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951.
952.
In this paper, a novel composite material the silica grafted by poly(N‐vinyl imidazole) (PVI), i.e., PVI/SiO2, was prepared using 3‐methacryloxypropyl trimethoxysilane (MPS) as intermedia through the “grafting from” method. The adsorption behavior of metal ions by PVI/SiO2 was researched by both static and dynamic methods. Experimental results showed that PVI/SiO2 possessed very strong adsorption ability for metal ions. For different metal ions, PVI/SiO2 exhibited different adsorption abilities with the following order of adsorption capacity: Cu2+ > Cd2+ > Zn2+. The adsorption material PVI/SiO2 was especially good at adsorbing Cu(II) ion and the saturated adsorption capacity could reach up to 49.2 mg/g. The empirical Freundlich isotherm was found to describe well the equilibrium adsorption data. Higher temperatures facilitated the adsorption process and thus increased the adsorption capacity. The pH and grafting amount of PVI had great influence on the adsorption amount. In addition, PVI/SiO2 particles had excellent eluting and regenerating property using diluted hydrochloric acid solution as eluent. The adsorption ability trended to steady during 10 cycles. 相似文献
953.
Ricardo Henrique Moreton Godoi Patricia Y. Hirata Andre V. L. Bitterncourt Ana F. L. Godoi Miguel Jafelicci Jr Francisco J. dos Santos Rafael Bini Liuz F. Zara Cynara L. N. Cunha Ana P. K Soares Eduardo F. Gobbi Sanja Potgieter‐Vermaak José E. F. C. Gardolinski José M. Reis Neto Giuliana Gatto Rotondo Rene van Grieken 《洁净——土壤、空气、水》2012,40(4):364-372
Suspended particles and dissolved substances in water provide reactive surfaces, influence metabolic activity and contribute to the net sediment deposition. It therefore plays an important part in the ecology and quality of the water mass. The water quality in reservoirs is crucial and it is naturally maintained by flushing and sedimentation, which continuously remove phosphorus from the water. In some reservoirs, however, these removal processes are countered by recycling of ions which could play a key role to start and/or maintain the eutrophic state. The combination of macro‐, trace‐ and microanalysis techniques can be useful to trace pollution sources through a chemical fingerprint, whether be during an acute environmental disaster or a long‐term release of pollutants. The water quality and total metal content of reservoir sediments were assessed in a reservoir, situated in the capital of the Paraná State, in the South‐Eastern part of Brazil. The goal of this paper was to determine the metal presence in the sediment and metal and ionic speciation in the Green River reservoir water. Water and bed sediment samples, collected from various sites during 2008 and 2009, were investigated using XRF, ICP‐OES, ICP‐MS, XRD and zeta potential measurements. Based on the results, the heavy metal concentration and chemical composition of the suspended matter in the water samples, as well as the sediment's chemical composition will be discussed. 相似文献
954.
This study aims to remove of Cu2+, Cd2+, and Pb2+ ions from solution and to investigate the adsorption isotherms, adsorption kinetics, and ion‐exchange affinities of these metals using waste activated sludge (AS) biomass. The adsorptions of the metals on biomass were optimal at an acidic pH value of 6.0 based on its monolayer capacities. Maximum monolayer capacities of AS biomass (qmax) were calculated as 0.478, 0.358, and 0.280 mmol g?1 for Cu2+, Cd2+, and Pb2+, respectively, and the adsorption equilibrium time was found as 60 min for each metal. The adsorbed amount of metal rose with increasing of initial metal ion concentration. The equilibrium adsorption capacity of AS for initial 0.25 mmol L?1 metal concentration was determined as 0.200, 0.167, and 0.155 mmol g?1 for Cu2+, Cd2+, and Pb2+ ions, respectively. These relevant values were determined as 0.420, 0.305, and 0.282 mmol g?1 for Cu2+, Cd2+, and Pb2+ ions, respectively, when initial metal concentration was 0.50 mmol L?1. In the multi‐metal sorption system, the adsorption capacity of AS biomass was observed in the order of Cu2+ > Cd2+ > Pb2+. In the presence of 100 mmol L?1 H+ ion, the order of ion‐exchange affinity with H+ was found as Cu2+ > Cd2+ > Pb2+. The adsorption kinetics were also found to be well described by the pseudo‐second‐order and intraparticle diffusion models. Two different rate constants were obtained as ki1 and ki2 and ki1 (first stage) was found to be higher than ki2 (second stage). 相似文献
955.
In this work the potential of live and active Phanerochaete chryosporium, a white rot fungi, to remove lower Cr(VI) concentration from aqueous solutions was reported for the first time. A medium pH had significant effect on the growth of the fungus and bioremoval of Cr(VI). Substrate inhibition on the growth of Phanerochaete chrysosporium was evident beyond 20 g L?1 of dextrose concentration. A maximum biomass concentration of 15.64 g L?1 was obtained for an initial dextrose concentration of 20 g L?1 in metal free medium at pH 6.0. An increase in Cr(VI) concentration beyond 10 mg L?1 inhibited the growth of the fungi, thereby, reducing the chromium bioremoval efficiency. A maximum reduction efficiency of 98.92% was reported for an initial metal concentration of 10 mg L?1. A mathematical expression for the bioreduction of Cr(VI) considering the organic compounds in the cells was proposed. 相似文献
956.
An assessment of water quality measurements during a spring flood in the Elbe River is presented. Daily samples were taken at a site in the middle Elbe, which is part of the network of the International Commission for the Protection of the Elbe River (IKSE/MKOL). Cluster analysis (CA), principal components analysis (PCA), and source apportionment (APCS apportioning) were used to assess the flood‐dependent matter transport. As a result, three main components could be extracted as important to the matter transport in the Elbe River basin during flood events: (i) re‐suspended contaminated sediments, which led to temporarily increased concentrations of suspended matter and of most of the investigated heavy metals; (ii) water discharge related concentrations of pedogenic dissolved organic matter (DOM) as well as preliminary diluted concentrations of uranium and chloride, parameters with stable pollution background in the river basin; and (iii) abandoned mines, i.e., their dewatering systems, with particular influence on nickel, manganese, and zinc concentrations. 相似文献
957.
Inductively coupled plasma atomic emission spectrometry and inductively coupled plasma MS are the major analytical tools for trace elements in environmental matrices, however, the underestimate of certain trace elements in analysis of air particulate matter by these two techniques has long been observed. This has been attributed to incomplete sample digestion. Here, we demonstrate that the combined effects of sample digestion, air filter impurities, and post‐adsorption of the analytes contribute to the interference of the analysis. Particular attention should be paid to post‐adsorption of analytes onto air filters after acid digestion. 相似文献
958.
Ahmed A. Abdelhafez Hassan H. Abbas Rafat S. Abd‐El‐Aal Nabil F. Kandil Jianhua Li Wahballah Mahmoud 《洁净——土壤、空气、水》2012,40(4):356-363
Excessive amounts of mineral fertilizers are unnecessarily applied to agricultural soils in Egypt to increase crop yield. The current study aims at assessing the impacts of fertilization with different mineral fertilizers for different cultivation periods on the accumulation of heavy metals in soils and plants grown thereon. In addition, human risks resulted due to the exposure to these metal ions through ingestion, and dermal routes were evaluated. Soil and plant samples were collected from several locations in El‐Behira Governorate, Egypt and their heavy metal contents were measured. The result indicated that there is a continuous accumulation of heavy metals in the soils and the plants grown thereon. Calculation of the hazard index (HI) revealed that humans, especially children, have a potential health risk for both Pb and Cd, which have levels greater than the safe level (1). Finally, the obtained results showed that the continuous application of mineral fertilizers containing high levels of heavy metals pose a potential health threat. 相似文献
959.
The variation of visibility at Great Wall Station (GWS) was analyzed using manual observational data for the period of 1986 to 2012. Results show that the frequencies of occurrence of high (≥ 10 km) and low visibility (0-1 km) are 61.0% and 8.0%, respectively. Visibility at GWS shows an evident seasonal variation: The highest visibility between November and March, and the lowest visibility from June to October. Sea fog and precipitation are the main factors for low visibility during summer, whereas frequent adverse weather, such as falling snow, blowing snow, or blizzards, are responsible for low visibility in winter. The frequency of occurrence of low visibility has decreased significantly from 1986 to 2012. Conversely, the frequency of occurrence of high visibility has shown a significant increasing trend, especially during winter. The decreasing tendencies of fog, blowing snow, and snowfall have contributed to the increasing trend of high visibility during winter. Visibility at GWS exhibits significant synoptic-scale (2.1 to 8.3 d), annual, and inter-annual periods (2 a, 4.1 a, and 6.9 a to 8.2 a), among which the most significant period is 4.1 a. The visibility observed during 2012 indicates that instrumental observation can be applied in the continuous monitoring of visibility at GWS. 相似文献
960.
卫星遥感资料在云南大雾监测中的应用 总被引:4,自引:2,他引:2
利用卫星遥感监测大雾具有及时、宏观的明显优势。图像纹理信息反映了图像的灰度性质及其空间关系。通过对雾的成因、辐射特性、雾遥感基本原理的阐述,结合中国FY-1D/美国NOAA系列极轨卫星资料通道特点,分析了雾的图像纹理信息,并依据雾在可见光波段和中红外波段与云类不同的光谱特性,选用光谱通道1、通道3、通道4组合进行大雾监测。实例分析结果表明这种监测方法能较好地分离无云地表、中高云和低层云雾,从而实现白天雾的监测。 相似文献