Equilibrium sorption of methionine on carboxyl cation exchangers from solutions of various acidities

The influence of the acidity of solutions of methionine on methionine interaction with KB-2 and KB-4 carboxyl cation exchangers in the protonated and deprotonated forms was studied by the calorimetric, sorption, and spectroscopic methods. It was found that nonexchange methionine absorption occurred from acid solutions, and mixed ion exchange and nonexchange sorption, from alkaline solutions. The enthalpies of sorption of methionine at various external solution pH values were determined. Original Russian Text ? D.V. Ovsyannikova, L.P. Bondareva, V.F. Selemenev, S.I. Karpov, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 5, pp. 961–966.     

Kinetics of formaldehyde sorption by a weakly basic anion exchanger under dynamic conditions

The kinetic principles of sorption of formaldehyde sorption on a polyfunctional weak-basic anion exchanger are considered. It is found that the limiting step of sorbate uptake is external diffusion. Parameters of formaldehyde sorption from aqueous solutions under dynamic conditions are determined.     

Quantum-chemical approach to the justification of the mechanisms of sorption of the triterpenoid saponin by highly basic anion exchanger AB-17-2P in the chloride form

Computer simulation of interaction of the structural fragments of triterpenoid saponins with the anion exchanger AV-17-2P was carried out using the Gaussian 03 software. The results showed that a decrease in the energy of the system that includes the sum of the energies of electrostatic interactions and hydrogen bonding at the absorption by the anion exchanger of the polar part of the saponin molecule equals 18.9 kJ mol^?1 and at the absorption of oleanolic acid, 31.9 kJ mol^?1, that is, the sorption capacity of the aglycone was higher than that of glucuronic acid.     

Mechanism of Sorption Interaction between L-Alanine and Carbon Nanotubes

Russian Journal of Physical Chemistry A - A complex consisting of a model carbon nanotube and L-alanine located on its outer side surface, inside it, and at its end is simulated by quantum-chemical...     

Determination of Citrate Ions by Potentiometric Titration with a Copper-Selective Electrode in Monitoring the Production of Citric Acid

A simple and rapid procedure was developed for the potentiometric titration of citrate ions in fermented solutions from citric acid production with the use of a copper-selective electrode.     

Electrodialysis of Binary Electrolyte Mixtures with Membranes Modified by Organic Species

The modification of anion-exchange membranes MA-40 by lauric acid and sodium polystyrenesulfonate is studied. By measuring the wetting angle and using IR spectroscopy, the mechanism of sorption of the modifiers by the membranes is established. The membrane modification is accompanied by hydrophobization of a surface layer and the formation of strong bonds between functional groups of membranes and modifiers. The concentration dependence of the ion separation coefficients in electrodialysis of binary electrolyte mixtures with modified and nonmodified membranes is studied. The selectivity of modified membranes to less-hydrated ions increases and the smaller the solution concentration, the larger the ions.     

The nonexchange sorption of histidine by low-basicity anion exchangers

The experimental data showed that the nonexchange absorption of histidine by AN-221, AN-251, AN-31, and EDE-10P anion exchangers in the HCl form depended on the structure of the anion exchanger. The activity coefficients of the components of the sorbent phase, thermodynamic equilibrium constants, and standard Gibbs energies of nonexchange sorption of histidine by the low-basicity anion exchangers were calculated and discussed.     

Ion exhange and molecular sorption of oxalic acid with a highly basic anion exchanger

Ab initio modeling of a matrix fragment of resin and geometry optimization of the molecular structure of oxalic acid were performed. The isotherm of oxalic acid sorption with AV-17-8 anion exchange resin was obtained by the variable concentrations technique. The ion-exchange and molecular components of sorbate fixation with the ion exchanger were determined. The hydration of the highly basic anion exchanger that absorbed different quantities of dicarboxylic acid was evaluated by the centrifuging method. The dependence of the amount of water and sorbate concentration in the resin was linear antibatic.     

Effect of temperature on the adsorption of phosphatidylcholine by silicon-containing materials with various degrees of order

Features of the adsorption of phosphatidylcholine (PCh) by inorganic silicon-containing materials with various degrees of order (MCM-41, MMC-1, and silica gel) from solutions in hexane under equilibrium conditions in the temperature range of 283–323 K are considered. It is found that the adsorption of the phospholipid within the C _e = (0.6–4.0) × 10^–4 mmol/dm³ range of concentrations on the investigated materials is characterized by monomolecular absorption. Differential thermodynamic characteristics (ΔG, ΔH, and ΔS) of the sorption of PCh by silicon-containing materials with various degrees of order in the temperature range of 283–323 K are considered. An increase in the affinity of silicon-containing materials toward the phospholipid upon an increase in the temperature of the sorption process is observed.