Synthesis of Hydrocalumite-like Adsorbent from Blast Furnace Slag using Alkali Fusion

Abstract

Blast furnace (BF) slag, one of the byproducts of iron- and steel-making plants, was converted into a hydrocalumite-like compound using the alkali fusion method. The slag was transformed into the precursor with reactive phases via alkali fusion, after which the precursor was added to distilled water and stirred at room temperature to synthesize the product including a hydrocalumite-like compound. The effects of the mixed ratio of NaOH to the slag (NaOH/slag ratio), fusion temperature, ratio of precursor mass to distilled water volume (W/V ratio) and crystallization reaction time on the product phase were investigated, and the removal abilities of the obtained product for certain ions from aqueous solution was examined. Optimal conditions for hydrocalumite synthesis are a NaOH/slag ratio of 1.6, fusion temperature of 600°C, W/V ratio of 125 g/L and reaction time of more than 24 h. The product could remove more NH₄⁺, Sr²⁺, F^–, PO₄^3– and AsO₄^3– than BF slag, while the removal of Cl^–, SO₄^2– and NO₃^– was almost zero. These results suggest that a hydrocalumite-like adsorbent able to remove pollutant ions in aqueous solution can be synthesized from BF slag via alkali fusion.