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1.
The total petroleum hydrocarbon (TPH) extraction potential of organic solvents including dichloromethane (DCM), pentane, hexane, methanol, ethanol, propanol, and acetone was investigated along with the effect of water content in solvents for their efficiency of extraction. The extent of TPH extraction was analyzed using various extraction schemes (i.e., solvent/solid ratio, treatment time, extraction method, solvent/water ratio) to better understand the physical and chemical factors controlling TPH release from contaminated soils. More TPH was extracted with increasing solvent/solid ratio and increasing time. The extent of TPH extracted also varied depending on the extraction method, solvent type, and solvent/water ratio, but was highest when using the total extraction method and 100% DCM. However, the efficiency of TPH extraction decreased dramatically with the increase in the water content in organic solvents. The results also showed that TPH extraction using DCM was the best option for achieving cost-effective, eco-friendly outcomes along with remediation goals. DCM used in solvent extraction to remediate diesel-contaminated soils showed low toxicity, low cost, high recycling potential, and high efficiency compared to the other solvents tested in this study.  相似文献   

2.
Four techniques, Soxhlet extraction （SOX）, ultrasonic extraction （USE）, fluidized-bed extraction （FBE） and accelerated solvent extraction （ASE） with different solvents （methanol, hexane/acetone and acetonitrile） were used for the extraction of DDT analogues in sediments. Results revealed that the four extraction techniques had high recoveries （〉 86.0%） with low standard deviations （〈 12.0%） for most of DDT analogues, meaning that they could all successfully extract DDT analogues in sediments. Accelerated solvent extraction using methanol and hexane/acetone （1：1）, fluidized-bed extraction using hexane/acetone （1：1） and the ultrasonic extraction using hexane/acetone （1：1） were comparable or better than Soxhlet extraction using hexane/acetone （1：1）. Considering solvent- and time-consumption, level of automation, and environmental risk, accelerated solvent extraction with hexane/acetone （1：1） was better than the other extraction techniques.  相似文献   

3.
The adsorption of herbicides on soil colloids is a major factor determining their mobility, persistence, and activity in soils. Solvent extraction could be a viable option for removing sorbed contaminants in soils. This study evaluated the extractability of three herbicides: 2,4 dichlorophenoxy-acetic acid (2,4-D), 4-chloro-2-methylphenoxypropanoic acid (mecoprop acid or MCPP), and 3,6-dichloro-2-methoxybenzoic acid (dicamba). Three solvents (water, methanol, and iso-propanol) and three methods of extraction (column, batch, and soxhlet) were compared for their efficiencies in removing the herbicides from three soils (loamy sand, silt loam, and silty clay). Both linear and non-linear Freundlich isotherms were used to predict sorption intensity of herbicides on soils subjected to various extraction methods and conditions. High Kdand Kfr, and low N values were obtained for all herbicides in silty clay soil by batch extraction. Methanol was the best solvent removing approximately 97% of all added herbicides from the loamy sand either by column or soxhlet extraction method. Isopropanol ranked second by removing over 90% of all herbicides by soxhelet extraction from all three soils. However, water was ineffective in removing herbicides from any of the soils using any of the three extracting procedures used in this study. In general, the extent of herbicide removal depended on soil type, herbicide concentration, extraction procedure, solvent type and amount, and extraction time.  相似文献   

4.
Summary Although organic solvents such as methanol and ethanol have been shown to act as energy sources for denitrifying microorganisms, no studies on the influence of organic solvents on denitrification in soil have been reported. Organic solvents have been used as an aid in the application of pesticides and other agricultural chemicals to soil, in studying the effects of these chemicals on denitrification in soil. During these applications, the soil is often aerated or heated to remove the solvent while leaving the chemical in the soil. The work reported here shows that treating soils with methanol, ethanol, or acetone had a very marked effect on their denitrifying ability, even when the soils were aerated thoroughly or heated at 50°C to remove these solvents. This indicates either that it is not possible to effect complete removal of organic solvents from soils by aeration or heating or that organic solvents promote denitrification by solubilizing a fraction of soil organic matter that is not available to denitrifying microorganisms before the addition of these solvents. Experiments using phenylmercuric acetate (a herbicide and nitrification inhibitor) showed that although this compound had a marked inhibitory effect on denitrification when added to soil in methanol, ethanol, or acetone, it had no inhibitory effect on denitrification when added to soil in water. The work reported shows that the use of an organic solvent in adding an agricultural chemical to soil can lead to erroneous conclusions in studies on the effects of the chemical on soil denitrification.  相似文献   

5.
The recovery of light hydrocarbon constituents from three soils using three kinds of extraction methods, conducted in duplicates, was evaluated. Higher molecular weight compounds were recovered at greater than 80% whereas the recoveries of benzene, toluene, ethylbenzene, and xylene were generally less than 50%. Using the most efficient extraction procedure, the average recovery of light hydrocarbon from a soil, was 78%. Increased soil moisture content decreased the extent of recovery. Methanol and 2-propanol showed similar extracting potential for light hydrocarbon from soil. The rate of hydrocarbon removal was faster when methanol was used as a solvent, but its efficiency was similar to 2-propanol. The batch and column extraction methods gave very similar results for both solvents. However, column extraction offered an advantage over the soxhlet and batch procedures by reaching equilibrium faster.  相似文献   

6.
A simple mixture process design based on the comparison of both quadratic and special cubic models and involving three mixture components (hexane/acetone/ethanol) as a solution for extracting lycopene from raw tomato, tomato sauce, and tomato paste was used to confirm the hypothesis that lycopene extraction rates are a function of the solvent used during the extraction process. Conventional criteria (p 相似文献   

7.
Pressurized fluid extraction (PFE) is a new sample extraction method operated at elevated temperatures and pressures with liquid solvents. The use of PFE was investigated for the extraction of four Hawaiian clayey soils fortified with the selected chloroacetanilide and nitrogen heterocyclic herbicides Alachlor, Bromacil, Hexazinone, Metribuzin, and Tebuthiuron. The effects of operation temperature, pressure, flush volume, and static cycles on PFE performance were studied. Water was the most effective modifier of PFE for quantitative recoveries of the five herbicides in soils. The simple extraction method required pretreatment of the soil with 37.6% water and subsequent two-static-cycle extraction with a total of 32 mL of acetone at 1500 psi and 100 degrees C. Average recoveries of Alachlor, Bromacil, Hexazinone, Metribuzin, and Tebuthiuron ranged from 93 to 103% by the water-assisted PFE, compared with only 68-83% recoveries of the corresponding chemicals when no water was used. The extraction time and total organic solvent consumption were reduced from 18 h and 300 mL by Soxhlet to 22 min or less and 80 mL or less of organic solvent by PFE.  相似文献   

8.
Phospholipid fatty acid (PLFA) analysis is an informative method for characterising and quantifying changes in the phenotypic profile of the soil microbial community when soils are exposed to chemical toxicants and other xenobiotics. However, where such materials are lipophilic, a range of non-polar compounds can be co-extracted with PLFAs and can consequently mask PLFA chromatograms. We found this to be the case with the lipophilic anti-microbial compound triclosan, which can enter the soil via the addition of sewage sludge. A simple method of washing soil in solvent prior to extraction was developed in order to remove triclosan without altering the relative abundance of PLFAs. Three contrasting soils were spiked with 500 mg kg−1 of triclosan before being washed with methanol (MeOH), dichloromethane (DCM), hexane or aqueous solutions of these solvents. PLFAs were then extracted and analysed. All treatments were found to remove triclosan effectively, allowing all peaks to be identifiable. Whilst the polar solvents MeOH and DCM significantly altered the relative abundance of extracted fatty acids in most of the soils tested, soil washing with a small quantity of hexane was able to remove triclosan whilst best preserving the fidelity of the PLFA profiles.  相似文献   

9.
针对国内缺乏土壤中多环芳烃（PAHs）检测的国家标准方法的现状,以提取效率和回收率作为不同溶剂、不同提取方式前处理优劣的表征,研究了目前国内较常用的3种提取技术（索氏提取、超声波提取、水平振荡提取）和2种不同的提取剂（二氯甲烷、二氯甲烷／丙酮=5：1）对提取效率和回收率的影响。结果表明,以二氯甲烷作为提取溶剂,水平恒温振荡提取4h,可以有效地提取土壤中的15种多环芳烃类污染物。此技术提取时间短,节省提取溶剂且提取效率较高,方法回收率在73．3％－117．5％范围内。  相似文献   

10.
Before wood ash can be safely used as a fertilizer in soils, possible negative effects such as input of organic contaminants or remobilization of contaminants already stored in the soil must be investigated. The objective of this study was to optimize and characterize extraction methods to isolate and quantitatively measure polycyclic aromatic hydrocarbons (PAHs) concentrations in wood ash that can be used as amendment of soils. It will be then possible to examine the effects of wood ash application on PAHs concentrations in the washing waters with the aim of evaluating their distribution by storage in the different compartments and what influences their stability and persistence. Simple, rapid and inexpensive methods have been set up for the determination of seven polycyclic aromatic hydrocarbons (PAHs) in wood ashes and ash aqueous extracts without interferences from other chemical contaminants using organic solvent extraction and/or SPE techniques and analyzed by an optimized RP-HPLC-FLD method. The feasibility of extraction for the determination of PAHs in wood ashes has been evaluated because PAHs are strongly sorbed to such a matrix, which explains why the PAHs content in ash was seldom studied. The method resulted to be of recoveries ranging from 81 to 97% for the different PAHs, with repeatabilities (RSDs%) better than 6%. Detection levels were from 0.2 to 2.2 microg/kg, while quantification limits were from 0.7 to 5.6 microg/kg, low enough to evaluate the presence of PAHs in wood ashes.  相似文献   

11.
Surfactant enhanced remediation is thought to be an effective method for the remediation of soils polluted with hydrophoblc organic compounds. Desorption of polycyclic aromatic hydrocarbons （PAHs） from an abandoned manufactured gas plant （MGP） soil was evaluated using four eluting agents including Triton X-100 （TX100）, sodium dodecylbenzene sulfonate （SDBS）, rhamnolipid water solution （RWS） and rhamnolipid fermentation broth （RFB）. The weight solubilization ratios for acenaphthene and fluorene were in the order of TX100 〉 SDBS 〉 RWS 〉 RFB. The Sm value, which indicates the maximum amounts of surfactants adsorbed in the soil, was in the order of RWS 〉 RFB 〉 SDBS 〉 TX100. By using 8 g L-1 of TX100, SDBS and RWS and 100% of RFB, the T-PAHs removal for the MGP soil contaminated with 207.86 mg T-PAHs kg-1 dry soil was 48.0%, 45.7%, 1.9%, and 8.6%, respectively, while that decreased to 41.6%, 37%, 0.38%, and 1.3% for the soil contaminated with 3494.78 mg T-PAHs kg-1 dry soil. Only 8 g L-1 TX100 could remove all types of the 16 PAHs partly in the MGP soil, and the removal efficiencies of different PAHs ranged from 13% to 77.8%. The results of this study herein provide valuable information for the selection of TX100 surfactant for remediating PAH-contaminated soils in MGP.  相似文献   

12.
Total phenolic and tocopherol contents and free radical scavenging capability of wheat bran extracted using conventional and microwave-assisted solvent extraction methods were studied. Three different solvents (methanol, acetone, and hexane) were used in the conventional solvent extraction. Methanol was the most effective solvent, producing higher extraction yield (4.86%), total phenolic compound content (241.3 μg of catechin equivalent/g of wheat bran), and free radical scavenging capability (0.042 μmol of trolox equivalent/g of wheat bran) than either acetone or hexane. However, there was no significant difference in the total tocopherol contents (13.6–14.8 μg/g of wheat bran) among the three different solvent extraction methods. Microwave-assisted solvent extraction using methanol significantly increased the total phenolic compound content to 467.5 and 489.5 μg of catechin equivalent; total tocopherol content to 18.7 and 19.5 μg; and free radical scavenging capability to 0.064 and 0.072 μmol of trolox equivalent/g of wheat bran at extraction temperatures of 100 and 120°C, respectively. However, extraction yields of conventional methanol solvent and microwave-assisted methanol extractions at different temperatures were not significantly different.  相似文献   

13.
该文提出了水媒法提油技术的概念。水媒法提油技术是指以水为主要媒介的提油技术(水媒法),可辅以或不辅以与水互溶的可食用物质(例如乙醇)、食品级酶、超声波、微波等处理以破坏油料细胞壁和/或破乳的食用油提取方法。水媒法的提油过程主要分为分成破碎、提取、破乳和分离四个阶段。水媒法发展至今60余年,已全面发展了水代法、水酶法和乙醇水提法等多种制油技术。目前水媒法的产业化还存在一些问题,如油料的预处理、酶的种类与成本等。但是,水媒法绿色健康、符合可持续发展要求,随着工艺设备、分离技术等的发展,该技术将更加完善,成为未来未来取代传统工艺的新主流。该文将水媒法研究领域的成果进行归纳总结并为其未来发展提供理论参考。  相似文献   

14.

Purpose

The assessing bias of rhizosphere effect on polycyclic aromatic hydrocarbons (PAHs) degradation in soils would come out from formation of nonextractable PAHs and extractability difference of various solvents. The aim of this study was to evaluate the role of rhizosphere effect in long-term PAHs polluted soils by using sequential extraction approach.

Material and methods

The scheme of sequential extraction included methanol/water extractable PAHs, butanol extractable PAHs, DCM extractable PAHs, humic acid-bound PAHs, crude humin-bound PAHs, and organic-C enriched humin-bound PAHs. PAHs in plant tissues were extracted by dichloromethane after saponifying. The correlations between PAHs in plant tissues and sequentially extracted fractions were generated by partial least squares regression.

Results and discussion

The profiles of sequentially extracted PAHs varied with plant species. The discrepancy of toxicity equivalency concentrations between rhizosphere and bulk soils was much more significant than that of total PAHs concentrations. In partial least squares regression models, the concentration of PAHs in plant tissues was correlated with fractions strongly associated with soil.

Conclusions

The novelty of this study is the evaluation of concentration and toxicity equivalency concentration of PAHs in rhizosphere of crops sampled in a field polluted with PAHs for long term. This study has highlighted more significant role of rhizosphere in cleanup of cancerogenic toxicity of soil than amount of PAHs in polluted soils.  相似文献   

15.
This study aimed to evaluate the efficacy, practicality and sustainability of a combined approach based on solvent extraction and biodegradation to remediate the soils contaminated with high levels of weathered petroleum hydrocarbons. The soils used in this study were obtained from the Shengli Oilfield in China, which had a long history of contamination with high concentrations of petroleum hydrocarbons. The contaminated soils were washed using a composite organic solvent consisting of hexane and pentane (4:1, v/v) and then bioremediated in microcosms which were bioaugmentated with Bacillus subtilis FQ06 strains and/or rhamnolipid. The optimal solvent extraction conditions were determined as extraction for 20 min at 25 °C with solvent-soil ratio of 6:1 (v/w). On this basis, total petroleum hydrocarbon was decreased from 140 000 to 14 000 mg kg-1, which was further reduced to < 4 000 mg kg-1 by subsequent bioremediation for 132 d. Sustainability assessment of this integrated technology showed its good performance for both short- and long-term effectiveness. Overall the results encouraged its application for remediating contaminated sites especially with high concentration weathered hydrocarbons.  相似文献   

16.
Humic substances from the Ah horizons of five differently calcareous soils from Greece were successively extracted with organic solvents and/or 0.1 N NaOH and they were characterized by UV/VIS/IR spectroscopy and differential thermal analysis (DTA). Diethylether, acetone and dioxane extracts contained non-humic substances such as aliphatic and aromatic ethers, esters, alcoholes and long aliphatic chains, while low molecular weight humic substances were found in the ethanol extracts. All the extracts were found to contain phenolic and ?-acceptor compounds. Some differences in the physical characteristics of the humic substances were associated with the kinds of vegetation. The IR-spectra showed no essential differences between HA's and FA's extracted directly with NaOH or after previous soil extraction with organic solvents. HA's extracted directly by NaOH from soil samples under grass had a higher degree of condensation and thermal stability and generally higher carbon contents than those from soils under pine, cultivation and sedges.  相似文献   

17.
For the determination of PAH availability to plants a plant accumulation test with Lepidium and sequential supercritical fluid extraction (SSFE) with carbon dioxide as extraction solvent was used, during which the extraction conditions were changed from mild to harsh in order to represent a broad range of potential pollutant-soil interactions. Both approaches were applied in laboratory experiments on industrial contaminated soils which, in addition, were also freshly spiked with PAHs in order to increase the bioavailability. Only Naphthalene, Phenanthrene and, in some cases, Pyrene accumulated from the industrial contaminated soils. Accumulation experiments with spiked industrial soils showed that other PAHs, for example Anthracene, Fluorene and even high weight PAHs like Benzo(a)pyrene, also could be taken up by plants. SSFE extraction data were compared to accumulated amounts of PAHs in the plants. Strong correlations were found for Phenanthrene between plant accumulation and extractability under very mild extraction conditions. For Naphthalene, accumulation did not correlate with its extractability in the industrial soils. The possibility exists that bioavailability in soil was eclipsed by an accumulation in the gas phase due to the high volatility of Naphthalene. Supercritical fluid extraction appears to be a promising tool to estimate Phenanthrene availability to plants, but further studies for the evaluation of other PAHs are recommended. This could be helpful for the determination of the feasibility of phytoremediation applications on industrially contaminated soils.  相似文献   

18.
Olive mill waste is a potential source for the recovery of phytochemicals with a wide array of biological activities. Phytochemical screening of hexane, methanol, and water extracts revealed a diversity of compounds, perhaps overlooked in previous studies through intensive cleanup procedures. Methanol and water extracts contained large amounts of biophenols, and further testing of polar extraction solvents, including ethyl acetate, ethanol, propanol, acetone, acetonitrile, and water/methanol mixtures, highlighted the latter as the solvent of choice for extraction of the widest array of phenolic compounds. Stabilization of the resulting extract was best achieved by addition of 2% (w/w) sodium metabisulfite. Quantitative data are reported for nine biophenols extracted using 60% (v/v) methanol in water with 2% (w/w) sodium metabisulfite. Six compounds had recoveries of greater than 1 g/kg of freeze-dried waste: hydroxytyrosol glucoside, hydroxytyrosol, tyrosol, verbascoside, and a derivative of oleuropein.  相似文献   

19.
几种豆科、禾本科植物对多环芳烃复合污染土壤的修复   总被引：3，自引：0，他引：3  
通过盆栽试验,研究了几种豆科植物与禾本科植物对多环芳烃(PAHs)复合污染土壤的修复作用。结果显示,90天后8种植物对土壤中PAHs均有不同程度降解效果,其中紫花苜蓿和多年生黑麦草对土壤PAHs的去除率分别达48.4%、46.8%,且对3环PAHs去除较为彻底,对4环及4环以上的PAHs去除效果较差。8种供试植物对PAHs均有一定的吸收、富集与转运的能力,紫花苜蓿和多年生黑麦草对土壤PAHs的生物富集系数分别为0.096、0.085,其提取修复效率为0.017%和0.013%。可见,紫花苜蓿和多年生黑麦草具有较好的根际修复潜力。  相似文献   

20.
In order to estimate the biomass of photoautotrophic organisms in biological soil crusts (BSCs), based on the extraction and determination of phytoplanktonic chlorophyll-a (Chl-a) in aquatic ecosystems, this paper comparatively studied the Chl-a extraction efficiencies in ethanol, acetone, N, N -dimethyl -formamide (DMF) and dimethyl sulphoxide (DMSO) from algae, lichen, and moss crusts, analyzed the effects of dominant organisms or development degree of BSCs, mass of sample, and soil characteristics on the extraction efficiency. The results showed that the extraction efficiencies of different organic solvents were significantly different, and such efficiencies declined with the increase of mass of sample. DMSO resulted in the greatest extraction efficiency, but was not suitable for lichen crusts; DMF strongly underestimated the Chl-a content of man-made crusts relative to the other extractants, and was particularly affected by interfering pigments from the well-developed crusts. Generally, the extraction efficiency of ethanol was greater than that of acetone, and ethanol method showed the greatest stability compared with other 3 solvents. In addition, Chl-a content showed an increasing trend with the succession of BSCs when it was expressed on an areal basis. On the basis of this and related experiments we suggest Chl-a content of BSCs be extracted by ethanol and expressed on an areal basis.  相似文献   

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