Dipodal Tetraamide Derivatives of 1,10-Diaza-18-Crown-6 and Alkylmalonic Acids—Synthesis and Use as Ionophores in Ion Selective Membrane Electrodes

Novel dipodal derivatives of an 18-membered diaza-crown ether with two diamide chains featuring methylmalonic or butylmalonic acid residues were obtained and tested as ionophores in ion-selective plasticized membrane electrodes. The objective of the study was to identify measurement conditions which ensure the most favorable performance for magnesium ion-selective electrodes. The relationship between the molar lipophilic anion salt-to-ionophore ratio and selectivity of electrodes was examined. The best result was obtained for the conventional electrode containing Mg2 ionophore. Calculated selectivity coefficients were as follows: logKMg/Ca = −2.77, logKMg/Na = −3.46 and logKMg.K = −2.24 (SSM, 1M).

New Polymer Inclusion Membranes in the Separation of Palladium, Zinc and Nickel Ions from Aqueous Solutions

The new polymer inclusion membrane (PIM) with a 1-alkyltriazole matrix was used to separate palladium(II) ions from aqueous chloride solutions containing a mixture of Zn-Pd-Ni ions. The effective conditions for transport studies by PIMs were determined based on solvent extraction (SX) studies. Furthermore, the values of the stability constants and partition coefficients of M(II)-alkyltriazole complexes were determined. The values of both constants increase with the growing hydrophobicity of the 1-alkyltriazole molecule and have the highest values for the Pd(II) complexes. The initial fluxes, selectivity coefficients, and recovery factors values of for Pd, Zn and Ni were determined on the basis of membrane transport studies. The transport selectivity of PIMs were: Pd(II) > Zn(II) > Ni(II). The initial metal ion fluxes for all the cations increased with the elongation of the alkyl chain in the 1-alkyltriazole, but the selectivity coefficients decreased. The highest values of the initial fluxes at pH = 4.0 were found for Pd(II) ions. The best selectivity coefficients Pd(II)/Zn(II) and Pd(II)/Ni(II) equal to 4.0 and 13.4, respectively, were found for 1-pentyl-triazole. It was shown that the microstructure of the polymer membrane surface influences the kinetics of metal ion transport. Based on the conducted research, it was shown that the new PIMs with 1-alkyltriazole can be successfully used in an acidic medium to separate a mixture containing Pd(II), Zn(II) and Ni(II) ions.

EFFECT OF STERIC ACCESSIBILITY OF EXCHANGE CENTER OF HIGHER QUATERNARY AMMONIUM SALTS AND PLASTICIZER NATURE ON CHARACTERISTICS OF ELECTRODES, REVERSIBLE TO DOUBLE-CHARGED ANIONS

The effect of the steric accessibility of the exchange center of higher quaternary ammonium salts and plasticizer nature on the selectivity and the limit of detection for film electrodes reversible to hydrophilic double-charged anions was studied. It was established the decrease in selectivity coefficients lgKi,jPot by 2.8−3.8 order of magnitude and low detection limit by 2−3 order of magnitude in the series of QAS: TOD≤TC<TL<TNODA<TB<TE<TM< DCPBTM. Also, the increase in low detection limit by 1−0.7 order of magnitude in the series of plasticizers: DBP>DDP>o-NPDE>1-BN was established. The composition of membranes of ion-selective electrodes was optimized.

Anion recovery from water by cross-linked cationic surfactant nanoparticles across dialysis membranes

Ion exchange selectivity coefficients for a new cross-linked micellar nanoparticle are reported and are used to predict specific ion recovery (e.g., phosphate) across dialysis membranes.