Magnesium oxide is a component of Portland cement used in dry-process cement plants.
Due to its acid-buffering capacity and effectiveness in stabilizing dissolved heavy metal species, magnesium oxide is widely used in soil and groundwater remediation, wastewater treatment, drinking water treatment, air emission control, and waste management.
Many heavy metals, such as lead and cadmium, are most soluble in water at acidic pH levels (<6) and high pH levels (>11). Metal solubility influences metal bioavailability and mobility within soil and groundwater systems. Since most metal species are toxic to humans at certain concentrations, it is essential to minimize their bioavailability and mobility.
Granular magnesium oxide is typically incorporated into metal-contaminated soil or waste-materials that often exhibit low (acidic) pH-to adjust the pH to the 8–10 range, where the solubility of most metals is at its minimum. Metal hydroxide complexes tend to precipitate from aqueous solution within this pH range. Magnesium oxide is widely recognized as the most effective metal stabilizer-outperforming Portland cement, lime, kiln dust products, power generation by-products, and various proprietary products-due to its superior buffering capacity, cost-effectiveness, and ease and safety of handling.
Most, if not all, products marketed for metal stabilization create extremely high pH conditions in the aquifer; in contrast, magnesium oxide establishes an ideal aquifer pH of 8–10. Furthermore, as magnesium is an essential element for most biological systems, its use in magnesium oxide-assisted metal remediation provides an additional benefit to soil and groundwater microbial populations.