Removal of Silicic Acid from Feed Water Using a Tiron Combined Anion Exchange Resin Column

Abstract

Thorough removal of silicic acid from treated water, as a water pretreatment procedure, is essential for the prevention of silica deposits on anion exchange resins and reverse osmosis membranes. In this study, thorough removal of silicic acid was achieved using a Tiron (1,2-dihydroxy-3,5-benzendisulfonate) combined resin. In the column experiment, it was confirmed that silicic acid could be removed below the detection limit of the molybdenum-blue methods. Tiron, which can form a stable 1:3 Si-Tiron complex in aqueous solutions, merges anion exchange resins (Tiron resin) and exhibits a strong silicic acid removal ability over a wide pH range (pH 2–10). In the regeneration process, silicic acid could be easily removed from the Tiron resin through acid treatment (pH 2, HCl), and a mild alkaline treatment (pH 8, NaOH solution) was used to restore the silicic acid removal ability. Following the acid and alkaline treatments, the removal ability of the regenerated Tiron resin was maintained, suggesting that the resin could be reused in water treatment systems. Excess inorganic anion species did not affect silicic acid removal.

Keywords

• Silicic acid
• Selective removal
• Tiron
• Complexation
• Tiron combined resin