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排序方式: 共有173条查询结果,搜索用时 171 毫秒
61.
G. Rangel-Porras J.B. García-Magno M.P. González-Muñoz J. A. Reyes-Aguilera 《Chemistry and Ecology》2014,30(4):350-363
Anthropogenic activities induce changes in a series of soil features. For example, continuous contact between soil and municipal solid waste leachates can encourage weathering processes as well as other mineral transformation reactions; consequently, the soil loses the function of environmental protection. Pollution-induced changes in the surface properties and morphology of soils have been rarely studied. In this work, the surface characteristics of calcareous soil located at a municipal solid waste disposal site in central Mexico were studied. Soil characterisation was carried out to determine the mesoporous size, particle surface area and crystallinity of collected samples. Comparison of these characteristics was made between soil in continuous contact with leachate flow and soil not in contact with leachate. The characterisation was carried out using X-ray diffraction, thermal analysis and nitrogen adsorption at 77 K. The presence of Pb, Cd, Zn, Ni and Cr was examined in both soils. Leachates in contact with this soil showed characteristics typical of liquid produced by the decomposition of municipal solid waste (pH, dissolved oxygen, redox potential and alkalinity). 相似文献
62.
Lazar M. Kaluđerović Zorica P. Tomić Rada D. Đurović-Pejčev Predrag J. Vulić Darko P. Ašanin 《Journal of environmental science and health. Part. B》2017,52(5):291-297
This study was undertaken to determine the impact of the organic complex concentration on the adsorption of herbicide (acetochlor) at the surface of the organic modified montmorillonite. In this work, natural montmorillonite from Bogovina (Boljevac municipality, Serbia) was used for organic modification. Cation-exchange capacity of this montmorillonite was determined using a methylene blue method (86 mmol/100 g of clay). Montmorillonite has been modified first with NaCl and then with hexadecyltrimethylammonium bromide (HDTMA-bromide) organic complex. Saturation of cation exchange capacity (CEC) was 50%, 100%, and 150%. Changes in the properties of the inorganic and organic montmorillonite have been examined using the X-ray diffraction, Fourier transform infrared spectroscopy, and batch equilibrium method. Montmorillonite modified with HDTMA-bromide demonstrated higher uptake of the herbicide, compared to the inorganic montmorillonite. Comparing the values Freundlich coefficients in batch equilibrium method, it can be seen that the adsorption of acetochlor decreased in the series: 0.5 CEC HM > 1 CEC HM > 1.5 CEC HM > NaM. 相似文献
63.
由于目前对炭基脱硫剂的活性吸附位缺乏一致认识,采用傅立叶红外光谱和X射线衍射技术研究了活性焦脱除烟气中SO2的活性位。结果表明:SO2在非载铜活性焦上的活性吸附位有C-O官能团、苯基与不饱和基团。而载铜活性焦除此3种活性位外,铜的存在可能促进C=O发生还原转化为C-O而增强其活性,并作为一种活性位参与脱硫反应形成硫酸铜。 相似文献
64.
焚烧飞灰预处理工艺及其无机氯盐的行为研究 总被引:1,自引:1,他引:1
研究表明WCCB(水洗+烧结)预处理工艺能更高效更节能地去除飞灰中的氯化物,以利于其作为水泥原料的使用.水洗工艺条件为两次水洗、水固比均为3∶1,搅拌速度均为150 r.min-1,第一次水洗时间5 min,第二次水洗时间10 min;利用原焚烧炉进行烧结处理,温度为1 000℃,10%氧气含量,停留时间1 h.本研究尝试了3种焚烧飞灰:节煤器出来的飞灰、石灰干法中和酸性气体后布袋收集的飞灰、NaHCO3中和酸性气体后布袋收集的飞灰.经该工艺处理后,焚烧飞灰残渣量减少20%以上,氯减少94%以上,尤以NaHCO3中和得到的飞灰削减量为最,分别达到了72.1%和99.8%.采用同步辐射的X射线吸收近边精细结构(X-ray absorption near edge structure,XANES)和普通X射线衍射(X-ray Diffraction,XRD)相结合的方法研究分析无机氯盐在工艺过程中的行为,发现焚烧飞灰中主要的氯盐主要有NaCl、KCl和CaCl2.焚烧炉烟气净化系统的酸中和剂会影响无机氯盐的生成.焚烧飞灰中难溶性无机氯盐的结构与Friedel’s盐相似,并且与CaCl2有关系. 相似文献
65.
The fate of pharmaceuticals in surface waters under solar irradiation was investigated. Photodegradation of pharmaceuticals caused by sun irradiation may be of major significance in the natural elimination process. Based on a data compilation from the literature, the lipid lowering agent metabolite clofibric acid, the iodinated X-ray contrast media iomeprol, which contribute to the adsorbable organic halogen compounds, and the antiepileptic drug carbamazepine were selected. The irradiation experiments were carried out in batch experiments with simulated UV–sunlight. The photodegradation of the pharmaceuticals showed a pseudo-first-order kinetics. The objective of this investigation was to demonstrate that the extent of photoinduced degradation of pharmaceuticals can vary significantly for the different pharmaceuticals and it strongly depends on the water constituents present in solution. The influences of different initial pharmaceutical concentrations, the presence of other pharmaceuticals like carbamazepine or clofibric acid and the presence of natural organic matter on the photochemical degradation rate of pharmaceuticals in aqueous solutions were investigated. Analyses of the pharmaceuticals and their photodegradation products were carried out by high performance liquid chromatography with diode-array and fluorescence detection. 相似文献
66.
Eshraq Ahmed Abdullah Abdul Halim Abdullah Zulkarnain Zainal Mohd Zobir Hussein Tan Kar Ban 《环境科学学报(英文版)》2012,24(10):1876-1884
A modified hydrophilic penta-bismuth hepta-oxide nitrate (Bi5O7NO3) surface was synthesized via a precipitation method using TiO2 and Ag as modified agents. The synthesized product was characterized by different analytical techniques. The removal efficiency was evaluated using mono-and di-sulphonated azo dyes as model pollutants. Different kinetic, isotherm and diffusion models were chosen to describe the adsorption process. X-ray photoelectron spectroscopy (XPS) results revealed no noticeable differences in the chemical states of modified adsorbent when compared to pure Bi5O7NO3;however, the presence of hydrophilic centres such as TiO2 and Ag developed positively charged surface groups and improved its adsorption performance to a wide range of azo dyes. Dyes removal was found to be a function of adsorbent dosage, initial dye concentration, solution pH and temperature. The reduction of Langmuir 1,2-mixed order kinetics to the second or first-order kinetics could be successfully used to describe the adsorption of dyes onto the modified adsorbent. Mass transfer can be described by intra-particle diffusion at a certain stage, but it was not the rate limiting step that controlled the adsorption process. Homogenous behavior of adsorbent surface can be explored by applying Langmuir isotherm to fit the adsorption data. 相似文献
67.
Recovery of phosphorus as struvite from sewage sludge ash 总被引:1,自引:0,他引:1
Phosphorus (P) is an element vital for all living organisms, yet the world's reserves of phosphate rock are becoming depleted. This study investigated an effective P recovery method from sludge ash via struvite precipitation. Results showed that more than 95% of the total P content was extracted from sludge ash by applying 0.5 mol/L HCl at a liquid/solid ratio of 50 mL/g. Although heavy metal leaching also occurred during P extraction, cation exchange resin efficiently removed the heavy metals from the P-rich solution. Orthogonal tests showed that the optimal parameters for P precipitation as struvite would be a Mg:N:P molar ratio of 1.6:1.6:1 at pH 10.0. X-ray diffraction analysis validated the formation of struvite. Further investigations revealed that the harvested precipitate had a high struvite content (97%), high P bioavailability (94%), and low heavy metal content, which could be considered a high quality fertilizer. 相似文献
68.
69.
本义对前期[1][2]的理论分析成果进行修改和验证。前期曾用大量文献上的晶体结构参数仅演为理论的X射线树木图,从中选出若干条特征峰,用逐步回归方法对其强度比与钙质闪石的11种阳离子占位度问,建立一系列经验公式,用以估算未知的钙质冈石样品阳离子占位度,精度在85%-98%之间,多数阳离子精度超过90%.在闪石晶体化学研究上具有重要意义的阳离子如M1、M3位中Mg、Fe2+、A位的K、三缺值Em及万位的Si等精度均超过90%;晶体化学类型定名的准确度达85%。成果表明,利用X射线衍射法估算闪石的阳离子占位在理论上是可能的。但还有待于用实测数据检验其可行性。本次工作的日的,便是以实测数据来验证前期理论成果并确定其可靠性。通过反复改变衍射圈上特征反射的选择和改变样本数,以实测结果验证各种组合建立的线性模型,所估算的各品位各种阳离子占位数的准确度在78%-96%之间,大多数大于80%,接近或超过90%的有八位的K、空缺值Em、位的Mg、Fe没+及T位的Si等。晶体化学类型定名的准确度可达80%。但在建立线性模型时,必须将理沦计算的粉末国与实测阁一起进行统计。所选用的实测样品愈多,该族矿物种后愈广泛,则建立的模型的代表性也愈广泛,可靠程度愈高。这一成果证实了用此类方式建立的 相似文献
70.