| 摘要 |
The ion exchanger consists entirely or substantially of a condensation product obtained from polyhydroxybenzene having not less than 2 adjacent hydroxyl groups (ortho-position) and formaldehyde in a molar excess of 5 to 15%, or contains such a condensation product incorporated therein, wherein the condensation product has a reversible water content of not less than 40% by weight. A process for preparing such an ion-exchanger comprises reacting in an inert medium (e.g. paraffin) 3.4 M pyrogallol with a 10% molar excess of 37% aqueous formaldehyde solution at 85-90 DEG C, and pH 6 to 6.8. The product is cured at 115 to 120 DEG C for 15 to 25 hours and then the inert medium filtered off. |
