Carboxylic Cationite Research Articles

Studies of H+-Mg2+ and H+-Ca2+ Exchanges on Acrylic Carboxylic Cationites from the Viewpoint of the Exchange Equilibrium Theory

The sorption of Mg2+ and Ca2+ ions by the H-form of the acrylic carboxylic cationite Lewatit CNP 80 as the magnesium sulphate or calcium chloride concentration in the external solution was varied by two orders of magnitude has been considered from the viewpoint of the ion-exchange equilibrium theory. The experimental data were obtained using a method which provided high precision measurements of the potentiometric titration curve over a wide range of resinate compositions for the ionite gel phase. The strong dependence of the effective equilibrium constant on the resinate solution composition was described satisfactorily by the exchange equilibrium theory. The selectivities towards Ca2+ and Mg2+ ion sorption by the H-type of carboxylic cationite studied were close. An explanation for this phenomenon was proposed.

Composition of the clathrate polyhydrate of a carboxyl cationite in the tetraisoamylammonium form

It is shown that a clathrate polyhydrate of constant composition is formed at 0 °C in the three-component system: cross-linked carboxylic cationite in tetraisoamylammonium form–water–ethanol in the range of ethanol concentration from 0 to 22 mass%.

Some features of the bonding of proteins to carboxylic macronetwork resins

A study has been made of the bonding of proteins (serum albumin, haemoglobin, chymotrypsinogen) to carboxylic macronetwork cationites synthesized from methacrylic acid and ethylenedimethacrylamide. It was found that a change in the degree of ionization of the cationites in the range α = 0·15−0·4 involving breakdown of the secondary structure of polymethacrylic acid chains between chemical crosslinks in the network, results in an increased sorptive capacity of the proteins, reaching a maximum at α = 0·35. The sorption of proteins on carboxylic cationites has been investigated for two degrees of ionization ( α = 0 and 0·4), where polymer chains of the network structure are in different conformational states. The cooperative character of the sorption isotherms was observed for proteins on the nonionized form of the cationite, when the PMAA chains are tighly packed into a secondary structure; the usual type of Langmuir isotherm appears when α = 0·4.

Influence of the porosity of carboxyl cationites of Solose K on the diffusion and kinetics of H 2O sorption

A kinetic study has been made of the sorption of H 2O vapour by Solose K samples of differing porosity. The porous structure of the sorbents influences the sorption kinetics. Properties of the porous polymeric sorbent change during the sorption process and approximate to those of the nonporous one, which is due to the closing of pores. This develops at very low levels of relative pressure of the sorbate (below 0·1).

Dynamic regularities of sorption of terrilytin Asp. terricola by carboxyl cationites

Dynamic regularities of sorption of terrilytin Asp. terricola by carboxyl cationites

Potentiometric titration of a suspension of crosslinked polymethacrylic acid

An aqueous suspension of a macro-mesh carboxylic cationite with particles of size ∼ 0·5 μ has been prepared from methacrylic acid and ethylene dimethacrylamide (2·5 mole %). The degree of dispersity was such that methods of polarized luminescence and potentiometric titration could be used for the investigation. Ionization of the polymethacrylic acid (PMAA) chain of the ionite network is accompanied by transition from the form with crosslinking due to hydrophobic interaction to a disordered form. This transition takes place as a cooperative process, and occurrs within a narrow interval of ionization degrees (α), as in the case of soluble PMAA. Three regions corresponding to the crosslinked and disordered forms, and to the transition, are readily distinguishable on the potentiometric titration curves plotted with the coordinates p K− α and pH-log (1−α)/α. The extent to which the ionic strength of solutions influences ionization of the suspention was investigated. The experimental results apply equally to coarse particle suspensions of the studied cationite.

Synthesis and properties of cationite KB 51�2, suitable for isolation and purification of proteases from culture liquids of microorganisms

1. A method has been developed for the synthesis of a lightly cross-linked carboxylic cationite suitable for the isolation of proteolytic enzymes from the culture liquids of microorganisms. 2. The principal sorption and physical properties of the ion exchange agent have been determined.