Presence Of Salting-out Agents Research Articles

Extraction of nitric acid and uranyl nitrate with tributyl phosphate in diluent in the presence of salting-out agents and its mathematical description

Database on separate and joint extraction of uranyl nitrate and nitric acid with 30% and 15% TBP in paraffin diluent in the presence of salting-out agents (sodium, magnesium, calcium, aluminum, and iron nitrates) is presented. The effect of the salting-out agents fits in the previously suggested mathematical description of these extraction equilibria without salting-out agents using the law of mass action and the previously suggested system of 11 equations with the corresponding concentration equilibrium constants without additional empirical corrections, but with recalculation of the concentrations of the aqueous phase components taking into account the molar volume of the salting-out agent in solution. With aluminum nitrate, it is also necessary to take into account its possible hydrolysis with variation of the calculated concentration of hydrated proton, but at an Al(NO3)3 concentration of 1 M without free HNO3 this correction is insufficient because of possible extraction of HNO3 produced by hydrolysis and of the shift of the extraction system to the region of acid-deficient aqueous solutions.

New Sorbents for Metal Salts based on Cation Exchange Extractants and Anion Exchange Resins: Their Preparation and Properties

Preparation and properties of binary sorbents containing a salt of cation exchange organic extractant in the matrix of a strongly basic anion exchanger were studied. Analysis of isotherms of exchange of chloride ions for dialkyldithiophosphate ions in the systems of various anion exchangers led to the conclusion that the stability of the binary sorbents depends on the amount of free water in the sorbent matrix. To improve the stability, it was proposed to use low cross-linked anion exchange resins or to use cation exchange extractants of moderate molecular volume. On the example of anion exchanger ММ-22x6.5 in the dibutyldithiophosphate form, it was shown that the binary sorbents efficiently recover chlorides of non-ferrous metals. The recovery increases in the series Ca2+<<Ni2+<Zn2+<<Cu2+. Because, in the systems studied, the anions are recovered together with cations, this leads to an increase in metal recovery in the presence of salting-out agents, and allows the desorbtion of the salts with water or with solutions of complexing agents. The binary sorbents offer good prospects for the recovery and separation of metal salts.

Extraction and preconcentration of anthocyan dye from aqueous solutions with water-soluble poly-N-vinylamides

Extraction of an anthocyan dye with poly-N-vinylpyrrolidone (PVP) and poly-N-vinylcaprolactam (PVC) under the conditions of separation of aqueous solutions of this polymer into two phases in the presence of salting-out agents (sodium chloride and sodium or ammonium sulfate) was studied.

Extraction and spectrophotometric determination of cobalt as pyridine-azide mixed ligand complex

Clem and Huffman [1] tested the efficiencies of extraction into chloroform of pyridine-azide complexes of eleven metals and suggested spectrophotometric methods for copper, nickel, and palladium in this system. The extracts of cobalt and gold were not sufficiently stable to warrant further investigations. A new spectrophotometric method for cobalt presented here is based on the extraction of pyridine-azide mixed complex of cobalt with methylisobutylketone (abbreviated as MIBK) in the presence of salting-out agent (calcium chloride). Solvents other than MIBK, including chloroform, benzene, nitrobenzene, cyclohexane, dichloroethane, n-butanol etc., resulted in very poor sensitivities; chloroform yielded only an apparent molar absorption coefficient of 501 tool 1 cm1 at 485 nm. The mixed ligand complex of cobalt was able to be extracted into MIBK over pH range of 5 6 . 5 in the presence of 2 M calcium chloride. Without the salting-out agent the maximum extraction was attained in the range pH 6 . 5 8, but the rate of extraction was sluggish; it took 1.5 h for the system to reach the extraction equilibrium. In the presence of 2 M calcium chloride the extraction became prompted, taking 30 rain to reach the maximum absorbance. The mixed complex showed an absorption maximum at 370 nm, its absorbance being held constant for at least 24 h. Azide concentration in the aqueous phase should be greater than 0.4M, and 1.5 ~ 2.5ml of pyridine was necessary for every 50 ml of the aqueous phase to get the highest absorbance. The volume of the aqueous phase should be held approximately constant to obtain reproducible results. Calcium chloride and sodium azide can be purified very effectively by a chelating resin Dowex A-1 column. Beer's law was obeyed in the range 0.1 4 p.g Co per ml of MIBK. Apparent molar absorption coefficient was 1.2 x 1041 tool~ cm~ (370 nm), the photometric sensitivity according to Sandell 0.005 ~tg cm -z. The sensitivity is somewhat better than that of the well known thiocyanate method (isoamyl alcohol) 0.055 (620 nm); 0.009 (310 nm) ~tg cm-2], and inferior to that of the Nitroso-R method [0.0019 ~tg cm -2] [2]. Effects of foreign ions were tested for the determination of 10.0 gg Co and a range of 10.3 _+ 0.5pg Co came out as the 95% confidence limit for the mean of population. The presence of 0.4 M nitrate, 0.4 M acetate, 0.04 M tartrate, and 0.04 M citrate did not interfere with the determination of 10.0 gg Co. A list of interference study is given in Table 1. Tartrate can act as a useful masking agent for aluminum(III), titanium(IV), and tin(IV), which otherwise form insoluble hydroxide precipitates. Iron(III), copper(II), and palladium(II) interfere seriously.