No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Health risk analysis of nitrosamine emissions from CO2 capture with monoethanolamine in coal-fired power plants
Abstract
Monoethanolamine (MEA)-based chemical absorption is extensively used in the capture processes of coal-fired power plants from flue gas. However, chemical carcinogens, such as nitrosamine, are released during MEA degradation, especially at the top of the absorber. This study analyzed five CO2 capture power plants with various capacities, and investigated nitrosamine exposure concentration at downwind direction. Tolerant exposure concentration was calculated under 10−4 and 10−6 risks during the health risk assessment. Safety distances D′ for the five scenarios (365, 3000, 40,000, 146,000, and 1,000,000 t/a) were calculated as first screening under the typically meteorological conditions over North China Plain (mixing height 1000 m, wind speed 5 m/s measured at reference anemometer height of 10 m, and atmospheric stability D). The emission rate and discharge height will affect the safety distance D′. When nitrosamines are directly emitted from absorber, the values D′ are 0, 0, 0, 1580, and 5700 m based on 10−6 risks. When nitrosamines are emitted from stacks of power plant, the health risks of nitrosamines can be negligible. Although the results were very uncertain, the health effects of nitrosamine emissions should be concerned and further studies are necessary to thoroughly investigate the emission rate of nitrosamines.
... Monoethanolamine is classed as a hazardous product: Xn is a harmful product causing irritation while C is a corrosive product causing burns. Basic characteristics of this amine are listed in Table 1 [6,7]. ...
... Diethanolamine has a harmful effect if inhaled or swallowed, or if it comes in contact with the skin. Basic characteristics of this amine are listed in Table 2 [7,8]. ...
... Therefore, the development of this particular technology of carbon dioxide capture requires a precise identification of potential hazards posed by emissions of the compounds mentioned above. The carcinogenic effect of the substances has already been identified as a health hazard, whereas the level of the hazard related to the use of MEA in CO 2 capture processes is still unknown [7][8][9]. ...
Amine-based post combustion carbon dioxide is one leading technology for coal-fi red power plants.
Monoethanolamine is commonly used in carbon dioxide absorption due to its many advantages such as
high reactivity, high carbon dioxide cyclic capacity, and low cost. Solvent degradation is a major problem
during the CO2
absorption process because in sunlight amines undergo reactions with atmospheric oxidation
(photo-oxidation) to form compounds such as nitrosamines, nitramines, and amides. They are toxic and
carcinogenic for humans at very low levels. This paper identifi es safety limits of amine emissions and
determines hazardous concentration zones
... aminebased adsorbents) that are exposed to the ambient air. The literature reveals that Amine-based sorbents can break down with time into ammonia, nitrosamines and other nitrogen-containing compounds that can damage the environment (Azzi et al., 2014;Karl et al., 2014;Ravnum et al., 2014;Zhang et al., 2014). ...
... The recent studies show that the volatile degradation products like ammonia and ethylamine are toxic and they may affect the human health through skin burns and irritation once they are vaporized with a treated flue gas (Låg et al. 2011;Verschueren 2008). Furthermore, the emission of carcinogenic nitrosamines and nitroamines poses large threat, even though the emission of these compounds is relatively low (Zhang et al. 2014;Bartsch and Montesano 1984). These emissions can lead to environmental hazards and solvent losses increasing operating costs (Knudsen et al. 2007). ...
Amine post-combustion carbon capture technology is based on washing the flue gas with a solvent that captures CO2. Thus, a small fraction of this solvent can be released together with the cleaned flue gas. This release may cause environmental concerns, both directly and indirectly through subsequent solvent degradation into other substances in the atmosphere. The paper presents the ammonia emission from CO2 capture pilot plant (1 tonne CO2 per day) using 40 wt% aminoethylethanolamine solvent, along with the efficiency of the water wash unit. In addition, the temperature effect of lean amine entering the absorber on ammonia emission was studied. Furthermore, the concentrations of other compounds such as SO2, SO3, NO2, CS2 and formaldehyde were monitored. The literature review on the NH3 emission from a pilot plant using aminoethylethanolamine solvent has not been published. The results show that the main source of ammonia emission is the absorber and that emission (in the range 27–50 ppm) corresponds to typical NH3 release from CO2 capture pilot plant using an amine solvent. The emission of amines and amine degradation products is a complex phenomenon which is difficult to predict in novel solvents, and for this reason the significance of new solvents testing in a pilot scale has been highlighted.
... As the flue gas from coal-fired power plant commonly contains 10–15 vol.% CO 2[20], it is necessary to determine the effect of CO 2 on SO 2 absorption, and the results are shown in Fig. 12. It can be observed that the SO 2 absorption efficiency is hardly influenced by the CO 2 volumetric concentration variation from 0 to 15 vol.%, while the DTHE shows an obvious variation from 40 to 22.2 min. ...
... Despite this, the environmental risk is considered low since these concentrations are generally several orders of magnitude higher than those reported in surface waters. The foremost environmental concern associated with amine-based CO 2 capture is the risk of contamination of drinking water supplies by nitrosamines and nitramines (Karl et al., 2011; Zhang et al., 2014). Approximately 90% of nitrosamines are believed to be carcinogenic (Nawrocki and Andrzejewski, 2011). ...
This review compiles available information on the concentrations, sources, fate and toxicity of amines and amine-related compounds in surface waters, including rivers, lakes, reservoirs, wetlands and seawater. There is a strong need for this information, especially given the emergence of amine-based post-combustion CO2 capture technologies, which may represent a new and significant source of amines to the environment. We identify a broad range of anthropogenic and natural sources of amines, nitrosamines and nitramines to the aquatic environment, and identify some key fate and degradation pathways of these compounds. There were very few data available on amines in surface waters, with reported concentrations often below detection and only rarely exceeding 10μg/L. Reported concentrations for seawater and reservoirs were below detection or very low, while for lakes and rivers, concentrations spanned several orders of magnitude. The most prevalent and commonly detected amines were methylamine (MA), dimethylamine (DMA), ethylamine (EA), diethylamine (DEA) and monoethanolamine (MEAT). The paucity of data may reflect the analytical challenges posed by determination of amines in complex environmental matrices at ambient levels. We provide an overview of available aquatic toxicological data for amines and conclude that at current environmental concentrations, amines are not likely to be of toxicological concern to the aquatic environment, however, the potential for amines to act as precursors in the formation of nitrosamines and nitramines may represent a risk of contamination of drinking water supplies by these often carcinogenic compounds. More research on the prevalence and toxicity of amines, nitrosamines and nitramines in natural waters is necessary before the environmental impact of new point sources from carbon capture facilities can be adequately quantified.
AOPs have showed considerable potential in the purification and treatment of water, especially for the removal of naturally occurring toxins, emerging pollutants, pesticides, and other harmful substances. It entails the generation of sufficient hydroxyl radicals to affect water purification. In a water treatment, the AOPs can significantly increase the breakdown of mono-ethanolamine (MEA), a recalcitrant pollutant with a main amine group. This research examines innovative AOPs for the treatment of MEA in the aqueous phase in depth. This paper gives a systematic assessment of MEA degradation mechanisms and pathways, as well as a complete examination of process parameters that influence degradation rate, such as pH, temperature, and MEA doses. Ozonation, UV, Fenton, and Plasma treatments, as well as hybrid processes such as per-oxone processes, catalytic ozonation, UV/Ozonation, UV/catalysis, UV/chlorination, and photo-Fenton processes, have all recently been reported as AOPs for MEA degradation. This review would also aid researchers in gaining a better understanding of critical operating parameters and laying the groundwork for the development of commercially viable solutions. Finally, this study concludes with some challenges and a brief assessment of future developments in this field of research.
Amines are frequently detected in atmospheric particles and are internally mixed with other particle-phase components. However, research on the further reactions of amine with reactive species after entering the particle phase is still limited. This study investigated the nitration reaction process of particulate dimethylamine (DMA), formed via a substitution reaction between DMA and (NH4)2SO4, with NOx. in situ attenuated total reflectance-infrared Fourier transform spectroscopy (in situ ATR-FTIR) and proton transfer reaction mass spectroscopy (PTR-MS), as well as DFT methods at the B3LYP level using the 6–311++G (d, p) basis set, were used to confirm the formation of nitramine and nitrosamine in the nitration/nitrosation process of DMA. A hydrogen-bonding intermediate ([(CH3)2N⋯HONO]) is initially formed when particulate DMA reacts with NO2 followed by aminyl radical formation, and then nitr- and nitros-amine form through addition reactions with NO2 and NO, respectively. The dimer of NO2 (i.e., N2O4) and the product of NO and NO2 (i.e., N2O3) can also react with DMA to attack the lone pair on the central N atom of DMA to finally form nitr- and nitros-amine. This study helps reveal the nitration reaction mechanism of organic amines in the particle phase. It also aids in understanding the process of nitrogen cycling in the atmosphere.
Amine-based post-combustion CO2 capture (PCCC) technology is regarded as one of the most viable solutions for the mitigation of CO2 emissions. It has been mature enough to be implemented on commercial scales. However, N-nitrosamines and N-nitramines can be formed as by-products of amine degradation during PCCC processes. They are suspected carcinogens and strictly regulated. With the development of PCCC technology across the global, PCCC facility may become a main source of N-nitrosamines and N-nitramines to the environment. Due to the possible adverse effects of N-nitrosamines and N-nitramines on the environment and human health, the interests in the occurrence, fate and mitigation of PCCC-derived N-nitrosamines and N-nitramines have been shared by a growing number of researchers recently. Therefore, this article provides a comprehensive review on the most recent efforts in this emerging field. In detail, this review focuses on (a) the formation, emission and degradation of N-nitrosamines and N-nitramines from amine-based PCCC processes, (b) the toxicology and environmental impact of PCCC-derived N-nitrosamines and N-nitramines, (c) the methods to destruct and remove N-nitrosamines and N-nitramines from PCCC waste, and (d) the future research perspectives.
A better understanding of key fundamental properties of nitrosamines, including their solubility in aqueous amine solvents, is needed to understand and accurately model the vapor-phase emission levels from operating CO2 capture systems. In this work, the first experimental Henry's volatility coefficient of a nitrosamine was obtained with a novel method using static headspace solid phase micro extraction (SPME) and gas chromatography mass spectrometry (GC/MS). The experimentally determined Henry's volatility coefficient of nitrosopyrrolidine (NPY) was found to be around 0.02 (dimensionless) at 25°C, and falls in the range of a semi-volatile compound. A linear temperature dependency of the Henry's volatility coefficient can be observed, however additional data is need to verify this trend.
Chemical absorption using amine–based solvents have proven to be the most studied, as well as the most reliable and efficient technology for capturing carbon dioxide (CO2) from exhaust gas streams and synthesis gas in all combustion and industrial processes. The application of single amine–based solvents especially the very reactive monoethanolamine (MEA) is associated with a parasitic energy demand for solvent regeneration. Since regeneration energy accounts for up to three–quarters of the plant operating cost, efforts in its reduction have prompted the idea of using blended amine solvents. This review paper highlights the success achieved in blending amine solvents and the recent and future technologies aimed at increasing the overall volumetric mass transfer coefficient, absorption rate, cyclic capacity and greatly minimizing both degradation and the energy for solvent regeneration. The importance of amine biodegradability (BOD) and low ecotoxicity as well as low amine volatility is also highlighted. Costs and energy penalty indices that influences the capital and operating costs of CO2 capture process was also highlighted. A new experimental method for simultaneously estimating amine cost, degradation rate, regeneration energy and reclaiming energy is also proposed in this review paper.
At the carbon dioxide capture process using the aqueous amine solution, degradation of absorbents is main factor to reducing the process performance. Also, degradation mechanism of absorbent is important for understanding the environmental risk, route of degradation products, health risk etc. In this study, the degradation products of MEA were studied to clarify mechanism in thermal degradation process. The degradation products were analyzed using a ^1H NMR (nuclear magnetic resonance) and ^{13}C NMR. The analysis methods used in this study provide guidelines that could be used to develop a degradation inhibitor of absorbent and a corrosion inhibitor.
Carbon dioxide capture and storage (CCS) is regarded as a powerful technology in mitigating the impacts of climate change and is considered as interim solution until other sustainable energy technologies can be used on a broader scale. Despite the fact that well conducted geological risk analyses exists, a major toxicological risk assessment including all components of the process is missing. Therefore, a literature study was undertaken with its focus on potential toxicological risks. These could appear in all parts of the CCS chain: in the capture process when chemicals are used for scrubbing, during transportation in case of accidents, and during geological storage when a leakage of CO2 or brine occurs. Toxicological hazards of special concern emerge not from CO2, but degradation products of scrubbing chemicals (nitrosamines and nitramines) or H2S-co-transportation. Additionally, contamination of potable aquifers due to mobilisation of hazardous trace elements, such as arsenic, nickel, and lead could become relevant in case of a leakage. Overall, to achieve further safety for the implementation of CCS as a mitigation technology, investigations in acute CO2-toxicity (with derivation of mass-intoxications threshold values), acute emergency management, and contaminants should be prime objectives for future CCS risk assessment research.
As carbon dioxide (CO2) emissions and other greenhouse gases (GHGs) represent both a great environmental challenge in terms of climate change and a problem for human health and social issues, their emission must be mitigated. Technological pathways to a low carbon economy include improving resource application/energy intensity, or by cutting carbon intensity through promoting low carbon technologies such as renewable energy or carbon capture and storage (CCS). For these technologies to be a truly effective option to mitigate climate change, they must be sustainable and be protective of the environment and human health over the long-term. Whilst analysis of most initiatives focuses on direct GHG quantification, other benefits and potential impacts are often not considered, and indirect emissions are often overlooked. In this chapter, the benefits of adapting to a low carbon economy are assessed, and technological adaptation strategies discussed along with associated impacts to human health and the environment. In particular, CCS is focused upon and life cycle assessment (LCA) shown as a particularly useful tool to give a holistic view of the impacts relating to mitigation options. These are important decision criteria for policymakers, and should be dealt with as such.
Carcinogenic nitrosamines have received much attention due to their formation in CO2 capture processes and probable emission into the atmosphere. Fortunately, nitrosamines are decomposed by exposure to UV irradiation. This may be an effective strategy to degrade nitrosamines, forming more benign products in the process. In this work, UV photolysis was used to examine the degradation kinetics and fate of nitrosamines (i.e., N-nitrosodiethylamine (NDEA), N-nitrosodibutylamine (NDBA), N-nitrosodimethylamine (NDMA), N-nitrosodiethanolamine (NDELA), and N-nitrosopyrrolidine (NPYR)) in water at 40°C. Nearly all nitrosamines were decomposed within the first 10 min of photodegradation using 4 W, low pressure Hg lamp. Pseudo-first order reaction rate constants were 1.8 × 10-2, 2.6 × 10-2, 2.6 × 10-2, 2.3 × 10-2, and 1.4 × 10-2 L/W-min for NDEA, NDBA, NDMA, NDELA, and NPYR, respectively. There was minimal change in total organic carbon (TOC) and total nitrogen (TN), suggesting negligible loss of nitrosamines and photodegradation products by evaporation.
A novel wet flue gas desulfurization process by aqueous ammonia-fulvic acid solution was proposed, in which fulvic acid (FA) could inhibit ammonia escape because carboxylic and phenolic groups in FA would interact with aqueous ammonia to form relatively stable ammonium fulvate. Experiments were conducted to research the effect of operating parameters such as initial pH value on the duration time of high efficiency (DTHE, time of above 95%) and absorption efficiency of SO2 in bubbling reactor. Results indicate that SO2 absorption efficiency and DTHE increase with increasing initial pH value, and SO2 absorption capacity of aqueous ammonia can be improved by synergic action of FA. FA concentration has slight effect on SO2 absorption efficiency (above 98.3%, pH0=8.5), but obvious effect on DTHE. FA can successfully inhibit ammonia escape from absorption liquid during desulfurization. When the pH of aqueous ammonia-FA absorption liquid is above 4.1, absorption efficiency can be kept above 99.0% (for pH0=10.0). Increasing of inlet SO2 concentration brings the reduction of absorption efficiency and DTHE. High CO2 concentration is detrimental to DTHE. O2 and ammonium sulfate concentration hardly affect SO2 absorption efficiency and DTHE. Among nine operational parameters, gas flow rate has the biggest influence on overall gas-side volumetric mass transfer coefficient. The ammoniation of FA and mechanism of SO2 absorption in aqueous ammonia-fulvic acid solution also were demonstrated by FT-IR.
The OH initiated gas-phase chemistry of several amines that are potential candidates for use in post-combustion carbon capture (PCCC) plants have been studied by laser flash photolysis with OH monitored by laser induced fluorescence. The rate coefficients for the reaction of OH with N-methylethanolamine (MMEA) and N,N-dimethylethanolamine (DMEA) have been measured as a function of temperature (∼300-500 K): , . The results for DMEA lie between previous values. This is the first kinetic study of the OH + MMEA reaction. At low pressures in the presence of oxygen, OH is recycled in the DMEA reaction as has been observed for other tertiary amines. Branching ratios for OH abstraction with MEA, DMEA and MMEA are dominated by abstraction from the αCH2 group. Abstraction from N-H is determined to be 0.38 ± 0.06 for MEA and 0.52 ± 0.06 for MMEA at 298 K. The impact of these studies has been assessed by using a modified chemical box model to calculate downwind concentrations of nitramines and nitrosamine formed in the photo-oxidation of MEA. Under clear sky conditions, the simulations suggest that current safe guidelines for nitramines may be significantly exceeded with predicted MEA emission rates.
Carbon capture and storage (CCS) is a technological solution that can reduce the amount of carbon dioxide (CO2) emissions from the use of fossil fuel in power plants and other industries. A leading method today is amine based post-combustion capture, in which 2-aminoethanol (MEA) is one of the most studied absorption solvents. In this process, amines are released to the atmosphere through evaporation and entrainment from the CO2 absorber column. Modelling is a key instrument for simulating the atmospheric dispersion and chemical transformation of MEA, and for projections of ground-level air concentrations and deposition rates. In this study, the Weather Research and Forecasting model inline coupled with chemistry, WRF-Chem, was applied to quantify the impact of using a comprehensive MEA photo-oxidation sequence compared to using a simplified MEA scheme. Main discrepancies were found for iminoethanol (roughly doubled in the detailed scheme) and 2-nitro aminoethanol, short MEA-nitramine (reduced by factor of two in the detailed scheme). The study indicates that MEA emissions from a full-scale capture plant can modify regional background levels of isocyanic acid. Predicted atmospheric concentrations of isocyanic acid were however below the limit value of 1ppbv for ambient exposure. The dependence of the formation of hazardous compounds in the OH-initiated oxidation of MEA on ambient level of nitrogen oxides (NOx) was studied in a scenario without NOx emissions from a refinery area in the vicinity of the capture plant. Hourly MEA-nitramine peak concentrations higher than 40pgm(-3) did only occur when NOx mixing ratios were above 2ppbv. Therefore, the spatial variability and temporal variability of levels of OH and NOx need to be taken into account in the health risk assessment. The health risk due to direct emissions of nitrosamines and nitramines from full-scale CO2 capture should be investigated in future studies.
Copyright © 2015 Elsevier B.V. All rights reserved.
A post-combustion amine based CO2 capture plant is associated with minor release of amine and amine degradation products to the atmosphere along with the treated flue gas. The possible health and environmental effect of this have been investigated extensively through the Norwegian CLIMIT-program, the CO2 Technology Centre Mongstad (TCM) and the planning of a full scale capture plant at Mongstad (CCM). Based on flue gas from a combined cycle gas power plant, the capacity of TCM's amine plant and CCM are 25 000 and 1 000 000 t/yr CO2, respectively. Special attention has been given to nitrosamines and nitramines and the investigations have provided new knowledge on their formation, degradation and dispersion, going from the capture plant towards the end point in the nature. The initiatives and programmes have also included means of emission reduction as well as refining of measurements techniques. Computer models for dispersion calculation and evaluation of maximum level of components in air and drinking water are important and are part of the environmental permit for TCM. Up to now, this new knowledge has significantly reduced the risk perception for the release of amine and amine degradation products to the atmosphere.
Global concentration of CO2 in the atmosphere is increasing rapidly. CO2 emissions have an impact on global climate change. Effective CO2 emission abatement strategies such as Carbon Capture and Storage (CCS) are required to combat this trend. There are three major approaches for CCS: post-combustion capture, pre-combustion capture and oxyfuel process. Post-combustion capture offers some advantages as existing combustion technologies can still be used without radical changes on them. This makes post-combustion capture easier to implement as a retrofit option (to existing power plants) compared to the other two approaches. Therefore, post-combustion capture is probably the first technology that will be deployed. This paper aims to provide a state-of-the-art assessment of the research work carried out so far in post-combustion capture with chemical absorption. The technology will be introduced first, followed by required preparation of flue gas from power plants to use this technology. The important research programmes worldwide and the experimental studies based on pilot plants will be reviewed. This is followed by an overview of various studies based on modelling and simulation. Then the focus is turned to review development of different solvents and process intensification. Based on these, we try to predict challenges and potential new developments from different aspects such as new solvents, pilot plants, process heat integration (to improve efficiency), modelling and simulation, process intensification and government policy impact.
Polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) were monitored in a seasonal passive sampling scheme during June 2008 and January 2009 to investigate the spatial concentration, congener profiles and evaluate the potential inhalation risk in different functional areas in Tianjin, China. The spatial air concentrations and I-TEQs ranged 1.08×102–8.19×103 fg m−3 (average 2.63×103 fg m−3) and 4.08–325 fg I-TEQ m−3 (average 91.4 fg I-TEQ m−3) respectively for PCDD/Fs. The concentration and I-TEQs of PCBs were 3.08×104–3.01×105 fg m−3 (average 1.39×105 fg m−3) and 1.72–49.6 fg I-TEQ m−3 (average 18.5 fg I-TEQ m−3). It is obvious that PCB concentrations were several hundred times higher than the PCDD/Fs. However, the ambient air PCDD/Fs contributed a major part to the total toxicity equivalents, varying from 72.7% to 89.0% (average 81.8%). The atmospheric PCDD/F levels were observed to be higher in winter for most of sampling sites in the downtown. Besides, inhalation risk assessment showed that local residents might suffer more risk near the point sources than those in living area, industrial zones and background area in Tianjin City. However, the total daily dioxin intake was approximately several to hundreds of times lower than the WHO criteria, showing relatively low exposure risks from the impact of industry point sources in Tianjin City.
To understand which part of the CO2 amine-based system is mostly responsible of amine degradation, MEA degradation under real CO2 capture conditions is compared with two laboratory experiments; a thermal degradation experiment representative of the stripper conditions (MEA 30 wt%, CO2 loaded, α=0.5, 135 °C) and an oxidative degradation experiment representative of the absorber conditions (MEA 30 wt%, CO2 loaded, α=0.4, sparged with air+CO2, 55 °C). Liquid Chromatography-Mass Spectrometry (LC-MS) was used for the quantification of the remaining amine and Gas Chromatography-Mass Spectrometry (GC-MS) was used for the identification and quantification of the main degradation compounds. This study suggests that MEA degradation in the pilot plant is more dominated by oxidative degradation than by thermal degradation. It is also found that reactions between MEA and carboxylic acids present in the solution may play a significant role in solvent degradation. This implies that carboxylic acids, usually referred to as “Heat Stable Salts”, are not stable and can react further to give more complex compounds.
As part of the EU project CASTOR, a 1 t/h CO2 absorption pilot plant has been erected at Esbjergværket (Esbjerg power station) in Denmark. The main purpose of the pilot plant is to demonstrate the post combustion capture technology in conjunction with a coal-fired power station. Additionally, the pilot plant has been used to test the performance of new energy efficient solvents and to validate modelling work. The pilot plant operates on a slipstream of flue gas from the power plant without any further pre- treatment. During the CASTOR project, four 1000-hours test campaigns have been conducted at the facility using conventional solvent, 30%-weight MEA as well as two novel amine-based solvents, CASTOR 1 and CASTOR 2. Among others, the test campaigns consisted of parameter variation tests and longer periods of continuous operation. This paper summarises the operation experience and some of the results obtained during the CASTOR project.
Thermal degradation of monethanolamine (MEA) is quantified as a function of initial amine concentration, CO2 loading, and temperature over a range of expected stripper conditions in an amine absorber/stripper unit. The sum of the degradation products N,N’-di(2-hydroxyethyl)urea, 1-(2-hydroxyethyl)-2-imidazolidone, and N-(2-hydroxyethyl)ethylenediamine make up the majority of total MEA loss. The temperature dependent rate constant has an activation energy similar to diethanolamine (DEA) of 29 kcal/mole which corresponds to a quadrupling of the degradation rate when the stripper temperature is increased 17 ∘C. At 135 ∘C the degradation rate varies from 2.5 to 6% per week. Using speciation data from an Aspen® model of a stripper unit, losses in the packing are significant, but the majority of MEA loss occurs in the reboiler and reboiler sump. Thermal degradation is minor when the reboiler temperature is held below 110 ∘C
A critical component in the assessment of long-term risk from geologic sequestration of CO2 is the ability to predict mineralogical and geochemical changes within storage reservoirs due to rock-brine-CO2 reactions. Impurities and/or other constituents selected for co-sequestration can affect both the chemical and physical (e.g. density, viscosity, interfacial tension) behavior of CO2 in the deep subsurface. These impurities and concentrations are a function of both the industrial source(s) of the CO2, as well as the carbon capture technology used to extract the CO2 and produce a concentrated stream for geologic sequestration. This report summarizes the relative concentrations of CO2 and other constituents in exhaust gases from major non-energy related industrial sources of CO2. Assuming that carbon-capture technology would remove most of the incondensable gases N2, O2, and Ar, leaving SO2 and NOx as the main impurities, we selected four test fluid compositions for use in geochemical experiments. These included: 1) a pure CO2 stream representative of food grade CO2 used in most enhanced oil recovery projects: 2) a test fluid composition containing low concentrations (0.5 mole %) SO2 and NOx (representative of that generated from cement production), 3) a test fluid composition with higher concentrations (2.5 mole %) of SO2, and 4) and test fluid composition containing 3 mole % H2S.
Post combustion CO2 capture using amine absorbents is the most mature process and therefore the most relevant choice for realising full-scale capture within the next few years. The health and environmental impact of emissions to air is, however, a potential risk. Amines may react in the process or in the atmosphere post emission to form new substances that may be more harmful than the parent amine itself.The main objective of the current work was to investigate the flue gas degradation of monoethanolamine (MEA) in the process with special emphasis on the NOx induced chemical reactions. Degradation experiments have been carried out at absorber like conditions in the Aminox™ rig, followed by further degradation of the used solvent at higher temperature in a lab scale autoclave. Liquid samples were analysed by a range of methods to identify the formation of degradation by-products, with special focus on potential harmful compounds like nitrosamines and nitramines. On-line FT-IR and MS instruments were used for qualitative detection of volatile degradation products and to measure amine slip.MEA is a primary amine which in itself is unable to form a stable nitrosamine. However, experiments show that under the influence of NOx, MEA degrades to the secondary amine diethanolamine (DEA) which is then nitrosated. This work shows that some nitrosamine formation in the process must be expected from any amine. Based on data from real emission measurements, health and environmental risk assessment should be investigated in further studies.
Post-combustion CO2 capture in flue gas with solvent is currently the most advanced technology. A major problem associated with chemical absorption of CO2 using the benchmark ethanolamine (MEA) is solvent degradation through irreversible side reactions with CO2 and O2. So, new amines development with higher chemical stability becomes essential. This work is based on chemical stability study of 17 different molecules: alkanolamines, diamines, and triamines without alcohol function. Effects of temperature, CO2, and O2 on degradation have been studied. Knowledge of degradation products and main reactions allows a better understanding of amines chemical stability for CO2 capture application.
Concentrated, aqueous piperazine (PZ) has been investigated as a novel amine solvent for carbon dioxide (CO2) absorption. The CO2 absorption rate of aqueous PZ is more than double that of 7 m MEA and the amine volatility at 40 °C ranges from 11 to 21 ppm. Thermal degradation is negligible in concentrated, aqueous PZ up to a temperature of 150 °C, a significant advantage over MEA systems. Oxidation of concentrated, aqueous PZ is appreciable in the presence of copper (4 mM), but negligible in the presence of chromium (0.6 mM), nickel (0.25 mM), iron (0.25 mM), and vanadium (0.1 mM). Initial system modeling suggests that 8 m PZ will use 10–20% less energy than 7 m MEA. The fast mass transfer and low degradation rates suggest that concentrated, aqueous PZ has the potential to be a preferred solvent for CO2 capture.
The chilled ammonia process absorbs the CO2 at low temperature (2–10 ∘C). The heat of absorption of carbon dioxide by ammonia is significantly lower than for amines. In addition, degradation problems can be avoided and a high carbon dioxide capacity is achieved. Hence, this process shows good perspectives for decreasing the energy requirement. However, a scientific understanding of the processes is required. The properties of the NH3- CO2- H2O system were described using the Extended UNIQUAC electrolyte model developed by Thomsen and Rasmussen in a temperature range from 0 to 110 ∘C and pressure up to 100 bars [1]. The results show that solid phases consisting of ammonium carbonate and bicarbonate are formed in the absorber. The energy requirements in the absorber and in the desorber have been studied. The enthalpy calculations show that an energy requirement for the desorber lower than 2 GJ/ton CO2 can be reached.
The simulation and modeling of post-combustion CO2 capture systems are considered to be an important strategy to obtain process integrity and gain design confidence for the construction and commissioning of commercial post-combustion CO2 capture plants. It is therefore essential to obtain an understanding of the fundamental concepts of designing and modeling. This article reviews the concepts of designing a CO2 capture system with specific emphasis on the absorber for diameter and height. It covers several steps (i.e., empirical design method, theoretical design method, laboratory method and pilot plant techniques) used to design the absorber. A conceptual design of an overall CO2 capture process is also given in the article. Process validations of the modeling using ProMax with four existing pilot plants. (the International Test Centre of CO2 Capture pilot plant, the Esbjerg CASTOR pilot plant, the Institute of Thermodynamics and Thermal Process Engineering, Stuttgart pilot plant and the SINTEF/NTNU pilot plant) are presented. Moreover, a discussion of process integration of the CO2 capture plant into a fossil fuel-fired power plant is included in this paper.
The first CO2 capture industrial-scale plant in China was demonstrated in Huaneng Beijing Power Plant, which shows the technology is a good option for capturing CO2 from commercial coal-fired power plants. The commissioning and industrial test were introduced. The tests show that in the early passivation phase the concentration variations in amine, anti-oxidant and Fe3+ were in the normal range, and the main parameters achieved the design value. The efficiency of CO2 capture was about 80%~85%, and about 900 t CO2 (99.7%) had been captured before February 2009. During operation, water unbalance problems in the system happened when the power station load changes greatly. Two solutions were proposed and compared, and it is found that pre-dewater solution has a lower steam consumption but extra power and water requirement.
A review of the significant developments, and changes in focus and perspective in the chemistry and biochemistry of nitrosamines and other N-nitroso compounds over the past twelve years is presented. Research in this field has moved away from identifying nitrosamine contaminants of commercial mixtures. Significant effort has been directed at understanding the possible role of endogenous nitrosation in man and development of analytical chemical markers to be used in molecular epidemiology. The successes and failures of this approach are reviewed. A highly significant sidelight to this research was the monumental discovery that NO is produced by many cells. Macrophages produce quantities sufficient to lead to the nitrosation of amines and the deamination of DNA. Fragments of nitrosamines derived from nicotine have been detected in human hemoglobin and DNA. Significant advances have been made in understanding the formation of nitrosamines from a variety of nitrogen containing compounds and new methods for blocking nitrosamine formation have been developed. The biochemistry of the α-hydroxylation of simple nitrosamines and other biochemical activation pathways applicable to nitrosamines containing OH, C=O, and other groups is much better understood and is reviewed. Possible future research needs and directions are presented.
Post-combustion CO2 capture based on CO2 absorption by aqueous amine solutions is the most mature gas separation technology. A main problem is amine degradation due to heat, CO2, O2, NOx and SOx. This review proposes to make a critical survey of literature concerning degradation, to list degradation products and to discuss mechanisms proposed by authors. Benchmark molecule is monoethanolamine (MEA) but diethanolamine (DEA), N-methyldiethanolamine (MDEA), piperazine (PZ) and 2-amino-2-methylpropan-1-ol (AMP) are also studied. Uses of other amines and amine blends are also considered. In the case of MEA, ammonia, N-(2-hydroxyethyl)-piperazin-3-one (HEPO) and N-(2-hydroxyethyl)-2-(2-hydroxyethylamino) acetamide (HEHEAA) are the main identified degradation products in pilot plants. Among lab studies, the most cited degradation products are ammonia, carboxylic acids, N-(2-hydroxyethyl)-formamide (HEF), N-(2-hydroxyethyl)-acetamide (HEA) and N-(2-hydroxyethyl)-imidazole (HEI) for oxidative degradation, and oxazolidin-2-one (OZD), N-(2-hydroxyethyl)-ethylenediamine (HEEDA) and N-(2-hydroxyethyl)-imidazolidin-2-one (HEIA) for thermal degradation. Numerous degradation products have been identified but some are still unknown. A lot of degradation mechanisms have been proposed but some are missing or need proofs. SOx and NOx effects are still few examined and much work remains to be done concerning volatile degradation products potentially emitted to atmosphere: their identification and their formation mechanisms need further investigations.
THE potential for the formation of N-nitrosamines in the human environment, either during the processing of foods or in vivo from nitrate and/or nitrite, and precursor amines has received considerable attention in recent years. Traditionally only secondary amines were thought to undergo N-nitrosation reactions. While secondary amines per se are not common in biological systems, tertiary amines and quaternary ammonium compounds do occur in plant and animal tissue. The possible formation of N-nitrosamines from these compounds must be considered because recent reports have appeared on the nitrosation of trimethylamine1,2 and trimethylamine oxide1 in connexion with the possible formation of N-nitrosamines in fish products cured with nitrate. The nitrosative cleavage of tertiary amines is not new and has been described before3,4.
CO2 solubility was measured in a wetted-wall column in 0.6–3.6molal (m) piperazine (PZ) and 2.5–6.2m potassium ion (K+) at 40–110°C. Piperazine speciation was determined using 1H NMR for 0.6–3.6m piperazine (PZ) and 3.6–6.2m potassium ion (K+) at 25–70°C. The capacity of CO2 in solution increases as total solute concentration increases and compares favorably with estimates for 7m (30wt.%) monoethanolamine (MEA). The presence of potassium in solution increases the concentration of CO32−/HCO3− in solution, buffering the solution. The buffer reduces protonation of the free amine, but increases the amount of carbamate species. These competing effects yield a maximum fraction of reactive species at a potassium to piperazine ratio of 2:1.A rigorous thermodynamic model was developed, based on the electrolyte nonrandom two-liquid (ENRTL) theory, to describe the equilibrium behavior of the solvent. Modeling work established that the carbamate stability of piperazine and piperazine carbamate resembles primary amines and gives approximately equal values for the heats of reaction, ΔHrxn (18.3 and 16.5kJ/mol). The pKa of piperazine carbamate is twice that of piperazine, but the ΔHrxn values are equivalent (∼−45kJ/mol). Overall, the heat of CO2 absorption is lowered by the formation of significant quantities of HCO3− in the mixed solvent and strongly depends on the relative concentrations of K+ and PZ, ranging from −40 to −75kJ/mol.
The deamination of 2-amino- and 3-aminoalkanols in the presence of nitrous acid is reported. The 2-aminoalkanols generated aldehydes upon loss of nitrogen, followed by oxazolidine formation by reaction with starting material and finally nitrosation to substituted N-nitroso-1,3-oxazolidines. Ethanolamine gave N-nitroso-2-methyl-1,3-oxazolidine; 2-amino-2-methyl-1-propanol was converted to N-nitroso-2-isopropyl-4,4-dimethyl-1,3-oxazolidine. Deamination of 1-amino-2-propanol gave propionaldehyde, which upon further reaction produced cis- and trans-N-nitroso-2-ethyl-5-methyl-1,3-oxazolidines. (E)- and (Z)-N-nitroso-2-ethyl-4-methyl-1,3-oxazolidines were obtained from the deamination of 2-amino-1-propanol. Propionaldehyde and formaldehyde were produced by diazotiazation of 1-amino-3-propanol. Further reaction of the aldehydes with unreacted amine formed N-nitroso-1,3-tetrahydrooxazine and N-nitroso-2-ethyl-1,3-tetrahydrooxazine. Nuclear magnetic resonance and deuterium-exchange studies of these compounds are discussed.
Tertiary amines react with aqueous nitrous acid, contrary to common belief, and undergo dealkylation to form a carbonyl compound, a secondary nitrosamine, and nitrous oxide. The ratios of products from meta-or para-monosubstituted tribenzylamines are affected but little by the electronic influence of the substituents, and obey the Hammett equation with a small negative value of the reaction constant. Susceptibility of an amine to nitrosative cleavage is markedly reduced by base-weakening effects, and is prevented altogether by quaternization. Quinuclidine, in which the tertiary nitrogen is at a bridgehead, is inert, α substituents in tribenzylamines and benzyldiethylamines strongly shift dealkylation to the unsubstituted groups, regardless of the electronic character of the α substituent (e.g., alkyl or carboethoxy). Tribenzylamine-α,αd2 shows a deuterium isotope effect kH/kD = 3.78. The facts are correlated by a mechanism (eq 4-6) involving formation of an N-nitrosoammonium ion and cis elimination of nitroxyl to form a ternary immonium ion, R2N+=CR2, which then undergoes hydrolysis and further nitrosation. Nitrosyl fluoroborate and tribenzylamine form an unstable 1:1 addition compound at -45°; above -20°, this substance decomposes to form tribenzylammonium and N,N-dibenzylbenzaldimmonium fluoroborates.
With years of full-scale experience for precombustion CO(2) capture, amine-based technologies are emerging as the prime contender for postcombustion CO(2) capture. However, concerns for postcombustion applications have focused on the possible contamination of air or drinking water supplies downwind by potentially carcinogenic N-nitrosamines and N-nitramines released following their formation by NO(x) reactions with amines within the capture unit. Analytical methods for N-nitrosamines in drinking waters were adapted to measure specific N-nitrosamines and N-nitramines and total N-nitrosamines in solvent and washwater samples. The high levels of amines, aldehydes, and nitrite in these samples presented a risk for the artifactual formation of N-nitrosamines during sample storage or analysis. Application of a 30-fold molar excess of sulfamic acid to nitrite at pH 2 destroyed nitrite with no significant risk of artifactual nitrosation of amines. Analysis of aqueous morpholine solutions purged with different gas-phase NO and NO(2) concentrations indicated that N-nitrosamine formation generally exceeds N-nitramine formation. The total N-nitrosamine formation rate was at least an order of magnitude higher for the secondary amine piperazine (PZ) than for the primary amines 2-amino-2-methyl-1-propanol (AMP) and monoethanolamine (MEA) and the tertiary amine methyldiethanolamine (MDEA). Analysis of pilot washwater samples indicated a 59 μM total N-nitrosamine concentration for a system operated with a 25% AMP/15% PZ solvent, but only 0.73 μM for a 35% MEA solvent. Unfortunately, a greater fraction of the total N-nitrosamine signal was uncharacterized for the MEA-associated washwater. At a 0.73 μM total N-nitrosamine concentration, a ~25000-fold reduction in concentration is needed between washwater units and downwind drinking water supplies to meet proposed permit limits.
IntroductionFormation of N-NitrosaminesProperties and Reactions of N-NitrosaminesBiological Properties of N-NitrosaminesN-NitrosoiminesAcknowledgementsReferences
Use of amines is one of the leading technologies for post-combustion carbon dioxide capture from gas and coal-fired power plants. This study assesses the potential environmental impact of emissions to air that result from use of monoethanol amine (MEA) as an absorption solvent for the capture of carbon dioxide (CO2). Depending on operation conditions and installed reduction technology, emissions of MEA to the air due to solvent volatility losses are expected to be in the range of 0.01–0.8 kg/tonne CO2 captured. Literature data for human and environmental toxicity, together with atmospheric dispersion model calculations, were used to derive maximum tolerable emissions of amines from CO2 capture. To reflect operating conditions with typical and with elevated emissions, we defined a scenario MEA-LOW, with emissions of 40 t/year MEA and 5 t/year diethyl amine (DEYA), and a scenario MEA-HIGH, with emissions of 80 t/year MEA and 15 t/year DEYA. Maximum MEA deposition fluxes would exceed toxicity limits for aquatic organisms by about a factor of 3–7 depending on the scenario. Due to the formation of nitrosamines and nitramines, the estimated emissions of DEYA are close to or exceed safety limits for drinking water and aquatic ecosystems. The “worst case” scenario approach to determine maximum tolerable emissions of MEA and other amines is in particular useful when both expected environmental loads and the toxic effects are associated with high uncertainties.
One of the highest priorities in carbon sequestration science is the development of techniques for CO 2 separation and capture, because it is expected to account for the majority of the total cost (∼75%). The most common currently used method of CO 2 separation is reversible chemical absorption using monoethanolamine (MEA) solvent. In the current study, solvent degradation from this technique was studied using degraded MEA samples from the IMC Chemicals Facility in Trona, California. A major pathway to solvent degradation that had not been previously observed in laboratory experiments has been identified. This pathway, which is initiated by oxidation of the solvent, is a much more significant source of solvent degradation than the previously identified carbamate dimerization mechanism.
This critical review addresses the atmospheric gas phase and aqueous phase amine chemistry that is relevant to potential emissions from amine-based carbon capture and storage (CCS). The focus is on amine, nitrosamine and nitramine degradation, and nitrosamine and nitramine formation processes. A comparison between the relative importance of the various atmospheric sinks for amines, nitrosamines and nitramines is presented.
The first industrial-scale CO2 capture plant in China has been demonstrated at Huaneng Beijing power plant has shown that this technology is a good option for the capture of CO2 produced by commercial coal-fired power plants. The commissioning and industrial tests are introduced in this paper. The tests show that in the early stages of the passivation phase, the concentration variations of amine, anti-oxidant and Fe3+ are in the normal range, and the main parameters achieve the design value. The efficiency of the CO2 capture was about 80-85%, and by the end of January 2009 about 900Â tons of CO2 (99.7%) have been captured. The equipment investment and consumptive costs, including steam, power, solution and others, have been analyzed. The results show: the cost of the absorber and the stripper account for about 50% of main equipment; the consumptive cost is about 25.3Â US/kWÂ h and the electricity purchase price increased by 29%.
This paper assesses the three leading technologies for capture of CO2 in power generation plants, i.e., post-combustion capture, pre-combustion capture and oxy-fuel combustion. Performance, cost and emissions data for coal and natural gas-fired power plants are presented, based on information from studies carried out recently for the IEA Greenhouse Gas R&D Programme by major engineering contractors and process licensors. Sensitivities to various potentially significant parameters are assessed.
Oxidative degradation of monoethanolamine (MEA) was studied at 55 °C, typical of absorbers for CO2 removal from flue gas. The rate of evolution of NH3, which was indicative of the overall rate of degradation, was measured continuously in a batch system sparged with air. Dissolved iron from 0.0001 to 1 mM yielded oxidation rates from 0.37 to 2 mM/h in MEA solutions loaded with 0.4 mol CO2/mol MEA. Ethylenediaminetetraacetic acid (EDTA) and N,N-bis(2-hydroxyethyl)glycine effectively decreased the rate of oxidation in the presence of iron by 40â50%. Ferrous caused oxidation in unloaded MEA with stoichiometry from 0.1 to 0.33 mol NH3/mol Fe2+. Fe2+ from 0.0001 to 3.2 mM yielded rates from 0.12 to 1.1 mM/h. Ferric did not appear to catalyze oxidation in unloaded MEA.
Nitrosamine formation has been associated with wastewater-impacted waters, but specific precursors within wastewater effluents have not been identified. Experiments indicated that nitrosamines form in low yields from quaternary amines, and that the nitrosamines form from the quaternary amines themselves, not just lower order amine impurities. Polymeric and benzylated quaternary amines were more potent precursors than monomeric quaternary alkylamines. Pretreatment of quaternary amines with ozone or free chlorine, which deactivate lower order amine impurities, did not significantly reduce nitrosamine formation. The nitrosamine formation pathway is unclear but experiments indicated that transformation of quaternary amines to lower order amine precursors via Hofmann elimination was not involved. Experiments suggest that the pathway may involve quaternary amine degradation by amidogen or chloramino radicals formed from chloramines. Quaternary amines are significant constituents of consumer products, including shampoos, detergents, and fabric softeners. Although quaternary amines may be removed by sedimentation during wastewater treatment, their importance should be evaluated on a case-by-case basis. The high loadings from consumer products may enable the portion not removed to serve as precursors.
The toxicological evaluation and histopathological findings of a long-term inhalation study in progress with N-nitrosodimethylamine (NDMA) are presented. Exposure was to three concentrations of NDMA: 0.04, 0.2 and 1.0 ppm (corresponding to 120, 600 and 3000 micrograms/m3). A significant reduction in median survival time (nine months) was seen in animals treated with the highest concentration of NDMA. Tumours occurred mainly in the nasal cavity, with the highest incidences in the groups receiving 1.0 and 0.2 ppm NDMA (19/36 and 31/36 tumour-bearing animals); in the lowest exposure group, 13/36 nasal tumours have been observed. The survival time of this treatment group, however, was about two months longer than that of the controls.
A Weibull analysis is presented of the dose and time relationships for the effects on 4080 inbred rats of chronic ingestion in the drinking water of 16 different doses of N-nitrosodimethylamine (NDMA) or N-nitrosodiethylamine (NDEA). The sites chiefly affected were the liver (by both agents) and the esophagus (by NDEA only). Since the experiment continued on into extreme old age, effects became measurable at doses of only 0.01 to 0.02 mg/kg/day, which is an order of magnitude lower than previously achieved. (After only 2 years of treatment, however, the TD50 doses needed to halve the proportion of tumorless survivors would have been about 0.06 mg/kg/day of NDEA, or about 0.12 mg/kg/day of NDMA.) The general pattern of response was that the natural logarithm of the probability of remaining tumorless was given by the product of two terms, the first (the "Weibull b value") depending on the dose rate but not on the duration of exposure and the second depending not on dose at all but only on duration. For all types of tumor the dependence on duration was fairly similar (and for each the second term was taken to be -t7, where t = years of treatment), but for different types of tumor the dependence on dose rate was quite different. For esophageal tumors, the "Weibull b value" was approximately proportional to the cube of the dose rate of NDEA (males 21 d3, females 11 d3, where d = dose rate in mg/kg adult body weight/day), and the background incidence was unmeasurably low. For liver tumors induced by NDEA, the b value was approximately proportional to the fourth power of dose rate + 0.04 mg/kg/day [males, 19 (d + 0.04)4; females, 32 (d + 0.04)4], although the relationships were somewhat different for the different cell types of liver tumor. This one formula implies both approximate linearity at low doses and an approximately cubic relationship within the higher range of doses that was studied. For liver tumors induced by NDMA, the Weibull b value was approximately proportional to the sixth power of dose rate + 0.1 mg/kg/day [males, 37 (d + 0.1)6; females, 51 (d + 0.1)6], again with some variation between liver cell types, and again implying approximate linearity at low doses. These algebraic formulae should, of course, be trusted only in the range of doses where they were derived, and particularly not above it.(ABSTRACT TRUNCATED AT 400 WORDS)
Four thousand eighty inbred rats were maintained from weaning on various different concentrations of N-nitrosodiethylamine (NDEA) or N-nitrosodimethylamine (NDMA). The principal aim was to characterize the dose-response relationship for the effects of these agents on esophageal cancer (NDEA) or on various types of liver cancer (NDEA and NDMA), although NDEA also caused a few tumors of the nasopharynx and NDMA also caused a few tumors of the lung. The numbers of tumors of mesenchymal and Kupffer cells in the liver were too few to allow easy characterization of the dose-response relationships, and although NDMA induced large numbers of bile duct neoplasms, NDEA did not. Thus, the four principal dose-response relationships studied were of NDEA on esophageal or liver cells and of NDMA on bile duct or liver cells. At doses sufficiently high for the median time to death from the disease of interest to be estimated, relationships were observed of the general form (Dose rate) x (median)n = constant where n was about 2.3 for the first three relationships and about 1 for the last one (NDMA on liver cell tumors). By contrast, at doses sufficiently low for longevity to be nearly normal (median survival about 2.5 years), there remained no material dependence on the dose rate of the age distribution of the induced neoplasms. At these low dose rates, the number of liver (but not of esophageal) neoplasms induced by treatment was simply proportional to the dose rate. This finding is not surprising, since the background incidence of liver (but not of esophageal) neoplasms was appreciable. The linear relationship observed at low dose rates (below 1 ppm) suggests that under these experimental conditions, among rats allowed to liver their natural life span, a dose of 1 ppm of NDEA or NDMA in the drinking water will cause about 25% to develop a liver neoplasm, a dose of 0.1 ppm will cause about 2.5% to do so, and a dose of 0.01 ppm will cause about 0.25% to do so, etc., with no indication of any "threshold." (At these low dose rates, the incidence of liver neoplasms appears likely to exceed greatly that of esophageal neoplasms.) In addition, even quite low dose rates of the test agents caused a variety of nonneoplastic liver abnormalities (e.g., hyperplastic nodules, or shrinkage of hepatocytes) at a frequency roughly proportional to the dose rate.
The questions of whether and how N-nitroso compounds (NOC) may be inducing cancer in humans are discussed. The principal subjects covered include nitrite-derived alkylating agents that are not NOC, reasons for the wide tissue specificity of carcinogenesis by NOC, the acute toxicity of nitrosamines in humans, mechanisms of in vivo formation of NOC by chemical and bacterial nitrosation in the stomach and via nitric oxide (NO) formation during inflammation, studies on nitrite esters, use of the nitrosoproline test to follow human gastric nitrosation, correlations of nitrate in food and water with in vivo nitrosation and the inhibition of gastric nitrosation by vitamin C and polyphenols. Evidence that specific cancers are caused by NOC is reviewed for cancer of the stomach, esophagus, nasopharynx, urinary bladder in bilharzia and colon. I review the occurrence of nitrosamines in tobacco products, nitrite-cured meat (which might be linked with childhood leukemia and brain cancer) and other foods, and in drugs and industrial situations. Finally, I discuss clues from mutations in ras and p53 genes in human tumors about whether NOC are etiologic agents and draw some general conclusions.
Capture and sequestration of CO2 from fossil fuel power plants is gaining widespread interest as a potential method of controlling greenhouse gas emissions. Performance and cost models of an amine (MEA)-based CO2 absorption system for postcombustion flue gas applications have been developed and integrated with an existing power plant modeling framework that includes multipollutant control technologies for other regulated emissions. The integrated model has been applied to study the feasibility and cost of carbon capture and sequestration at both new and existing coal-burning power plants. The cost of carbon avoidance was shown to depend strongly on assumptions about the reference plant design, details of the CO2 capture system design, interactions with other pollution control systems, and method of CO2 storage. The CO2 avoidance cost for retrofit systems was found to be generally higher than for new plants, mainly because of the higher energy penalty resulting from less efficient heat integration as well as site-specific difficulties typically encountered in retrofit applications. For all cases, a small reduction in CO2 capture cost was afforded by the SO2 emission trading credits generated by amine-based capture systems. Efforts are underway to model a broader suite of carbon capture and sequestration technologies for more comprehensive assessments in the context of multipollutant environmental management.
In the United States, pancreatic cancer is the fourth most frequent cause of cancer death in males as well as females, after
lung, prostate or breast, and colorectal cancer. Each year, approximately 30 000 Americans are diagnosed with pancreatic cancer
and about the same number die of it. Germline mutations in a few genes including p16 and BRCA2 have been implicated in a small
fraction of cases, as has chronic pancreatitis. The one established risk factor for pancreatic cancer is cigarette smoking:
current smokers have two to three times the risk of nonsmokers. Studies of dietary factors have not been entirely consistent
but do suggest associations of higher risk with consumption of smoked or processed meats or with animal foods in general and
lower risk with consumption of fruits and vegetables. Colonization by Helicobacter pylori appears to increase risk, and a history of diabetes mellitus may also increase risk. The purpose of this epidemiologic review
is to consider the possibility that risk of pancreatic cancer is increased by factors associated with pancreatic N-nitrosamine or N-nitrosamide exposures and with chronic excess gastric or duodenal acidity. Host genetic variation in inflammatory cytokine
mechanisms may also be involved in this process. Many features of the evidence bearing on the pathophysiology of pancreatic
cancer appear to support connections with N-nitroso compounds and with gastric acidity.
N-Nitroso compounds (NOCs) are recognized neural carcinogens in animal models and are suspected human carcinogens. A meta-analysis was performed examining the possible association of maternal intake of cured meat (an important source of dietary NOCs) during pregnancy and the risk of pediatric brain tumors.
Data from epidemiological studies were pooled using a general variance-based meta-analytic method employing confidence intervals described by Greenland in 1986. The outcome of interest was a summary relative risk (RR) reflecting the risk of childhood brain tumor (CBT) development associated with maternal intake of cured meats during pregnancy. Sensitivity analyses were performed when necessary to explain any observed statistical heterogeneity.
Seven observational studies were found that met the protocol-specified inclusion criteria. Analysis for heterogeneity demonstrated a lack of statistical heterogeneity (p = 0.59), indicating that the data could be statistically combined. Pooling data from the 6 reports containing data on maternal cured meat intake of all types yielded an RR of 1.68 (1.30- 2.17), being a statistically significant result. Analyzing CBT risk by type of cured meat ingested showed that hot dog consumption increased CBT risk by 33% (1.08-1.66), with a similar increase shown by frequent ingestion of sausage, i.e. 44%.
The data provide support for the suspected causal association between ingestion of NOCs from cured meats during pregnancy and subsequent CBT in offspring. Limitations in study design preclude definitive conclusions, but the relationship warrants exploration via additional observational and laboratory-based studies.
The support vector machine (SVM), as a novel type of learning machine, was used to develop a classification model of carcinogenic properties of 148 N-nitroso compounds. The seven descriptors calculated solely from the molecular structures of compounds selected by forward stepwise linear discriminant analysis (LDA) were used as inputs of the SVM model. The obtained results confirmed the discriminative capacity of the calculated descriptors. The result of SVM (total accuracy of 95.2%) is better than that of LDA (total accuracy of 89.8%).
Nitrosamine, bekannt als aktive Cancerogene, werden in der Stadtluft, im Boden, im Wasser und in Abwässern gefunden.
Improved technology to capture CO2 from industrial gaseous streams
- A Aboudheir
Aboudheir, A., 2013. Improved technology to capture CO2 from industrial gaseous streams. In: 1st International Industrial Seminar Messer Benelux.
The chemistry of functional groups, the chemistry of amino, nitroso and nitro compounds and their derivates
- B C Challis
- J C Challis
Challis, B.C., Challis, J.C., 1982. The chemistry of functional groups, the chemistry of amino, nitroso and nitro compounds and their derivates, Supplement F, Part
From engineering to procurement to construction of the Boundary Dam carbon capture system
- G Couturier
- D Mello
Couturier, G., D'Mello, M., 2013. From engineering to procurement to construction of the Boundary Dam carbon capture system. In: SaskPower CCS Consortium 2013 Information & Planning Symposium.
CO2 capture Mongstad-Project B-Theoretical evaluation of the potential to form and emit harmful compounds. In: Task 1: Process Chemistry. The Commonwealth Scien-tific and Industrial Research Organisation (CSIRO) Report, Australia
- N Dave
- T Do
- P Jackson
- P Feron
- M Azzi
- M Attalla
Dave, N., Do, T., Jackson, P., Feron, P., Azzi, M., Attalla, M., 2010. CO2 capture Mongstad-Project B-Theoretical evaluation of the potential to form and emit harmful compounds. In: Task 1: Process Chemistry. The Commonwealth Scien-tific and Industrial Research Organisation (CSIRO) Report, Australia. Davis, J., Rochelle, G., 2009. Thermal degradation of monoethanolamine at stripper conditions. Energy Procedia 1 (1), 327–333.2014) 37–42
A new test rig for studies of degradation of CO2 absorption solvents at process conditions; comparison test rig results and pilot plant data for degradation of MEA European Commission, 2007. Opinion on the presence and release of nitrosamines and nitrosatable compounds from rubber balloons
- A Einbu
- E Dasilva
- G Haugen
- A Grimstveit
Einbu, A., DaSilva, E., Haugen, G., Grimstveit, A., 2012. A new test rig for studies of degradation of CO2 absorption solvents at process conditions; comparison test rig results and pilot plant data for degradation of MEA. In: GHGT-11, Tokyo, Japan. European Commission, 2007. Opinion on the presence and release of nitrosamines and nitrosatable compounds from rubber balloons. In: Health & Consumer Protection Directorate-General, Scientific Committee on Consumer Products, SCCP/1132/07.
Synergised Uptake of CO2 by Enzyme and Amine Combinations for Application to Post-Combustion Capture. GHGT-10
- V S Haritos
- G Dojchinov
- A C Warden
- G Puxty
- M Su
Haritos, V.S., Dojchinov, G., Warden, A.C., Puxty, G., Su, M., 2010. Synergised Uptake of CO2 by Enzyme and Amine Combinations for Application to Post-Combustion Capture. GHGT-10, Amsterdam, Netherlands.
An Introduction to CO2 Separation and Capture Technologies. Energy Laboratory Working Paper
- H Herzog
Herzog, H., 1999. An Introduction to CO2 Separation and Capture Technologies. Energy Laboratory Working Paper. Massachusetts Institute of Technology, Cambridge, MA, pp. 1–8.
A research program for promising retrofit technologies. In: Pre-pared for the MIT Symposium on Retro-fitting of Coal-Fired Power Plant for Carbon Capture
- H Herzog
Herzog, H., 2009. A research program for promising retrofit technologies. In: Pre-pared for the MIT Symposium on Retro-fitting of Coal-Fired Power Plant for Carbon Capture.