Currently, activated coke is widely used in the removal of multiple pollutants from industrial flue gas. In this paper, a series of novel FexLayOz/AC catalysts was prepared by the incipient wetness impregnation for NH3-SCR denitrification reaction. The introduction of Fe-La bimetal oxides significantly improved the denitrification performance of activated coke at mid-high temperature, and 4% Fe0.3La0.7O1.5/AC exhibited a superior NOx conversion efficiency of 90.1% at 400 °C. The catalysts were further characterized by BET, SEM, XRD, Raman, EPR, XPS, FTIR, NH3-TPD, H2-TPR, et al., whose results showed that the perovskite-type oxide of LaFeO3 and oxygen vacancies were produced on the catalysts’ surfaces during roasting. Fe-La doping enhanced the amount of acid sites (mainly Lewis and other stronger acid sites) and the content of multifarious oxygen species, which were beneficial for NOx removal at mid-high temperature. Moreover, it was investigated that the effect of released CO from activated coke at mid-high temperature on the NOx removal through the lifetime test, in which it was found that a large amount of CO produced by pyrolysis of activated coke could promote the NOx removal, and long-term escaping of CO on the activated coke carrier did not have a significant negative impact on catalytic performance. The results of the TG-IR test showed that volatile matter is released from the activated coke while TG results showed that the weight loss rate of 4% Fe0.3La0.7O1.5/AC only was 0.0015~0.007%/min at 300–400 °C. Hence, 4% Fe0.3La0.7O1.5/AC had excellent thermal stability and denitrification performance to be continuously used at mid-high temperature. Finally, the mechanisms were proposed on the basis of experiments and characterization results.
Environmental Science and Pollution Research - Fetal growth has been demonstrated to be an important predictor of perinatal and postnatal health. Although the effects of maternal exposure to air... 相似文献
A solid-phase microextration-based sampling method was employed to determine the concentrations of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and its metabolites, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD), 1,1-dichloro-2,2-bis(p-chlorophenyl)ethene (DDE) and 1-chloro-2,2-bis(p-chlorophenyl)ethene (DDMU), in two estuarine bays, Daya Bay and Hailing Bay, of South China. Six DDT components including p,p′-DDT, o,p′-DDD, p,p′-DDD, o,p′-DDE, p,p′-DDE, and p,p′-DDMU were detected in Hailing Bay, while only p,p′-DDD was found in Daya Bay. p,p′-DDD was the most abundant DDT component in both bays, sharply different from the previous finding in the water column of the Palos Verdes Shelf, California, USA that p,p′-DDE was prevalent. In addition, the occurrence of p,p′-DDMU (with a range of 0.047-0.21 ng/L in Hailing Bay) has not been reported around the globe, and its presence in our study region appeared to stem from dehydrochlorination of p,p′-DDD, favored under aerobic conditions, but further investigations are clearly needed to confirm the mechanism for generation of DDMU in estuarine environments. 相似文献
Background, aim, and scope Pharmaceuticals and personal care products (PPCPs) including antibiotics, endocrine-disrupting chemicals, and veterinary pharmaceuticals
are emerging pollutants, and their environmental risk was not emphasized until a decade ago. These compounds have been reported
to cause adverse impacts on wildlife and human. However, compared to the studies on hydrophobic organic contaminants (HOCs)
whose sorption characteristics is reviewed in Part IV of this review series, information on PPCPs is very limited. Thus, a
summary of recent research progress on PPCP sorption in soils or sediments is necessary to clarify research requirements and
directions.
Main features We reviewed the research progress on PPCP sorption in soils or sediments highlighting PPCP sorption different from that of
HOCs. Special function of humic substances (HSs) on PPCP behavior is summarized according to several features of PPCP–soil
or sediment interaction. In addition, we discussed the behavior of xenobiotic chemicals in a three-phase system (dissolved
organic matter (DOM)–mineral–water). The complexity of three-phase systems was also discussed.
Results Nonideal sorption of PPCPs in soils or sediments is generally reported, and PPCP sorption behavior is relatively a more complicated
process compared to HOC sorption, such as the contribution of inorganic fractions, fast degradation and metabolite sorption,
and species-specific sorption mechanism. Thus, mechanistic studies are urgently needed for a better understanding of their
environmental risk and for pollution control.
Discussion Recent research progress on nonideal sorption has not been incorporated into fate modeling of xenobiotic chemicals. A major
reason is the complexity of the three-phase system. First of all, lack of knowledge in describing DOM fractionation after
adsorption by mineral particles is one of the major restrictions for an accurate prediction of xenobiotic chemical behavior
in the presence of DOM. Secondly, no explicit mathematical relationship between HS chemical–physical properties, and their
sorption characteristics has been proposed. Last but not least, nonlinear interactions could exponentially increase the complexity
and uncertainties of environmental fate models for xenobiotics. Discussion on proper simplification of fate modeling in the
framework of nonlinear interactions is still unavailable.
Conclusions Although the methodologies and concepts for studying HOC environmental fate could be adopted for PPCP study, their differences
should be highly understood. Prediction of PPCP environmental behavior needs to combine contributions from various fractions
of soils or sediments and the sorption of their metabolites and different species.
Recommendations and perspectives More detailed studies on PPCP sorption in separated soil or sediment fractions are needed in order to propose a model predicting
PPCP sorption in soils or sediments based on soil or sediment properties. The information on sorption of PPCP metabolites
and species and the competition between them is still not enough to be incorporated into any predictive models. 相似文献
In this paper, we report the results and analysis of a recent field campaign in August 2007 investigating the impacts of emissions from transportation on air quality and community concentrations in Beijing, China. We conducted measurements in three different environments, on-road, roadside and ambient. The carbon monoxide, black carbon and ultrafine particle number emission factors for on-road light-duty vehicles are derived to be 95 g kg?1-fuel, 0.3 g kg?1-fuel and 1.8 × 1015 particles kg?1-fuel, respectively. The emission factors for on-road heavy-duty vehicles are 50 g kg?1-fuel, 1.3 g kg?1-fuel and 1.1 × 1016 particles kg?1-fuel, respectively. The carbon monoxide emission factors from this study agree with those derived from remote sensing and on-board vehicle emission testing systems in China. The on-road black carbon and particle number emission factors for Chinese vehicles are reported for the first time in the literature. Strong traffic impacts can be observed from the concentrations measured in these different environments. Most clear is a reflection of diesel truck traffic activity in black carbon concentrations. The comparison of the particle size distributions measured at the three environments suggests that the traffic is a major source of ultrafine particles. A four-day traffic control experiment conducted by the Beijing Government as a pilot to test the effectiveness of proposed controls was found to be effective in reducing extreme concentrations that occurred at both on-road and ambient environments. 相似文献
Based on analysis of groundwater hydrochemical and isotopic indicators, this article aims to identify the groundwater flow
systems in the Yangwu River alluvial fan, in the Xinzhou Basin, China. Groundwater δ2H and δ18O values indicate that the origin of groundwater is mainly from precipitation, with local evaporative influence. d-excess values lower than 10% in most groundwaters suggest a cold climate during recharge in the area. Major ion chemistry,
including rCa/rMg and rNa/rCl ratios, show that groundwater salinization is probably dominated by water–rock interaction (e.g.,
silicate mineral weathering, dissolution of calcite and dolomite and cation exchange) in the Yangwu River alluvial fan, and
locally by intensive evapotranspiration in the Hutuo River valley. Cl and Sr concentrations follow an increasing trend in
shallow groundwater affected by evaporation, and a decreasing trend in deep groundwater. 87Sr/86Sr ratios reflect the variety of lithologies encountered during throughflow. The groundwater flow systems (GFS) of the Yangwu
River alluvial fan include local and intermediate flow systems. Hydrogeochemical modeling results, simulated using PHREEQC,
reveal water–rock interaction processes along different flow paths. This modeling method is more effective for characterizing
flow paths in the intermediate system than in the local system. Artificial exploitation on groundwater in the alluvial fan
enhances mixing between different groundwater flow systems. 相似文献
At a former wood preservation plant severely contaminated with coal tar oil, in situ bulk attenuation and biodegradation rate constants for several monoaromatic (BTEX) and polyaromatic hydrocarbons (PAH) were determined using (1) classical first order decay models, (2) Michaelis–Menten degradation kinetics (MM), and (3) stable carbon isotopes, for o-xylene and naphthalene. The first order bulk attenuation rate constant for o-xylene was calculated to be 0.0025 d− 1 and a novel stable isotope-based first order model, which also accounted for the respective redox conditions, resulted in a slightly smaller biodegradation rate constant of 0.0019 d− 1. Based on MM-kinetics, the o-xylene concentration decreased with a maximum rate of kmax = 0.1 µg/L/d. The bulk attenuation rate constant of naphthalene retrieved from the classical first order decay model was 0.0038 d− 1. The stable isotope-based biodegradation rate constant of 0.0027 d− 1 was smaller in the reduced zone, while residual naphthalene in the oxic part of the plume further downgradient was degraded at a higher rate of 0.0038 d− 1. With MM-kinetics a maximum degradation rate of kmax = 12 µg/L/d was determined. Although best fits were obtained by MM-kinetics, we consider the carbon stable isotope-based approach more appropriate as it is specific for biodegradation (not overall attenuation) and at the same time accounts for the dominant electron-accepting process. For o-xylene a field based isotope enrichment factor εfield of − 1.4 could be determined using the Rayleigh model, which closely matched values from laboratory studies of o-xylene degradation under sulfate-reducing conditions. 相似文献