Adsorption of gas on ion exchangers. III. The pore structure of m‐aminophenol–formaldehyde condensation resins

Abstract

Abstractm‐Aminophenol was condensed with formaldehyde in an acid medium in the presence of a water‐soluble inorganic salt (NaCl, CaCl2 etc) and/or poly(ethylene glycol). The pore structure characteristics of the condensation products were investigated by measurements of average pore size, pore size distribution of channels, total pore volume, surface area, and electron microscopic observation. The type and concentration of inorganic salts appeared to be a significant variable for the resulting pore structure, while poly(ethylene glycol) had a little effect. The nongel interstices of products were channels between many agglomerates of minute spherical gel particles with narrow pore size distribution. The diameters of these spherical gel particles were 3–10 × 10−1µ from the scanning electron microscopic observation. Apparent dissociation constants of functional groups of resin, pKa and pKb, estimated by using the Henderson‐Hasselbach equation, were 10.94 and 10.99, respectively. The resin had an ion‐exchange capacity of 1.0 meq/g for base and 4.8 meq/g for acid.