Emissions of atmospheric pollutants such as methane(CH4),hydrogen sulfide(H2S),ammonia(NH3),and volatile organic compounds(VOCs)from wet waste treatment plants pose serious environmental and health risks.Conventional monitoring methods,which rely on fixed stations or manual sampling,often face challenges such as limited spatial coverage,delayed data collection,and operational safety hazards.To address these limitations,this study developed a gas monitoring system utilizing a multi-parameter sensor integrated with an unmanned aerial vehicle(UAV).Field monitoring was conducted at a wet waste treatment plant in Shanghai to assess pollutant distribution,vertical concentration gradients,and correlations with environmental factors across different functional areas.The results revealed that CH4 concentrations were significantly higher than those of other gases,reaching up to 1860 μg/m3 throughout the plant,making CH4 the primary contributor to the total emission load.In contrast,H2S and NH3 exhibited distinct point-source characteristics,with high concentrations closely associated with specific processing stages,including the kitchen waste workshop,the catering waste workshop,the drying workshop,and the unloading hall.Although VOC concentrations were relatively low,their complex composition presented potential environmental risks.Vertical profile monitoring showed that CH4 maintained high concentrations at all heights(1800-1900 μg/m3);NH3 tended to accumulate in the upper sections of the facility,while H2S concentrations gradually increased with height.Conversely,VOCs exhibited a relatively homogeneous vertical distribution across the plant.These diffusion trends suggest that NH3 could intensify odor pollution,while VOCs may enhance ozone formation and the generation of secondary organic aerosols.Correlation analysis indicated that humidity and air pressure were key environmental factors influencing the release and dispersion of these gases.Among these factors,humidity demonstrated the most significant influence on NH3 and VOC levels,suggesting its critical role in determining their atmospheric residence time and transport behavior.This study demonstrates the effectiveness of UAV-based sensing for detecting pollutant gases in complex industrial settings.By enabling precise monitoring and real-time data acquisition,this approach improves environmental risk assessment and supports the creation of targeted pollution control strategies for wet waste treatment plants.Our findings confirm that UAV-mounted systems provide significant advantages over conventional methods,specifically in terms of expanded spatial coverage and enhanced operational safety.Overall,this study highlights the transformative potential of UAV technology in environmental monitoring,offering critical insights for air quality management and evidence-based policymaking in waste treatment sectors.
Biomass sorption-enhanced steam reforming is a promising route for the efficient conversion of biomass into H2-rich syngas by improving H2 selectivity and yield.This study investigates the design and performance of CaO-based hybrid materials for the sorption-enhanced steam reforming(SESR)of pine sawdust for H2 production.The hybrid materials were synthesized by incorporating different proportions of polymorphic Ca2SiO4 into CaO via a hydrothermal method followed by carbon-template removal.A homogeneous precursor solution containing Ni,Ca,and Si species was transferred into a 50 mL autoclave and subjected to hydrothermal treatment at 200 ℃ for 36 h.The obtained samples were then dried and calcined in air by heating to 800 ℃ at a rate of 5 ℃·min-1,followed by a holding period of 2 h.After carbon-template removal,hollow-shell sorbents were obtained.The CO2 sorption capacity and cyclic stability of the undoped sorbents were evaluated,and 10 wt.%Ni was subsequently introduced into the optimized sample.The results indicate that Ca2SiO4 loading significantly affects the balance between CO2 uptake and cyclic stability.Among the tested sorbents,the sample containing 10 wt.%Ca2SiO4 exhibited the best overall performance,achieving the highest cumulative CO2 uptake over 10 cycles while maintaining relatively high CaO utilization.Structural characterization revealed that the stabilization effect of Ca2SiO4 arises both from the dilution of the active phase and from its role as a spatially distributed inert framework between CaO grains.The results from X-ray diffraction(XRD),Brunauer-Emmett-Teller(BET)surface area analysis,and scanning electron microscopy with energy-dispersive X-ray spectroscopy(SEM-EDS)consistently suggest that Ca2SiO4 was uniformly dispersed within the hollow shell.This distribution physically separated adjacent CaO particles,restricted grain growth during repeated carbonation and calcination,and helped preserve pore volume and accessible surface area.Consequently,this microstructural stabilization effectively suppressed sintering and delayed the loss of fast-reaction sites.Furthermore,Ni incorporation reduced the CaO crystallite size and improved the utilization of active CaO while preserving the hollow-shell morphology.Upon further doping with 10 wt.%Ni,both H2 production and purity were significantly enhanced compared with those of the undoped sorbents.After 10 carbonation cycles,the Ni10Ca9Si1-HS sorbent maintained a H2 yield of 1.80 mmol/(gbm·gmat·min),representing only a 4.32%decrease from the initial value of 1.88 mmol/(gbm·gmat·min).Meanwhile,the H2 purity decreased slightly from 71.50%to 67.63%,demonstrating excellent cyclic stability.This study demonstrates that morphological control and the use of polymorphic stabilizers are crucial for improving the cyclic stability of catalyst-sorbent hybrid materials for sustainable H2 production from biomass,providing guidance for the structural design of highly efficient CaO-based hybrid materials.
In addressing the critical challenge of persistently increasing atmospheric concentrations of greenhouse gases (CO2, CH4, N2O), merely measuring their bulk concentrations has proven insufficient for accurately assessing their diverse sources, sinks, and the complex biogeochemical processes that control their global budgets. The stable isotopic compositions of these gases (such as δ13C, δ18O, δ15N) provide powerful "natural fingerprints", offering unique insights that transcend concentration data alone. These isotopic signatures enable researchers to effectively discriminate between biogenic and fossil fuel emission sources, quantitatively apportion contributions from different anthropogenic and natural processes, and reveal the underlying microbial mechanisms governing their production and consumption across various ecosystems. This comprehensive review synthesizes recent methodological advancements in isotopic analysis techniques specifically applied to greenhouse gases. It critically examines the fundamental principles, technical characteristics, and optimal application scenarios of mainstream analytical methods. These include the established benchmark technique of isotope ratio mass spectrometry (IRMS), alongside rapidly developing optical methods such as Fourier transform infrared spectroscopy (FTIR), tunable diode laser absorption spectroscopy (TDLAS), cavity ring-down spectroscopy (CRDS), and off-axis integrated cavity output spectroscopy (OA-ICOS). The comparative advantages and limitations of each technique are discussed in the context of precision, operational requirements, and field deployability. Furthermore, the article systematically elaborates on the transformative applications of these isotopic techniques across a wide spectrum of environmental research. Key areas covered include high-precision tracing of urban emission sources, elucidating production and consumption pathways in aquatic ecosystems, constraining carbon cycling dynamics in soils and wetlands, quantifying greenhouse gas fluxes in sensitive polar regions like the Antarctic tundra, and providing crucial validation for carbon cycle models that incorporate geological sources. Finally, the review critically discusses the persistent challenges confronting the field, particularly the pressing need for advanced capabilities in in-situ, high-frequency, and simultaneous multi-component isotopic measurements. It outlines promising future research directions, strongly emphasizing that the integration of multi-isotope observational networks with sophisticated atmospheric and process-based models will be paramount for precisely deciphering global and regional greenhouse gas budgets. Such integrated approaches are identified as foundational for formulating targeted and effective emission reduction strategies, as well as for advancing our predictive understanding of the biosphere's response to a changing climate.
With the continuous development of industries such as integrated circuits,wind power,and nuclear energy,the accumulation of spent thermosetting resin-based composites has emerged as an increasingly pressing environmental issue.Pyrolysis represents a promising technology for the resource recovery and value-added utilization of these wastes.To elucidate the pyrolysis characteristics of such wastes,this study systematically investigated the thermal decomposition behavior of spent ion-exchange resins based on a styrene-divinylbenzene backbone functionalized with sodium sulfonate groups.In addition,artificial intelligence models were developed to predict key pyrolysis parameters across different types of thermosetting resin-based composite wastes.The mass-loss behavior and heat flow evolution during pyrolysis were analyzed using thermogravimetry-differential scanning calorimetry(TG-DSC).The composition and distribution of gaseous and liquid products were further characterized by thermogravimetry-mass spectrometry(TG-MS)and pyrolysis-gas chromatography/mass spectrometry(Py-GC/MS).The results indicate that the cleavage of the styrene-divinylbenzene crosslinked backbone occurred predominantly between 415 and 505 ℃.During this stage,the major pyrolysis products were styrene,ethylbenzene,and toluene—high-value chemicals that accounted for approximately 77%of the detected products at 455 ℃.At temperatures above 581 ℃,CH4,H2,and CO2 became the dominant gaseous products,forming combustible gases with potential for energy recovery,while a char yield of approximately 45%was observed.An increase in heating rate led to a higher temperature corresponding to the maximum mass-loss rate,a broader temperature range for backbone cleavage,and a higher overall mass-loss rate.These changes collectively influenced the temperature window and yield of volatile products as well as the amount of residual char.Therefore,the heating rate is a key process parameter for the efficient recovery of gas,liquid,and char products from spent ion-exchange resins.Furthermore,regression models and artificial neural network(ANN)models were developed by integrating experimental results from this study with literature data on various thermosetting resin-based wastes.Based on feature importance analysis using the F-test,these models were trained using the proximate and ultimate analyses of spent resins to predict their pyrolysis parameters,including onset temperature,temperature of maximum mass-loss rate,termination temperature,and overall weight loss.Among all modeling approaches,the ANN trained using the Levenberg-Marquardt algorithm exhibited the best predictive performance,achieving a coefficient of determination(R2)of 0.99 and a mean squared error of 0.0007.In future research,emphasis should be placed on improving the purity of gaseous and liquid products,enhancing the performance of char materials,expanding the experimental database,and employing more advanced machine learning techniques.These efforts will further improve the generalization and predictive accuracy of models,thereby providing more reliable guidance for optimizing pyrolysis processes toward the efficient synergistic recovery of gas,liquid,and char products from thermosetting resin-based composite wastes.
In recent years,heated tobacco products(HTPs)have gained increasing popularity worldwide due to their reduced emissions of harmful substances compared to conventional cigarettes.To evaluate their environmental and health impacts,characterizing their physical and chemical properties is essential.This work employs a Scanning Mobility Particle Sizer(SMPS)to measure the puff-resolved concentrations of heated tobacco aerosols in real time.The aerosols were generated by two types of heating devices:an electromagnetic heating device and an infrared heating device.The puff-resolved concentrations of monodisperse particles at multiple selected sizes were measured to derive the overall size distributions.Subsequently,the puff-by-puff total particle number concentrations and mode diameters of the tobacco aerosols were determined.The key findings are as follows:(1)Due to distinct heating mechanisms,the aerosols produced by the two devices exhibit different puff-resolved distribution characteristics.The electromagnetic heating device offers relatively high heating efficiency but results in uneven heat distribution.Consequently,the aerosol concentration fluctuates within a range from 6.3×106 to 8.9×106 particles·cm-3,and the mode diameter varies between 220 and 283 nm.The infrared heating device provides more uniform heating but has lower heating efficiency,leading to a gradually increasing operating temperature during puffing,especially under insufficient preheating.The aerosol concentration increases puff-by-puff from 2.3×106 to 8.7×106 particles·cm-3,with mode diameters increasing from 151 to 319 nm.(2)Heated tobacco aerosol particles in different size ranges exhibit a distinct dependence on heating temperature.Smaller particles(≤80 nm)tend to be produced in large quantities at lower temperatures,while larger particles(≥300 nm)are more likely to be generated at higher temperatures.(3)The total particle concentrations and mode diameters of heated tobacco aerosols vary synchronously.The temperature of the heating device significantly affects both the total particle concentration and the mode diameter.As the heating temperature increases,both the aerosol concentration and the mode diameter rise markedly.These results demonstrate that the total particle number concentrations and mode diameters of heated tobacco aerosols are highly sensitive to the operating temperature and heating mechanism.Thus,the substantial release of small particles under insufficient heating conditions poses challenges for the design of heating control modules,emphasizing the need for adequate preheating and stable operating temperatures.
