Cu-Co multiple-oxides modified on HNO3-pretreated activated coke (ACN) were optimized for the simultaneous removal of gaseous CO and elemental mercury (Hg0) at low temperature (< 200 °C). It was found that 2%CuOx-10%CoOx/ACN catalyst calcined at 400°C resulted in the coexistence of complex oxides including CuO, Cu2O, Co3O4, Co2O3 and CoO phases, which might be good for the simultaneous catalytic oxidation of CO by Co-species and removal of Hg0 by Cu-species, benefiting from the synergistic catalysis during the electro-interaction between Co and Cu cations (CoO ? Co3O4 and Cu2O ? CuO). The catalysis removal of CO oxidation was obviously depended on the reaction temperature obtaining 94.7% at 200 °C, while no obvious promoting effect on the Hg0 removal (68.3%-78.7%). These materials were very substitute for the removal of CO and Hg° from the flue gas with the conditions of 8–20 vol.% O2 and flue-gas temperature below 200 °C. The removal of Hg° followed the combination processes of adsorption and catalytic oxidation reaction via Langmuir-Hinshelwood mechanism, while the catalysis of CO abided by the Mars-van Krevelen mechanism with lattice oxygen species. 相似文献
In situ and simultaneous remediation of a variety of pollutants in sediments remains a challenge. In this study, we report that the combination of electrocoagulation (EC) and electrooxidation (EO) is efficient in the immobilization of phosphorus and heavy metals and in the oxidation of ammonium and toxic organic matter. The integrated mixed metal oxide (MMO)/Fe anode system allowed the facile removal of ammonium and phosphorus in the overlying water (99% of 10 mg/L NH4+-N and 95% of 10 mg/L P disappeared in 15 and 30 min, respectively). Compared with the controls of the single Fe anode and single MMO anode systems, the dual MMO/Fe anode system significantly improved the removal of phenanthrene and promoted the transition of Pb and Cu from the mobile species to the immobile species. The concentrations of Pb and Cu in the toxicity characteristic leaching procedure extracts were reduced by 99% and 97% after an 8 hr operation. Further tests with four real polluted samples indicated that substantial proportions of acid-soluble fraction Pb and Cu were reduced (30%–31% for Pb and 16%–23% for Cu), and the amounts of total organic carbon and NH4+-N decreased by 56%–71% and 32%–63%, respectively. It was proposed that the in situ electrogenerated Fe(II) at the Fe anode and the active oxygen/chlorine species at the MMO anode are conducive to outstanding performance in the co-treatment of multiple pollutants. The results suggest that the EC/EO method is a powerful technology for the in situ remediation of sediments contaminated with different pollutants. 相似文献
Heavy metals are considered toxic to humans and ecosystems. In the present study, heavy metal concentration in soil was investigated using the single pollution index (PIi), the integrated Nemerow pollution index (PIN), and the geoaccumulation index (Igeo) to determine metal accumulation and its pollution status at the abandoned site of the Capital Iron and Steel Factory in Beijing and its surrounding area. Multivariate statistical (principal component analysis and correlation analysis), geostatistical analysis (ArcGIS tool), combined with stable Pb isotopic ratios, were applied to explore the characteristics of heavy metal pollution and the possible sources of pollutants. The results indicated that heavy metal elements show different degrees of accumulation in the study area, the observed trend of the enrichment factors, and the geoaccumulation index was Hg > Cd > Zn > Cr > Pb > Cu ≈ As > Ni. Hg, Cd, Zn, and Cr were the dominant elements that influenced soil quality in the study area. The Nemerow index method indicated that all of the heavy metals caused serious pollution except Ni. Multivariate statistical analysis indicated that Cd, Zn, Cu, and Pb show obvious correlation and have higher loads on the same principal component, suggesting that they had the same sources, which are related to industrial activities and vehicle emissions. The spatial distribution maps based on ordinary kriging showed that high concentrations of heavy metals were located in the local factory area and in the southeast-northwest part of the study region, corresponding with the predominant wind directions. Analyses of lead isotopes confirmed that Pb in the study soils is predominantly derived from three Pb sources: dust generated during steel production, coal combustion, and the natural background. Moreover, the ternary mixture model based on lead isotope analysis indicates that lead in the study soils originates mainly from anthropogenic sources, which contribute much more than the natural sources. Our study could not only reveal the overall situation of heavy metal contamination, but also identify the specific pollution sources.
Environmental Science and Pollution Research - The concentration characteristics, sources, and potential ecological risk assessment of 16 PAHs were investigated in the surface water from the... 相似文献
In this report, we refer to pharmaceuticals that are widespread in the urban aquatic environment and that mainly originate from wastewater treatment plants or non-point source sewage as “wastewater-marking pharmaceuticals” (WWMPs). To some extent, they reflect the condition or trend of water contamination and also contribute to aquatic environmental risk assessment. The method reported here for screening typical WWMPs was proposed based on academic concerns about them and their concentrations present in the urban aquatic environment, as well as their properties of accumulation, persistence, eco-toxicity and related environmental risks caused by them. The screening system consisted of an initial screening system and a further screening system. In the former, pharmaceuticals were categorised into different evaluation levels, and in the latter, each pharmaceutical was given a normalised final evaluation score, which was the sum of every score for its properties of accumulation, persistence, eco-toxicity and environmental risk in the aquatic environment. The system was applied to 126 pharmaceuticals frequently detected in the aquatic environment. In the initial screening procedure, five pharmaceuticals were classified into the “high” category, 16 pharmaceuticals into the “medium” category, 15 pharmaceuticals into the “low” category and 90 pharmaceuticals into the “very low” category. Subsequently, further screening were conducted on 36 pharmaceuticals considered as being of “high”, “medium” and “low” categories in the former system. We identified 7 pharmaceuticals with final evaluation scores of 1–10, 10 pharmaceuticals with scores of 11–15, 15 pharmaceuticals with scores from 16 to 20 and 4 pharmaceuticals with scores above 21. The results showed that this screening system could contribute to the effective selection of target WWMPs, which would be important for spatial-temporal dynamics, transference and pollution control of pharmaceuticals in the urban aquatic environment. However, there remains a number of pharmaceutical parameters with measured data gaps, such as organic carbon adsorption coefficients and bioconcentration factors, which, if filled, would improve the accuracy of the screening system. 相似文献
为研究南京地区昼夜大气PM2.5中的硫同位素组成情况,采用Delta V Advantage同位素质谱仪技术对2016年3-4月南京北郊地区大气PM2.5中昼夜δ34S(硫同位素值)进行分析,结合大气颗粒物化学组成,追溯昼夜大气PM2.5及SO42-的来源.结果表明:南京北郊地区PM2.5和SO42-的整体变化趋势一致,具有同源性.南京北郊地区白天大气PM2.5的δ34S范围为4.23‰~7.16‰,平均值为5.45‰±0.91‰;晚上δ34S的范围为4.20‰~6.73‰,平均值为5.22‰±0.83‰.相较于晚上,白天δ34S略高主要与NOx对SO2的异相氧化反应和机动车尾气的排放有关.重霾天δ34S范围为4.20‰~7.16‰,平均值为5.39‰±0.87‰;清洁天δ34S范围为3.14‰~5.14‰,平均值为4.03‰±0.57‰.重霾天的硫源与燃煤、机动车尾气排放及NOx对SO2的异相氧化反应有关;而清洁天主要受到机动车尾气排放及SO2与O3均相氧化反应的影响.研究显示,南京北郊地区ρ(PM2.5)昼大于夜,而ρ(SO42-)夜大于昼,重霾天大气PM2.5的δ34S高于清洁天,这主要与NOx、SO2、O3的相互转化有关. 相似文献