Synthesis of reactive MgO from reject brine via the addition of NH$_{4}$OH

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 NH$_{4}$OH. The molar amount of NH$_{4}$OH was optimized at a NH$_{4}$OH/Mg$^{2 +}$ 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 2 h 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 Mg$^{2 +}$ and the synthesis of reactive MgO with a wide range of potential applications.The authors would like to acknowledge research scholarship from Energy Research Institute at Nanyang Technological University