氢氧化钠溶液中氢氧化镁的水热改性

考察了团聚态氢氧化镁在氢氧化钠溶液中的水热改性行为，分析了氢氧化钠浓度与水热产物形貌、结构与分散性的关系. 水热改性后氢氧化镁晶体的生长方向发生变化，特征衍射峰强度I(001)/I(101)比值明显变大，产物形貌规则、大小均匀、比表面积小、分散性好. 实验条件(1~5 mol/L NaOH)下，氢氧化钠浓度越高，水热改性效果越显著. 热力学计算结果表明，Mg(OH)2-NaOH-H2O体系中，OH-浓度远高于可溶性含镁组份Mg(OH)2(aq), MgOH+, Mg2＋]的浓度，高浓度氢氧化钠体系中氢氧化镁水热改性效果的强化可归因于OH-浓度的增加.

Hydrothermal Modification of Mg(OH)2 Particles in NaOH Solution

The hydrothermal modification behavior of Mg(OH)2 particles in aqueous NaOH solution was investigated, with focus on the influence of NaOH concentration on the morphology, crystalline structure and dispersion properties of the hydrothermal products. Regular hexagonal plates of Mg(OH)2 with uniform size and smaller specific area were formed after hydrothermal treatment. The dispersion properties of the hydrothermal products were improved owing to the alteration of growth direction for Mg(OH)2 crystals, resulting in the increase of I(001)/I(101). Under the experimental conditions (1.5 mol/L of NaOH), the increase of NaOH concentration is favorable to the hydrothermal modification of Mg(OH)2 particles. Thermodynamic calculation indicated that in the Mg(OH)2 NaOH-H2O system, the concentration of OH- ions was much higher than that of soluble Mg-bearing species Mg(OH)2(aq), MgOH+ and Mg2+]. The improvement for the hydrothermal modification of Mg(OH)2 in the comparatively concentrated NaOH solution may be attributed to the increase of OH- concentration.