Enthalpies of transfer for conjugate-base anions of weak acids in acetonitrile–methanol mixtures. An approach to molecular thermodynamics of ionization for weak acids in the aqueous phase

1992 ◽  
Vol 88 (20) ◽  
pp. 3019-3023 ◽  
Author(s):  
Yasuhiko Kondo ◽  
Wataru Sugitani ◽  
Masaki Tokui
Keyword(s):  
Aqueous Phase ◽  
Weak Acids ◽  
Enthalpies Of Transfer ◽  
Molecular Thermodynamics ◽  
Conjugate Base ◽  
Thermodynamics Of Ionization

Aqueous Phase Diffusion in Crystalline Rock

1981 ◽  
Vol 11 ◽  
Author(s):  
M.H. Bradbury ◽  
D. Lever ◽  
D. Kinsey
Keyword(s):  
Radioactive Waste ◽  
Aqueous Phase ◽  
Water Movement ◽  
Degradation Products ◽  
Crystalline Rock ◽  
Crystalline Rocks ◽  
Radionuclide Transport ◽  
Fracture Networks ◽  
Phase Diffusion ◽  
Main Factors

One of the options being considered for the disposal of radioactive waste is deep burial in crystalline rocks such as granite. It is generally recognised that in such rocks groundwater flows mainly through the fracture networks so that these will be the “highways” for the return of radionuclides to the biosphere. The main factors retarding the radionuclide transport have been considered to be the slow water movement in the fissures over the long distances involved together with sorption both in man-made barriers surrounding the waste, and onto rock surfaces and degradation products in the fissures.

Liquid-liquid extraction of succinate using a dicopper cryptate

2020 ◽  
Author(s):  
Riccardo Mobili ◽  
Sonia La Cognata ◽  
Francesca Merlo ◽  
Andrea Speltini ◽  
Massimo Boiocchi ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Visible Spectrum ◽  
Tca Cycle ◽  
Residual Concentration ◽  
Waste Products ◽  
Liquid Liquid Extraction ◽  
The Tca Cycle ◽  
Quantitative Extraction ◽  
Uv Visible

<div> <p>The extraction of the succinate dianion from a neutral aqueous solution into dichloromethane is obtained using a lipophilic cage-like dicopper(II) complex as the extractant. The quantitative extraction exploits the high affinity of the succinate anion for the cavity of the azacryptate. The anion is effectively transferred from the aqueous phase, buffered at pH 7 with HEPES, into dichloromethane. A 1:1 extractant:anion adduct is obtained. Extraction can be easily monitored by following changes in the UV-visible spectrum of the dicopper complex in dichloromethane, and by measuring the residual concentration of succinate in the aqueous phase by HPLC−UV. Considering i) the relevance of polycarboxylates in biochemistry, as e.g. normal intermediates of the TCA cycle, ii) the relevance of dicarboxylates in the environmental field, as e.g. waste products of industrial processes, and iii) the recently discovered role of succinate and other dicarboxylates in pathophysiological processes including cancer, our results open new perspectives for research in all contexts where selective recognition, trapping and extraction of polycarboxylates is required. </p> </div>

A method for selective separation of scandium (III) from yttrium and a number of rare-earth elements for its subsequent determination

2018 ◽  
Vol 84 (11) ◽  
pp. 23-27
Author(s):  
M. I. Degtev ◽  
A. A. Yuminova ◽  
A. S. Maksimov ◽  
A. P. Medvedev
Keyword(s):  
Rare Earth ◽  
Aqueous Phase ◽  
Selective Isolation ◽  
Optimum Ratio ◽  
Extraction Condition ◽  
Sulfosalicylic Acid ◽  
Salting Out ◽  
Subsequent Determination ◽  
Toxic Organic Solvents ◽  
Metal Ions Extraction

The possibility of using an aqueous stratified system of antipyrine — sulfosalicylic acid — water for the selective isolation of scandium macro- and microquantities for subsequent determination is studied. The proposed extraction system eliminates the usage of toxic organic solvents. The organic phase with a volume of 1.2 to 2.0 ml, resulting from delamination of the aqueous phase containing antipyrine and sulfosalicylic acid is analysed to assess the possibility of using such systems for metal ions extraction. Condition necessary for the formation of such a phase were specified: the ratio of the initial components, their concentration, presence of inorganic salting out agents. The optimum ratio of antipyrine to sulfosalicylic acid is 2:1 at concentrations of 0.6 and 0.3 mol/liter in a volume of the aqueous phase of 10 ml. The obtained phase which consists of antipyrinium sulfosalicylate, free antipyrine and water, quantitatively extracts macro- and microquantities of scandium at pH = 1.54. Macro- and microquantities of yttrium, terbium, lanthanum, ytterbium and gadolinium are not extracted under the aforementioned conditions thus providing selective isolation of scandium from the bases containing yttrium, ytterbium, terbium, lanthanum, and gadolinium.

Structure of Ni/HZSM-5 Catalyst and Its Catalytic Performance for Aqueous Phase Hydrogenation of Sorbitol to Alkanes

2011 ◽  
Vol 32 (4) ◽  
pp. 612-617
Author(s):  
Ke QIU ◽  
Qing ZHANG ◽  
Ting JIANG ◽  
Longlong MA ◽  
Tiejun WANG ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Catalytic Performance

Promoting Effect of Cu on MnCeOx-Catalyzed Phenol Oxi-dation in Aqueous Phase

2010 ◽  
Vol 31 (9) ◽  
pp. 1185-1188
Author(s):  
Changshui TONG ◽  
Xiaoxia TONG ◽  
Menggui JIN ◽  
Nianjun YE
Keyword(s):  
Aqueous Phase ◽  
Promoting Effect

Methodology of Research in Micropollutants – Heavy Metals

1982 ◽  
Vol 14 (12) ◽  
pp. 107-125 ◽  
Author(s):  
Roland Wollast
Keyword(s):  
Heavy Metals ◽  
Mathematical Models ◽  
Aqueous Phase ◽  
Suspended Matter ◽  
Solid Phase ◽  
Aquatic Organisms ◽  
Biological Processes ◽  
Particulate Phase ◽  
Sources Of Pollution ◽  
Adsorption Desorption

A comparison of the concentration of dissolved and of particulate heavy metals in the aquatic system indicates that these elements are strongly enriched in the suspended matter. The transfer between the aqueous phase and the solid phase may be due to dissolution-precipitation reactions, adsorption-desorption processes or biological processes. When these processes are identified, it is further possible to develop mathematical models which describe the behaviour of these elements. The enrichment of heavy metals in the particulate phase suspended or deposited and in aquatic organisms constitutes a powerful tool in order to evaluate sources of pollution.

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