmed due to the biomass adaptation process. Geobacter, Pseudomonas and Acinetobacter for LAS degradation were proven to be not efficient in this study. In contrast, AE was efficiently degraded by Geobacter and converted into methane.

Portable, rapid, accurate and on-site detection of analysis target has always been the goal of continuous efforts in the field of analysis. In this work, a novel intelligent and rapid detection system based on an AIE dye (TPA-DCV) was established for portable and on-site detection of trace water in organic solvents and CN− in water by integrating the smartphone and linear discriminant analysis (LDA). The TPA-DCV displayed remarkable solvatochromism effect and showed different fluorescence colors to different water contents of different solvents, with the minimum detection limit of 54 ppm. In addition, TPA-DCV also exhibited specific response to CN−, and showed significant fluorescence changes to different amounts of CN−. With the assist of this detection system, these different fluorescence color signals could be accurately classified in canonical score plot. What's more, the classification and distribution of fluorescence color in canonical score plot showed regular change with the target concentration, which could be used to quantify the trace water and CN−. The rationality and practicability of this detection system were preliminary verified by a large number of real sample analyses. This detection system greatly simplifies the analysis process, which is in the proof of intelligent and rapid detection just using a simple color analysis without any instrument test, which may be a big step forward.

To develop a highly sensitive colorimetric detection method for the diabetes early diagnosis by determining the glucose in urine instead of blood can avoid the painful blood collection and risks of cross infection. In this paper, novel artificial enzyme mimics were formed by loading bimetallic nanoparticle Fe Pd on the surface of reduced graphene (rGO). Also, we proposed a Fe Pd/rGO coupled with portable paper sensor for the detection of glucose in urine. The results indicated that urine glucose can be sensitively detected in a wide range of 1–200 μM with a limit of detection (LOD) of 1.76 μM. Most important, the color difference along with the increase of urine glucose concentration can be easily distinguished by naked eyes, which is important to its practical usage in screening and diagnosis of diabetes. Furthermore, the reason of the high sensitivity of Fe Pd/rGO towards glucose was investigated in detail via various probing experiments. Fe Pd/rGO has an artificial enzyme mimic activity, which can catalyze O2 and generate H2O2 from glucose oxidation. The electron transfer between Fe Pd and H2O2 will produce •OH that can oxidize terephthalic acid (TMB) by emitting a blue color. The findings in this study provide a promising alternative for the early screening and diagnosis of diabetes.

In this paper, a simple and effective ratiometric fluorescent nanoprobe for visual detection of hypochlorous acid (HOCl) has been developed by loading silicon coated rhodamine B (RBDS) nanospheres on the surface of amino-modified graphene oxide (GO-NH2) nanosheets. The fabricated nanoprobe exhibits dual-emissions peaked at 427 and 585 nm, under a single excitation wavelength of 365 nm. The blue fluorescence of GO-NH2 can be selectively quenched by oxidation of HOCl, while the red fluorescence of RBDS remain unchanged, resulting in a distinguishable fluorescent color change from blue to pink under a UV lamp. Nanoprobes present high selective and sensitive for HOCl determination with a limit of detection (LOD) of 2.92 μM. Moreover, potable paper sensor has been prepared by coating the ratiometric fluorescent probe on filter paper, which provides a convenient and simple approach for HOCl visual detection.

Recently, perovskite is becoming a promising alternative as peroxymonosulfate (PMS) activator for the remediation of organic pollutants in water. But the factor determining PMS activation efficiency of perovskite and the evolution of reactive oxygen species (ROS) remain equivocal and elusive. In this study, we proposed an oxygen defect dependent PMS activation mechanism over perovskite with the singlet oxygen (1O2) as the dominant ROS. Among the tested four perovskites, ofloxacin (OFX) degradation efficiency increased with the following order: LaFeO3

Accurate recognition and speciation analysis of heavy-metal ions in complex hydrological environments is always a serious challenge. In this work, we proposed a small-molecule-based ultrasensitive colorimetric detection strategy and successfully applied it to the accurate detection of Fe2+, Fe3+, Co2+, and Hg2+ in groundwater through the specific recognition of multiple ligands of different metal ions. The detection limits for Hg2+, Co2+, Fe2+, and Fe3+ are calculated to be 6.51, 0.34, 0.49, and 1.01 ppb, respectively, which are far below the drinking water standards and superior to most of the reported colorimetric sensors. Remarkably, the speciation analysis of Fe2+/Fe3+ also has been successfully realized by a one-step method without complex pretreatment. The speciation and concentration of Fe2+ and Fe3+ in actual water samples can be accurately identified and monitored. In addition, as an attempt of visual onsite detection, we have developed a simple test strip, which has been applied to visual monitoring of four metal ions with the detection limit estimated by the naked eye to be as low as ppb level. This proposed colorimetric method realizes the rapid, sensitive, and portable multiple metal ions recognition and Fe2+/Fe3+ speciation analysis, displaying great potential for onsite rapid water quality analysis.

A novel hydrophilic ratiometric fluorescence sensor for instant visual detection of Fe3+ was successfully prepared by integrating silica-embedded CdTe quantum dots (QDs) with rhodamine derivative. The rich hydrophilic group and large specific surface area of CdTe@SiO2 QDs favored the adsorption of rhodamine derivative on silica and improvement of its water solubility. The results proved that the ratiometric fluorescence sensor shows a much higher selectivity towards Fe3+ with the detection limit as low as 26.5 nM than other typical cations and anions in aqueous solution. Moreover, the fluorescence response occurs instantaneously and reaches stability less than one second. Additionally, a simple and rapid paper-based analytical device was designed for on-site and visual detection of Fe3+ in actual water samples. Hence, this study provided a good candidate for the on-site and visual sensing of Fe3+ in the environmental analysis.

Arsenic contamination in groundwater is a severe and major environmental problem that endangers public health. As such, a sensitive and selective methodology for the detection of this toxic metalloid must be urgently developed. Aldimine condensation reactions of p-phenylenediamine with salicylaldehyde derivatives yielded “turn-on” fluorescence probes (HBHP, HBBP and HMBP) for the detection of As(V) with high sensitivity. Among these, as a typical AIEgen, HBHP exhibits the highest detection sensitivity. The detection limit of HBHP for As(V) was calculated to be 0.88 ppb, which is due to its higher ability to form intermolecular hydrogen bonds to convert twisted intramolecular charge transfer (TICT) into planar intramolecular charge transfer (PICT) and its higher molecular planarity triggered by specific electronic effects. Job's plots and DFT theoretical studies indicate that HBHP binds to As(V) with a stoichiometry of 1 : 2, and the binding constant was determined using the Benesi–Hildebrand equation to be 4.26 × 104 M2. Commonly existing anions and cations in groundwater exhibited no interference with the selective detection of As(V). Spiking and recovery tests of HBHP in the presence of As(V) in actual water samples gave satisfactory experimental results. Our research would provide novel principles of molecular construction and materials for the detection of As(V) in groundwater.

Ratiometric fluorescence sensing based on intrinsic dual-emitting nanomaterials is very intriguing for their simplicity and efficacy. However, intrinsic dual-emitting gold nanocluster-based fluorescence ratiometry remains unexplored. In this work, a ratiometric fluorescence assay for detection of mercuric ions (Hg2+) has been developed using sole intrinsic dual-emitting gold nanoclusters (DE-AuNCs). The DE-AuNCs, simply synthesized by reducing chloroauric acid with an appropriate amount of glutathione, had two distinct intrinsic emission bands peaked at 610 nm and 810 nm respectively. When exposed to Hg2+, the 610 nm emission of the DE-AuNCs was remarkably quenched serving as a reporter signal, while the 810 nm emission almost kept unchanged serving as a reference signal, and thus giving a ratiometric signal. This ratiometric method showed high sensitivity and selectivity for sensing Hg2+ with low LOD down to 0.19 ppb which is quite lower than the WHO drinking-water guideline for inorganic mercury, and was successfully applied to the detection of Hg2+ in environmental water samples.

Peroxymonosulfate (PMS) activation has drawn increasing attention in eliminating the recalcitrant organic pollutants in water. Manipulation of generated reactive oxygen species (ROS) over Ce doped Mn2O3 during the PMS activation was firstly reported for the complete degradation of 2,4-dichlorophenol (2,4-DCP) in this study. Ce in-situ introduction can greatly enhance the PMS activation performance of Mn2O3. For example, 100% of 2,4-DCP degradation can be obtained at 90 min over 4 wt% Ce doped Mn2O3 at pH 7 (82.1% for Mn2O3 at 90 min). The reaction rate constant (k) was also about 3.6 times higher than that of Mn2O3 (0.0668 min−1 for Ce doped Mn2O3 vs. 0.0186 min−1 for Mn2O3). Besides 1O2, OH and SO4 − were identified and involved in 2,4-DCP degradation process over Ce doped Mn2O3, while only 1O2 was detected over 3D Mn2O3. Moreover, the contribution of OH and SO4 − to 2,4-DCP degradation can be regulated by adjusting the Ce doping amount. The key role of Ce substitution in the regulation of reactive oxygen species was further investigated by XPS and electrochemical experiments. The Ce dopant can lead to a higher current density and greater reductive capability due to the improved charge transfer capability, which is important to the generation of more aggressive OH and SO4 − and complete 2,4-DCP degradation.

Sulfidated zerovalent iron (S-ZVI) has been extensively used for reducing pollutants. In this study, the oxidation process in the reductive removal of

The performance of the Fenton reaction under alkaline conditions is important to promote its application in practical water treatment. In this study, a sulfide doped mesoporous carbon (SC) and CuFeO2 composite (SC@CuFeO2) was prepared and its Fenton-like activity was evaluated by the degradation of sulfamethoxazole (SMX) in an alkaline solution especially in the presence of bicarbonate. The results indicated that 93% of SMX was efficiently degraded over SC@CuFeO2 at pH 8.7 with 15 mM HCO3− in water. In comparison, the SMX removal efficiency was only about 20% without HCO3−. Furthermore, the introduction of SC can indeed improve the Fenton activity of CuFeO2. For instance, the removal efficiency of SMX over CuFeO2 and SC@CuFeO2 was 80% and 70%, respectively, under the same conditions. Based on the characterization results, electron paramagnetic resonance spectra, probe experiments and ˙OH radicals' quantitative measurement, more radical production especially the transformation processes involving reactive oxygen species (˙OH, O2˙− CO3˙− and 1O2) were responsible for the enhanced SMX degradation over SC@CuFeO2 under alkaline conditions. Finally, the intermediates of SMX degradation were detected by GC-MS/MS and the degradation pathway was discussed. These findings suggest that the effect of the water matrix on the oxidation efficiency of the Fenton reaction should be considered in real water treatment.

UV-H

Developing a portable device for visual and on-site detection of fluoride in groundwater is highly anticipated. In this paper, 2-(tert-butyl-diphenylsilanyloxy)−5-nitro-1H-benzoimidazole (1) has been rationally designed via a silanization reaction for self-calibration detection of fluoride, and the detection limit was calculated as 0.11 μM. The contact of 1 with fluoride would induce the cleavage of Si-O bond and trigger the emergence of excited state intramolecular proton transfer (ESIPT) process, and then the enol-like emission at 437 nm decreased accompanying with the increase of keto-like tautomerism emission at 550 nm. More importantly, considering the demand of field detection for fluoride in groundwater and combining the function of smartphone to obtain the chroma of photos. The chroma value of the fluorescence color changes from blue to yellow could be conveniently determined through a color recognizer application installed in smartphone. The device can accurately reflect the concentration of fluoride by analyzing the chroma value. The test in actual water samples confirmed that the simple device based on smartphone could be used efficiently for visual, on-site and accurate detection of fluoride in groundwater.

As(iii) pollution has caused increasing concern due to its significant impact in environmental safety and human health. Carbon dots (CDs)-MnO2 nanocomposites were prepared and characterized for As(iii) detection. The intense blue fluorescence of CDs can be greatly quenched by functionalization with MnO2 nanosheets due to the existence of the fluorescence resonance energy transfer (FRET) effect. CDs-MnO2 nanocomposites were then used as a fluorescence sensor for As(iii) detection with high detection sensitivity and selectivity. The redox reaction between As(iii) and MnO2 nanosheets can induce the decomposition of MnO2 and termination of the FRET process. Then the blue fluorescence originating from CDs can be recovered. The detection limit of CDs-MnO2 nanocomposites toward As(iii) was calculated to be 16.8 nM (1.40 ppb) in a linear concentration range of 0-200 nM. CDs-MnO2 nanocomposites were also found to possess highly selective ability toward As(iii) detection. In addition, the spiked and recovery test also confirmed the practicality and reliability of CDs-MnO2 nanocomposites toward As(iii) detection in real water samples, such as groundwater etc. Our research has provided a reliable tool and strategy for visual detection of As(iii) with outstanding sensing ability.

Perovskites with flexible texture structures and excellent catalytic properties have attracted considerable attention in peroxymonosulfate (PMS) activation for addressing organic contaminants in water. In this study, the role of copper to promote PMS activation performance of LaMnO

Due to the huge threat of formaldehyde (FA) on human beings, the development of chemical sensors for swift detection of FA in solutions and gas phase is highly anticipated. In this paper, a versatile logic detector and a portable fluorescent film based on small-scaled Eu-based MOF were applied successfully to detect FA in solutions and gas phase, respectively. For FA in aqueous solution, the design of logic detector will efficiently identify FA in different concentration ranges: when the FA concentration are 0–500 ppb, 500–1000 ppb and >1000 ppb, the output signals of logic detector are the concentration level of FA ("L", "H" and "VH"), and accompanied by red, purple and blue signal lamps to remind, respectively. For FA in the air, the color of rigid film sensor will gradually change from red to blue with the increase of FA under UV lamp, and the detection limit of gaseous FA is 11.8 ppb. Through the preparation of logic devices and fluorescent films, Eu-based MOF realized swift detection of FA in solutions and gas phase, which will be very helpful to improve the human response level to FA from different emission sources.

An essential strategy to eliminate emerging contamination in water is to initiate more reactive oxygen species (ROS) in the catalytic systems. 0.14 wt.% Au loaded Bi

An efficient strategy for enhancing iron efficiency in heterogeneous Fenton reaction via the pyrolysis of ferrocene chemically modified sepiolite (Sep) was proposed in this study. Highly dispersed FeC

In this study, an efficient and reusable heterogeneous Fenton catalyst Fe