Incomplete Combustion Processes Research Articles

Analisis Pengaruh Emisi Zat Karbon terhadap Kerusakan Kualitas Udara dan Pencemaran Lingkungan

Carbon monoxide is called the "silent killer" because this gas is colorless and odorless. This gas is produced from incomplete combustion of fossil fuels. Carbon monoxide, referred to as CO, is flammable and very dangerous but is non-irritating and tasteless, making it difficult to detect by the human senses. Carbon monoxide can form naturally or artificially. Human activities are the main source of its formation. Carbon monoxide (CO) which comes from nature is CO gas which comes from oceans, mountains, forest fires, electrical storms and metal oxidation in the atmosphere. The source of CO gas that comes from human activities generally comes from incomplete combustion processes, such as the combustion process that occurs in motorized vehicles, burning coal, combustion products from industrial machines, cigarette smoke or other combustion that produces gas. This research aims to determine the effect of carbon monoxide on the environment and health. The method used in this writing is literature study. The library sources taken in compiling this literature study were through journals taken from the Google Scholar website. The results are based on a review of (number of journals) journals related to the title, namely the effect of carbon emissions on damage to air quality and environmental pollution.

Overestimation of black carbon light absorption due to mixing state heterogeneity

Black carbon (BC) aerosols, which arise from incomplete combustion processes, possess the capacity to absorb solar radiation, thereby contributing significantly to the issue of climate warming. However, accurately estimating their radiative effect is challenging, influenced by emissions, sizing, morphology, and mixing state. BC particles undergo aging processes that can alter their physical characteristics and mixing state, consequently affecting their optical properties. In this study, we assessed the mixing state of BC across diverse atmospheric environments. Results demonstrate that mixing state heterogeneity is a ubiquitous phenomenon. In background atmospheres, BC exhibited less homogeneous states compared to those in urban and suburban areas, where heterogeneity was driven by primary emissions. Our study provides direct observational evidence that the heterogeneity of particle-particle mixing can reduce the light absorption enhancement of BC in all atmospheres, with a deviation of up to approximately 24% under background conditions.

Metal-free C2N catalyst with superior H2O/SO2 tolerance for NO reduction with CO during incomplete combustion process

Designing a highly effective catalyst for purification NOx emissions during the incomplete combustion process in coal-fired power plants is a valuable yet challenging task. The presence of H2O and SO2 during the NOx reduction process for flue gas treatment in coal-fired power plants is a major concern because it can lead to catalyst deactivation due to the deposition of ammonium sulfate. In this work, we propose a novel method for removing NO and CO without the traditional NH3 injection (2NO + 2CO = N2 + 2CO2) by utilizing density functional theory (DFT) calculations. Specifically, we designed metal-free single and double atomic catalysts named MFn/C2N and demonstrated that the Si-DAC (Si2/C2N) system has the highest activity for NO reduction, with outstanding resistance to deactivation from H2O and tolerance to SO2. Our findings show that Si-DAC has the best catalytic performance for NO reduction, with an extremely low energy barrier of 0.28 eV, suggesting that Si-DAC is the most effective among the reported computational results for NO removal. Overall, this work could pave the way towards designing catalytic systems with excellent activity and stability for reactions beyond NOx reduction.

Excited State Dynamics of Dibenzothiophene Derivatives.

Polycyclic aromatic sulfur heterocycles are environmental pollutants formed from incomplete combustion processes and crude oil spills. Their excited state dynamics are not understood. Herein, femtosecond transient absorption is combined with steady-state spectroscopy and computational methods to elucidate the relaxation mechanisms of three dibenzothiophene derivatives. The low-energy singlet and triplet states all have ππ* character in the Franck-Condon region, and two minima were located in the S1 surface. Excitation at 320 nm populates their S1 state directly, which relaxes with lifetimes ranging from 4 to 13 ps. Most of the S1 population undergoes efficient intersystem crossing to the triplet state with lifetimes ranging from 820 ± 50 to 900 ± 30 ps. The compounds exhibit negligible nonradiative internal conversion, low fluorescence yields of 1.2 to 1.6%, and triplet yields of ca. 98%. Linear interpolation of internal coordinates reveals the chemical basis for relaxing the spin-forbidden intersystem crossing in these π-aromatic systems.

Polycyclic Aromatic Hydrocarbon (PAH) Contents of Four Species of Smoked Fish from Different Sites in Senegal.

Polycyclic aromatic hydrocarbons (PAHs) are compounds resulting from any incomplete combustion process. These are pollutants that have proven toxicity due to their carcinogenic nature and can contaminate food during traditional smoking methods. Their highly toxic effect on human health requires monitoring of their levels in food products and the development of appropriate analytical methods for their determination. Thus, this study was conducted to assess the level of PAHs contamination of four (4) species of smoked fish (Arius heudelotii, Sardinella aurita, Ethmalosa fimbriata, and Sardinella maderensis) which were sampled in seventeen (17) localities in Senegal. The compounds targeted in this study were benzo(a)pyrene (B(a)P), benzo(a)anthracene (B(a)A), benzo(b)fluoranthene (B(b)F), and chrysene (Chr). The QuEChERS method was used for the extraction of PAHs, and their contents were quantified by gas chromatography (GC) coupled with mass spectroscopy (MS). The validation method was performed in accordance with the French standard NF V03-110 (2010). Satisfactory linearity (R2 > 0.999), LOD (0.05-0.09 μg/kg), LOQ (0.19-0.24 μg/kg), and precision (1.33-3.13%) of the four PAHs were obtained. The results of analysis in the 17 localities showed that all samples are contaminated by the four (4) PAHs with great variability of the contents between the different species and their origin. The B(a)P and ∑4PAHS contents in the samples ranged from 1.7 to 33 µg/kg and from 4.8 to 1082.3 µg/kg, respectively. Twelve (12) samples showed high levels of B(a)P, ranging from 2.2 to 33 µg/kg, thus exceeding the maximum authorized level (2 µg/kg). Fourteen (14) samples showed an overall ∑4PAHS content varying from 14.8 to 1082.3 µg/kg, which is above the maximum authorized limit (12 µg/kg). The principal component analysis showed that sardinella (Sardinella aurita and Sardinella maderensis) have very low levels of B(a)P, B(b)F, B(a)A, and Chr contents. However, high ∑4PAHS contents characterize smoked fish of the Kong species (Arius heudelotii), from Cap Skiring, Diogne, Boudody, and Diaobé, and of the Cobo species (Ethmalosa fimbriata) from Djiffer. Thus, based on the authorized limits for PAHs in smoked fish, it appears that smoked fish of the sardinella species are less carcinogenic for human consumption.

Black Carbon Emissions, Transport and Effect on Radiation Forcing Modelling during the Summer 2019–2020 Wildfires in Southeast Australia

The emission of black carbon (BC) particles, which cause atmospheric warming by affecting radiation budget in the atmosphere, is the result of an incomplete combustion process of organic materials. The recent wildfire event during the summer 2019–2020 in south-eastern Australia was unprecedented in scale. The wildfires lasted for nearly 3 months over large areas of the two most populated states of New South Wales and Victoria. This study on the emission and dispersion of BC emitted from the biomass burnings of the wildfires using the Weather Research Forecast–Chemistry (WRF–Chem) model aims to determine the extent of BC spatial dispersion and ground concentration distribution and the effect of BC on air quality and radiative transfer at the top of the atmosphere, the atmosphere and on the ground. The predicted aerosol concentration and AOD are compared with the observed data using the New South Wales Department of Planning and Environment (DPE) aethalometer and air quality network and remote sensing data. The BC concentration as predicted from the WRF–Chem model, is in general, less than the observed data as measured using the aethalometer monitoring network, but the spatial pattern corresponds well, and the correlation is relatively high. The total BC emission into the atmosphere during the event and the effect on radiation budget were also estimated. This study shows that the summer 2019–2020 wildfires affect not only the air quality and health impact on the east coast of Australia but also short-term weather in the region via aerosol interactions with radiation and clouds.

SOSIALISASI BAHAYA SAMPAH ORGANIK DAN NON ORGANIK BAGI MANUSIA DAN LINGKUNGAN PADA SANTRI MA'HAD AL JAMI'AH IAIN AMBON

Plastic waste is a material that has a negative impact for our life in earth. This is due to several reasons including; plastic waste takes 1000 years to decompose completely, the destruction of plastic waste by burning cause an incomplete combustion process that can produce toxic gases that are harmful to health, scientists from SCIRO (Commonwealth Scientific and Industrial Research Organization) and Imperial College London said that 90% of seabirds have plastic in their stomachs and it is estimated that number will continue to increase to 99% in the 2050. The purpose of carrying out this Community Service activity is to provide an understanding of the dangers of organic and non-organic waste for living things and the environment, an understanding of management of organic and non-organic waste, and an understanding of a lifestyle that is minimal in waste. The method used in this activity is lectures with presentation slide media on the dangers of organic and non-organic waste for humans and the environment. The results of the socialization show that the students of Ma'had Al-Jamiah IAIN Ambon understand the dangers of organic and non-organic waste, how to manage organic and non-organic waste and understand a lifestyle that is zero waste.

ASSESSMENT OF RIVER SEDIMENT QUALITY ACCORDING TO THE EU WATER FRAMEWORK DIRECTIVE IN LARGE RIVER FLUVIAL CONDITIONS. A CASE STUDY IN THE LOWER DANUBE RIVER BASIN

Increase of pollution of surface water and water sediments with hazardous substances (HSs) in the Danube River Basin requires implementation of systematic monitoring and evaluation of the sediment quality. The present study is focused on the ’South Danube’ Test Area (SDTA) that covers parts of the Lower Danube Basin in Romania, Serbia and Bulgaria. The SD area represents an extended region where Danube reaches its largest widths and depths and where pollution (industrial, mining, agricultural, waste etc.) from tributaries and land is supposed to accumulate in the sediments. Sampling of river bottom sediment (BS), suspended sediment (SS) and overbank (floodplain) sediment at two layers (0-5 cm in the top layer (FS TS) and 40-50 cm in the bottom layer (FS BS)), was carried out at 11 locations in order to analyze the concentration and distribution of 8 metal(oid)s (Cu, Pb, Zn, Cd, Hg, Ni, Cr, As), 6 polycyclic aromatic hydrocarbons (PAHs) and 6 pesticides as hazardous substances. The 2013/39/EU Directive and EU Water Framework Directive standards were used to sediment quality assessment. As a whole, the concentrations of heavy metals in the sediments are comparatively low and are around the normal values for soils. On the other hand, some sampling sites and sediment types have high or very high metal concentrations which exceed intervention levels. Our study well recognizes mining pollution sources in the Danube tributaries Borska Reka, Timok, Ogosta, Malak Iskar and Iskar from past and/or recent mining activity. This pollution is limited to the Danube tributaries and around their confluences into the Danube River. The concentration of heavy metals is strongly diluted in the Danube River and drops around normal values. The studied sediments reveal low concentrations of PAHs. Only fluoranthene content is higher in most of the sediment types and sampling sites on the Danube River, but exceeds the interventional level only at Pristol and at Hârșova. Our results show that the sediments in the Danube River are more polluted with PAHs than its tributaries. The identified organic compounds are assumed to be generated during incomplete or low temperature combustion processes or during road transportation and/or the navigation on the Danube River.

The Role of Sulfur Emission from the Petroleum Industry on Ultrafine Particle Number Concentration in Singapore

Ultrafine particles, defined as particles with a diameter (dp) smaller than 100 nm, serve as an important component of cloud condensation nuclei, in addition to impacting human health. The dominant sources of ultrafine particles include traffic emissions and nucleation. Singapore is a tropical city that hosts petrochemical industries. To identify the sources of ultrafine particles, a year-long observation of the number size distribution was conducted in Singapore in 2018 and 2019. The concentrations of CO, CO2, CH4, and SO2 were also monitored. The particle number concentration during the southwest monsoon season was high, while that during the northeast monsoon period was relatively low. The CO concentration increased during the morning traffic rush hours, which was associated with relatively minor enhancements in ultrafine particle number concentration. The events for a high number concentration of the Aitken mode particles (dp < 50 nm) were identified during high SO2 concentration periods. The SO2 concentration was high during the afternoon because the sea breeze transported the emissions from the coastal industrial area to the observation site. The enhancements in CH4 from its background level (ΔCH4) and SO2 had a quasi-inverse relationship, as the major emission sources of these two chemical species were different. The particle number concentration (dp > 50 nm) correlated with the enhancements in CO concentration (ΔCO) for CH4-dominant air masses, suggesting that incomplete combustion processes, such as traffic emission, are important for the size range. Conversely, the number concentration of the Aitken mode particles (dp < 50 nm) increased for SO2-dominant air masses, suggesting the importance of industrial plume.

Optimization of a simple, effective, and greener methodology for polycyclic aromatic hydrocarbon extraction from human adipose tissue.

Polycyclic aromatic hydrocarbons (PAHs) are environmentally persistent organic pollutants formed during incomplete combustion and pyrolysis processes. Humans are continuously exposed to PAHs which are linked to severe health effects such as diabetes, cancer, infertility, and poor foetal development, amongst others. PAHs are lipophilic compounds prone to accumulating in adipose tissue. Even though adipose tissue is the ideal matrix to assess over time accumulation of lipophilic pollutants, only a few analytical methods have been developed for this matrix. Aiming to reduce the existent gap, a method for the extraction of PAHs from adipose tissue samples using ultrasound-assisted extraction (UAE) was developed. The behaviour of PAHs (retention, adsorption, and volatilization) over several steps of the analytical procedure was studied. Validation tests were performed on the optimized method. PAHs were quantified using a high performance liquid chromatography (HPLC) system equipped with a photodiode array (PDA) and fluorescence (FLD) detector inline. The method achieved a low matrix effect and presents low method detection (MDL) and quantification (MQL) limits, showing suitability for a selective and sensitive determination of PAHs in adipose tissue. The extraction is performed with 0.4 g of adipose tissue and 6 mL of n-hexane and it does not require clean-up afterwards. Additionally, an Eco-Scale score of 74 and an Analytical GREEnness score of 0.66 were obtained. The method achieved is effective, simpler, greener, and easy to perform, being an alternative to conventional extraction methods. Furthermore, this method can be used as a multi-analyte methodology since it has been previously validated by the authors for the analysis of other lipophilic compounds. Naphthalene (Naph), acenaphthene (Ace), fluorene (Flu), phenanthrene (Phe), anthracene (Ant), fluoranthene (Fln), pyrene (Pyr) and benzo[k]fluoranthene (B[k]Ft) were found in all the tested adipose tissue samples.

Performance and Characteristics of Bio-Oil from Pyrolysis Process of Rice Husk

This study aims to modify the pyrolysis device that produces bio-oil with methyl esters, determine the content of methyl esters with GC/MS analysis, and test the performance of biodiesel using a diesel engine. This research modified the pyrolysis tube wall by changing the thickness of the stainless-steel material to 1.5 mm to facilitate the combustion process and heat transfer and reduce the equipment weight. Meanwhile, the tube base still uses 3 mm stainless steel to prevent leakage during the process because of high temperature (300 – 400°C). Using wood and coconut shell could accelerate the incomplete combustion process and produce higher methyl ester than using a gas stove. The process using wood and coconut shell could produce 35.88% of bio-oil produced while the process using a gas stove only produces 30%. The GC/ MS analysis has discovered that the content of methyl ester and ethanol was 60.12% and 1.13%, respectively. The obtained methyl ester was separated from the tar using a rotary evaporator based on the boiling point difference. Methyl ester from this husk can turn on the diesel engine with B20-B60.

Monitoring and Occurrence of Heavy PAHs in Pomace Oil Supply Chain Using a Double-Step Solid-Phase Purification and HPLC-FLD Determination.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental and processing contaminants generated by both spontaneous and anthropogenic incomplete combustion processes of organic matter. Contamination of PAHs in vegetable oils can result from several factors and processes, including environmental contamination, oil processing, and migration from food contact materials. The determination of PAHs in edible oil presents a challenge because of the complexity of the matrix. Since PAHs are present at lower levels than triglycerides, it is necessary to isolate the compounds of interest from the rest of the matrix. To this purpose, a new purification approach based on a double solid-phase extraction (SPE) step followed by high performance liquid chromatography–fluorometric detector (HPLC-FLD) analysis was developed. The method involves a first purification step by using a 5 g silica SPE cartridge, previously washed with dichloromethane (20 mL), dried completely, and then conditioned with n-hexane (20 mL). The triglycerides are retained by the silica, while the PAH-containing fraction is eluted with a mixture of n-hexane/dichloromethane (70/30, v/v). After evaporation, the residue is loaded on a 5 g amino SPE cartridge and eluted with n-hexane/toluene (70/30, v/v) before HPLC-FLD analysis. The focus was the evaluation of the contribution of the various phases of the pomace oil supply chain in terms of the heavy PAHs (PAH8) concentration. Data collected showed that pomace contamination increased (by 15 times) as storage time increased. In addition, the process of pomace drying, which is necessary to reduce its moisture content before solvent extraction of the residual oil, appeared to significantly contribute to the total heavy PAHs content, with increases in value by up to 75 times.

ASSESSMENT OF RIVER SEDIMENT QUALITY ACCORDING TO THE EU WATER FRAMEWORK DIRECTIVE IN MOUNTAINOUS FLUVIAL CONDITIONS. A CASE STUDY IN THE UPPER TISA AREA, DANUBE RIVER BASIN

Discharge of hazardous substances (HSs) in hydrographic basins represent a danger to aquatic biological activity and water supplies and can severely pollute surface water sediments. The increase of pollution in the Danube Basin requires the implementation of systematic monitoring and evaluation of the sediments quality as dictated by the EU Water Framework Directive. For this system development, applicable in mountainous conditions, the Upper Tisa region in the northwest part of Romania on the border with Ukraine, Hungary and Slovakia was selected as a test area. Sampling of overbank (floodplain) sediment, river bottom sediment and suspended sediment was carried out at 10 locations in the test area in order to analyze the concentration and distribution of eight metal(oid)s (Cu, Pb, Zn, Cd, Hg, Ni, Cr and As), in addition to 3 organic components (anthracene, fluoranthene, benzo(e)pyrene) as hazardous substances (HSs). The sediment quality assessment was carried out according to the 2013/39/EU Directive and EU Water Framework Directive standards. Most of the analyzed HS concentrations in river bottom sediment and overbank (floodplain) sediments fall within the limits of environmental quality standards (EQS). As, Cu, Pb, and Zn tend to exceed the EQS at some locations. The highest exceedances were recorded for Pb, for which contents of up to 987 mg/kg were detected. The highest contents were found in the overbank sediments sampled, and the lowest in river bottom sediments, which may indicate historical pollution. Mercury contents in overbank sediment samples exceed all standards, while cadmium content is below the international standards. Anthracene, fluoranthene and benzo(e)pyrene concentrations in overbank and bottom sediments comply with international standards. A few samples in suspended sediments slightly exceed the lowest environmental standard value (i.e., Romanian normal value). HS concentrations remain low in the suspended sediments showing that it is not the main transport route for pollution in this area. HS contents decrease gradually from upstream to downstream due to dilution along the river course. In the last testing point at Someș Aciua, the concentration of metal(oid)s measured in the sediments remain below the EQS limit values, thus there is no risk of transboundary pollution. The main source of metal(oid) contamination is historic base-metal ore mining and the associated mine waste sites in the Baia Mare and other mining areas scattered around the whole region. The main source of the studied organic compounds is the incomplete or low-temperature coal combustion processes that occur in households in rural areas

Smouldering organic waste removal technology with smoke emissions cleaned by self-sustained flame

Smouldering is slow, low-temperature and flameless, and has been potentially regarded as an alternative for organic waste removal technology. However, as an incomplete combustion process, toxic smoke and pollution from the smouldering are significant concerns that limit its popularization. This work applies a newly developed smouldering-based waste removal technology to investigate the removal of coffee waste, wood waste, and organic soil (simulated sludge) via using a flame to clean smouldering emissions at different airflow velocities (3–24 mm/s). Once ignited from the top, the smouldering front first propagates downwards where a stable flame situated above could be piloted and sustained to purify the smouldering emissions until the smouldering front reached the bottom of the fuel bed. The efficiency of pollution mitigation was demonstrated by significantly lower CO and VOCs emission after purification by self-sustained flame. The equivalent critical mass flux of flammable gases required for igniting the smouldering emissions is 0.5 g/m2∙s, regardless of the fuel type. The smouldering temperature, propagation rate and burning flux all increase with the airflow velocity but are also slightly sensitive to the type of waste. This work enriches strategies for the clean treatment of smouldering emissions and promotes an energy efficient and environmentally friendly method for organic waste removal.

The design of fuel dryer in palm oil processing industries by utilizing the heat product of boiler based on computational fluid dynamic

Incomplete combustion process from boiler in palm oil processing industry usually discharged into the air in the form of black smoke due to the high water contain in the fuel of the boiler which will pollute the air. With this problem the research was conducted of designing a simulation of fuel dryer to dry out the boiler fuel before it used by utilizing the exhaust heat of the combustion system in the boiler. The simulation design of the fuel dryer is based on computational fluid dynamic (CFD) with parameters control are air velocity and heat temperature of fuel dryer. The results obtained the distribution of air velocity in the dryer has a value range of 0-40 m/s with the highest velocity occurring when hot exhaust air enters the dryer while the temperature distribution inside the dryer has a value range of 90-270 °C with the highest temperature appearing around hot air inlet exhaust and the lowest temperature appears in the hot air outlet section of the dryer.

Limits of sustaining a flame above smoldering woody biomass

ABSTRACT Smoldering is slow, low-temperature, and flameless burning of porous fuel, and it is also an emerging method for energy conversion and waste removal. However, smoldering combustion is an incomplete combustion process, so the pollutions resulted from smoldering emissions are significant concerns. This work explores the flaming of emission gases from the smoldering wood chips (200 kg/m3) under different oxidizer flow velocities (4 mm/s-24 mm/s) and oxygen concentrations (14%-21%) through porous media. Once ignited on the top, the smoldering front first propagates downward (1st stage, opposed) to the bottom and then propagates upward (2nd stage, forward). We found that during the 1st-stage downward smoldering propagation, a stable flame of smoldering emissions could be piloted and sustained. The critical smoldering burning rate for maintaining a stable flame remains constant at 10–12 g/m2∙s. To reach such a minimum smoldering burning rate, the required opposed flow velocity increases from 6 to 24 mm/s, as the oxygen concentration decreases from 21 to 14%. A simplified heat transfer process is proposed to reveal the limiting conditions for the co-existence of flaming and smoldering. This work enriches strategies for the clean treatment of smoldering emissions and promotes an energy-efficient and environment-friendly method for biowaste removal.

Diesel exhaust particulate emissions and in vitro toxicity from Euro 3 and Euro 6 vehicles

Incomplete combustion processes in diesel engines produce particulate matter (PM) that significantly contributes to air pollution. Currently, there remains a knowledge gap in relation to the physical and chemical characteristics and also the biological reactivity of the PM emitted from old- and new-generation diesel vehicles. In this study, the emissions from a Euro 3 diesel vehicle were compared to those from a Euro 6 car during the regeneration of a diesel particulate filter (DPF). Different driving cycles were used to collect two types of diesel exhaust particles (DEPs). The particle size distribution was monitored using an engine exhaust particle sizer spectrometer and an electrical low-pressure impactor. Although the Euro 6 vehicle emitted particulates only during DPF regeneration that primarily occurs for a few minutes at high speeds, such emissions are characterized by a higher number of ultrafine particles (<0.1 μm) compared to those from the Euro 3 diesel vehicle. The emitted particles possess different characteristics. For example, Euro 6 DEPs exhibit a lower PAH content than do Euro 3 samples; however, they are enriched in metals that were poorly detected or undetected in Euro 3 emissions. The biological effects of the two DEPs were investigated in human bronchial BEAS-2B cells exposed to 50 μg/mL of PM (corresponding to 5.2 μg/cm2), and the results revealed that Euro 3 DEPs activated the typical inflammatory and pro-carcinogenic pathways induced by combustion-derived particles, while Euro 6 DEPs were less effective in regard to activating such biological responses. Although further investigations are required, it is evident that the different in vitro effects elicited by Euro 3 and Euro 6 DEPs can be correlated with the variable chemical compositions (metals and PAHs) of the emitted particles that play a pivotal role in the inflammatory and carcinogenic potential of airborne PM.

Efficient CO sensing by a CuO:Au nanocomposite thin film deposited by PLD on a Pyrex tube

Carbon monoxide gas is a highly toxic, poison gas in air that can lead to death, if inhaled by humans for a prolonged time. It is produced from incomplete various combustion processes (natural gas, gasoline of cars, outdoor fires, etc.), and circulates the same way as air as its density is close to air density. Moreover, it is a tasteless, colorless and odorless gas. Therefore, efficient CO sensors are necessary with high efficiency, low cost and easily production, low power consumption, simplicity and robustness in their operation. Such sensors can be realized by electrochemical, semiconducting metal oxide thin films. A p-type pure CuO and CuO:Au compound thin film sensor has been grown by Pulsed Laser Deposition on the surface of a Pyrex tube (Din = 8 mm, thickness 1 mm) and CO sensing has been performed with a concentration as low as ca. 60 ppm/air. A cheap, home-made and with low power consumption ceramic heater was inserted into the tube reaching operating temperature up to 450 °C. A granular film surface revealed by AFM and SEM measurements, indicating a large effective surface for gas sensing. EDS surface mapping indicated the Au existence on the CuO:Au compound film homogeneously covering the whole film surface. CO sensing measurements were performed for 305, 325, 345 °C operating temperatures and for a large number of CO concentrations in air.

Measurement and evaluation of gaseous and particulate emissions from burning scented and unscented candles

It has been known for a long time that incomplete combustion processes produce by-products that are harmful to human health. Particularly high concentrations of such by-products can arise in indoor environments when operating open flames without venting. The emission behavior of many combustion sources, including candles, has already been examined in detail. However, to date there are no studies in which the chemical composition of the candles is known exactly or where the candles were specifically manufactured for comparative measurements. In this respect, the study presented here, which was designed in collaboration with candle manufacturers and fragrance houses, demonstrates new insights into the emissions of burning candles depending on their composition.All investigations were carried out under controlled climatic conditions in an 8 m3 stainless steel chamber. Combinations of four different fuels (waxes) and five different fragrances in addition to one set of unscented control candles were examined. This resulted in 24 experiments, 20 with scented candles and four with unscented candles. The typical combustion gases carbon monoxide, carbon dioxide and NOx, organic compounds, such as formaldehyde, benzene, and polycyclic aromatic hydrocarbons, PM2.5 and ultrafine particles were monitored in the chamber air and the emission rates were determined. The data were statistically evaluated using parametric and non-parametric methods as well as hierarchical cluster analysis. Exposure scenarios typical for indoor environments were calculated from the emission rates and the results were compared with indoor guidance and reference values.As expected, a multitude of gaseous and particulate emissions were detected. These were typical combustion products as well as evaporated constituents of the fragrance mixtures. In most cases, the calculated indoor concentrations were well below the respective guidance and reference values. The exceptions observed in some cases for nitrogen dioxide, acrolein and benzo[a]pyrene are discussed critically.

Commodity plastic burning as a source of inhaled toxic aerosols

Commodity plastic is ubiquitous in daily life and commonly disposed of via unregulated burning, particularly in developing regions. We report here the much higher emission factors (13.1 ± 7.5 g/kg) and toxicities of inhalable aerosols emitted from the unregulated burning of plastic waste based on field measurements and cellular experiments, including oxidative stress and cytotoxic tests in A549 cells. Plastic foam burning emitted aerosols possesses the highest EFs (34.8 ± 4.5 g/kg) and toxicities, which are 4.2- to 13.4-fold and 1.1- to 2.7-fold higher than those emitted from the burning of other waste types. These quantified toxicities are mainly attributed to aerosols containing carbonaceous matter, especially persistent organic pollutants, including polycyclic aromatic hydrocarbons and dioxins, which originate from incomplete combustion processes. The aerosol emission amounts were estimated from the obtained experimental results. Approximately 70.2 million tons (29%) of plastic waste was burned without regulation worldwide in 2016, leading to 0.92 ± 0.53 million tons of toxic aerosols being released into the air, a majority of which occurred in developing regions. The results indicate improved combustion technology and control strategies are urgently needed in developing regions for discarded plastic -waste to mitigate toxic exposure risks and achieve sustainable development.