共查询到18条相似文献,搜索用时 343 毫秒
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固体和液体中的金属离子能在含有有机螯合剂的超临界二氧化碳(SC-CO2)流体中被有效地萃取出来。超临界流体萃取(SFE)金属离子的效率取决于下列因素:螯合剂在SC-CO2中的稳定性和溶解性、金属络合物在SC-CO2中的溶解度、水、pH值、压力、温度及金属离子的化学形式和基质的性质等。 相似文献
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薤白挥发油成分的超临界CO2萃取及GC-MS分析 总被引:3,自引:0,他引:3
采取超临界CO2萃取和水蒸气蒸馏两种方法提取薤白中的挥发油,比较了两种提取方法得到的挥发油的理化性质,并利用GC-MS对它们进行了定性、定量分析。两种方法的主要提取物均为含硫化合物,但超临界CO2萃取法得到的含硫化合物的数量和质量都高于水蒸气蒸馏法得到的提取物。采用水蒸气蒸馏法提取8 h得到的萃取率为1.72%。通过设计的超临界CO2萃取的正交实验,得到了最佳萃取工艺条件为:压力25 MPa,温度40℃,CO2流量为25L/h。最佳萃取时间为120 min,萃取率为4.41%,是水蒸气蒸馏法萃取率的2.8倍。实验结果表明,超临界CO2萃取法简单易行,可以较快速、有效地提取薤白中的挥发油。 相似文献
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《Journal of Coordination Chemistry》2012,65(1-4):187-200
Abstract The factors involved in the design of therapeutic chelating agents are outlined on the basis of the theoretical analyses of ligand design and experimental data obtained in animal studies. The starting point in such design must always be those factors which assure that a sufficiently high stability constant be achieved, and here the analyses presented by Martell and his co-workers furnish a general approach. If the removal of intracellular metal deposits is to be achieved, additional factors need to be considered to incorporate variables which govern the interaction of the chelating agent with the membrane systems of those organs within which the toxic metal is concentrated. For these, the QSAR (quantitative structure activity relationship) procedure of Hansch furnishes a useful guide. This allows the development of direct structure-efficacy correlations (DSEC) involving molecular parameters in addition to those which are directly involved in the determination of the stability constant. In several cases data are available which indicate how the relative efficacy of two chelating agents with essentially identical stability constant expectations is dependent upon structural features which govern the relative ease with which such molecules can gain access to intracellular deposits. The combination of these approaches allows the joint use of in vitro and in vivo data to design improved therapeutic chelating agents with an increased probability of success when tested in vivo. 相似文献
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Various polyfunctional oximes chelate with metals pro vided that the other functional group is proximal to the oxime and contains a good donor atom or is a good donor itself. Thus alpha-oximinocarboxamides are potential chelating agents of analytical value since the amide function attached to the carbon atom bearing the oxime has two groups capable of functioning as donors (ketone and amine). Two isomers of alpha-oximinophenylacetamide (AOPA) were obtained by two different synthetic routes, and structures were assigned by spectrometric methods. syn-AOPA was found to have chelating properties, but the anti-isomer did not. The synthesis and details of structure assignments are reported here. 相似文献
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综述了分散液-液微萃取的基本原理和萃取过程,介绍了萃取剂、分散剂、螯合剂的浓度、萃取时间、pH值、盐效应、共存离子等因素对萃取效果的影响,评述了分散液-液微萃取技术在有机化合物和痕量金属离子分析中的应用情况,引用文献42篇。 相似文献
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在微波辅助下,以聚丙烯腈纤维(PANF)为基体材料,二乙烯三胺(DETA)和硫化钠为改性试剂,通过两步接枝反应快速制备了含有大量硫原子的螯合纤维吸附剂。利用傅里叶变换红外光谱仪(FT-IR)和热重分析仪(TGA)对改性前后的纤维进行表征,同时考察了pH值、初始浓度、吸附时间和温度对螯合纤维吸附汞离子的影响。结果表明,微波辅助是一种高效、节能、经济和绿色的改性方法,改性过程在无毒的水环境中进行,试剂用量少,且改性时间大大缩短。改性纤维对汞离子的吸附是一个准二级动力学过程,较好的符合Langmuir吸附模型。在pH=7的条件下,螯合纤维对汞离子的最大吸附容量达到333.1mg/g,是一种有效的去除水中汞污染的吸附材料。 相似文献
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M. Motta C. V. Deimling M. J. Saeki P. N. Lisboa-Filho 《Journal of Sol-Gel Science and Technology》2008,46(2):201-207
Several routes and procedures have been used in these last years as an effort to achieve single-phase mesoscopic-size superconducting
samples. In this paper, the effects of using citric acid (CA), tartaric acid (TA) and ethylenediaminetetraacetic acid (EDTA)
as chelating agents and ethylene-glycol (EG) as polyhydroxy alcohol were studied in order to establish conditions to avoid
the occurrence of BaCO3 undesirable secondary phase in YBa2Cu3O7−δ (YBCO). Thermal evolution of intermediate compounds formed during the calcinations process by the use of different chelating
agents was traced using thermogravimetric and spectroscopic methods. The obtained results indicated that the polymer breakdown
of samples prepared using EDTA occurs at higher temperatures than others chelating agents and also reduces the occurrence
of BaCO3 secondary phase as studied by X-ray diffraction measurements. Furthermore, the magnetic response of the mesoscopic-size YBCO
specimens obtained was verified showing that samples present different superconducting response. 相似文献
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螯合剂与牛血清白蛋白竞争镉作用的研究 总被引:4,自引:0,他引:4
研究了十一种螯合剂使结合在牛血清白蛋白(BSA)上的镉活动化的能力。由凝胶色谱法测得的F值将螯合剂活动镉的能力排成以下顺序:DTP>EDTA>EGTA>NTA>TRIEN>;PEN>CYS>HIS>SA氨羧络合剂型配体能有效地与BSA竞争,而且它们的lgF与lgKCdL间有一线性关系。 相似文献
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Extraction of heavy metal ions from solid matrix by means of an incorporation of chelating agents with supercritical carbon dioxide(scCO2) was investigated experimentally. Four commercially available chelating agents, diethylammonium diethyldithiocarbamate(Et2NH2DDC), trifluoroacetylacetone(TFA), hexafluoroacetylacetone(HFA) and thenoyltrifluoroacetone(TTA) were tested. The extraction experiments were conducted at 50 °C and 1.39×107― 2.80×107 Pa. According to the experimental results, for the extraction of Cu2+, all the chelating agents investigated here are effective. For other metal ions, such as Pb2+, Ni2+ and Cd2+, Et2NH2DDC exhibited a better extraction result, while other chelating agents were less effective. This investigation is expected to provide a tentative evaluation on the scCO2-based metal extraction from solid media. 相似文献