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1.
Waste Manag ; 179: 163-174, 2024 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-38479255

RESUMO

Catalytic tar cracking is a promising technique for hot syngas cleaning unit in gasification plants because it can preserve tars chemical energy, so increasing the syngas heating value. The cost associated with catalyst preparation is a key issue, together with its deactivation induced by coke deposition. Iron is a cheap and frequently used catalyst, which can also be found in some industrial wastes. The study aims to assess the catalytic efficiency for tar cracking of two waste-derived materials (red mud and sewage sludge) having high content of iron. The catalysts were supported on spheres of γ-Al2O3, and their efficiency was compared to that of a pure iron catalyst. The role of support was investigated by testing pure red mud, with and without the support. A series of long-term tests using naphthalene as tar model compound were carried out under different values of process temperatures (750 °C-800 °C) and steam concentrations (0 %-7.5 %). The waste derived catalysts showed lower hydrogen yields compared to pure iron catalyst, due to their lower content of iron. On the other hand, the conversion efficiencies of all the tested catalysts resulted rather similar, since the Alkali and Alkaline-Earth Metallic species present on the surface of waste-derived catalyst help in preventing coke deposition. The iron oxidation state appears to play an important role, with reduced iron more active than its oxidised form in the tar cracking reactions. This indicates the importance of tuning steam concentration to keep constant the reduced state of iron while limiting coke deposition.


Assuntos
Coque , Vapor , Hidrogênio/análise , Ferro , Alcatrões/química , Biomassa , Catálise
2.
Int J Mol Sci ; 22(19)2021 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-34638570

RESUMO

The microbial biodegradation of new PLA and PCL materials containing birch tar (1-10% v/v) was investigated. Product of dry distillation of birch bark (Betula pendula Roth) was added to polymeric materials to obtain films with antimicrobial properties. The subject of the study was the course of enzymatic degradation of a biodegradable polymer with antibacterial properties. The results show that the type of the material, tar concentration, and the environment influenced the hydrolytic activity of potential biofilm degraders. In the presence of PCL films, the enzyme activities were higher (except for α-D-glucosidase) compared to PLA films. The highest concentration of birch tar (10% v/v) decreased the activity of hydrolases produced by microorganisms to the most significant extent; however, SEM analysis showed the presence of a biofilm even on plastics with the highest tar content. Based on the results of the biological oxygen demand (BOD), the new materials can be classified as biodegradable but, the biodegradation process was less efficient when compared to plastics without the addition of birch tar.


Assuntos
Anti-Infecciosos/química , Betula/química , Plásticos Biodegradáveis/química , Poliésteres/química , Alcatrões/química , Aminopeptidases/metabolismo , Anti-Infecciosos/farmacologia , Bactérias/efeitos dos fármacos , Bactérias/enzimologia , Betula/microbiologia , Plásticos Biodegradáveis/farmacologia , Biofilmes , Análise da Demanda Biológica de Oxigênio , Destilação , Ensaios Enzimáticos , Esterases/metabolismo , Lipase/metabolismo , Casca de Planta/química , Casca de Planta/microbiologia , Poliésteres/metabolismo , Alcatrões/farmacologia , alfa-Glucosidases/metabolismo , beta-Glucosidase/metabolismo
3.
Chem Res Toxicol ; 34(6): 1588-1603, 2021 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-34033466

RESUMO

Widespread smoke from wildfires and biomass burning contributes to air pollution and the deterioration of air quality and human health. A common and major emission of biomass burning, often found in collected smoke particles, is spherical wood tar particles, also known as "tar balls". However, the toxicity of wood tar particles and the mechanisms that govern their health impacts and the impact of their complicated chemical matrix are not fully elucidated. To address these questions, we generated wood tar material from wood pyrolysis and isolated two main subfractions: water-soluble and organic-soluble fractions. The chemical characteristics as well as the cytotoxicity, oxidative damage, and DNA damage mechanisms were investigated after exposure of A549 and BEAS-2B lung epithelial cells to wood tar. Our results suggest that both wood tar subfractions reduce cell viability in exposed lung cells; however, these fractions have different modes of action that are related to their physicochemical properties. Exposure to the water-soluble wood tar fraction increased total reactive oxygen species production in the cells, decreased mitochondrial membrane potential (MMP), and induced oxidative damage and cell death, probably through apoptosis. Exposure to the organic-soluble fraction increased superoxide anion production, with a sharp decrease in MMP. DNA damage is a significant process that may explain the course of toxicity of the organic-soluble fraction. For both subfractions, exposure caused cell cycle alterations in the G2/M phase that were induced by upregulation of p21 and p16. Collectively, both subfractions of wood tar are toxic. The water-soluble fraction contains chemicals (such as phenolic compounds) that induce a strong oxidative stress response and penetrate living cells more easily. The organic-soluble fraction contained more polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs and induced genotoxic processes, such as DNA damage.


Assuntos
Antineoplásicos Fitogênicos/farmacologia , Células Epiteliais/efeitos dos fármacos , Pulmão/efeitos dos fármacos , Extratos Vegetais/farmacologia , Alcatrões/farmacologia , Madeira/química , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/isolamento & purificação , Biomassa , Morte Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Estrutura Molecular , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Solubilidade , Alcatrões/química , Alcatrões/isolamento & purificação , Células Tumorais Cultivadas , Água/química
4.
Int J Mol Sci ; 23(1)2021 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-35008694

RESUMO

The objective of this study was to produce bactericidal polymer films containing birch tar (BT). The produced polymer films contain PLA, plasticiser PEG (5% wt.) and birch tar (1, 5 and 10% wt.). Compared to plasticised PLA, films with BT were characterised by reduced elongation at break and reduced water vapour permeability, which was the lowest in the case of film with 10% wt. BT content. Changes in the morphology of the produced materials were observed by performing scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis; the addition of BT caused the surface of the film to be non-uniform and to contain recesses. FTIR analysis of plasticised PLA/BT films showed that the addition of birch tar did not change the crystallinity of the obtained materials. According to ISO 22196: 2011, the PLA film with 10% wt. BT content showed the highest antibacterial effect against the plant pathogens A. tumefaciens, X. campestris, P. brassicacearum, P. corrugata, P. syringae. It was found that the introduction of birch tar to plasticised PLA leads to a material with biocidal effect and favourable physicochemical and structural properties, which classifies this material for agricultural and horticultural applications.


Assuntos
Betula/química , Fenômenos Químicos , Desinfetantes/farmacologia , Poliésteres/farmacologia , Alcatrões/química , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Cloreto de Cálcio/química , Testes de Sensibilidade Microbiana , Permeabilidade , Plásticos/química , Espectroscopia de Infravermelho com Transformada de Fourier , Vapor , Propriedades de Superfície
5.
Ecotoxicol Environ Saf ; 196: 110571, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32276159

RESUMO

Environmentally persistent free radicals (EPFRs) was considered unrecognized composition of air pollutants and might help explain the long-standing medical mystery of why non-smokers develop tobacco-related diseases like lung cancer. EPFRs in airborne fine particulate matter (PM2.5) can induce oxidative and DNA damage when inhaled. We assessed the inhalation risk of EPFRs in PM2.5 and factors influencing this risk in Beijing as a large city with frequent haze events. The average concentration of EPFRs in PM2.5 was 6.00 × 1017 spins/m3 in spring, autumn, and winter; lower concentrations were recorded in the summer. To estimate the daily inhalation risk of EPFRs in PM2.5, we used the equivalent EPFRs in cigarette tar. The average daily inhalation exposure of EPFRs in PM2.5 was estimated to be the equivalent of 33.1 cigarette tar EPFRs per day (range: 0.53-226.9) during both haze and non-haze days. The major factors influencing EPFR concentrations in the atmosphere were precipitation and humidity, which reduced airborne concentrations. Levels of PM2.5 and carbon monoxide were positively correlated with EPFR concentrations. The health risks of inhaling airborne EPFRs could be significant and should be recognized and quantified.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Radicais Livres/análise , Exposição por Inalação/análise , Material Particulado/análise , Atmosfera/química , Pequim , Humanos , Oxirredução , Medição de Risco , Estações do Ano , Alcatrões/química
6.
Nicotine Tob Res ; 22(6): 990-996, 2020 05 26.
Artigo em Inglês | MEDLINE | ID: mdl-30726984

RESUMO

INTRODUCTION: Despite regulations that forbid cigarette packages from displaying messages such as "mild," "low-tar," and "light," many smokers still have misperceptions about "light" or "low-tar" cigarettes. One reason may be that tar amount displays continue to be permitted. This study examines whether removing tar delivery information from packaging reduces consumer misperceptions about "low-tar" cigarettes. METHODS: An online experiment was conducted in South Korea among 531 smokers who were randomly assigned to one of two conditions: with and without tar information on cigarette packages. Participants evaluated which type of cigarette was mildest, least harmful, easiest for nonsmokers to start smoking, and easiest for smokers to quit. RESULTS: Ten out of 12 chi-square tests showed that people judged the lowest reported tar delivery cigarette to be the mildest (p < .01), least harmful (p < .05), easiest to start (p < .05), and easiest to quit (p < .05)-less so in the "no-tar" condition than the "tar" condition. A higher level of misbeliefs about supposed low-tar cigarettes were found in the "tar" condition compared to the "no-tar" condition for all three brands (t = 5.85, 4.07, 3.82, respectively, p < .001). Regression analyses showed that the "no-tar" condition negatively predicted the level of misbeliefs after controlling for demographic and smoking-related variables (B [SE] = -.72 (.12), -.50 (.12), -.48 (.13), respectively, p < .001). CONCLUSIONS: Banning reported tar deliveries from cigarette packages is likely to reduce smokers' misconceptions about "low-tar" cigarettes. When reported tar deliveries are absent, smokers have inconsistent judgments about differently packaged cigarettes. IMPLICATIONS: When cigarette packages depict lower reported tar number deliveries, participants erroneously perceive them to be less harmful than packages displaying higher tar numbers. These misperceptions of harm may prompt smokers who might otherwise attempt to quit smoking to instead consume cigarettes with lower tar deliveries due to the mistaken belief that they will reduce their risk.


Assuntos
Conhecimentos, Atitudes e Prática em Saúde , Embalagem de Produtos/métodos , Fumantes/psicologia , Fumar/psicologia , Alcatrões/química , Produtos do Tabaco/estatística & dados numéricos , Adolescente , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , República da Coreia/epidemiologia , Fumar/epidemiologia , Alcatrões/análise , Adulto Jovem
7.
Proc Natl Acad Sci U S A ; 116(39): 19336-19341, 2019 09 24.
Artigo em Inglês | MEDLINE | ID: mdl-31488715

RESUMO

Biomass burning (BB) emits enormous amounts of aerosol particles and gases into the atmosphere and thereby significantly influences regional air quality and global climate. A dominant particle type from BB is spherical organic aerosol particles commonly referred to as tarballs. Currently, tarballs can only be identified, using microscopy, from their uniquely spherical shapes following impaction onto a grid. Despite their abundance and potential significance for climate, many unanswered questions related to their formation, emission inventory, removal processes, and optical properties still remain. Here, we report analysis that supports tarball formation in which primary organic particles undergo chemical and physical processing within ∼3 h of emission. Transmission electron microscopy analysis reveals that the number fractions of tarballs and the ratios of N and O relative to K, the latter a conserved tracer, increase with particle age and that the more-spherical particles on the substrates had higher ratios of N and O relative to K. Scanning transmission X-ray spectrometry and electron energy loss spectrometry analyses show that these chemical changes are accompanied by the formation of organic compounds that contain nitrogen and carboxylic acid. The results imply that the chemical changes increase the particle sphericity on the substrates, which correlates with particle surface tension and viscosity, and contribute to tarball formation during aging in BB smoke. These findings will enable models to better partition tarball contributions to BB radiative forcing and, in so doing, better help constrain radiative forcing models of BB events.


Assuntos
Poluentes Atmosféricos/química , Biomassa , Material Particulado/química , Fumaça/análise , Alcatrões/química , Aerossóis/química , Clima , Compostos Orgânicos/análise , Tensão Superficial , Viscosidade
8.
J Agric Food Chem ; 67(13): 3733-3743, 2019 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-30835454

RESUMO

The facile preparation, characterization, and application of novel dual-shell TpBD (a kind of covalent-organic framework) coated magnetic nanospheres as sorbents for simple, fast, and high selectivity capture of 14 heterocyclic aromatic amines (HAAs) are reported. Quantum chemistry theory calculations were conducted to directly and quantifiably describe the multiple interactions, including π-π, hydrogen bonding, cation-π, static electricity, and ion-exchange, between TpBD and heterocyclic aromatic amines. The excellent adsorption capacity of TpBD coated magnetic nanospheres was further evaluated by extraction of 14 HAAs from nonsmokers' and smokers' urine samples. Under the optimized conditions, the magnetic solid phase extraction process can be completed with high recovery ranging from 95.4% to 129.3%. After being washed with acetonitrile and water successively, the collected sorbents can be easily recycled and reused five times without any significant difference in performance. Coupled with the ultra performance liquid chromatography-tandem mass spectrometer detection, the exposure level of HAAs in nonsmokers and smokers smoking cigarettes with different tar yields were successfully explored. And, this implied that the robust method based on the versatile TpBD coated dual-shell magnetic nanospheres sorbents represents a great potential application in the analysis of disease markers and body fluids.


Assuntos
Aminas/química , Cromatografia Líquida de Alta Pressão/métodos , Estruturas Metalorgânicas/química , Nanosferas/química , Espectrometria de Massas em Tandem/métodos , Alcatrões/química , Produtos do Tabaco/análise , Aminas/urina , Feminino , Humanos , Magnetismo , Masculino , não Fumantes , Fumantes
9.
J Air Waste Manag Assoc ; 69(4): 502-512, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30540545

RESUMO

In the gasification of biomass, it is necessary to limit the amount of by-product tar and increase the yields of hydrogen (H2) and carbon monoxide (CO) (syngas). Therefore, we conducted gasification and reforming experiments on woody biomass using an electric tubular furnace, to evaluate the gas reforming and tar decomposition performance of a NiO/SBA-15 catalyst. As a result, we found that this catalyst is effective for H2 production. It is believed that the increase in H2 volume due to the catalyst occurs through a steam reforming reaction involving hydrocarbons, including methane (CH4), and the water-gas shift reaction. With respect to the influence of the gasifying agent on the reforming effect of the catalyst, the amount of generated carbon dioxide (CO2) and hydrogen (H2) increases because the shift reaction is promoted by supplying steam. On the other hand, it was inferred that the shift reaction rarely occurred because it approaches equilibrium by supplying O2. Furthermore, it is suggested that light aromatic hydrocarbons are decomposed by the catalyst. Implications: The mesoporous silica catalyst NiO/SBA-15 was highly effective for H2 production and decomposition of light aromatic compounds in the gasification of woody biomass. In the catalyst reaction, supplying steam promoted H2 production. From thermodynamic analysis and discussion, it was also inferred that supplying O2 might prevent the water gas shift reaction. The results are useful for designing a process needed for rich H2 production and gas refining process for further use of syngas.


Assuntos
Biomassa , Níquel/química , Energia Renovável , Dióxido de Silício/química , Madeira/química , Catálise , Gases/química , Alcatrões/química
10.
In Vivo ; 32(3): 493-497, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29695551

RESUMO

We investigated the anti-metastatic action of nicotine- and tar-removed cigarette smoke extract (CSE) on highly metastatic mouse Colon-26 cells using syngeneic BALB/c mice. Colon-26 cells were injected into the spleen of mice, cells were grown in the spleen as the primary lesion, and some metastasized from the spleen to liver and established a metastatic lesion. CSE (10, 30, and 100%) was intraperitoneally administered daily to the mice for 14 days after tumor inoculation. As a result, the relative spleen weights of CSE-administered mice did not differ significantly from those of the control mice. However, the relative liver weights of CSE 30%-administered mice significantly decreased compared to control mice. In order to identify the active component in CSE, we examined the action of methyl vinyl ketone (MVK) on the invasiveness of Colon-26 cells. MVK significantly reduced the invasiveness of cells. MVK may be a candidate active component of CSE.


Assuntos
Fumaça/efeitos adversos , Fumar , Alcatrões/química , Alcatrões/farmacologia , Animais , Butanonas/farmacologia , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Feminino , Camundongos , Nicotina/farmacologia , Neoplasias Retais
11.
Regul Toxicol Pharmacol ; 91: 235-239, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29097238

RESUMO

Cigarette filter ventilation allows air to be drawn into the filter, diluting the cigarette smoke. Although machine smoking reveals that toxicant yields are reduced, it does not predict human yields. The objective of this study was to investigate the relationship between cigarette filter ventilation and mouth level exposure (MLE) to tar and nicotine in cigarette smokers. We collated and reviewed data from 11 studies across 9 countries, in studies performed between 2005 and 2013 which contained data on MLE from 156 products with filter ventilation between 0% and 87%. MLE among 7534 participants to tar and nicotine was estimated using the part-filter analysis method from spent filter tips. For each of the countries, MLE to tar and nicotine tended to decrease as filter ventilation increased. Across countries, per-cigarette MLE to tar and nicotine decreased as filter ventilation increased from 0% to 87%. Daily MLE to tar and nicotine also decreased across the range of increasing filter ventilation. These data suggest that on average smokers of highly ventilated cigarettes are exposed to lower amounts of nicotine and tar per cigarette and per day than smokers of cigarettes with lower levels of ventilation.


Assuntos
Boca/anatomia & histologia , Nicotina/química , Fumaça/análise , Alcatrões/química , Produtos do Tabaco/análise , Adulto , Feminino , Humanos , Exposição por Inalação/análise , Masculino , Fumantes , Fumar/efeitos adversos , Nicotiana/química , Ventilação/métodos , Adulto Jovem
12.
Mar Pollut Bull ; 113(1-2): 277-281, 2016 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-27692487

RESUMO

Tarballs, the remnants of crude oil which change into semi-solid phase due to various weathering processes in the sea, are rich in hydrocarbons, including toxic and almost non-degradable hydrocarbons. Certain microorganisms such as fungi are known to utilize hydrocarbons present in tarballs as sole source of carbon for nutrition. Previous studies have reported 53 fungal taxa associated with tarballs. There is apparently no gene sequence-data available for the published taxa so as to verify the fungal identification using modern taxonomic tools. The objective of the present study is to isolate fungi from tarballs collected from Candolim beach in Goa, India and investigate their phylogenetic diversity based on 5.8S rRNA gene and the flanking internal transcribed spacer regions (ITS) sequence analysis. In the ITS-based NJ tree, eight tarball-associated fungal isolates clustered with 3 clades of Dothideomycetes and 2 clades of Saccharomycetes. To the best of our knowledge, this is the first study that has employed ITS-based phylogeny to characterize the fungal diversity associated with tarballs. Further studies are warranted to investigate the role of the tarball-associated fungi in degradation of recalcitrant hydrocarbons present in tarballs and the role of tarballs as carriers of human pathogenic fungi.


Assuntos
Petróleo/microbiologia , Saccharomycetales/isolamento & purificação , Alcatrões/química , Poluentes Químicos da Água , Praias/normas , Biodegradação Ambiental , DNA Fúngico/genética , DNA Espaçador Ribossômico , Humanos , Índia , Filogenia , Saccharomycetales/genética , Análise de Sequência de DNA
13.
Sci Rep ; 6: 26928, 2016 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-27229886

RESUMO

COPD is characterized by persistent airflow limitation, neutrophilia and oxidative stress from endogenous and exogenous insults. Current COPD therapy involving anticholinergics, ß2-adrenoceptor agonists and/or corticosteroids, do not specifically target oxidative stress, nor do they reduce chronic pulmonary inflammation and disease progression in all patients. Here, we explore the effects of Sul-121, a novel compound with anti-oxidative capacity, on hyperresponsiveness (AHR) and inflammation in experimental models of COPD. Using a guinea pig model of lipopolysaccharide (LPS)-induced neutrophilia, we demonstrated that Sul-121 inhalation dose-dependently prevented LPS-induced airway neutrophilia (up to ~60%) and AHR (up to ~90%). Non-cartilaginous airways neutrophilia was inversely correlated with blood H2S, and LPS-induced attenuation of blood H2S (~60%) was prevented by Sul-121. Concomitantly, Sul-121 prevented LPS-induced production of the oxidative stress marker, malondialdehyde by ~80%. In immortalized human airway smooth muscle (ASM) cells, Sul-121 dose-dependently prevented cigarette smoke extract-induced IL-8 release parallel with inhibition of nuclear translocation of the NF-κB subunit, p65 (each ~90%). Sul-121 also diminished cellular reactive oxygen species production in ASM cells, and inhibited nuclear translocation of the anti-oxidative response regulator, Nrf2. Our data show that Sul-121 effectively inhibits airway inflammation and AHR in experimental COPD models, prospectively through inhibition of oxidative stress.


Assuntos
Anti-Inflamatórios não Esteroides/farmacologia , Antioxidantes/farmacologia , Cromanos/farmacologia , Hipersensibilidade/prevenção & controle , Piperazinas/farmacologia , Doença Pulmonar Obstrutiva Crônica/tratamento farmacológico , Espécies Reativas de Oxigênio/antagonistas & inibidores , Animais , Linhagem Celular Transformada , Cromanos/química , Misturas Complexas/antagonistas & inibidores , Misturas Complexas/farmacologia , Modelos Animais de Doenças , Regulação da Expressão Gênica , Cobaias , Humanos , Sulfeto de Hidrogênio/agonistas , Sulfeto de Hidrogênio/sangue , Hipersensibilidade/etiologia , Hipersensibilidade/imunologia , Hipersensibilidade/metabolismo , Inflamação , Interleucina-8/antagonistas & inibidores , Interleucina-8/genética , Interleucina-8/imunologia , Lipopolissacarídeos/administração & dosagem , Pulmão , Masculino , Malondialdeído/antagonistas & inibidores , Malondialdeído/metabolismo , Miócitos de Músculo Liso/efeitos dos fármacos , Miócitos de Músculo Liso/imunologia , Miócitos de Músculo Liso/patologia , Fator 2 Relacionado a NF-E2/antagonistas & inibidores , Fator 2 Relacionado a NF-E2/genética , Fator 2 Relacionado a NF-E2/imunologia , Neutrófilos/efeitos dos fármacos , Neutrófilos/imunologia , Neutrófilos/patologia , Estresse Oxidativo , Piperazinas/química , Doença Pulmonar Obstrutiva Crônica/imunologia , Doença Pulmonar Obstrutiva Crônica/metabolismo , Doença Pulmonar Obstrutiva Crônica/fisiopatologia , Espécies Reativas de Oxigênio/metabolismo , Alcatrões/química , Alcatrões/toxicidade , Fator de Transcrição RelA/antagonistas & inibidores , Fator de Transcrição RelA/genética , Fator de Transcrição RelA/imunologia
14.
Environ Sci Pollut Res Int ; 23(22): 22253-22266, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26996917

RESUMO

The main objective of this work concerns the coupling of biomass gasification reaction and CO2 sorption. The study shows the feasibility to promote biomass steam gasification in a dense fluidized bed reactor with CO2 sorption to enhance tar removal and hydrogen production. It also proves the efficiency of CaO-Ca12Al14O33/olivine bi-functional materials to reduce heavy tar production. Experiments have been carried out in a fluidized bed gasifier using steam as the fluidizing medium to improve hydrogen production. Bed materials consisting of CaO-based oxide for CO2 sorption (CaO-Ca12Al14O33) deposited on olivine for tar reduction were synthesized, their structural and textural properties were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), and temperature-programmed reduction (TPR) methods, and the determination of their sorption capacity and stability analyzed by thermogravimetric analysis (TGA). It appears that this CaO-Ca12Al14O33/olivine sorbent/catalyst presents a good CO2 sorption stability (for seven cycles of carbonation/decarbonation). Compared to olivine and Fe/olivine in a fixed bed reactor for steam reforming of toluene chosen as tar model compound, it shows a better hydrogen production rate and a lower CO2 selectivity due to its sorption on the CaO phase. In the biomass steam gasification, the use of CaO-Ca12Al14O33/olivine as bed material at 700 °C leads to a higher H2 production than olivine at 800 °C thanks to CO2 sorption. Similar tar concentration and lighter tar production (analyzed by HPLC/UV) are observed. At 700 °C, sorbent addition allows to halve tar content and to eliminate the heaviest tars.


Assuntos
Biomassa , Dióxido de Carbono/química , Vapor , Adsorção , Compostos de Cálcio/química , Catálise , Gases/química , Compostos de Ferro , Compostos de Magnésio , Óxidos/química , Poaceae/química , Silicatos , Alcatrões/química , Tolueno/química
15.
Bioresour Technol ; 200: 64-71, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26476166

RESUMO

To introduce application status and illustrate the good utilisation potential of biomass pyrolytic polygeneration using retort reactors, the properties of major products and the economic viability of commercial factories were investigated. The capacity of one factory was about 3000t of biomass per year, which was converted into 1000t of charcoal, 950,000Nm(3) of biogas, 270t of woody tar, and 950t of woody vinegar. Charcoal and fuel gas had LHV of 31MJ/kg and 12MJ/m(3), respectively, indicating their potential for use as commercial fuels. The woody tar was rich in phenols, while woody vinegar contained large quantities of water and acetic acid. The economic analysis showed that the factory using this technology could be profitable, and the initial investment could be recouped over the factory lifetime. This technology offered a promising means of converting abundant agricultural biomass into high-value products.


Assuntos
Reatores Biológicos , Biotecnologia/instrumentação , Biotecnologia/métodos , Agricultura , Biocombustíveis , Biomassa , Biotecnologia/economia , Carvão Vegetal , Investimentos em Saúde , Fenóis , Alcatrões/química
16.
Water Environ Res ; 88(9): 847-851, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26488721

RESUMO

Submerged tar-contaminated sediment are generally very loose, which makes remediation challenging. We tested if a modified version of freeze-dredging could be used to remove and dewater such sediment in a canal down-stream a coking plant. PVC hoses carrying a heat medium were placed horizontally in the submerged sediment. Five days of freezing allowed straightforward removal of most of the sediment. Flat freeze cells were placed side by side in the canal to remove the rest. The freeze-thaw process increased the dry substance content from approximately 50 to 80%. Outdoors storage under rainy conditions did not re-wet the dried sediment. The material was successfully used as feed-stock in the coking plant, with the double cost-benefit of avoided transportation to deposit and reduced use of coal. The study demonstrates that freeze-dredging can facilitate removal, storage and beneficial re-use of submerged tar-contaminated sediment.


Assuntos
Sedimentos Geológicos/química , Reciclagem/métodos , Alcatrões/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Coque , Sedimentos Geológicos/análise , Resíduos Industriais/análise , Suécia , Alcatrões/análise , Poluentes Químicos da Água/análise
17.
J Hum Evol ; 85: 22-34, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26073074

RESUMO

South Africa has in recent years gained increasing importance for our understanding of the evolution of 'modern human behaviour' during the Middle Stone Age (MSA). A key element in the suite of behaviours linked with modern humans is heat treatment of materials such as ochre for ritual purposes and stone prior to tool production. Until now, there has been no direct archaeological evidence for the exact procedure used in the heat treatment of silcrete. Through the analysis of heat-treated artefacts from the Howiesons Poort of Diepkloof Rock Shelter, we identified a hitherto unknown type of organic residue - a tempering-residue - that sheds light on the processes used for heat treatment in the MSA. This black film on the silcrete surface is an organic tar that contains microscopic fragments of charcoal and formed as a residue during the direct contact of the artefacts with hot embers of green wood. Our results suggest that heat treatment of silcrete was conducted directly using an open fire, similar to those likely used for cooking. These findings add to the discussion about the complexity of MSA behaviour and appear to contradict previous studies that had suggested that heat treatment of silcrete was a complex (i.e., requiring a large number of steps for its realization) and resource-consuming procedure.


Assuntos
Evolução Biológica , Incêndios , Tecnologia/métodos , Animais , História Antiga , Hominidae , Temperatura Alta , Humanos , Dióxido de Silício , Alcatrões/química , Tecnologia/história , Comportamento de Utilização de Ferramentas
18.
Bioresour Technol ; 192: 23-30, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26005925

RESUMO

This work aimed to investigate effects of inherent alkali and alkaline earth metallic species (AAEMs) on biomass pyrolysis at different temperatures. The yield of CO, H2 and C2H4 was increased and that of CO2 was suppressed with increasing temperature. Increasing temperature could also promote depolymerization and aromatization reactions of active tars, forming heavier polycyclic aromatic hydrocarbons, leading to decrease of tar yields and species diversity. Diverse performance of inherent AAEMs at different temperatures significantly affected the distribution of pyrolysis products. The presence of inherent AAEMs promoted water-gas shift reaction, and enhanced the yield of H2 and CO2. Additionally, inherent AAEMs not only promoted breakage and decarboxylation/decarbonylation reaction of thermally labile hetero atoms of the tar but also enhanced thermal decomposing of heavier aromatics. Inherent AAEMs could also significantly enhance the decomposition of levoglucosan, and alkaline earth metals showed greater effect than alkali metals.


Assuntos
Metais Alcalinos/química , Metais Alcalinoterrosos/química , Biomassa , Dióxido de Carbono/química , Etilenos/química , Gases/química , Hidrogênio/química , Alcatrões/química , Temperatura , Água/química
19.
Environ Technol ; 36(20): 2556-67, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25867082

RESUMO

The aim of this paper is the study of the treatment of flue gas issued from a process of biomass gasification in fluidized bed. The flue gas contains tar which should be selectively removed from the fuel components of interest (e.g. H2, CO and light hydrocarbons) to avoid condensation and deposits in internal combustion engine. The chosen flue gas treatment is the gas-liquid absorption using solvents, which present specific physicochemical properties (e.g. solubility, viscosity, volatility and chemical and thermal stability) in order to optimize the unit on energetic, technico-economic and environmental criteria. The rational choice of the proper solvent is essential for solving the tar issue. The preselection of the solvents is made using a Hansen parameter in order to evaluate the tar solubility and the saturation vapour pressure of the solvent is obtained using Antoine law. Among the nine families of screened solvents (alcohols, amines, ketones, halogenates, ethers, esters, hydrocarbons, sulphured and chlorinates), acids methyl esters arise as solvents of interest. Methyl oleate has then been selected and studied furthermore. Experimental liquid-vapour equilibrium data using bubbling point and absorption cell measurements and theoretical results obtained by the UNIFAC-Dortmund model confirm the high potential of this solvent and the good agreement between experimental and theoretical results.


Assuntos
Biomassa , Compostos Orgânicos/química , Solventes/química , Alcatrões/química , Alcatrões/isolamento & purificação , Fenômenos Químicos , Gases/química
20.
Appl Spectrosc ; 69(1): 143-53, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25588231

RESUMO

The analysis of tar, mostly characterized as polycyclic aromatic hydrocarbons (PAHs), describes a topic that has been researched for years. An online analysis of tar in the gas stream in particular is needed to characterize the tar conversion or formation in the biomass gasification process. The online analysis in the gas is carried out with ultraviolet-visible (UV-Vis) spectroscopy (190-720 nm). This online analysis is performed with a measuring cell developed by the Fraunhofer Institute for Chemical Technology (ICT). To this day, online tar measurements using UV-Vis spectroscopy have not been carried out in detail. Therefore, PAHs are analyzed as follows. The measurements are split into different steps. The first step to prove the online method is to vaporize single tar substances. These experiments show that a qualitative analysis of PAHs in the gas stream with the used measurement setup is possible. Furthermore, it is shown that the method provides very exact results, so that a differentiation of various PAHs is possible. The next step is to vaporize a PAH mixture. This step consists of vaporizing five pure substances almost simultaneously. The interpretation of the resulting data is made using a chemometric interpretation method, the multivariate curve resolution (MCR). The verification of the calculated results is the main aim of this experiment. It has been shown that the tar mixture can be analyzed qualitatively and quantitatively (in arbitrary units) in detail using the MCR. Finally it is the main goal of this paper to show the first steps in the applicability of the UV-Vis spectroscopy and the measurement setup on online tar analysis in view of characterizing the biomass gasification process. Due to that, the gasification plant (at the laboratory scale), developed and constructed by the Fraunhofer ICT, has been used to vaporize these substances. Using this gasification plant for the experiments enables the usage of the measurement setup also for the spectroscopic analysis of the tar formation during the biomass gasification.


Assuntos
Hidrocarbonetos Policíclicos Aromáticos/análise , Espectrofotometria Ultravioleta/métodos , Alcatrões/química , Absorção Fisico-Química , Análise Multivariada
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