[en] Enthalpies of Cl^– anion exchange for anions of nicotinic, isonicotinic, dipicolinic, and cinchomeronic acids on the strongly basic anionite AV-17-8 are measured at 298 K by means of microcalorimetry. Partial and standard enthalpies of sorption of pyridinecarboxylic acid anions on the Cl-form of AV-17-8 anionite from aqueous solutions are determined. The values of standard enthalpies lie in the range 3–14 kJ/mol, increasing in the order nicotinate, isonicotinate, dipicolinic acid anions, and cinchomeronic acid anions.

[en] Ion-exchange encapsulation of niacin into nanocontainers on polymer matrices was performed. Dowex-50 cation-exchange resin, sulfonated polymer based on metacyclophanoctol, zirconium phosphate, and Dowex-1 strongly basic anion-exchange resin were used as matrices. The niacin encapsulation was proved by the experimental data on the material balance of niacin in the equilibrium solution and polymer and was confirmed by solid-state ¹³С and ¹⁵N NMR spectroscopy of the polymers. Niacin in the nanocontainers occurs in the form of cations or anions. The niacin content of the nanocontainers on Dowex-1 and Dowex-50 matrices is 33 and 64% relative to the polymer weight. Niacin was released from the nanocontainers by elution with aqueous HCl and NaCl solutions simulating the electrolyte composition of the human gastrointestinal tract.

[en] Thermodynamics and kinetics of sorption with the participation of nicotinic and isonicotinic acids on the strongly basic anion exchanger АВ-17-8 were studied. According to calorimetric measurements, partial (differential) heat of sorption was estimated for anions and zwitterions of pyridinecarboxylic acids upon sorption by the OH-form of the anion exchanger AB-17-8 at 298K. Sorption of zwitterions of pyridinecarboxylic acids by the OH-form of the strongly basic anion exchanger can be presented as the process that involves independent reactions of ion exchange, dissociation of pyridinecarboxylic acid, and neutralization. The kinetics of sorption on the strongly basic anion exchanger with the participation of nicotinic and isonicotinic acids is shown to be controlled by the slow diffusion of the components in the polymer phase. For the organic anion in the phase of the anion exchanger АВ-17-8, the diffusion coefficient is equal to (1.3±0.4)•10^–12 m² s^–1.

[en] The sorption—desorption kinetics of nicotinic and isonicotinic acids on strong acid cationites (sulfocationite CU-2-8, sulfonated polycalixarene) were considered. The rate of the processes, following both the cation exchange mechanism H⁺ ⇄ Cat⁺ and the ion exchange mechanism accompanied by the chemical reaction of protonation of pyridinecarboxylic acid zwitterions, is determined by a slow diffusion of components in the polymeric phase. The interdiffusion coefficient in sulfocationite CU-2-8 for the process H⁺ ⇄ Cat⁺ was equal to ~1•10^–11 m² s^–1, in sulfonated polycalixarene the corresponding value was in the range of (1—4)•10^–12 m² s^–1.