•Tubular MgO was fabricated via ammonium sulfate leaching and precipitation method.•The fabrication process of MgO was environmentally friendly.•Calcined dolomite (CaCO3·MgO) was obtained by calcination at 800 °C.•Mg was separated effectively via ammonium sulfate leaching from calcined dolomite.•The crystal growth behavior of MgO nanocrystals was analyzed.Tubular magnesium oxide (MgO) nanocrystals were fabricated via combining ammonium sulfate leaching and precipitation method with calcined dolomite (CaCO3·MgO) as magnesium source. The relationship between (NH4)2SO4/MgO molar ratio, volume of distilled ammonia and dosage of calcined dolomite and the leaching rate of magnesium were investigated, and the highest value of 96.81% for leaching rate was obtained by optimizing leaching conditions. The tubular MgO nanocrystals were synthesized by precipitation and calcination process, which were characterized by XRD, FT-IR, SEM and TEM. After calcination process, the crystallite size of MgO nanocrystals varies from 12.4 nm to 42.2 nm with the calcination temperature increases from 500 °C to 1000 °C. The activation energy for crystal growth of MgO nanocrystals is about 10.69 ± 1.13 kJ/mol before 650 °C, while it increases to about 27.02 ± 0.95 kJ/mol after 650 °C.Download high-res image (98KB)Download full-size image