Allelopathy is an ecological phenomenon in which organisms interfere with each other. As a management strategy in agricultural systems, allelopathy can be mainly used to control weeds, resist pests, ...and disease and improve the interaction of soil nutrition and microorganisms. Volatile organic compounds (VOCs) are allelochemicals volatilized from plants and have been widely demonstrated to have different ecological functions. This review provides the recent advance in the allelopathic effects of VOCs on plants, such as growth, competition, dormancy, resistance of diseases and insect pests, content of reactive oxygen species (ROS), enzyme activity, respiration, and photosynthesis. VOCs also participate in plant-to-plant communication as a signaling substance. The main methods of collection and identification of VOCs are briefly summarized in this article. It also points out the disadvantages of VOCs and suggests potential directions to enhance research and solve mysteries in this emerging area. It is necessary to study the allelopathic mechanisms of plant VOCs so as to provide a theoretical basis for VOC applications. In conclusion, allelopathy of VOCs released by plants is a more economical, environmentally friendly, and effective measure to develop substantial agricultural industry by using the allelopathic effects of plant natural products.
Developing efficient sensing materials with superior sensing capabilities of sensitive, fast, selective detection of volatile organic compounds (VOCs) is necessary for fields like environmental gas ...monitoring and non-invasive disease diagnosis. Recently, carbon nanotubes, graphene, MXene, and other carbon-based nanomaterials have been paid much attention for possible use as high-performance VOCs sensing materials due to unique physical structures and excellent electric properties. The tunability of the chemical character and surface properties of the carbon-based nanomaterials increases their potential in constructing selective sensors targeting VOCs gases. Besides, the mechanical flexibility of the carbon-based nanomaterials allows the new designs of gas sensing platforms and puts the carbon-based nanomaterials at the forefront of other sensing materials for wearable applications. In this review, we highlight the most recent progress of the carbon-based nanomaterials in the detection of VOCs gases with an emphasis on the available strategies for the construction of these VOCs gas sensors. These strategies are proved by addressing some representative paradigms, and their suitability in applications like environmental gas monitoring and non-invasive disease diagnosis is assessed. This review is intended to offer timely sources of information and provide insight for future research works on designing high-performance VOCs gas sensors by utilizing carbon-based materials.
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•Types, source and characteristics of typical VOCs are summarized.•Research development and mechanistic understanding of adsorbents and catalysts for VOCs removal are overviewed.•Barriers (e.g. water ...vapor; CO byproduct, coking) in adsorptive removal/catalytic oxidation of VOCs are discussed.•Perspectives of future research on adsorptive and catalytically oxidative removal of VOCs are given.
Volatile organic compounds (VOCs) have been recognized as one of the major environment hazards in air that seriously harm both the environment and human health. Adsorptive removal and catalytic oxidation are two potential technologies for the effective removal of VOCs. The development of efficient adsorbents and catalysts for VOCs with varied nature are critical. In this review, the types of typical VOCs and their properties are summarized. Research progresses on the development of adsorbents and catalysts for different types of typical VOCs removal are overviewed and compared in parallel. Possible adsorption/catalytic oxidation mechanisms are introduced. The barriers, i.e. competitive adsorption of water vapor in adsorptive removal of VOCs, CO byproduct, water vapor and coking suppressions in catalytic oxidation of VOCs are summarized. The perspectives on the potential future directions of the adsorptive removal and catalytic oxidation of VOCs are given.
The selective and sensitive detection of chemical agents is demanded by a wide range of practical applications. In particular, sensing of volatile organic compounds (VOCs) at parts-per-billion level ...is critical for environmental monitoring, process control, and early diagnosis of human diseases. In this report, we demonstrate a specific and highly sensitive detection of ketone compounds using two-dimensional (2D) molybdenum ditelluride (MoTe
). We investigated the effects of UV activation on the sensing performance to a variety of VOCs. It is found that the MoTe
field-effect transistor (FET) exhibits an opposite sensing response to ketone compounds before and after UV light activation, whereas the responses to other types of VOCs remain in the same direction regardless of the illumination. This unique behavior enables the discriminative detection of ketone molecules including acetone and pentanone from other VOCs in a gas mixture. The activation of UV light also results in a very high sensitivity and low detection limit toward acetone (∼0.2 ppm). Moreover, the MoTe
FET shows a stable sensing performance in a high humidity environment. The results demonstrate the potential of MoTe
as a promising candidate for high-performance acetone sensors in important applications such as human breath analysis. The scheme of light-tunable sensing can be applied to a broad range of sensing platforms based on 2D materials.
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•Presents a Mxene based virtual sensor array (VSA).•Proposes a convenient strategy for VSA.•We demonstrate correct rates of 90.9%, 90.5%, 90% for the different groups of ...VOCs.•Demonstrates an accuracy of 93.2% for the prediction of ethanol concentrations.
Two-dimensional transition metal carbides/nitrides, known as MXenes, have recently received significant attention for gas sensing applications. However, MXenes have strong adsorption to many types of volatile organic compounds (VOCs), and therefore gas sensors based on MXenes generally have low selectivity and poor performance in mixtures of VOCs due to cross-sensitivity issues. Herein, we developed a Ti3C2Tx-based virtual sensor array (VSA) which allows both highly accurate detection and identification of different VOCs, as well as concentration prediction of the target VOC in variable backgrounds. The VSA’s responses from the broadband impedance spectra create a unique fingerprint of each VOC without a need for changing temperatures. Based on the methodologies of principal component analysis and linear discrimination analysis, we demonstrate highly accurate identifications for different types of VOCs and mixtures using this MXene based VSA. Furthermore, we demonstrate an accuracy of 93.2% for the prediction of ethanol concentrations in the presence of different concentrations of water and methanol. The high level of identification and concentration prediction shows a great potential of MXene based VSA for detection of VOCs of interest in the presence of known and unknown interferences.
Trends and applications in plant volatile sampling and analysis Tholl, Dorothea; Hossain, Oindrila; Weinhold, Alexander ...
The Plant journal : for cell and molecular biology,
April 2021, 2021-Apr, 2021-04-00, 20210401, Letnik:
106, Številka:
2
Journal Article
Recenzirano
Odprti dostop
SUMMARY
Volatile organic compounds (VOCs) released by plants serve as information and defense chemicals in mutualistic and antagonistic interactions and mitigate effects of abiotic stress. Passive ...and dynamic sampling techniques combined with gas chromatography–mass spectrometry analysis have become routine tools to measure emissions of VOCs and determine their various functions. More recently, knowledge of the roles of plant VOCs in the aboveground environment has led to the exploration of similar functions in the soil and rhizosphere. Moreover, VOC patterns have been recognized as sensitive and time‐dependent markers of biotic and abiotic stress. This focused review addresses these developments by presenting recent progress in VOC sampling and analysis. We show advances in the use of small, inexpensive sampling devices and describe methods to monitor plant VOC emissions in the belowground environment. We further address latest trends in real‐time measurements of volatilomes in plant phenotyping and most recent developments of small portable devices and VOC sensors for non‐invasive VOC fingerprinting of plant disease. These technologies allow for innovative approaches to study plant VOC biology and application in agriculture.
Significance Statement
Determining the emission of volatile organic compounds released by plants represents a key methodology in understanding and monitoring chemical interactions of plants with their biotic and abiotic environment in agriculture and natural ecosystems. This review presents recent developments and state‐of‐the‐art technical advances in volatile organic compound sampling and analysis in belowground environments and as integrated technology of plant phenotyping and disease diagnostics.
Volatile organic compounds (VOCs) are directly associated with human health concerns and environment safety. Therefore, it is urgent to achieve an accurate detection of VOCs both qualitatively and ...quantitatively. In this work, the qualitative detection of ethyl benzene (EB), isopropyl alcohol (IPA), ethyl acetate (EA) - three pure VOCs in liquid phase were discussed using terahertz (THz) microfluidic Electromagnetic Induced Transparency (EIT) meta-sensor. The THz response illustrated that with an increase in VOCs' volumes (1~6μL), resonant frequencies of dual transmission dips (0.855, 1.724 THz) and the EIT peak (1.213THz) exhibited red shift. The limit of detections for pure IPA, EA, EB can achieve 5.45μg, 13.46μg, 4.35μg, respectively. The multivariate fusion (MF) model based on the EIT responses to VOCs was utilized to improve the accuracy of trace detection and classification of VOCs. Furthermore, the above method combined with principal component analysis with Gaussian mixture model (PCA-GMM) and the neural network classification algorithm support vector machine (SVM) was applied to the recognition of VOCs. In addition, the THz method is not feasible to detect trace amounts of VOCs (typically 0.3mg/L) in waste water because water is highly absorbable in THz band and VOCs will evaporate if water is removed. Here, IPA, EA, EB in soil were detected and classified by PCA-GMM combined with MF. Our results provide a new terahertz meta-sensor platform to trace detection of VOCs in liquid phase and in soil and may be used to identify hazardous wastes in illegal dumping.
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•Optimum proportion of benzoic acid for synthesis of more defects UiO-67.•Defects, methyl and benzene ring enhance π-π interaction to promote VOCs adsorption.•Multiple experiments and ...DFT calculation analyze interaction between VOCs and MOFs.
The harm that is caused by volatile organic compounds (VOCs) has attracted worldwide attention. In production, industrial processes such as fossil fuel combustion, plastics, and paints have caused complex and diverse VOCs emissions. Therefore, studying the phenomenon and influencing factors of typical VOCs adsorption is of practical significance for the treatment of multicomponent VOCs. In this work, defective UiO-67 was prepared by changing the amount of benzoic acid. Then, the adsorption performance was tested, and the adsorption kinetics were considered. The experimental results showed that the 67-ben-10 sample (for which the molar ratio of Zr4+ to benzoic acid was 1:10) achieved the maximum toluene adsorption capacity (480 mg g−1), which was due to the presence of more adsorption sites, higher benzoate content, strong π-π stacking and excellent adsorption diffusion behavior. In addition, the adsorption properties of the 67-ben-10 benzene series (BTX: benzene, toluene, o-xylene, p-xylene and m-xylene) and acetone were further investigated. The results showed that the adsorption performance was related to the polarizability of the VOCs molecules, the method of pore entry and the molecular size. Finally, through desorption experiments, density functional theory (DFT) and kinetics, the binding energy was confirmed to play an important role in adsorption and diffusion.
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In this paper, a simple solvothermal synthesis method was proposed for the preparation of metal organic framework/graphene oxide hybrid nanocomposite (UiO-67/GO). A series of ...UiO-67/GO composites were prepared by varying the addition forms and amounts of GO, and the optimal synthesis conditions were screened. The composites were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), transmission Electron Microscope (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopic (XPS), water contact angles (CA) and thermogravimetric analysis (TGA). The adsorption capacity and the adsorption process of toluene were investigated by dynamic adsorption and adsorption kinetics, respectively. The results indicated that 67/GO-0.5% reached the maximum adsorption capacity (876 mg g−1), which far exceeded the other adsorbents. Kinetic model and the Weber-Morris model correlated satisfactorily to the experimental data. The improved adsorption performance was attributed to GO, which enhanced π-π interaction, promoted defect generation and provided more adsorption sites. Finally, the excellent regeneration performance of the adsorbent was verified by temperature programmed desorption (TPD) and cyclic adsorption–desorption experiments. Moreover, the adsorption mechanism was further revealed. Combined with the related adsorption experiments and the density functional theory (DFT) analysis, the efficient removal of toluene by UiO-67/GO was attributed to the cooperation of defects, π-π interaction and hydrogen bonding.
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