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排序方式: 共有147条查询结果,搜索用时 171 毫秒
91.
建立了HD-8阳离子交换树脂微色谱柱分离富集矿石中锆的方法。研究了上柱酸度、淋洗液、洗脱液、干扰离子等对锆的吸附性能的影响。结果表明,上柱最佳酸度0.5~2 mol/L HCl、淋洗液1 mol/L HCl、洗脱液1 mol/L H2SO4,锆的吸附与洗脱效果最好。选用邻氯苯基荧光酮为显色剂,直接在硫酸介质中显色,胶束增溶光度法测定,操作简便,灵敏度高,选择性好。树脂的吸附容量为81.4 mg/g。与常规柱相比,微色谱柱吸附后,洗脱体积减少了16倍,柱效高,分离速度快,试剂用量少,灵敏度高。该方法可以用于实际矿石的分离测定,经标准值验证,测定值与标准值相近,多次平行测定后,方法的相对标准偏差为1.9%~2.7%,说明此法可用于分析实际样品。 相似文献
92.
Ecological city is the advanced mode of harmonious development of city. Constant improvement is being made in the development of ecological city. However, building ecological city is an enormous project that calls for a huge amount of capital. The government fund is far from adequate. This paper probes into the fund issue and discusses in detail the mechanism of investment and financing in building ecological city from various aspects such as diversification of the investment subjects and the modes of financing. 相似文献
93.
Dorota Grabek-Lejko Kinga Tomczyk-Ulanowska 《Journal of environmental science and health. Part. B》2013,48(12):1089-1096
Seventeen natural sweeteners available on the Polish market were screened for total phenolic content, by the Folin-Ciocalteu method, and for antioxidant activity, using the ferric reducing antioxidant power (FRAP) assay and the 2,2′-Azinobis (3-ethylbenzthiazoline-6-sulphonic acid) radical cation decolorization assay (ABTS·+). In addition, we analyzed antibacterial activities against Staphylococcus aureus strains: both those susceptible and those resistant to methicillin (MRSA). The results of the study showed that total phenolic content, antioxidant activity and antibacterial activity differ widely among different samples of sweeteners. Phenolic content, expressed as a gallic acid equivalent, ranged from 0 mg kg?1 in white, refined sugar, xylitol and wheat malt syrup to 11.4 g kg?1 in sugarcane molasses. Antioxidant activity was lowest in refined white sugar, xylitol, brown beet sugar, liquid fructose, and rape honey; it was average in spelt syrup and corn syrup, and highest in sugar cane, beet molasses, date and barley syrups. Despite the great variety of sweeteners, a strong correlation was noted between the concentration of phenolics and antioxidant properties, as determined by the ABTS·+ method (r = 0.97) and the FRAP assay (r = 0.77). The strongest antibacterial activity was observed in sugarcane molasses, which was lethal to S. aureus strains at 2 and 4% concentrations in medium for susceptible and MRSA strains respectively. Other sweeteners kill bacteria in 6–15% solutions, whereas some did not show any antibacterial activities against S. aureus strains, even at 20% concentrations. Due to their high antioxidant and antibacterial activities, some of the tested sweeteners have potential therapeutic value as supporting agents in antibiotic therapy. 相似文献
94.
Stankov Jovanovic VP Ilic MD Markovic MS Mitic VD Nikolic Mandic SD Stojanovic GS 《Chemosphere》2011,84(11):1584-1591
Fire has been considered as an improving factor in soil quality, but only if it is controlled. Severe wild fire occurred in the summer 2007 on the Vidlic Mountain (Serbia) overspreading a huge area of meadows and forests.Main soil characteristics and content of heavy metals (Cu, Pb, Cd, Zn) in different fractions obtained after sequential extraction of soil from post-fire areas and from fire non disturbed areas were studied. In four plant species of Lamiaceae family (Ajuga genevensis L., Lamium galeobdolon (L.) L., Teucrium chamaedrys L., Acinos alpinus (L.) Moench.), that grow in typical habitats of the mountain, distribution of heavy metals in aerial parts and roots was investigated too.For all samples from post-fire area cation exchange capacity and soil organic matter content are increased while rH is decreased. Fire caused slightly increased bioavailability of the observed metals but more significant rise happened in metal amounts bound to oxides and organics. The plants showed variable behavior. T. chamaedrys collected on the post-fire area contained elevated concentrations of all analyzed metals. A. alpinus showed higher phytoaccumulation for Zn and Cd, while the other two plant species for Pb and Cd in the post-fire areas. 相似文献
95.
A polyvinylidene fluoride-based membrane bearing the diethylenetriaminepentaacetic acid chelating group was employed to recover Cu(II) from the Cu(II)-ethylenediaminetetraacetic acid complex aqueous solution. Effects of Ca(II), Fe(II), and Fe(III) on Cu(II) uptake were investigated by static batch adsorption tests and dynamic adsorption filtration. Isotherms, kinetics, and breakthrough curves of Cu(II) uptakes in the presence of the three cations at concentrations of 1 mmol L?1 were elucidated. The three cations showed a positive effect on the Cu(II) uptake; the stimulative roles were in the order of Fe(III) > Fe(II) > Ca(II). They did not alter the adsorption behavior of the membrane; adsorption isotherms and kinetics could be described by Langmuir and Lagergren second-order models, and Cu(II) adsorption was a spontaneous and exothermic process. The presence of Ca(II), Fe(II), and Fe(III) increased the sorption capacity of the membrane stack by 1.3, 1.9, and 3 times. Breakthrough time and the exhaustion time of membrane stacks were also extended. 相似文献
96.
97.
对所收集的47个碱性闪石结构数据计算出理论X射线粉末图,同时实测出5个碱 性闪石样品的粉末图及其晶体化学占位,从这52个样品的X射线衍射圈中选出18条特征衍射 强度,将强度比值与各晶位各阳离子占位用多元统计分析统计出经验公式,以之作为估算未知 样品各阳离子占位的线性模型。回代实践表明,本线性模型具有较钙质闪石更高的可靠性与精 确度。预测5个实测样品的晶体化学类型与原定名对比完全符合,准确度达100%。按国际分 类表纠正个别样品原定名的错误。在12种阳离子占位中,估算的准确度有8种大于90%,3种 近于90%!唯有T位Si的准确度仅66%,这可能是因为所选样品中T位基本上为Si占位,其 占位数均超过 7.5,占位度均大于 0.9,总变化幅度小从而降低其相关性。因 52个样品中,也包 含钠钙闪石亚族,故对整个闪石族用X射线衍射估算阳离子占位的问题已基本解决。 相似文献
98.
99.
阳离子树脂法提取活性污泥胞外聚合物的研究 总被引:4,自引:0,他引:4
考察了树脂法提取活性污泥中胞外聚合物(extracellular polymeric substance,EPS)的影响因素,确定了最佳的提取条件.试验结果表明,树脂量60g/g VSS,振摇频率200r/min下处理4 h,EPS的提取量达到111.20 mg/L,DNA占提取量的12.13%.该方法的重现性试验结果还表明,EPS及其各成分的相对标准偏差在2.21%~6.07%之间,能较好地满足试验要求,是一种可靠的EPS提取方法. 相似文献
100.
改性凹凸棒石对模拟含酚废水处理机制的研究 总被引:31,自引:0,他引:31
利用有机阳离子表面活性剂对凹凸棒石表面进行改性,研究改性凹凸棒石吸附去除模拟含酚水中苯酚的机理,同时对影响吸附去除苯酚的因素进行探讨.结果表明,用十六烷基三甲基溴化铵(HDTMA)和溴代十六烷基吡啶(CPB)等有机阳离子对天然凹凸棒石进行改性后能大大提高对苯酚的吸附去除率;HDTMA和CPB改性土对苯酚的吸附机制主要是其有机相对苯酚的分配作用;HDTMA和CPB改性土对苯酚的吸附等温线呈线性,L型吸附等温方程更适合该吸附过程.在pH>10时,HDTMA改性土除通过分配作用以外还可通过静电吸附增强对苯酚的吸附;随着HDTMA改性剂用量的增加,HDTMA改性土对苯酚的吸附去除率也逐渐增加并达到最大值. 相似文献