Phosphoric Acid Cation Research Articles

Synthesis of phosphoric acid cation- exchange polymer of polycondensation type

Synthesis of phosphoric acid cation- exchange polymer of polycondensation type

Radiation stable graft copolymers based on petroleum asphaltite

A new type of the latent reactivity of petroleum asphaltites, which manifested itself under the action of γ-radiation, was determined. γ-Radiation facilitates the conversion of the asphaltites into macromolecular initiators onto which the macromolecular chains of styrene, methyl methacrylate, and acrylic acid are grafted. Based on this new type of reactivity, phosphoric acid cation exchangers and multifunctional cation exchangers were synthesized using the most environmentally appropriate non-power-consuming wasteless method.

Preparation and characterization of phosphoric acid cation exchangers from petroleum asphaltites

A phosphoric acid cation exchanger having an exchange capacity of 3.5 mg-equiv/g and a mechanical strength of 95% was prepared based on a graft copolymer of asphaltite and styrene using chloromethylation and then phosphorylation reactions. A number of metal chloride catalysts and the reaction kinetics of phosphorylation were studied. It was found that the resulting phosphoric acid cation exchangers are more stable than analogous commercial materials.

New phosphorus-containing sorbents based on wheat straw and glycidyl methacrylate for Hg2+ removal

The possibility of preparing new phosphoric acid cation exchangers based on wheat straw and glycidyl methacrylate was explored. The mercury(II) ion sorption properties of the prepared cation exchangers were studied.

Phosphoric acid cation exchanger based on immobilized cis-calix[4]resorcinolarene

New phosphoric acid cation exchanger was synthesized on the basis of immobilized calix[4] resorcinolarene and its service characteristics were determined.

Sorption of uranium from nitric acid solutions on various ion exchangers

Sorption of uranium from model nitric acid solutions on ion-exchange resins of various types was studied. Phosphoric acid cation exchanger KRF-20, an ampholyte with iminodiphosphonic groups (S-950), and a cation exchanger with phosphonic and sulfonic groups (S-957) exhibit the best sorption properties. The dependences of the static exchange capacity of the above resins for uranium on the HNO3 concentration, the sorption isotherms in 1 and 3 M solution of HNO3, and the capacity for uranium to breakthrough were determined. The possibility of uranium desorption with a hot solution o Na2CO3 was demonstrated.

Uranium sorption from nitric acid solutions with cation exchangers and polyampholytes

Sorption of uranium ions with KU-2 × 8 sulfonic cation exchanger, KFP-12 phosphoric acid cation exchanger, and aminophosphoric acid ampholytes was examined in nitric acid solutions containing different amounts of HNO3. Formation of polymeric complexes was confirmed by IR spectra. The ion-coordination mechanism of U sorption with KFP-12 cation exchanger was clearly manifested; also possible is sorption of U as a single-charged nitrate complex ion. The isotherms of sorption of the U ions with KFP-12 cation exchanger have a convex shape with a sharply ascending portion at low U concentrations, which is favorable for U recovery from raffinate solutions. Nitrogen-phosphorus-containing polyampholytes also possess a high sorption power with respect to the U ions in nitric acid solutions. The highest exchange capacity is exhibited by ANKF-80 and ANKF-86 polyampholytes on polyacrylate base.

Proton Hopping in Phosphoric Acid Solvated Nafion Membrane: A Molecular Simulation Study

Molecular simulation studies of the microstructure and of the proton transport properties of phosphoric acid solvated Nafion membrane are carried out. The ab initio calculations show that the phosphoric acid is a good solvent to promote the proton ionization of the sulfonic acid group, and only two phosphoric acid molecules are necessary for the dissociation of one sulfonic acid group. A mechanism of proton hopping between phosphoric acid and protonated phosphoric acid cation in the hydrophilic subphase is also elucidated by ab initio calculations. The molecular dynamics simulations, conducted at a phosphoric acid concentration of 25.4% (wt) which is slightly lower than that of phosphoric acid swollen Nafion, show that the phosphoric acid exists in subphases and that it cannot develop into a continuous subphase. Thus, proton-hopping pathways are interrupted, and the conductivity is expected to be lower than that for pure phosphoric acid. The molecular dynamics simulations, conducted at a phosphoric acid concentration of 45.1% (wt) which corresponds to an unstable state, show that the hydrophobic poly(tetrafluoroethylene) backbones trend to gather together forming hydrophobic clusters and that the phosphoric acid forms a continuous subphase with the sulfonic acid groups located at the hydrophobic/hydrophilic interface. Thus, proton-hopping pathways can develop uninterruptedly like the pure phosphoric acid, and high conductivity is expected. The molecular dynamics study also shows that the hydrogen-bonding characteristics of phosphoric acid and sulfonate anion are similar regardless of the factor that the former can move freely while the latter is attached to Nafion backbone.

Phosphoric acid cation exchange resins from chemically modified polyvinyl chloride

AbstractPVC modified by Cl displacement reaction with meta‐aminophenol (MAP), bisphenol A (BISA), and phenolphthalein (PHEN) has been converted into phosphoric acid cation exchange resins. These resins have been characterized in regard to their structure, ion exchange properties, and thermal stability. The ion exchange capacities fall into the range 5.5–8.0 (meq/g) for the resins. The overall thermal stability is considerably higher than that for the corresponding sulfonic acid resins, as well as for the PVC–MAP, PVC–BIS A, and PVC–PHEN condensates. The resins exhibit ca. 4–6% capacity losses under isothermal hydrolytic cleavage at 100°C for 24 h.

Dynamics and kinetics of the desorption of oxytetracycline from phosphoric acid cation exchangers

Dynamics and kinetics of the desorption of oxytetracycline from phosphoric acid cation exchangers

Determination of the association constants of H4PO4+HSO4− by 31P NMR and cation-exchange methods

The existence of the phosphoric acid cation H4PO4+ in concentrated mixtures of sulphuric acid and phosphoric acid, and in the sulphonic type cation exchanger phase was confirmed, though this cation is usually present associated with an anion. The association constants of H4PO4+HSO4− were determined by using 31P NMR and cation-exchange methods, with newly-introduced equilibrium analyses involving a constant water activity concept.

Kinetics of ion exchange sorption of oxytetracycline on phosphoric acid cation exchange resins

The rate of an ion exchange process depends on the structure of the absorbent, the particle size, the amount and chain length of cross-linking agent, mixing conditions, temperature, ion concentration, selectivity of sorption, and other conditions. In a series of studies it was shown that Changing these factors may influence the kinetics of the ion exchange process to a significant extent. The lowest diffusion coefficients for tetracycline (2.5-5 • 10 -I~ cm2/sec) and for oxytetracycline (6 • 10 -I~ cm2/sec) were obtained in Dowextype polymerized resins [i, 2]. On going over to a condensation resin the diffusion coefficient was somewhat increased (approximately twofold). Use of macroreticular sorbents made it possible to obtain a diffusion coefficient of the order of 10 -8 cm2/sec. An appreciable increase in the rate of the process may be obtained without changing the diffusion coefficients by taking a finely dispersed fraction of ion exchange resin [3].