Sorption of Fluoride Ions by Iron Oxyhydrate Fixed on the Carriers Part I. Organic Carriers

Abstract

The possibility of using an inorganic sorbent of iron oxyhydrate (IOH) for the removal of F^– ions from process solutions of zinc production is considered. The synthesis method of IOH is chosen. The results of scanning electron microscopy and X-ray phase analysis are presented. The possibility in principle of using ion-exchange resins as carriers modified by IOH is considered. The formation of an active substance on anion-exchange and cation-exchange resins is investigated. It is shown that the strongest composite sorbents are formed when using strong acidic cation-exchange resins with sulfonate groups. The method of IOH incorporation into the structure of carrier materials and the formation of composite sorbents is described. The KU-2×8 cation exchanger is recommended as the composite basis. To form IOH crystals of the β-modification distributed over the ion-exchanger grain bulk, iron-saturated cation exchangers are held in the sodium chloride solution with a concentration of 2.5 g/dm³ for 24 h at 85°C. Anion exchangers are held in the iron(III) sulfate solution with the sodium chloride additive for 24 h at t = 85°C. Herewith, the formation of IOH films on the surface of sorbent grains is observed. The fluorine was sorbed in a static mode from a model solution with the concentration of F^– = 100 mg/dm³ at t = 60°C. The sorption on the AV-17×8 anion exchanger is performed at t = 20°C. Adsorbed fluorine is desorbed by the 0.1 M NaOH solution at t = 60°C for 2 h. The synthesized KU-2×8-IOH composite sorbent has a capacity of 0.7–1.1 mg/g with respect to fluorine and can be regenerated with the formation of easily utilizable fluorine-containing eluate.