Detection Of Sulfur Dioxide Research Articles

Sensitive SO2 gas sensor utilizing Pt-doped graphene nanoribbon: First principles investigation

The objective of this work is to seek a highly sensitive gas sensor for the detection of sulfur dioxide (SO2) by investigating the impacts of passivation as well as metal doping of armchair-edge graphene nanoribbon (AGNR) on the adsorption capacity. Herein, two AGNR based sensor materials for SO2 are passivated with hydrogen and nitrogen (AGNRH and AGNRN) then investigated theoretically using density functional theory (DFT). The results demonstrate that AGNRH is more sensitive to SO2 gas than AGNRN with −0.532 eV adsorption energy (Ead) and 0.05 e charge transfer (ΔQ). Furthermore, two more sensor materials are examined via doping AGNRH and AGNRN with platinum: Pt-AGNRH and Pt-AGNRN. Interestingly, the adsorption energies and charge transfer increased remarkably to −6.327 eV (almost 12 times the non-doped case) and 0.373 e, respectively, for the case of the SO2/Pt-AGNRH system. The same trend is observed as well for the case of SO2/Pt-AGNRN. The significant improvement of the adsorption parameters specifies that Pt doping has a considerable impact on enhancing the sensing performance of passivated AGNR toward the detection of SO2 gas.

Synthesis and Properties of a Water-soluble Fluorescent Probe Based on ICT System for Detection of Ultra-trace SO2 Derivatives.

SO2 and its derivatives are widely present in the environment and living organisms, endangering the environment and human health. Therefore, it is of great significance for the effective detection of sulfur dioxide (SO2) and its hydrated derivatives (HSO3- /SO32-). In this study, based on the mechanism of intramolecular charge transfer (ICT), a water-soluble colorimetric fluorescent probe (E)-2-(4-acetamidostyryl)-3-(5-carboxypentyl)-1, 1-dimethyl-1H-benzo[e]indol-3-ium (ABI) for the detection of SO2 derivatives was successfully synthesized from p-acetaminobenzaldehyde by connecting the benzo[e]indoles cationic fluorophore containing highly activated methyl via C = C double bond, and the ABI structure was characterized by HRMS and 1H NMR, 13C NMR. Studies have shown that the ABI probe has some advantages such as good selectivity for SO2 derivatives, high sensitivity (detection limit LOD = 14.9 nM), and fast reaction rate. After adding HSO3-, the color of the probe solution changed from light yellow to colorless within 10 s, which provides a simple way to identify bisulfite with the naked eye. Studies on the effect of pH on the fluorescence performance of ABI showed that fluorescence performance of ABI was stable in the range of pH (7.0-10.26). Therefore, ABI is expected to become an effective tool for detecting SO2 derivatives in cells and organisms in the future.

A novel fluorescent probe for rapid detection of sulfur dioxide in living cells.

Sulfur dioxide is one of the reactive sulfur species, which has significant physiological functions in cells. Some physiological processes are closely related to SO2 in organisms, and the high concentration of SO2 in living cells can cause many diseases. In order to investigate the unique function of SO2 at the subcellular level, developing a molecular tool which could detect of SO2 within organelles is imperative. Hence, we developed a cationic dye named HQ-SO2 as a new fluorescent probe to specifically monitor SO2 , which was easy to obtain through one-step reaction. It took Michael addition reaction as the mechanism of reaction for detection of SO2 . In addition, this probe showed a series of highly favorable properties such as rapid response rate, low cytotoxicity, high selectivity, low detection limit, and good photostability, which enabled the probe to track SO2 in living cells.

Hollow Zinc Oxide Microsphere–Multiwalled Carbon Nanotube Composites for Selective Detection of Sulfur Dioxide

This work reports the first utilization of anthocyanin extracted from black rice (Oryza sativa L.) grains as a structure-directing agent for the synthesis of hollow zinc oxide (ZnO) spheres via a simple solvothermal reaction and their subsequent modifications with various amounts of multiwalled carbon nanotubes (MWCNTs). Following hybridization with MWCNTs, some MWCNTs are observed to penetrate into the inner cavities of the spheres, while ZnO nanoparticles are formed on the surface of some MWCNTs. When employed as a sulfur dioxide (SO2) sensor, the ZnO-MWCNT (15:1) composite displays a high response of 156 to 70 ppm of SO2 at an optimum temperature of 300 °C as well as good selectivity to SO2 with the response to 50 ppm of SO2 gas being 3 times higher than those to other gases, such as CO, CO2, methanol, toluene, hexane, and xylene. Interestingly, the sensing behavior of this composite is strongly influenced by the proportion of MWCNTs. Specifically, n-type sensing behavior is observed for both ZnO-MWCNT (10:1) and (15:1) composites, while p-type behavior is observed for the ZnO-MWCNT (5:1) composite. The switch in sensing behavior suggests the major contribution of p-type MWCNTs to the electronic and sensing properties of the ZnO/MWCNT composites. The density functional theory (DFT) simulations on the adsorption of SO2 on the ZnO/CNT system reveal that the SO2 molecule only chemically interacts with the O adatom of ZnO (i.e., oxygen atom adsorbed on the surface of ZnO) to form sulfur trioxide (SO3), and charge transfer is observed from ZnO to CNT, which enhances the change in resistance of the composite sensor upon exposure to SO2 gas.

Detection of sulfur dioxide at low parts-per-million concentrations using low-cost planar electrodes with ionic liquid electrolytes

Sulfur dioxide (SO2) is a toxic gas at low parts-per-million (ppm) concentrations, with a permissible exposure limit (PEL) of 2 ppm. Its detection is mandatory, particularly in the fields of occupational health and safety, and environmental pollution. In this work, ppm concentration detection of sulfur dioxide was performed in six room temperature ionic liquids (RTILs), as well as on two different electrode materials – platinum and gold – and with two different electrode geometries, i.e. macro thin-film electrodes (TFEs) and microarray thin-film electrodes (MATFEs). Calibration curves were established for 10–200 ppm SO2 using cyclic voltammetry to determine the optimum combination of RTIL, electrode surface and geometry for the sensing. The RTIL 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonium)imide ([C4mpyrr][NTf2]) with a platinum thin-film electrode was found to give the best response due to the relatively low viscosity of the RTIL combined with the high sensitivity and a clean blank response. On MATFEs, deposited sulfur particles – confirmed using scanning electron microscopy (SEM) coupled to an energy dispersive spectrometer – were found to passivate and block some of the microholes, leading to unstable long-term chronoamperometric responses. To the best of our knowledge, this is the first observation of sulfur deposition from SO2 reduction in aprotic ionic liquids. Consecutive additions of 2 ppm SO2 were studied in [C4mpyrr][NTf2] on a TFE using long-term chronoamperometry, showing excellent reproducibility upon successive additions. This demonstrates that small volumes of RTILs can be combined with miniaturized, low-cost TFEs and applied for the reliable and continuous monitoring of sulfur dioxide gas at concentrations lower than the permissible exposure limit of 2 ppm.

Temperature-compensated ppb-level sulfur dioxide detection system based on fourier transform ultraviolet differential optical absorption spectrum method

Sulfur dioxide (SO2) is a toxic gas which poses a great threat on environmental protection and human health even at low concentration. Hence, considerable attention has been devoted to achieve accurate SO2 monitoring at ppb level. In this work, we report on a ppb-level SO2 detection system via deep ultraviolet differential optical absorption spectroscopy (DUV-DOAS). A novel concentration-retrieval algorithm and spectral data-processing method were proposed to overcome the ubiquitous cross-sensitivity. The differential optical density (DOD) signal of SO2 component was identified and decomposed by FFT (fast Fourier transform) from overall DOD signal of gas mixture, followed by a reconstruction by IFFT (Inverse fast Fourier transform) after frequency domain filtering. Via this method, SO2 DOD signal was accurately extracted regardless of strong interference from NO, NO2 and NH3, indicating a remarkably enhanced SO2 selectivity. Besides, a detection limit (DL) of 4 ppb and a quantitation limit (QL) of 20 ppb were achieved, which are among the best cases of related reports thus far. Moreover, a compensation model was offered to compensate for deviations caused by gas temperature variation and thus enhance the system accuracy and adaptability.

USE OF BIOMONITORING TO IDENTIFY HAZARDS IN CRITICAL INFRASTRUCTURE PROJECTS

The study addresses the possibility of integrating biomonitoring into the environmental impact assessment process of critical infrastructure projects. It has been established that critical infrastructure projects include projects related to the construction, reconstruction and operation of critical infrastructure facilities. Critical infrastructure projects can be hazardous to the environment, but the timely identification of the nature, intensity, degree of danger of the critical infrastructure project for the state of the environment and public health will be able to prevent processes of manifestation and accordingly promote successful implementation. The peculiarities of carrying out the procedure of environmental impact assessment and its importance as a factor of successful passage of the project throughout the life cycle are determined. It has been established that a comprehensive environmental impact assessment procedure will help to make environmentally sound management decisions that will benefit the environment. An algorithm for carrying out environmental impact assessment for critical infrastructure projects has been developed. A rapid assessment of atmospheric air pollution was carried out using the method of dendroindication based on the study of the stability of tree plantations at all stages of ontogenesis to identify hazards in projects of critical infrastructure. Practical application of the method of dendroindication will allow to improve the possibilities for the detection of sulfur dioxide in the atmosphere and to estimate the total value of anthropogenic load on plant organisms. It is established that the use of dendrology as an additional method in carrying out the environmental impact assessment will significantly increase the opportunities in the field of hazard identification for critical infrastructure projects, especially in the aspect of project activities for their reconstruction and operation. The application of the proposed method in the project activities will help to reduce their possible negative impact on the state of the environment.

Surface lanthanide activator doping for constructing highly efficient energy transfer-based nanoprobes for the on-site monitoring of atmospheric sulfur dioxide.

The sensitive and on-site detection of sulfur dioxide (SO2) is in great demand in the fields of food safety and environmental protection. Here, we developed a novel upconversion nanoprobe based on the luminescence energy transfer mechanism for monitoring the atmospheric SO2 concentrations. The lanthanide emitters, Tm3+ ions, were optimized to be doped on the surface layer of the upconversion nanoparticles to improve their energy transfer efficiency by minimizing the distance between the emitters and the surface quencher, a cyanine dye. As a proof-of-concept, the optimal nanoprobe was utilized to detect SO2 water derivatives, bisulfite ions, exhibiting a linear luminescence increase in the range of 1 nM to 10 nM. Furthermore, we assembled the cyanine-modified upconversion nanoparticles onto a test paper, and used a smartphone-based detection platform to achieve portable and visual detection of SO2. The test paper showed a strong luminescence stability, homogeneity and good anti-interference. The limit of detection for SO2 gas was found to be 1 ng L-1. This novel upconversion test paper was also demonstrated to directly monitor the concentration of SO2 gas in atmosphere.

A mitochondria-targeting ratiometric fluorescent probe for the detection of sulfur dioxide in living cells

A mitochondria-targeting ratiometric fluorescent probe was developed for the detection of sulfur dioxide in living cells.

One-pot hydrothermal synthesis of nano-sheet assembled NiO/ZnO microspheres for efficient sulfur dioxide detection

The nano-sheet assembled NiO/ZnO microspheres with a diameter of ca. 2 μm have been synthesized via facile hydrothermal method followed by a thermal treatment process. The gas-sensing measurement results show that the sensor using nano-sheet assembled NiO/ZnO microspheres exhibits improved response to sulfur dioxide gas compared with the pure ZnO microspheres sensor. In particular, the sensor with a Ni/Zn molar ratio of 0.5 (0.5 mol% NiO/ZnO) shows high response value (S = 107) and superior selectivity to 10 ppm sulfur dioxide at a low operating temperature of 160 °C and the detection limit of the NiO/ZnO sensor toward sulfur dioxide is down to 1 ppm (S = 6). The enhanced sensing performance is attributed to the formation of p-n heterojunctions on the interface, the catalytic function of NiO and the three-dimensional microspheres composed of the lamellar structure with a large specific surface area. The three-dimensional microspheres provide more active sites for gas adsorption, and the interlayer gap facilitates the diffusion of gas in three-dimensional structure, resulting in high sensitivity and superior selectivity. This work provides a simple method for the synthesis of NiO/ZnO heterojunction microspheres with superior gas-sensing performance, which can be used as a potential material for sulfur dioxide detection.

Tunable formation of nanostructured SiC/SiOC core-shell for selective detection of SO2

Silicon carbide is a well-known material with high thermal, mechanical and chemical stability. These properties have allowed, over time, its wide use as an inert material to be employed as a substrate or support in different applications. In this work, we demonstrate that, under proper conditions, it is possible to activate the chemical reactivity of nanostructured SiC, which can be employed for chemoresistive purposes. With this aim, a commercial powder of SiC has been characterized from a morphological, structural and thermal point of view. Then, screen–printed thick films were obtained from SiC powder and thus tested as a functional material for chemoresistive gas sensors, in thermo-activation mode. The samples were exposed to 13 gases with important chemical differences. Analyses showed that SiC is an extremely selective functional material for the detection of sulphur dioxide (SO2) in concentrations within the ppm range. This interesting result was found at high working temperatures (600−800 °C), useful for harsh environments, and the measurements proved to be completely free from humidity negative interference. Thermo-gravimetric and X-ray photoelectron spectroscopy characterizations highlighted that the high selectivity of the SiC layer is promoted by the thermal formation of a SiC/SiOC core-shell, tunable by controlling temperature and humidity parameters. An interpretation of the gas sensing mechanism occurring between SO2 molecules and SiC/SiOC core-shell has been proposed.The unexpected chemical activity, identified for nanostructured SiC, can be exploited for the specific detection of SO2, since this gaseous compound plays an important role in air pollution, industrial processes and winemaking.

Multi-wavelength UV imaging detection system applied for varying environmental conditions: Detection of SO2 as an example

We demonstrate a multi-wavelength ultraviolet (UV) imaging detection system for gaseous pollutants with absorption characteristics in the UV band. As a proof of concept, the detection of sulfur dioxide (SO2) was used as an example to develop a method based on UV imaging. The critical component of the system is a highly sensitive CCD array (1024 × 1024 pixels) UV camera with high quantum efficiency (QE) in the UV range (>30% transmission at 200–240 nm, >50% transmission at 240–400 nm), multiple different wavelength bandpass filters (270 nm, 280 nm, 300 nm, and 310 nm for SO2), environmental condition controller (temperature range 278–318 K, relative humidity range 35–85%), and a compact and robust design (362 mL of the gas absorption cell with a 4.2 m optical path length). The advantages of this system are convenient, fast, and can realize visualization. The system was applied for detecting SO2 in various conditions (different concentrations, temperatures, and humidity). After optimization, the detection limit for SO2 detection is 4 ppb, and the uncertainty of concentration measurement is only about 2.7%.

Rational Design of a Rigid Fluorophore-Molecular Rotor-Based Probe for High Signal-to-Background Ratio Detection of Sulfur Dioxide in Viscous System.

Many viscous microenvironments exist in living systems. For instance, at the cellular level, the viscosity of subcellular organelles (mitochondria, lysosomes, endoplasmic reticulum, nucleus, etc.) is much greater than that of cytoplasm; at the organismal level, compared with normal states of health, blood, or lymphatic fluid viscosity will increase to some extent in diabetes, hypertension, inflammation, tumors, and so on. However, due to the design shortcoming, there is a lack of efficient tools for detecting biomolecules in viscous living systems. Herein, we propose a rational design strategy for constructing ratiometric fluorescent probes with superior response signal-to-background (S/B) ratio in viscous systems based on rigid-fluorophore-molecular rotor platform, and a practical sulfur dioxide (SO2) probe (RFC-MRC) based on conmarin-cyanine dyad was prepared as a proof-of-concept. The probe performs a significant enhancement (71.5-fold) of ratiometric response signal stimulated by SO2 in viscous aqueous media. The cationic probe can selectively in mitochondria and was successfully utilized to sense SO2 in living HeLa cells through ratiometric fluorescence imaging. What's more, in the fluorescence imaging experiments of monitoring SO2 in apoptotic cells using probe RFC-MRC, a more obvious superior of S/B ratio was observed in the early apoptotic cells than in the lately apoptotic cells.

A dual electron-withdrawing enhanced selective/sensitive chemodosimeter for detection on bisulfate and its living cell imaging.

Fluorescence detection of sulfur dioxide has attracted great interest from researchers in recent years. Usually double bonds and aldehyde group were employed as reaction sites for sulfur dioxide. In this work, the double bond was linked with cyano and carboxyl group as dual electron-withdrawing to enhance the reaction reactivity between the probe and sulfite. Meanwhile, coumarin with good biocompatibility was introduced as fluorophore. Thus D-π-A form constructs intramolecular charge transfer (ICT), the probe has weak yellow fluorescence emission (565 nm), after addition reaction taking place between the probe and bisulfate, conjugated double bond is broken, the system showed a short-wavelength fluorescence emission (483 nm). All these realized a ratiometric fluorescence detection for bisulfate. The study found that dual electron-withdrawing groups enhanced the specificity and sensibility (with a low detection limit 82 nM) of the probe recognizing bisulfate. These excellent properties led directly to the use of probes to image sulfur dioxide in living cells. Further applications are still being on the way.

Multifunctional microchip-based distillation apparatus II - Aerated distillation for sulfur dioxide detection

A multifunctional microchip-based distillation apparatus is presented for the distilled of sulfur dioxide (SO2) in food products. The microchip is fabricated on poly(methyl methacrylate) (PMMA) substrates, and comprises a sample zone, a buffer zone, a serpentine distillation column, and a collection zone. In the process, the sample is introduced into the sample zone and is heated under carefully controlled temperature and time conditions. The resulting SO2 and water vapor are carried by nitrogen (N2) gas to the distillation column, where the SO2 is separated from the water vapor via the condensing effects of a continuous cold water flow. Finally, the SO2 is transported to the collection zone, where it is collected with hydrogen peroxide (H2O2) and its concentration determined using an alkali-based titration and paper-based detection method. A distillation efficiency of 90.5% is obtained under the optimal distillation conditions at concentrations of 20–4000 ppm. Moreover, a linear correlation (R2 = 0.9997) is observed between the experimental measurements of the SO2 concentration and the known concentration. The validity of the presented microchip-based distillation apparatus is further investigated by distilling the SO2 concentrations of 25 commodity samples. The detection results show that the deviation does not exceed 5.4% compared with the traditional official method.

Non-dispersive UV Absorption Spectroscopy: A Promising New Approach for in-situ Detection of Sulfur Dioxide

A new type of instrument for in-situ detection of volcanic sulfur dioxide is presented on the basis of non-dispersive UV absorption spectroscopy. It is a promising alternative to presently used compact and low-cost SO2 monitoring techniques, over which it has a series of advantages, including an inherent calibration, fast response times (< 2 s to reach 90 % of the applied concentration), a measurement range spanning about 5 orders of magnitude and small, well known cross sensitivities to other gases. Compactness, cost-efficiency and detection limit (< 1 ppm, few ppb under favourable conditions) are comparable to other presently used in-situ instruments. Our instrument prototype has been extensively tested in comparison studies with established methods. In autumn 2015, diverse volcanic applications were investigated such as fumarole sampling, proximal plume measurements and airborne measurements several kilometers downwind from the vent on Mt. Etna and White Island. General capabilities and limitations of the measurement principle are discussed, considering different instrument configurations and future applications.

A PET/paper chip platform for high resolution sulphur dioxide detection in foods

A convenient assay platform comprising a PET/paper chip (PP-chip) and a smart analytical device is developed for detection of sulphur dioxide (SO2) concentration. In the presented approach, the distilled SO2 solution is dropped onto the detection region of the PP-chip and undergoes a reaction with an acid-based reagent. The resulting color variation is analyzed through a high-resolution camera (CMOS) and the reacted image is processed by a RGB (red, green and blue) analytical app installed on a smartphone. Results show that the known SO2 concentrations ranging from 10 to 300 ppm indicate that the high linear relationship (R2 = 0.9981) between the (R (red) + G (green) − B (blue)) value and SO2 concentration. Moreover, a high measurement resolution is equal to 1.45 ppm/a.u. The presented assay platform was proved to detect the SO2 concentrations of twenty-five practical food samples. Compared with the developed assay platform and certified inspection technique, the deviation of SO2 measurement does not exceed 3.82%. It was satisfactory to apply this developed assay platform to analyze the SO2 concentration in the practical samples.

Design and synthesis of a novel colorimetric fluorescent probe for the selective detection of sulfur dioxide in SH-SY5Y neuroblastoma cells and its applications in traditional Chinese medicines

A fast response time, low limit of detection and high fluorescence quantum yield probe DTCC was designed and synthesized to detect SO2 derivatives based on coumarin-thiophene dye which was fused with a coumarin moiety and 2-thiophenecarboxaldehyde.

Reaction-based fluorescent probe for detecting of sulfur dioxide derivatives and hydrazine via distinct emission signals

Recently, the construction of multiple analytes responsive fluorescent probes with distinct emission signals has attracted widely attention. Thus, we have designed and synthesized a new fluorescent probe, 2-(2-hydroxyphenyl)benzothiazole dye skeleton (HBT-1), for the detection of sulfur dioxide and hydrazine. Significant fluorescence enhancements in two distinct emission bands (λem = 464 nm and 498 nm) were generated when HBT-1 reacted with sulfur dioxide derivatives or hydrazine, respectively. Furthermore, the probe HBT-1 response can be saturated surpurisingly at the low concentration (100 μM), shorter reaction time for sulfur dioxide derivatives, while a longer reaction time and greater concentration (400 μM) for hydrazine. In other words, the probe HBT-1 can detect sulfur dioxide derivatives without hydrazine interference at low analyte concentrations.

Mass analysis of CH4/SO2 gas mixture by low-pressure MEMS gas sensor

The mass analysis of natural gas for the extraction and separation of the undesirable component such as sulfur dioxide is significant for industrial applications. In this research, numerical simulations are performed to investigate the capability of the Knudsen thermal force for the detection of sulfur dioxide in CH4/SO2 gas mixture. Recently, a new micro gas sensor (MIKRA) is introduced to apply this force for measurement of the pressure. In fact, this device operates due to temperature difference inside a rectangular enclosure with heat and cold arms at low pressure condition. In order to simulate a rarefied gas inside the micro gas detector, Boltzmann equations are applied to obtain high precision results. To solve these equations, Direct Simulation Monte Carlo (DSMC) approach is used as a robust method for the non-equilibrium flow field. This study has focused on the effect of various concentrations of the CH4/SO2 gas mixture and reveals the main mechanism of force generation inside the device. Our findings show that value of generated Knudsen force significantly changes when the fraction of SO2 in CH4/SO2 gas mixture is varied. This indicates that this micro gas sensor could precisely detect the concentration of sulfur dioxide gas inside a low-pressure CH4/SO2 gas mixture.