China
Africa
Explore chapters and articles related to this topic
Precipitation
Published in Juan A. Asenjo, Separation Processes in Biotechnology, 2020
By this approach the effect of salt addition on solubility occurs through alteration (relative to the pure water case) of the free-energy contributions for formation of a solute-sized cavity in the solvent and for electrostatic free-energy contributions. All other contributions to the free-energy change on dissolution are assumed unchanged by the presence of salt. The electrostatic contribution favors solubility in the presence of salt; the dependence is nonlinear at low salt concentration and linear at high concentrations. It is responsible for “salting-in, ” or increased solubility at low salt concentrations. The cavity formation or hydrophobic contribution reduces solubility in the presence of salt; it exceeds the electrostatic contribution as salt concentration is increased, resulting in “salting-
Sample Handling of Pesticides in Food and Environmental Samples
Published in José L. Tadeo, Analysis of Pesticides in Food and Environmental Samples, 2019
Francisco Barahona, Esther Turiel, Antonio Martín-Esteban
Obviously, a proper selection of the SPME sorbent is a key factor in the success of the analysis. In general, the polarity of the fiber should be as similar as possible to that of the analyte of interest. In this sense, there are nowadays a great variety of fibers commercially available that cover a wide range of polarities (e.g., carbowax/DVB for polar compounds or polydimethylsiloxane for hydrophobic compounds). Also, both the fiber thickness and the porosity of the sorbent will influence the final extraction efficiency. Besides, other physical and chemical parameters such as temperature, exposition time, agitation, pH, or ionic strength (“salting out” effect) of the sample can be optimized. An example of that is the extraction of dinoseb, an alquil-substituted dinitrophenol, in water. The SPME of this compound can be favored by using a poliacrylate fiber and by adding 10% of NaCl at pH=2 due to the produced “salting out” effect and the lower ionization of dinoseb at low pH values.
A Physical and Chemical Equilibrium
Published in Danny D. Reible, Fundamentals of Environmental Engineering, 2017
As indicated previously, the influence of cosolutes, or other compounds in the water, can significantly influence the solubility of a substance. The presence of dissolved salts or minerals leads to a salting out effect, or decreases in the solubility of a substance. The relationship between solubility and salt concentration has been given by () logS˜wS˜ws=α(S˜w)s
Understanding the dehydration of acetone, 1-butanol, and ethanol fermentation-based biofuel
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Figure 5 illustrates how the aqueous ethanol solution’s mutual solubility is affected by the salting-out temperature. When the salt concentration is the same, increasing the temperature (17.5–50°C) for salting out is beneficial to reduce the water content in the organic phase. On the other hand, more ethanol were moving to the upper phase when increasing the temperature (17.5–50°C). Increasing the temperature led to an increase in the distribution coefficient of ethanol but a decrease in the distribution coefficient of water. As a result, there was water moving to the aqueous phase and ethanol moving to the upper phase. Increasing the salt addition and temperature is beneficial to ethanol recovery.
Comparison of conventional and extractive fermentation using aqueous two-phase system to extract fibrinolytic proteases produced by Bacillus stearothermophilus DPUA 1729
Published in Preparative Biochemistry & Biotechnology, 2021
Raimundo Felipe da Cruz Filho, Januário Gama dos Santos, Rosana Antunes Palheta, Valéria Carvalho Santos-Ebinuma, Daniela de Araújo Viana Marques, Maria Francisca Simas Teixeira
Considering the partitioning coefficient, the salt effect was positive showing that high phosphate concentration can promote a “salting out” effect making the partition of enzyme more pronounced to top (rich-PEG) phase probably due to electrostatic interaction between the system components and the target biomolecule. As PEG is a nonionic polymer, the interaction repulsive or attractive is among the salt and the fibrinolytic enzymes. The “salting out” effect results from the tendency of water molecules to preferentially interact with the salt ions.[44]
A Survey of Extraction Chromatographic f-Element Separations Developed by E. P. Horwitz
Published in Solvent Extraction and Ion Exchange, 2020
Erin R. Bertelsen, Jessica A. Jackson, Jenifer C. Shafer
Previous solvent extraction work by Horwitz using Aliquat-336 in xylene had shown large separation factors between Am(III) and Cm(III) by salting-out with lithium, magnesium, or aluminum nitrate.[8,45] The phenomenon known as “salting-out” is largely due to the effective decrease in the aqueous phase water concentration as the electrolyte concentration within the aqueous phase increases, thus causing the cation of interest to be less solvated by water molecules.[27] This, in turn, makes the cation less hydrophilic and easier to extract.