A study of the combustion chemistry of petroleum and bio-fuel oil asphaltenes

The combustion of heavy fuel oils such as Bunker C and vacuum residual oil (VRO) are widely used for industrial applications such as furnaces, power generation and for large marine engines. There is also the possible use of bio-oils derived from biomass. Combustion of these oils generates carbonaceous particulate emissions and polynuclear aromatic hydrocarbons (PAH) that are both health hazards and have an adverse effect on the climate. This paper explores the mechanism of the formation of fine particulate soot and cenospheres. The chemical structure of petroleum asphaltene have been investigated via pyrolysis techniques. The results are consistent with a structure made up of linked small aromatic and naphthenic clusters with substituent alkyl groups, some in the long chains, with the building blocks held together by bridging groups. Other functional groups also play a role. The corresponding bio-asphaltene is made up of similar aromatic and oxygenated species and behave in an analogous way

Organic Carbon Emissions from the Co-firing of Coal and Wood in a Fixed Bed Combustor

Co-firing of biomass and coal and biomass reduces the emission of pollutants and the overall effects have been extensively studied, but many aspects of the detailed mechanism remain uncertain. A number of studies have been previously made by us of emissions from the combustion in a fixed-bed furnace of bituminous coal and wood, both individually and together, and it was observed that biomass produced less soot and lower NOX emissions. These data are combined with recent measurements of emissions of black carbon (BC) and organic carbon (OC), which are an important source of climate forcing, from the combustion of a number of solid fuels. Conclusion are drawn about the nature of the OC and how the values are dependent on the measurement technique used. Complementary analytical-scale combustion and pyrolysis experiments were also carried out. The results of the analysis of emissions and reaction products, mainly by gas chromatography–mass spectrometry (GC–MS), were interpreted so as to construct a model for pollutant formation during co-firing

The use of conservation biomass feedstocks as potential bioenergy resources in the United Kingdom

A number of countries have introduced energy policies to reduce the emission of carbon dioxide which, in the case of bio-heat, has resulted in increased use of small wood burning stoves and boilers, particularly in Europe. There are issues surrounding the supply of sustainable wood feedstock, prompting a desire to utilise local biomass resources. This includes biomass generated through the management of natural woodlands in nature reserves and conservation areas. These management practices can also extend to other areas, such as raised bog wildernesses and estuary Reed beds. We term the biomass from this resource as conservation biomass. This study is concerned with the viability of this resource as a fuel within the United Kingdom, and combustion tests were carried out using a small domestic stove. It was concluded that there is as much as 500 kt y−1 that could be used in this way

The Impact of Fuel Properties on the Composition of Soot Produced by the Combustion of Residential Solid Fuels in a Domestic Stove

Soot is formed from the incomplete combustion of biomass and conventional fossil fuels. It consists largely of a carbonaceous core termed Elemental Carbon (EC) with adsorbed volatile organic species, commonly termed Organic Carbon (OC). Estimation of the ratio of BC/OC is critical as climate models have recognised the Global Warming Potential (GWP) of BC as the second most important climate forcing agent after carbon dioxide. This paper presents values of EC, OC and EC/TC (where TC = EC + OC) for three different soot types: Firstly, soots collected on filters from the combustion of eight fossil fuel and biomass residential solid fuels (RSF), burned in a 6 kW heating stove. Secondly, chimney soot deposits taken from 'real-life' stoves installed in domestic homes; and finally wick burner soots generated from biomass model compounds; namely eugenol, furfural and anisole. Values of the EC/TC ratios for wood logs, torrefied briquettes, coal and smokeless fuel are given. These ratios are highly dependent on burning conditions; namely the flaming and smouldering phases. The results of this study suggest that EC and OC emissions from various solid fuels differ substantially in composition and relative proportion, which is useful information for climate models

Emissions performance of high moisture wood fuels burned in a residential stove

A study has been made of the effect of fuel moisture content on emissions from a wood burning domestic stove. Two fuel types were studied: beech which is a hardwood, and spruce which is a softwood. The moisture contents investigated were for a freshly felled wood, a seasoned wood and a kiln dried wood. The effect of the moisture measurement method was considered using a commercial electrical conductivity probe moisture meter which was compared with laboratory analysis by drying in an oven at 105 °C. It was shown that the probe can significantly underestimate the actual moisture content in certain cases. Correlations were made of the burning rate, the Emission Factors for the formation of gaseous and particulate pollutants as a function of the moisture content. We also studied the ratio of Black Carbon to Total Carbon (BC/TC) to obtain information on the organic content of the particles. The NOₓ emissions from this type of stove were only dependent on the fuel-nitrogen content and not on the moisture content

Characteristics of C-4 photosynthesis in stems and petioles of C-3 flowering plants

Most plants are known as C-3 plants because the first product of photosynthetic CO2 fixation is a three-carbon compound. C-4 plants, which use an alternative pathway in which the first product is a four-carbon compound, have evolved independently many times and are found in at least 18 families. In addition to differences in their biochemistry, photosynthetic organs of C-4 plants show alterations in their anatomy and ultrastructure. Little is known about whether the biochemical or anatomical characteristics of C-4 photosynthesis evolved first. Here we report that tobacco, a typical C-3 plant, shows characteristics of C-4 photosynthesis in cells of stems and petioles that surround the xylem and phloem, and that these cells are supplied with carbon for photosynthesis from the vascular system and not from stomata. These photosynthetic cells possess high activities of enzymes characteristic of C-4 photosynthesis, which allow the decarboxylation of four-carbon organic acids from the xylem and phloem, thus releasing CO2 for photosynthesis. These biochemical characteristics of C-4 photosynthesis in cells around the vascular bundles of stems of C-3 plants might explain why C-4 photosynthesis has evolved independently many times

Mixing State of Carbonaceous Aerosols of Primary Emissions from “Improved” African Cookstoves

Designs of “improved” stoves are introduced recently to benefit the solid fuel consumption of cooking activities in developing countries, but the uncertainties concerning the combustion processes and particulate emissions remain poorly characterized. To help understand this, combustion in three examples of “improved” African cookstoves was investigated in the laboratory. A typical European heating stove was included for comparison purpose. Detailed aerosol emissions were studied in real-time with an Aerosol Mass Spectrometer and Single Particle Soot Photometer, to explore interactions between black carbon (BC) and organic carbon aerosols, which were parametrized according to modified combustion efficiency (MCE), a common metric used within the atmospheric emission community. Greater than 50% of the total organic matter (OM) was found in BC-containing particles when MCE was >0.95 for dry oak and coal fuels, whereas at lower MCE, over 80% of the total OM for most of the fuels existed in particles without detectable BC. When the OM mass fraction of total particulate matter (PM1) > 0.9, the mass ratio of OM to refractory BC in BC-containing particles was about 2–3, but only ∼0.8 when OM mass fraction <0.9. These findings are not currently included in models and such information should be considered in the future emission scenarios

Pollutant Emissions from Improved Cookstoves of the type used in Sub-Saharan Africa

Emissions from traditional cookstoves are a major health concern in developing world households. Improved cookstoves can reduce fuel use and pollutant emissions and here we compare three types of improved cookstoves widely used in Sub-Saharan Africa. These are a raised-bed charcoal stove, a rocket-type stove using wood and straw, and a gasifier stove. Laboratory measurements were made of the main gaseous pollutants, particle size distribution and composition. The genotoxicity of the particles was assessed using a comet assay. The rocket-type stove using dry wood had the highest emission factors for particulate matter and NOX. Emissions of CO and CH4 were a factor of 6-7 higher from the charcoal stove compared with the other stoves tested in this work, and also higher for burning high moisture wood. Fuel properties were critical for emitted particle size, and for the emissions of NOX, black carbon and organic matter

Decision making and experiences of young adults undergoing presymptomatic genetic testing for familial cancer: A longitudinal grounded theory study

Enabling informed choice is an essential component of care when offering young adults presymptomatic testing for a genetic condition. A systematic review on this topic revealed that many young adults grew up with little information regarding their genetic risk and that parents had applied pressure to them during the testing decision-making process. However, none of the studies retrieved were conducted in South European countries. To address this gap, we undertook a qualitative study based on grounded theory to explore the psychosocial implications of presymptomatic testing for hereditary cancer in Italian young adults aged 18-30 years. Interviews were conducted on three occasions: 1 month before counselling, and 2 weeks and 6 months after results. Data were coded and grouped under themes. A total of 42 interviews were conducted. Four themes emerged: knowledge, genetic counselling process, decision making and dealing with test results. Although participants grew up with little or no information about their genetic risk, none expressed regret at having the test at a young age. Pre-test counselling was appreciated as a source of information, rather than support for decision making. Decisions were often made autonomously and sometimes conflicted with parents' wishes. Participants reported no changes in health behaviours after testing. This evidence highlights the need for a comprehensive, longitudinal counselling process with appropriate timing and setting, which supports 'parent-to-offspring' risk communication first and decision making by young adults about presymptomatic testing and risk management afterwards. In conclusion, it is clear that counselling approaches for presymptomatic testing may require modification both for young adults and their parents. &copy; 2017 European Society of Human Genetics

Exploring behaviors, treatment beliefs, and barriers to oral chemotherapy adherence among adult leukemia patients in a rural outpatient setting

Objective: Adherence to oral chemotherapy is essential for patients with chronic myeloid leukemia (CML) and multiple myeloma (MM) to remain in remission. Few studies have used a Likert-type scale to measure medication adherence in CML and MM patients. We applied a validated treatment adherence tool, the ASK-12 (Adherence Starts with Knowledge®) survey, which assessed inconvenience and forgetfulness, treatment beliefs, and medication-taking behaviors recorded on a five-point Likert-type scale at two visits. Results: A medication adherence survey was administered to 42 newly diagnosed or pre-existing CML or MM patients at two outpatient oncology clinics affiliated with an academic medical center in rural eastern North Carolina. Thirty-one patients completed surveys at visit 1 and visit 2 (median 4.5 months apart). Most patients were treated for MM (65%), were non-Hispanic black (68%) and female (58%). Within subscales, mean adherence scores decreased between visits, signaling better adherence. Overall, visit scores were correlated (0.63, p = 0.001). Forgetting to take medication sometimes was the most common reason for non-adherence. Medication costs were not a barrier for MM patients. Greater patient–provider informed decision-making was identified as an opportunity for quality improvement among CML patients. The ASK-12 survey provided a strategy to obtain robust information on medication adherence