4.2.2. Steel industry wastes (blast furnace slag, sludge and dust)
The steel industry also produces a number of wastes in large quantities such as blast furnace slag, dust and sludge, etc. and these have been investigated as adsorbents. Dimitrova investigated ungranulated blast furnace slag for the removal of Cu2+, Ni2+, and Zn2+ ions from water and reported that slag alkalizing activity creates conditions for adsorption through hydroxocomplex formation and colloidal particles of silicic acid. Slag columns were utilized by the same worker for lead removal. Kanel et al. used blast furnace slag for As(III) remediation. The maximum As(III) adsorption by slag was reported as 1.40 mg As(III)/g of slag at 1 mg/L As(III) initial concentration. Several other researchers also tested the potential of slag for different metal ions removal.