Materials for removing suspended impurities and use thereof

A regeneratable (H form) cation exchange resin which is a particulate organic polymeric adsorbent for adsorbing and removing suspended impurities present in trace amounts in the water to be treated and which are chiefly composed of metal oxides, said resin:

• (a) having a dual structure with a skin layer being present to a depth of at least 0.1-10 .mu.m from the surface,
• (b) comprising particles in a true spherical form having a diameter of 0.2-1.2 mm and an effective specific surface area of 0.02-0.20 m m.sup.2 per gram of dry resin, with the effective specific surface area being measured on the basis of the amount of adsorption of krypton and/or a gas equivalent to krypton;
• (c) having such a surface layer structure that unit granules having a size of 0.1-1.0 .mu.m are seen to bind with one another when examined under a scanning electron microscope in the field of view ranging from a magnification of 50 to 200.000, preferably from 1,000 to 10.000;
• (d) having a honeycomb and/or scaly surface structure with grooves in the surface, unit honeycombs and/or scales each having a unit surface area of 1-50 .mu.m.sup.2 and agglomerating together to form an irregular surface structure and morphology, with the surface being such that the individual unit honeycombs and/or scales are adjacent to one another via grooves having a width of 0.1-5.0 .mu.m and a depth of 0.1-5.0 .mu.m, said grooves having an overall length of 100-1,000 mm/mm.sup.2 ;
• (e) having a crosslinking degree of from 3% to 8%;
• (f) having a surface pH (the concentration of hydrogen ions at the solid surface) of 1.50-1.90 in a wet state;
• and
• (g) having an interfacial electrokinetic potential (zeta potential) of -20 to -40 mV in a powder state in the range of about 50-100 .mu.m (about 150-300 mesh) obtained by pulverizing said resin.