Synthesis of reactive MgO from reject brine via the addition of NH₄OH

Reactive magnesia (MgO) with a high purity and reactivity is used in several high-end applications. This study reports the feasibility of synthesizing high reactivity MgO from reject brine with the use of NH₄OH. The molar amount of NH₄OH was optimized at a NH₄OH/Mg²⁺ molar ratio of 6 to provide maximum magnesium oxide yield and purity. This led to the synthesis of Mg(OH)₂ with a purity of 93.5%, which was further calcined at 500 °C for 2h to produce reactive MgO with a SSA of 78.8 m²/g. This study shed light on the significant potential of reject brine in the recovery of Mg²⁺ and the synthesis of reactive MgO with a wide range of potential applications.