oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Numerical Modeling of Supercritical Out-Salting in the Atlantis II Deep (Red Sea) Hydrothermal System
Martin Hovland, H kon Ruesl tten, Tatyana Kutznetsova, Bj rn Kvamme, Gunnar E. Fladmark and Hans Konrad Johnsen
The Open Geology Journal , 2007, DOI: 10.2174/1874262900701010001]
Abstract: Supercritical water behaves close to that of a non-polar fluid and its ability to dissolve salt ions is very low. In rifting locations world-wide, where hot vents occur, it has been shown that seawater attains supercritical conditions. We therefore anticipate that circulation of seawater in hydrothermal systems passing through regions of the supercritical domain results in spontaneous precipitation of salt particles. Thus, the hot ‘geysers’ of saturated brines observed in the ‘Atlantis II Deep’ of the Red Sea could result from re-dissolution of salts accumulated in underground fracture systems. Here we report on an advanced numerical modeling study which demonstrates, for the first time, that there is a forced convection cell where salts precipitate and accumulate. These combined numerical thermodynamic simulations and basin modelling results also demonstrate that hot brines reflux back to surface immediately above the magma chamber located beneath the axis of the rift. Based on this study, we predict that hydrothermal ‘out-salting’ is the main cause of dense, warm brines accumulating in the central portion of the Red Sea. Furthermore, the results are relevant for understanding how large volumes of evaporites (salts) accumulate along rifted plate margins.
Pesticide Removal from Aqueous Solutions by Adding Salting Out Agents  [PDF]
Fátima Moscoso,Francisco J. Deive,José M. S. S. Esperan?a,Ana Rodríguez
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms141020954
Abstract: Phase segregation in aqueous biphasic systems (ABS) composed of four hydrophilic ionic liquids (ILs): 1-butyl-3-methylimidazolium methylsulfate and 1-ethyl-3-methylimidazolium methylsulfate (C nC 1im C 1SO 4, n = 2 and 4), tributylmethyl phosphonium methylsulfate (P 4441 C 1SO 4) and methylpyridinium methylsulfate (C 1Py C 1SO 4) and two high charge density potassium inorganic salts (K 2CO 3 and K 2HPO 4) were determined by the cloud point method at 298.15 K. The influence of the addition of the selected inorganic salts to aqueous mixtures of ILs was discussed in the light of the Hofmeister series and in terms of molar Gibbs free energy of hydration. The effect of the alkyl chain length of the cation on the methylsulfate-based ILs has been investigated. All the solubility data were satisfactorily correlated to several empirical equations. A pesticide (pentachlorophenol, PCP) extraction process based on the inorganic salt providing a greater salting out effect was tackled. The viability of the proposed process was analyzed in terms of partition coefficients and extraction efficiencies.
Salting-out extraction of catechol and hydroquinone from aqueous solutions and urine samples  [PDF]
Nikoli? Goran M.,Perovi? Jelica M.,Nikoli? Ru?ica S.,Caki? Milorad D.
Facta Universitatis Series : Physics, Chemistry and Technology , 2003, DOI: 10.2298/fupct0305293n
Abstract: The influence of ammonium, sodium, potassium, and magnesium chlorides and sulfates on the extraction of catechol and hydroquinone with diethyl and diisopropyl ether was studied. All the salts investigated in this study largely increased the extraction efficiency of both catechol and hydroquinone from aqueous solutions, magnesium salts being the most efficient salting-out agents. The extraction efficiency in the presence of magnesium salts in comparison to the extraction efficiencies from the salt-free aqueous solutions increased from 14%, in the case of catechol extraction with diethyl ether, up to about 90%, in the case of hydroquinone extraction with diisopropyl ether. The extraction from spiked urine samples proved that investigation of salting-out effect in aqueous solutions could be used as a good model system for the reliable choice of optimal conditions for catechol and hydroquinone extraction from real samples.
Selective Separation and Analysis of Pb(II) Using a New Surface Imprinted Multi-Walled Carbon Nanotubes Combined with AAS  [PDF]
Haisheng Zhang, Weiping Zhou, Hongqing Wang, Yuyuan Wang, Fangfang He, Zhiqiang Cheng, Honglin Li, Jinhui Tang
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2012, DOI: 10.4236/jasmi.2012.22012
Abstract: A new surface ion-imprinted Multi-walled carbon nanotubes (MCNTs), which was 6,6'-((1E,1'E)-(pyridine-2,6-diyl- bis(azanylyl))bis(methanylylidene))bis(2-allyl-phenol) and Pb(II) complex as functional monomer and template ion was presented for extracting and enrichment traces of Pb(II) ion. Parameters affecting the recovery of Pb(II) have been investigated in detail. The novel IMCNTs display high affinity, specificity, and selectivity for Pb(II) with a maximum uptake capacity of 115.5 mg·g–1 at pH 4.0. Meanwhile, only 11 mins was enough for extracting 98.5% Pb(II) for the IMCNTs. No significant loss in adsorption capacity is observed when the IMCNTs are reused for eleven times. Separation and preconcentration with IMCNTs particles results in a limit of detection of 0.47 μg·L–1 (3σ) and RSD (n = 8) of 1.16% by using atomic absorption spectrophotometer (AAS)
Protocolo de extracción de DNA por salting-out para peque?os volúmenes de sangre
Riera,Mario Alejandro; Rojas,María Eugenia; Zapata,Pedro Darío;
Revista de ciencia y tecnolog?-a , 2010,
Abstract: a modified salting-out procedure for dna extraction from decremental blood sample volumes was developed (300; 100; 50; 25; 10; 5; 2,5; 1 and 0,5 μl). a 345 bp human prothrombin gene fragment and a str marker commonly used for filiation analyses (lpl) were then amplified by polymerase chain reaction and visualized in a 6.4 % polyacrylamide gel. in all cases the amplification reaction was successful, showing that the dna extraction method proposed here yields dna of reasonable purity and quantity from small blood sample volumes. therefore, the quantity of sample needed to perform a molecular study can be reduced, which is fundamental in certain areas such as forensic genetics, where the quantity of samples available could be limited.
Selective extraction and separation of Fe, Mn oxides and organic materials in river surficial sediments
LI Feng-mei,WANG Xiao-li,LI Yu,GUO Shu-hai,ZHONG Ai-ping,
LI Feng-mei
,WANG Xiao-li,LI Yu,GUO Shu-hai,ZHONG Ai-ping

环境科学学报(英文版) , 2006,
Abstract: In order to investigate the adsorption mechanism of trace metals to surficial sediments (SSs), a selective extraction procedure was improved in the present work. The selective extraction procedure has been proved to selectively remove and separate Fe, Mn oxides and organic materials (OMs) in the non-residual fraction from the SSs collected in Songhua River, China. After screening different kinds of conventional extractants of Fe and Mn oxides and OMs used for separation of heavy metals in the soils and sediments, NH2OH · HCl (0.1 mol/L) + HNO3 (0.1 mol/L), (NH4)2C2O4 (0.2 mol/L) + H2C2O4 (pH 3.0), and 30% of H2O2 were respectively applied to selectively extract Mn oxides, Fe/Mn oxides and OMs. After the extraction treatments, the target components were removed with extraction efficiencies between 86.09%–93.36% for the hydroxylamine hydrochloride treatment, 80.63%–101.09% for the oxalate solution extraction, and 94.76%–102.83% for the hydrogen peroxide digestion, respectively. The results indicate that this selective extraction technology was effective for the extraction and separation of Fe, Mn oxides and OMs in the SSs, and important for further mechanism study of trace metal adsorption onto SSs.
Developing an objective function to characterize the tradeoffs in salting out and the foam and droplet fractionation processes
Cherry, J.;Ko, S.;Grainger, R.;Prokop, A.;Tanner, R. D.;
Brazilian Journal of Chemical Engineering , 2000, DOI: 10.1590/S0104-66322000000200011
Abstract: there are many methods for separating and purifying proteins from dilute solutions, such as salting out/precipitation, adsorption/chromatography, foam fractionation, and droplet fractionation. in order to determine the optimal condition for a selected separation and purification process, an objective function is developed. the objective function consists of three parameters, which are the protein mass recovery, the separation ratio, and the enzymatic activity ratio. in this paper the objective function is determined as a function of the ph of the bulk solution for egg albumin, cellulase, and sporamin (for foam fractionation) and invertase ( for droplet fractionation). it is found that the optimal ph for all the systems except for cellulase is near their isoelectric point.
Developing an objective function to characterize the tradeoffs in salting out and the foam and droplet fractionation processes  [cached]
Cherry J.,Ko S.,Grainger R.,Prokop A.
Brazilian Journal of Chemical Engineering , 2000,
Abstract: There are many methods for separating and purifying proteins from dilute solutions, such as salting out/precipitation, adsorption/chromatography, foam fractionation, and droplet fractionation. In order to determine the optimal condition for a selected separation and purification process, an objective function is developed. The objective function consists of three parameters, which are the protein mass recovery, the separation ratio, and the enzymatic activity ratio. In this paper the objective function is determined as a function of the pH of the bulk solution for egg albumin, cellulase, and sporamin (for foam fractionation) and invertase ( for droplet fractionation). It is found that the optimal pH for all the systems except for cellulase is near their isoelectric point.
Salting-out Extraction of Lactic Acid from Fermentation Broth
发酵液中乳酸的盐析萃取

WEI Bo-chao,SONG Zhi-yuan,SUN Ya-qin,XIU Zhi-long,
魏搏超
,宋志远,孙亚琴,修志龙

过程工程学报 , 2012,
Abstract: Salting-out extraction was used for recovery of lactic acid from fermentation broth.The different hydrophilic organic solvents-inorganic salts systems were investigated for their extraction ability.The results showed that the K2HPO4-methanol and K2HPO4-ethanol systems appeared to be favorable.The partition coefficient and recovery rate of lactic acid reached up to 4.01 and 86.0% for the system of 25%(ω) K2HPO4-26%(ω) methanol,when the concentration of lactic acid was 167 g/L in the broth.For the system of 14%(ω) K2HPO4-30%(ω) ethanol,the partition coefficient and recovery rate of lactic acid reached up to 3.23 and 90.6%.The removal rate of glucose,cells and proteins reached 67.3%,100% and 85.9%,respectively.
Salting-Out Assisted Liquid-Liquid Extraction Combined with HPLC for Quantitative Extraction of Trace Multiclass Pesticide Residues from Environmental Waters  [PDF]
Yosef Alemayehu, Teshome Tolcha, Negussie Megersa
American Journal of Analytical Chemistry (AJAC) , 2017, DOI: 10.4236/ajac.2017.87033
Abstract: In this study, salting-out assisted liquid-liquid extraction combined with high performance liquid chromatography diode array detector (SALLE-HPLC-DAD) method was developed and validated for simultaneous analysis of carbaryl, atrazine, propazine, chlorothalonil, dimethametryn and terbutryn in environmental water samples. Parameters affecting the extraction efficiency such as type and volume of extraction solvent, sample volume, salt type and amount, centrifugation speed and time, and sample pH were optimized. Under the optimum extraction conditions the method was linear over the range of 10 - 100 μg/L (carbaryl), 8 - 100 μg/L (atarzine), 7 - 100 μg/L (propazine) and 9 - 100 μg/L (chlorothalonil, terbutryn and dimethametryn) with correlation coefficients (R2) between 0.99 and 0.999. Limits of detection and quantification ranged from 2.0 to 2.8 μg/L and 6.7 to 9.5 μg/L, respectively. The extraction recoveries obtained for ground, lake and river waters were in a range of 75.5% to 106.6%, with the intra-day and inter-day relative standard deviation lower than 3.4% for all the target analytes. All of the target analytes were not detected in these samples. Therefore, the proposed SALLE-HPLC-DAD method is simple, rapid, cheap and environmentally friendly for the determination of the aforementioned herbicides, insecticide and fungicide residues in environmental water samples.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.