Anion exchange extraction of tallium (III) and mercury (II) complex salts and application of the procedure to extraction-photometric determination of the microquantities of mercury (II)

The goal is to study the anion-exchange extraction of complex thallium (III) and mercury (II) halides (chlorides, bromides, iodides) by a method of a competing intermediate ion using the anions of various dyes — methyl orange, sodium picrate, 2,4-dinitrophenol, methyl red. Mercury (II) and thallium (III) are poisons of high toxicity. The developed method was used to study the anion-exchange extraction of acidocomplexes A solution of methyl orange trinonyloctadecylammonium (TNODA) in toluene was used as an extractant. The method provides determination of mercury (II) with an accuracy of ±2% when the concentration in the initial solution ranges within 2 – 8 × 10–8 mol/liter. It is shown that the values of the exchange constants for the same metal are larger for iodide complexes than for bromide and chloride ones. The extractability of metal halide complexes is mainly determined by their mass. Anions with a large mass have a large surface area, a low charge density, and are weakly hydrated, and thus are better extracted. The results of anion-exchange extraction were used to develop a procedure for the extraction-photometric determination of mercury (II) in granosan (ethylmercury chloride a prohibited insectofungicide of the 1st hazard class) the illegal use and storage of which could be a source of mercury pollution of groundwater in a number of regions of the Republic of Belarus. The relative error of determination does not exceed ±2%.

Calix[4]arene-crown-5 as a selective extraction reagents for K+/H+, Rb+/H+ and Rb+/Cs+ separations

From extraction experiments, the exchange extraction constants corresponding to the general equilibriums M+ (aq) + NaL+ (org) ⇔ ML+ (org) + Na+ (aq) or M+ (aq) + CsL+ (org) ⇔ ML+ (org) + Cs+ (aq), which take place in the two-phase water–nitrobenzene extraction system (M+ = Li+, H3O+, Ag+, K+, NH4 +, Tl+, Rb+; L = calix[4]arene-bis crown5(1,3-alternate), 26,28-dipropoxycalix[4]arene-crown-5(1,3-alternate), 11,23-dibromo-25,28-dipropoxycalix[4]arene-crown-5 (1,3-alternate) and 1,3-alternate-25,27-dihydroxycalix[4]arene-crown-5; aq = aqueous phase, org = organic phase), were evaluated. The stability constants of the NaL+ and CsL+ complexes were calculated from the extraction of the respective picrates in the system of water–nitrobenzene solution of L. Further, the stability constants of the ML+ complexes in nitrobenzene saturated with water were determined. High selectivities were found in some systems under study.

STUDY OF ANION EXCHANGE EXTRACTION OF SOME ANIONIC COMPLEXES OF IRON (III) BY ORGANIC SOLUTIONS OF QUARTERLY AMMONIUM SALTS

The anion-exchange extraction of salicylate, thiosulphate and thiocyanate iron (III) complexes by solutions of chlorides of quaternary ammonium salts (QAS) in organic solvents (toluene, carbon tetrachloride, ethyl acetate, isobutyl alcohol, nitrobenzene) was studied. The composition of the iron (III) anionic complexes was established by the analysis of the calibration curves E = f(pCFe (III)) constructed from iron (III) solutions against the background of various contents of thiocyanate, thiosulphate and salicylate ions and the steepness of the electrode function. As an indicator electrode the ion-selective electrode was used with a membrane, which based on a nitrobenzene solution of tetradecylammonium bromide. The solution containing of alkyldimethylbenzylammonium chloride and alkyldimethylethylbenzylammonium chloride and the corresponding organic solvent were mixed in a ratio of 1:1. An organic layer containing the QAS was selected. The anion-exchange extraction was provided in contact with aqueoses solutions of Fe(III) anionic complexes. The extraction process is estimated quantitatively using a distribution coefficient (D). The value of D is calculated taking into account the iron (III) concentration in the aqueous phase before and after extraction. The content of iron (III) in solutions is determined spectrophotometrically (λ = 440 nm). It is established that the value of the distribution coefficient depends on the permittivity (ε) of the organic solvent. In the row toluene - carbon tetrachloride - ethyl acetate - isobutyl alcohol - nitrobenzene, the permittivity increases. In the same sequence, D increases for all studied complex iron(III) ions. Moreover, a decrease in the concentration of the extracted particle leads to an insignificant decrease in the value of the distribution coefficient. The composition and stability of the complex iron (III) ion have a significant effect on the extraction activity.