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91.
92.
The influence of SO2 on the performance of Ag-Pd/Al2O3 for the selective catalytic reduction (SCR) of NOx with C2H5OH was investigated experimentally. The activity test results suggest that Ag-Pd/Al2O3 shows a small activity loss in the presence of SO2 when using C2H5OH as a reductant. In situ DRIFTS spectra show that the activity loss originates from the formation of surface sulphate species on the Ag-Pd/Al2O3. The surface sulphate species formation inhibits the formation of nitrate, whereas hardly changes the partial oxidation of C2H5OH. Compared with the NOx reduction by C3H6, an obvious suppression of the surface sulphate species formation was observed by DRIFTS experiment when using C2H5OH as a reductant. This phenomenon reveals the better catalytic performance and strong SO2 tolerance of Ag-Pd/Al2O3-C2H50H system. 相似文献
93.
离子色谱法测定水中无机阴离子水样的预处理 总被引:2,自引:0,他引:2
本文介绍了用离子色谱法测定无机阴离子,对污染严重的水样通常采用预处理柱法。论述了预处理柱的制备、再生,测定了预处理柱对重金属及有机物的去除率及无机阴离子的回收率。 相似文献
94.
95.
以聚硫酸铁(PFS)为絮凝剂,考察强化混凝去除饮用水源水中五价锑(Sb(V))时原水pH值、PFS投量、共存阴离子(HCO3-和PO43-)及腐殖酸(HA)等对其去除效果影响及作用机制.结果表明,原水pH值对强化混凝过程Sb(V)存在形态及PFS的水解产物有重要影响,表现为较低pH值和较高PFS投量均有利于提高Sb(V)的去除率;由于竞争吸附作用的存在,共存阴离子与HA均对Sb(V)的混凝去除产生负面效应.此外, PFS除Sb(V)过程较为符合准二级动力学模型. 相似文献
96.
阐述了氨法烟气脱硫技术的原理和工艺特点.介绍了Walther氨法、AMASOX氨法、GE氨法、NADS氨-肥法、电子束氨法和流光放电氨法烟气脱硫工艺,重点介绍了新型流光放电氨法烟气脱硫技术的特点及其工程应用情况.展望了氨法烟气脱硫技术的应用前景. 相似文献
97.
98.
Howard D. Passell Clifford N. Dahm Edward J. Bedrick 《Journal of the American Water Resources Association》2004,40(1):111-127
ABSTRACT: Hydrological and geochemical spatial patterns and temporal trends were analyzed using U.S. Geological Survey (USGS) water quality data collected from 1975 to 1999 along the uppermost 600 km of the Rio Grande in Colorado and New Mexico. Data on discharge, specific conductivity (SC), total dissolved solids (TDS), pH, Ca2+, Na+, Mg2+, K+, HCO3?, SO42‐, Cl?, F?, and SiO2 came from six USGS stations ranging from the Colorado‐New Mexico border to below Albuquerque, New Mexico. Linear regression, Kendall's S, and Seasonal Kendall's S’ were used to detect trends, and ANOVA was used to analyze spatial differences between stations. Statistically significant increasing trends occurred in SC, TDS, Ca2+, Na+, Mg2+, K+, Cl?, and F?in the uppermost reaches, and significant decreasing trends of SC, TDS, Ca2+, Mg2+, K+, HCO3?, and SO42‐occurred at the lower stations around Albuquerque. Both fluoride concentrations and pH values increased at and below Albuquerque over the study period. Discharge data show an increasing trend across all stations. Spatially, data for dissolved substances show generally linear upstream to downstream increases in concentrations in the upper four stations, with several notable nonlinear increases at and below Albuquerque (SC, TDS, Na+, Cl?). Significant increases in pH appear at and below Albuquerque, relative to upstream stations, probably due to improved sewage treatment. 相似文献
99.
Within the European monitoring network (EMEP, ) several different sampling procedures for measuring the main air components have been applied. This has contributed to systematic
concentration differences and a comparability problem. Since 1997 co-located experiments in 15 countries have been carried
out to quantify these differences. In addition, three major measurement campaigns were organized by EMEP between 1985 and
1991. Differences among results depend on the concentration level and methods used. The decrease in SO2 concentrations over the last twenty years has placed greater demands on the methodology. Absorbing solutions methods for
SO2, (H2O2 and tetrachloromercurate (TCM)) typically have higher detection limits than the reference method, which uses KOH impregnated
filters. The TCM method also has problems with negative interference, especially in summertime. UV fluorescence monitors have
in a few cases proven to give good results, but interferences, detection limit and poor maintenance can be problems. For NO2, many countries are using the TGS absorption solution method, which has a higher detection limit than the reference method
using NaI impregnated glass sinters. The Salzmann method gives unreliable results at concentrations below 1 μgN/m3, and even at higher concentrations the uncertainty is rather unsatisfactory. The chemiluminescence monitor with molybdenum
converters tends to systematically overestimate NO2 concentrations, possibly because zero-drift problems and the non-specific response to NO2. Particulate sulphate measurements in general have lower bias and uncertainties than gas and other aerosol measurements. 相似文献
100.
Effects of maize root exudates and organic acids on the desorption of
phenanthrene from soils 总被引:2,自引:0,他引:2
The effects of maize root exudates and low-molecular-weight-organic anions (LMWOAs) on the desorption of phenanthrene from eight artificially contaminated soils were evaluated. A significant negative correlation was observed between the amounts of phenanthrene desorbed and the soil organic carbon (SOC) contents (P<0.01), and the influences of soil pH and clay content on phenanthrene desorption were insignificant (P>0.1). Neither maize root exudates nor oxalate and citrate anions influenced desorption of phenanthrene with the addition of NAN3. A faster phenanthrene desorption occurred without the addition of NaN3 in the presence of maize root exudates than oxalate or citrate due to the enhanced degradation by root exudates. Without the addition of NaN3, oxalate or citrate at different concentrations could inhibit phenanthrene desorption to different extents and the inhibiting effect by citrate was more significant than by oxalate. This study leads to the conclusion that maize root exudates can not enhance the desorption under abiotic condition with the addition of NaN3 and can promote the desorption of phenanthrene in soils without the addition of NAN3. 相似文献