Synthesis of magnesium carbonate polymorphs from Indonesia traditional salt production wastewater

Magnesium carbonate nesquehonite crystals were synthesized by mixing of the salt manufacture wastewater (bittern) and Na ₂ CO ₃ with molar ratio 1:1 at room temperature. The effect of pH range (8-10) and initial magnesium concentration range (10,000-40,000 ppm) were investigated. Crystal morphology was observed using scanning electron microscopy and energy dispersive X-ray spectroscopy confirmed with X-ray diffraction. Large changes in morphology were observed in the increasing of initial concentration, which strongly depend on the pH. With an increase of pH, magnesium carbonate nesquehonite crystals change to hydromagnesite. However, reaction crystallization with initial magnesium concentration 40,000 ppm is found do not produce magnesium carbonate hydrated. Crystallization of magnesium carbonate nesquehonite is favored in the pH 8-9 with initial concentration in 10,000-20,000 ppm.