Results 1 - 10 of 3599
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[en] The results of SO2 radiation-induced oxidation in nitrogen-oxygen mixtures (long-pulse electron beams; dose rate 10 - 100 MGy/s) are considered. It is shown that SO2 removal in the presence of water vapor has two step has low energy efficiency and occurs during the electron pulse. The slow step has high energy efficiency and takes place 5-10 min after the electron pulse
[en] Graphical abstract: Batch digester with coffee pulp/cow dung produced high amounts of methane for 8 months. The FTIR gas spectroscopy analysis revealed the presence of over 70 chemical compounds in biogas generated after 4 months of coffee pulp and cow dung mixture co-digestion, several being hazardous to environment and human and animal health (e.g. isocyanic acid, bromomethane). Biogas produced was burned in a laboratory combustor. The FTIR gas spectroscopy analysis showed that combustion emissions contained: CH4, C3H8, CO, SO2, HI, and probably Br2 which are strongly harmful to human and animal health. - Highlights: • Batch digester with coffee pulp/cow dung produced high amounts of methane for 8 months. • Biogas from coffee pulp/cow dung codigestion contained 60% methane and 20% propane. • Biogas FTIR analysis revealed the presence of isocyanic acid and bromomethane. • Biogas FTIR analysis showed also the presence of HI. • Biogas combustion emissions contained CH4, HI, SO2 and probably Br2. - Abstract: Biogas could be produced by the co-digestion of coffee-pulp and cow-dung mixture under solar radiation. Gas chromatography and FTIR spectroscopy were used to analyze the chemical compositions of the generated biogas and its postcombustion emissions. From the first month of co-digestion at mesophylic conditions, methane content in the biogas attains 50% of the yield. This content increased up to 60% and remained almost constant for at least 8 months of further digestion. The FTIR gas spectroscopy analysis revealed the presence of over 70 chemical compounds in the biogas generated after 4 months of co-digestion along with several compounds hazardous to environment and animal health like isocyanic acid, and bromomethane. Combustion emission of the biogas contained several components like CH4, C3H8, CO, SO2, HI, and probably Br2 which are strongly harmful to human and animal health. Results presented in this work indicate that if the biogas is to be considered as a fuel, the conventional combustion technology has to be upgraded to prevent these hazardous emissions to the atmosphere
[en] A critical assessment of biodesulfurization technology for the treatment of the coals before their burning i.e. before SO2 formation is done in the report. The mechanisms of inorganic and organic sulfur removal from coals are discussed and the difficulties for the implementation of this process are underlined
[en] We present molecular line and 1.4 mm continuum observations toward five massive star-forming regions at arcsecond resolution using the Submillimeter Array. We find that the warm molecular gas surrounding each H II region (as traced by SO2 and OCS) appears to be undergoing bulk rotation. From the molecular line emission and thermal component of the continuum emission, we independently derived gas masses for each region which are consistent with each other. From the free-free component of the continuum emission, we estimate the minimum stellar mass required to power the H II region and find that this mass, when added to the derived gas mass, is a significant fraction of the dynamical mass for that region.
[en] Poly-Ethylene Glycol (PEG) 300+H_2O solutions (PEGWs) has been used as a promising medium for the absorption of SO_2. We investigated the UV, FTIR, "1H-NMR, and fluorescence spectra in the absorption processes of SO_2 in PEGWs to present an important absorption mechanism. Based on the spectral results, the possibility of intermolecular hydrogen bond formation by hydroxyl oxygen atom in the PEG molecule with hydrogen atom in H_2O and S…O interaction formation by the oxygen atoms in PEG with the sulfur atom in SO_2 are discussed. This shows that the spectral changes may be due to the formation of -CH_2CH_2O(H)…HOH… and -CH_2-CH_2-O(CH_2-CH_2-)…HOH… in PEGWs and the formation of -CH_2CH_2OH…OSO…, and intermolecular S…O interaction between PEG and SO_2 as the formation of -CH_2CH_2OCH_2CH_2O(H)…(O)S(O)… and -CH_2-CH_2-O(CH_2-CH_2-) …(O)S(O)…. The existence of these bonds benefits the absorption and desorption processes of SO_2 in PEGWs
[en] The design and metrological characteristics of a photometric gas analyzer for atmospheric sulfur dioxide that is equipped with adsorbing polymer films are considered. It is shown that the device can solve ecological and health safety issues and has small overall dimensions and power consumption.
[en] It is well known that natural and synthetic zeolites (molecular sieves) can adsorb gaseous SO2 from flue gas and do it more efficiently than lime based scrubbing materials. Unfortunately their cost ($500-$800 per ton) has deterred their use in this capacity. It is also known that zeolites are easy to synthesize from a variety of natural and man-made materials. The overall objective of the current work has been to evaluate the feasibility of having a utility synthesize its own zeolites, on-site, from fly ash and other recycled materials and then use these zeolites to adsorb SO2 from their flue gases. Work to date has shown that the efficiency of the capture process is related to the degree of crystallinity and the type of zeolite that forms in the samples. Normally, those samples cured at 150C contained a greater proportion of zeolite and as such were more SO2 adsorptive than their low-temperature counterparts. However, in order for the project to be successful, on site synthesis must remain an option, i.e. 100C synthesis. In light of this, the experimental focus now has two aspects. First, compositions of the starting materials are being altered by blending the current suite of fly ashes with other fly ashes, ground glass cullet and silica fume to promote the formation and growth of well crystallized and highly adsorptive zeolites. Second, greater degrees of reaction at significantly lower temperatures are being promote by ball milling the fly ash prior to use, by the use of more concentrated caustic solutions, and by the addition of zeolite seeds to the reactants. In all cases studies will focus on the effect of structure type and degree of conversion on SO2 adsorption. Future work will concentrate on the study of the effect of weathering on the suitability of converting fly ash into zeolites. This is an especially important study, considering the acres of fly ash now in storage throughout the country
[en] The 1990 US Clear Air Act mandated a 50 per cent reduction in SO2 emissions by 2010 and emphasized reliance on a market-based mechanism to achieve this goal. It outlined a two-phase emission reduction programme for electric utilities using fuels containing sulphur, estimated to account for 70 per cent of all SO2 emissions. Phase I, which comes into effect in 1995, covers 100 eastern and midwest coal-fired plants which will be issued annual allowances based on emission limits and their average historical fossil fuel consumption. Each allowance entitles the holder to emit one ton of SO2 during or after the year specified. At year end, each utility must hold sufficient allowances to cover its prior year emissions or face stringent penalties. The Chicago Board of Trade (CBoT) is licensed to operate cash, futures and options markets for these emission allowances. Its claim to be 'the world's first environmental exchange' rests also on its designation by the Environmental Protection Agency (EPA) to administer, on its behalf, annual auctions and direct sales of SO2 emission allowances. The first auction will take place this spring, with direct sales, intended primarily to accommodate new power plants, following shortly thereafter. (author)