Abstract: Precipitation of various forms of magnesium carbonate hydrates was investigated by the reaction of MgSO4 with Na2CO3 at the temperatures from 283 to 363 K. XRD and SEM analysis showed that the reaction temperature had great effect on the morphology of precipitate. Three morphologies, needle-like, spherical-like and sheet-like, were obtained. The needle-like nesquehonite (MgCO3×3H2O) was synthesized from 283 to 313 K. When the temperature was below 303 K, the crystals obtained exhibited a smooth surface, with the increase of reaction temperature to 313 K, the needle-like particles displayed coarse surface covered by little rod-like crystals. When the temperature was up to 323~363 K, the spherical-like crystals were obtained, and with the temperature increasing, the diameter of crystals increased. The initial concentration of MgSO4 and Na2CO3 titration speed had also significant effect on crystal morphology of nesquehonite.

Key words: nesquehonite, hydromagnesite, composition, morphology, reaction temperature

摘要： 研究了由MgSO4和Na2CO3在283~363 K反应沉淀得到的碳酸镁水合物的组成和形貌随反应温度的变化规律，并对产品进行了表征. 结果表明，在283~313 K间，可得到棒状三水碳酸镁(MgCO3×3H2O)；当温度升高到323 K时，产物由棒状三水碳酸镁变为球形碱式碳酸镁，且随着反应温度升高，球形碱式碳酸镁的直径增大. MgSO4的初始浓度和Na2CO3滴加速率对三水碳酸镁晶体形貌有明显的影响.

关键词: 三水碳酸镁, 碱式碳酸镁, 组成, 形貌, 反应温度