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41.
在时花椒风味物质的研究中,采用传统的有机溶剂萃取,并通过GC-MS对提取物进行了定性,实验结果表明,花椒中的香味物质主要有棕榈酸、芳樟醇、胡椒酮. 相似文献
42.
通过分析垢的组成和形成原因,提出预防沥青状物质、硫酸(氢)钠结晶、氢氧化铁沉淀进入萃取机,预防氢氧化铁沉淀进入反萃机的防垢措施,实验验证了FA、FB溶剂分别为萃取机转鼓积垢和反萃机转鼓积垢的优良洗脱剂. 相似文献
43.
In this work the development of a process for the recovery of copper from contaminated industrial soils is presented. Experimental tests on a standard soil contaminated with a solution of copper chloride were carried out. The metal was extracted from the contaminated soil by flushing with a 0.1 M aqueous solution of an ethylenediaminetetraacetic acid (EDTA) sodium salt. A maximum copper extraction efficiency of about 60% was observed. Copper was then separated from the extracted solution by precipitation with sodium hydroxide after addition of ferric sulfate. 相似文献
44.
The extraction of PCBs from spiked soils using the Medium‐Pressure Liquid‐Extraction method showed good recovery rates. Comparison of MPLE and Soxhlet extraction of naturally contaminated soil showed similar results. However, too large quantities of solvents have to be used in MPLE procedure and the elution profile makes it unlikely, that the aspired separation from PAHs would be sufficient. 相似文献
45.
The study of operating variables in soil washing with EDTA 总被引:7,自引:0,他引:7
Zou Z Qiu R Zhang W Dong H Zhao Z Zhang T Wei X Cai X 《Environmental pollution (Barking, Essex : 1987)》2009,157(1):229-236
This study discusses the operating variables for removal of metals from soils using EDTA, including the type of EDTA, reaction time, solution pH, dose, temperature, agitation, ultrasound and number of extractions. For As, Cd, Cu, Pb and Zn, the removal efficiency order was: H4-EDTA > Na2EDTA > (NH4)2EDTA. At low EDTA concentrations the removal increased progressively with increasing dose while above 0.4 mmol/g only small increases in extraction efficiency were observed. EDTA induced a two-step process including a rapid desorption within the first hour, and a gradual release in the following hours. The extraction efficiency of metals decreased with increasing pH in the range of 2-10. Consecutive extractions using low concentrations were more effective than a single extraction with concentrated EDTA if the same dose of EDTA was used. 相似文献
46.
Despite numerous reviews suggesting that microbial biosensors could be used in many environmental applications, in reality they have failed to be used for which they were designed. In part this is because most of these sensors perform in an aqueous phase and a buffered medium, which is in contrast to the nature of genuine environmental systems. In this study, a range of non-exhaustive extraction techniques (NEETs) were assessed for (i) compatibility with a naphthalene responsive biosensor and (ii) correlation with naphthalene biodegradation. The NEETs removed a portion of the total soil naphthalene in the order of methanol > HPCD > βCD > water. To place the biosensor performance to NEETs in context, a biodegradation experiment was carried out using historically contaminated soils. By coupling the HPCD extraction with the biosensor, it was possible to assess the fraction of the naphthalene capable of undergoing microbial degradation in soil. 相似文献
47.
The optimized BCR sequential extraction procedure was applied to nine roadside soil samples for the determination of Cd, Cr,
Pb and Ni. The extractable metals were isolated into three operationally defined fractions viz: acid extractable, reducible
and oxidizable. The residue was treated with aqua regia solution. Metal analysis was done using flame atomic absorption spectrophotometry
with air–acetylene flame. Results obtained showed the concentrations of the metals as relative abundance in the mobile phases
of the samples (based on the sum of the first three fractions) are in the following order: Cd(91.9) > Pb(82.8) > Ni(49.5) > Cr(39.0).
The most non-mobilizable metals were Cr and Ni which are generally lithogenic, associated with the silicate matrix, and the
order is as follows: Cr(61.0) > Ni(50.5) > Pb(17.2) > Cd(8.1). The recovery of all the metals expressed as the ratio of total
metal concentration to fractional sum of the optimized BCR sequential extraction procedure was of the order: Cr(95.6) > Pb(95.0) > Ni(94.8) > Cd(92.4). 相似文献
48.
Yuan Meng Weiyi Liu Xiaohui Liu Jinlan Zhang Meng Peng Tingting Zhang 《环境科学学报(英文版)》2021,33(3):260-281
Pharmaceutical and personal care products (PPCPs) and corresponding transformation products have caused widespread concern due to their persistent emissions and potential toxicity. They have wide octanol-water partition coefficients (Kow) and different ionization constants (pKa) resulting in a poor analysis accuracy and efficiency. A suitable analytical method is the first prerequisite for further research on their environmental behavior to prioritize the substances. This study reviewed a full-scale analytical protocol for environmental samples in the recent ten years: from sampling to instrumental methods. Passive sampling techniques were compared and recommended for long-term continuous and scientific observation. A quick and effective sample extraction and clean-up method are highly required. Chromatographic methods coupled to mass spectrometry for determining PPCPs with a wide range of logKow (?7.53 to 10.80) were summed up. High-resolution mass spectrometry was confirmed to be a promising strategy for screening unknown transformation products, which would provide a nanogram level of detection limits and more accurate mass resolution. Screening strategies and mass change principles were summarized in detail. The recovery rate was important in multiple contaminants analysis identification and factors affecting the recovery rate of PPCPs were also discussed in this review, including sample matrix, target compounds characteristics, extraction method and solid-phase adsorbent. This review provides useful information for the selection of appropriate analytical methods and future development directions. 相似文献
49.
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