The application of metal–organic frameworks (MOFs) as SERS‐active platforms in multiplex volatile organic compounds (VOCs) detection is still unexplored. Herein, we demonstrate that MIL‐100 (Fe) ...serves as an ideal SERS substrate for the detection of VOCs. The limit of detection (LOD) of MIL‐100(Fe) for toluene sensing can reach 2.5 ppm, and can be even further decreased to 0.48 ppb level when “hot spots” in between Au nanoparticles are employed onto MIL‐100 (Fe) substrate, resulting in an enhancement factor of 1010. Additionally, we show that MIL‐100(Fe) substrate has a unique “sensor array” property allowing multiplex VOCs detection, with great modifiability and expandability by doping with foreign metal elements. Finally, the MIL‐100(Fe) platform is utilized to simultaneously detect the different gaseous indicators of lung cancer with a ppm detection limit, demonstrating its high potential for early diagnosis of lung cancer in vivo.
MIL‐100(Fe) is demonstrated to serve as an ideal “SERS‐active” and “sensory array” platform for multiplex sensing of volatile organic compounds (VOCs) as well as the gaseous biomarkers of diseases with low Raman cross‐sections.
Nitrogen oxides (NOx) and volatile organic compounds (VOCs) may cause ozone formation and photochemical smog pollution, which may damage to human health and ecological environment seriously. An ...aerobic Denitrifying BioTrickling Filter (DBTF) for collaborative removal of nitrogen oxides (NOx) and toluene in flue gas was investigated. NOx and toluene removal efficiency were up to 90% and 95%, respectively. Mycobacterium, Comamonas and Pseudomonas were predominant bacteria; Mycobacterium, Pseudomonas, Comamonas, Microbacterium, Reyranella, Stenotrophomonas and Alicycliphilus were the core toluene oxidizing-denitrifying genera, denitrification genes (narGHI, nirK, nasB, napAB, nosZ and norC) and toluene oxidation genes (tom, E1.14.13.7, xyl, cat, todE, tes, mhp, pch, pob, pca, lig, gal) responsible for bacterial oxidation of toluene and NOx reduction, as shown by16S rDNA and metagenomic sequencing. Bacterial oxidation of toluene was coupled to NOx reduction in which toluene served as the electron donor while NOx served as the electron acceptor and thereby redox between toluene and NOx was formed, toluene was degraded through the classical aerobic aromatic compound degradation pathway. DBTF was capable of both toluene oxidation and NOx reduction by denitrification. These results show that the DBTF is achievable and open new possibilities for applying the DBTF to simultaneous removal of NOx and VOCs.
Catalysis in VOC Abatement Ojala, Satu; Pitkäaho, Satu; Laitinen, Tiina ...
Topics in catalysis,
11/2011, Letnik:
54, Številka:
16-18
Journal Article
Recenzirano
Volatile organic compounds (VOCs) are harmful to environment and human health. Catalytic oxidation has been used in VOC abatement for over 60 years, and it has proven to be an effective technology. A ...large variety of VOCs set high demands for the treatment, and therefore catalytic oxidation needs still to be developed further. This paper reviews current aspects and future research needs related to VOCs and catalytic VOC treatment concentrating on solvent-based, chlorinated and sulphur-containing VOCs.
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•The species and possible location of Mn in Mn/zeolite are summarized.•The techniques for of characterizing various Mn species were analyzed.•The mechanism of Mn/zeolite in NOx ...purification and VOCs purification was clarified.•Methods and strategies for obtaining ideal Mn species were proposed.
Due to the excellent redox properties and channel structure brought by the combination of both Mn and zeolites, Mn/zeolite are widely utilized in the catalytic purification of gaseous pollutants. The Mn in zeolite possesses higher surface energy than that in monolithic manganese oxide catalyst, resulting in dispersing in zeolites in the form of clusters or nanoparticles, which shows both good accessibility and electron gain/loss ability to pollutant molecules. Therefore, in this work, taking the properties of Mn species, which had a decisive effect on the catalytic effect, as a clue, the chemical state and characterization techniques of Mn species in zeolites were teased out and summarized. Then, the current application status of Mn/zeolites in SCR denitrification and VOCs purification was systematically reviewed. Additionally, we conclude on factors influencing the diversity of Mn species in zeolites from the perspective of introduction methods for Mn and measures to obtain ideal Mn species. It was hoped that this work could provide some theoretical reference for designing and getting Mn/zeolite catalysts with high activity for certain application.
Most of the volatile organic compounds (VOCs) and especially the chlorinated volatile organic compounds (Cl–VOCs), are regarded as major pollutants due to their properties of volatility, diffusivity ...and toxicity which pose a significant threat to human health and the eco-environment. Catalytic degradation of VOCs and Cl–VOCs to harmless products is a promising approach to mitigate the issues caused by VOCs and Cl–VOCs. Non-thermal plasma (NTP) assisted catalysis is a promising technology for the efficient degradation of VOCs and Cl–VOCs with higher selectivity under relatively mild conditions compared with conventional thermal catalysis. This review summarises state-of-the-art research of the in plasma catalysis (IPC) of VOCs degradation from three major aspects including: (i) the design of catalysts, (ii) the strategies of deep catalytic degradation and by-products inhibition, and (iii) the fundamental research into mechanisms of NTP activated catalytic VOCs degradation. Particular attention is also given to Cl–VOCs due to their characteristic properties of higher stability and toxicity. The catalysts used for the degradation Cl–VOCs, chlorinated by-products formation and the degradation mechanism of Cl–VOCs are systematically reviewed in each chapter. Finally, a perspective on future challenges and opportunities in the development of NTP assisted VOCs catalytic degradation were discussed.
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•Catalytic degradation of Cl–VOCs under NTP condition is systematically reviewed.•The different catalysts used in NTP for Cl-VOC control are covered.•Formation and control strategies of hazardous by-products are reviewed.•Techniques used for understanding the degradation mechanisms are reviewed.
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•Oxidation-etching of MOF to assemble CoMn mixed oxide catalyst was proposed for the first time.•Abundant mesoporous structures and multifarious active regions in the catalyst were ...achieved.•The obtained catalyst exhibited excellent low-temperature toluene catalytic performance.•Stepwise oxidation mechanism was explored with DFT calculations and in situ DRIFTS technique.
For the first time, a nanosheet-state CoMnx mixed oxide with multifarious active regions was synthesized by oxidation-etching assembly of metal organic framework (MOF) precursor and applied for catalytic combustion of toluene at low temperatures. The obtained optimum catalyst denoted as CoMn6 showed excellent performance, which achieved 90% conversion of 1,000 ppm toluene under a weight hourly space velocity (WHSV) of 60,000 mL/(g·h) at 219 °C. While, it also exhibited long-term stability with strong water resistance property. The characterizations of physicochemical properties indicated that the oxidation-etching assembly process built an abundant mesoporous structure in the CoMnx catalyst, which greatly increased the specific surface area (SSA). Especially, potassium permanganate as oxidant and manganese source led to uniform dispersion and assembling of cobalt atoms, which caused the generation of low-crystallinity CoMnx mixed oxide with abundant dislocations, vacancies, phase interfaces and amorphous structures, resulting in excellent low-temperature reducibility, outstanding lattice oxygen mobility and abundant active species such as Mn3+, Co3+ and adsorbed oxygen species. Density functional theory (DFT) calculations demonstrated that gaseous oxygen with the longer bond length (1.406 Å) and stronger adsorption energy (−4.443 eV) could be adsorbed and activated well on the MnCo2O4.5 (311) plane, which is beneficial for the toluene oxidation. In situ diffuse reflectance infrared spectroscopy (DRIFTS) technique was applied to track the intermediates of toluene combustion under different atmospheres, which further deduced the contributions of different active regions and oxidation mechanism over the CoMnx catalyst. The present facile strategy of oxidation-etching assembly of the MOF precursor for the creating of novel catalyst with high performance could be applied in a wide variety of materials besides VOC combustion catalysts.
Surface enhanced Raman scattering (SERS) is a trace detection technique that extends even to single molecule detection. Its potential application to the noninvasive recognition of lung malignancies ...by detecting volatile organic compounds (VOCs) that serve as biomarkers would be a breakthrough in early cancer diagnostics. This application, however, is currently limited by two main factors: (1) most VOC biomarkers exhibit only weak Raman scattering; and (2) the high mobility of gaseous molecules results in a low adsorptivity on solid substrates. To enhance the adsorption of gaseous molecules, a ZIF‐8 layer is coated onto a self‐assembly of gold superparticles (GSPs) in order to slow the flow rate of gaseous biomarkers and depress the exponential decay of the electromagnetic field around the GSP surfaces. Gaseous aldehydes that are released as a result of tumor‐specific tissue composition and metabolism, thereby acting as indicators of lung cancer, are guided onto SERS‐active GSPs substrates through a ZIF‐8 channel. Through a Schiff base reaction with 4‐aminothiophenol pregrafted onto gold GSPs, gaseous aldehydes are captured with a 10 ppb limit of detection, demonstrating tremendous prospects for in vitro diagnoses of early stage lung cancer.
A high‐sensitivity surface enhanced Raman scattering (SERS) substrate is used for volatile organic compounds (VOCs) detection in exhaled breath, wherein ordered gold superparticles act as SERS hotspots and a metal‐organic‐framework layer is employed to slow the flow rate and strengthen the adsorption of gaseous analytes. Gaseous aldehyde VOCs are captured with a parts per billion limit of detection in this analyte‐detection system.
Smart and precise sensing is very important for the protection of both environment and personal security in modern civilized society. There are numerous sensing devices for detecting physical and ...chemical changes such as temperature, humidity, pressure, and chemical species. In this regard, conducting polymers is at the core of attention for the fabrication of next-generation sensor applications. Polypyrrole (PPy), is one of the emerging intelligent materials with a wide range of applications in the field of optical, electronic, and electrochromic devices and sensors. The stability in a different environment, ease of deposition from aqueous and non-aqueous media, adherence to diverse substrates, and high electrical conductivity made PPy a unique choice for sensor development. In recent years, PPy has proven an excellent candidate for sensing volatile organic compounds (VOCs) due to its selectivity and sensitivity towards target gas molecules, and detection of inorganic gases and VOCs. Consequently, to develop outstanding sensing devices attempts have been dedicated to developing PPy-based sensors for excellent mechanical and electrochemical performance. This review aims to provide a recent overview of progress in PPy-based advanced sensing devices. This review aims to provide a recent overview of progress in PPy-based advanced sensing devices. We have systematically discussed the challenges and future development of various sensing devices. Furthermore, the current understanding and performance evaluation of gas sensing mechanisms in PPy-based sensors are discussed theoretically and experimentally. We have also identified gaps in the state-of-the-art and hope that this study would lead to further research works into using PPy to make gas sensors. Finally, the future directions of various sensors with advanced PPy-based sensing systems have been prospected.
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•Polypyrrole (PPy) was an excellent candidate for capturing a broad range of VOCs.•Doping, surface modification, side-chain selection, and PPy-chain-arrangements were reported.•The complementary roles of experimental and theoretical studies were clearly described.•Reported families of PPy and their current utilities were elaborated.•Gaps were identified both from fundamental and applied standpoints.
Petroleum related emissions are the major anthropogenic sources of volatile organic compounds (VOCs), which served as important precursors for secondary organic aerosol (SOA). However, little is ...known about the relationship among VOCs emissions from petrochemical industries, SOA formation, and regional PM2.5. In this paper, VOCs emitted from a petrochemical industry in Yangtze River Delta (YRD, China) were continuously monitored by an online gas chromatography-photo ionization detector/flame ionization detector (GC-PID/FID) system. Results showed that the total concentration of 68 VOCs species was 151.0 ± 155.6 ppbv, and ethylene, ethane, 2-methylpentane, chloroform, 2,3-dimethyl-butane and propane were the richest species. SOA yield calculated by time-resolved approach was 7.18 ± 10.97 μg m−3, accounted for 3.35–86.4% of the corresponding PM2.5 concentration, which was a bit higher than previously reported values. VOCs-sensitiveness (VOCs-S) coefficient was adopted to investigate the quantitative relationship between VOCs and PM2.5, found VOCs were more sensitive to PM2.5 in clean domains than in polluted domains. An exponential function was fitted (y = 3.94x0.293 – 3.62, r2 = 0.816) between VOCs-S coefficient versus specific-to-background PM2.5 ratio for aromatic hydrocarbon. VOCs emitted from petrochemical industry had influence on regional PM2.5 in this study, and reducing petrochemical emissions might be effective in alleviating haze episodes.
•The composite profile of VOCs emitted from a petrochemical industry were determined.•Secondary organic compound yields from VOCs precursors were calculated by two different approaches.•Isoprene, m,p-xylene and toluene are the major contributors to SOA formation in petrochemical industry.•Alkane and alkene were more sensitivity to PM2.5 in low particle concentrations than polluted episodes.
