Synthesis of magnesium sulfate from seawater using alkaline industrial wastes,sulfuric acid,and organic solvents

ABSTRACT

In this study, we used three processes to synthesize magnesium sulfate from seawater. First, alkaline industrial wastes, cement kiln dust and paper sludge ash, were injected to the seawater to precipitate magnesium in the form of magnesium hydroxide (Mg(OH)₂). Then, magnesium was eluted with a small amount of H₂SO₄ to make a high concentration magnesium solution. Finally, an organic solvent was added to precipitate magnesium sulfate (MgSO₄). Over 90% of magnesium was recovered through the three processes. It is expected that 11.3 kg of magnesium sulfate (based on MgSO₄ · 6H₂O) can be synthesized from 1 ton of seawater.