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761.
Lignin-based Carbon Fibers: Effect of Synthetic Polymer Blending on Fiber Properties 总被引:2,自引:0,他引:2
Carbon fibers have been produced from hardwood lignin/synthetic polymer blend fibers. Hardwood kraft lignin was thermally blended with two recyclable polymers, poly(ethylene terephthalate) (PET) and polypropylene (PP). Both systems were easily spun into fibers. A thermostabilization step was utilized prior to carbonization to prevent fusion of individual fibers. For the lignin-based carbon fibers, careful control of heating rate was required. However, PET–lignin blend fibers can be thermostabilized under higher heating rates than the corresponding homofibers. Carbon fiber yield decreased with increasing incorporation of synthetic plastic. However, carbon fiber yield obtained for a 25% plastic blend fiber was still higher than that generally reported for petroleum pitch. Blend composition also affected surface morphology of the carbon fibers. Immiscible lignin–PP fibers resulted in a hollow and/or porous carbon fiber; whereas carbon fiber produced from miscible lignin–PET fibers have a smooth surface. Synthetic polymer blending also affected the mechanical properties of the fibers, especially MOE; lignin-based carbon fiber properties improved upon blending with PET. 相似文献
762.
Abdul-Wahab SA 《Environmental management》2004,34(3):372-382
The CAL3QHC model was used to predict carbon monoxide (CO) concentrations from motor vehicles at an existing urban intersection (Star Cinema in Muscat area, Oman). The CO concentrations predicted from the model were compared with those measured in the field. Predicted average CO concentrations were found to compare favorably with measured values obtained at all eight receptors considered within the modeled intersection. In general, the comparison indicates good agreement with some underprediction for CO. For receptor 6, the model overpredicts the average CO concentration. This overprediction is associated with the presence of trees and green area in the location of receptor 6. In general, the measurements and the model results indicated that the highest CO concentrations were found to occur close to the intersection and, hence, a decrease in the concentration levels was seen as the distance from the road increased. The results indicated that the levels of CO were well below the ambient air quality standard and that probably no health risk was present in areas adjacent to the star cinema intersection. However, the predicted worst-case 1-h CO concentrations assuming inversion atmospheric stability conditions (class F) and wind speed of 1 m/s indicated that the levels of CO were close to or higher than the Omans National Ambient Air Quality Standards (NAAQS) value of 35 ppm at all receptors considered. The results of this study are useful in transport development and traffic management planning.Published online. 相似文献
763.
Cushman RM 《Environmental management》2003,31(2):0292-0300
In addition to national inventories of emissions of greenhouse gases, there are inventories for most, but not all, states
constituting the United States. This paper analyzes the state inventories to see if reported emissions of carbon dioxide,
methane, and nitrous oxide are additive. Considerable reanalysis of the state inventories is required before they can be added
to yield a larger-scale inventory. Some specific sources were considered by some states but not by others. Estimation techniques
evolved over time as inventories were produced, and there are instances of both double-counting (two states reporting the
same emission) and omission (neither state reporting the same emission), where interstate transfers of energy or materials
occurred. Nevertheless, the inventories, when adjusted for obvious double-counting or omissions, are probably approximately
additive, although it is difficult to quantify the extent to which this is true. 相似文献
764.
Jerry C. Ritchie 《Journal of the American Water Resources Association》1989,25(2):301-308
ABSTRACT: Carbon content was measured in sediments deposited in 58 small reservoirs across the United States. Reservoirs varied from 0.2 to 4000 km2 in surface area. The carbon content of sediment ranged from 0.3 to 5.6 percent, with a mean of 1.9 ± 1.1 percent. No significant differences between the soil and sediment carbon content were found using a paired t-test or ANOVA. The carbon content of sediments in reservoirs was similar to the carbon content of surface soils (0–10 cm) in the watershed, except in watersheds with shrub or steppe (desert) vegetation. Based on the sediment accumulation rates measured in each reservoir, the calculated organic carbon accumulation rates among reservoirs ranged from 26 to 3700 gC m-2yr-1, with a mean of 675 ± 739 gC m-2yr-1. The carbon content and accumulation rates were highest in sediments from grassland watersheds. High variability was found in carbon content, carbon accumulation, and sediment accumulation rates due to individual watershed and reservoir characteristics rather than to any broad physiographic patterns. The carbon accumulation rates in these reservoir sediments indicate that reservoir sediments could be a significant sink for organic carbon. 相似文献
765.
Anna Korre Ji Quan Shi Claire Imrie Carlos Grattoni Sevket Durucan 《International Journal of Greenhouse Gas Control》2007,1(4):492-501
Laboratory studies and a number of field pilots have demonstrated that CO2 injection into coal seams has the potential to enhance coalbed methane (CBM) recovery with the added advantage that most of the injected CO2 can be stored permanently in coal. The concept of storing CO2 in geologic formations as a safe and effective greenhouse gas mitigation option requires public and regulatory acceptance. In this context it is important to develop a good understanding of the reservoir performance, uncertainties and the risks that are associated with geological storage. The paper presented refers to the sources of uncertainty involved in CO2 storage performance assessment in coalbed methane reservoirs and demonstrates their significance using extensive digital well log data representing the Manville coals in Alberta, Canada. The spatial variability of the reservoir properties was captured through geostatistical analysis, and sequential Gaussian simulations of these provided multiple realisations for the reservoir simulator inputs. A number of CO2 injection scenarios with variable matrix swelling coefficients were evaluated using a 2D reservoir model and spatially distributed realisations of total net thickness and permeability. 相似文献
766.
Nadja Müller T.S. Ramakrishnan Austin Boyd Shinichi Sakruai 《International Journal of Greenhouse Gas Control》2007,1(4):456-472
Elevated levels of CO2 in the atmosphere have been linked to the rise in land and sea temperature [Climate Change, 2001. In: Houghton, J.T., Ding, Y., Griggs, D.J., Noguer, M., van der Linden, P.J., Xiaosu, D. (Eds.), The Scientific Basis Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). Cambridge University Press, UK, p. 944]. To demonstrate geological carbon sequestration as a mitigation technique, a carbon dioxide injection experiment was conducted in East Texas. The target – Frio formation – is a highly porous, permeable and unconsolidated sandstone. The specific interval is the Frio C sand, which originally was saturated with saline formation water. At the injection location, the Frio C sand dips 18° to the south. To monitor the injected CO2 spreading in the formation, an old well from 1956 drilled into the deeper Yegua formation was selected as the observation well. The injection well was drilled at a distance of 100 ft downdip from the monitoring well. Several borehole measurement methods were available to monitor the CO2 injection, but the most suitable technology was thought to be the pulsed neutron logging. This logging is used widely in cased hole, and the measured macroscopic thermal absorption cross-section (Σ) is sensitive to CO2 saturation in high porosity saline water environments. Several log examples are given demonstrating successful the monitoring of the CO2 plume moving through the two boreholes and the resulting saturation changes. 相似文献
767.
再生水资源是水资源的一种特殊形式,它的价格是影响污水回用的重要因素之一。再生水价格有多种形式,其中甲醇的投加是一笔不小的成本。以污水处理厂二级出水为水源进行深度处理以实现污水资源化的过程中,存在着总氮含量高、有机物含量低的水质特点。再生水处理中反硝化阶段需要有机物,也就是碳源。碳源影响脱氮效果,投加甲醇为外碳源可以促进反硝化水平。 相似文献
768.
通过分析2002~2011年间陕西省建设用地和碳排放的变化,基于LMDI模型分解方法,探讨了10年间建设用地变化对碳排放增长的影响。结果表明:研究时序内,陕西省建设用地和碳排放量均呈增长态势,建设用地年扩展率1.25%,碳排放年均增长8.84%,建设用地变化与碳排放量正向效应显著,建设用地对碳排放的贡献度为12.36%,对建设用地采取总量控制原则,能有效控制碳排放量,对陕西省实现"十二五"期间碳减排目标具有重大意义。 相似文献
769.
770.
Laura Domingo Stephen T. Grimes M. Soledad Domingo M. Teresa Alberdi 《Die Naturwissenschaften》2009,96(4):503-511
Expansion of C4 grasses during Late Miocene and Early Pliocene constitutes one of the most remarkable biotic events of the Cenozoic era.
The Teruel–Alfambra region (northeastern Spain) contains one of the most complete Miocene–Pliocene sequences of mammalian
fossil sites in the world. In this study, stable isotope (δ
13C and δ
18O) analyses have been performed on the tooth enamel from the equid Hipparion from 19 localities spanning a time interval from approximately 10.9 to 2.7 Ma. This time range starts with the first appearance
of this genus in Spain and ends at its extinction. An increase in δ
13C at about 4.2 Ma has been observed, indicative of a shift toward a more open habitat. This shift may be related to a large
scale vegetation change which occurred across the Miocene–Pliocene boundary when C4 grasses expanded. This expansion might in turn be linked to global tectonic events such as the uplift of the Himalaya and/or
the closure of the Panama Isthmus. However, other more regional factors may have ultimately enhanced the trend toward more
open habitats in the Western Mediterranean Basin. The Messinian Salinity Crisis was a major environmental event that may have
been responsible for the isotopic changes seen in the equid Hipparion from the Iberian Peninsula along with an increase in the aridity detected ~4.6 Ma ago in the Sahara. Even though the exact
factor triggering the isotopic change observed in the Hipparion enamel remains mostly unknown, this study demonstrates that the global environmental changes detected across the Miocene–Pliocene
boundary are also recorded in the realm of the Iberian Peninsula.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献