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›› 2008, Vol. 8 ›› Issue (1): 72-77.

• 过程与工艺 • 上一篇    下一篇

甲醇溶析铝酸钠制备氢氧化铝

王雪,郑诗礼,张懿   

  1. 中国科学院过程工程研究所
  • 出版日期:2008-02-20 发布日期:2008-02-20

Preparation of Aluminum Hydroxide with Dissolution of Sodium Aluminate in Methanol-Water Solvent

WANG Xue,ZHENG Shi-li,ZHANG Yi   

  1. Institute of Process Engineering, Chinese Academy of Sciences
  • Online:2008-02-20 Published:2008-02-20

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摘要： 以甲醇水溶液分解铝酸钠晶体，采用溶析法制备了超细氢氧化铝. 考察了30℃下氧化铝、氧化钠溶解度随甲醇质量分数的变化规律，研究了甲醇质量分数和反应温度对水合铝酸钠晶体分解工艺的影响，用XRD, IR, SEM及粒度分析、纯度分析等手段对制备的氢氧化铝产品进行了表征. 结果表明，随着溶剂中甲醇质量分数的增加，氧化铝和氧化钠溶解度均下降，但氧化铝下降幅度更大；铝酸钠溶液分子比(氧化钠/氧化铝摩尔比)先增加后减小，到甲醇质量分数为0.8左右时达到最大值. 30℃下水合铝酸钠晶体与甲醇质量分数为0.5~0.8的甲醇-水混合溶剂反应1~3 h，铝酸钠分解率可达到80%~90%，温度升高，分解率略有下降. 甲醇溶析得到的氢氧化铝30℃下为拜耳石型，温度升高逐渐变为三水铝石型，红外光谱完整. 产品形貌规则，为高纯薄片状超细氢氧化铝，平均厚度100 nm，平均粒径1.05 mm.

关键词: 溶析法, 铝酸钠, 甲醇, 溶解度, 氢氧化铝

Abstract: Aluminum hydroxide was prepared by solventing-out method using methanol and water in the decomposition of sodium aluminate. The solubility of Al2O3 and Na2O in methanol-water solvent with different mass ratios of methanol was investigated at 30℃. In addition, the effects of mass ratio of methanol and reaction temperature on decomposition process of sodium aluminate hydrate were studied, and the obtained product was characterized by XRD, IR, SEM techniques, particle size distribution and purity analysis. The results showed that the solubility of Al2O3 and Na2O decreased with the increase of methanol mass ratio to solvent, its effect on solubility of Al2O3 was more remarkable, increasing the molar ratio of sodium aluminate significantly up to a peak value when the mass ratio of methanol was 0.8. The decomposition rate of sodium aluminate hydrate reached to 80%~90% in 1~3 h when the mass ratios of methanol to solvent were 0.5~0.8, while the rate would slightly decrease with the increase of temperature. The product was identified as bayerite with integrated IR peaks at 30℃, and it transformed to gibbsite when the temperature was higher. The prepared aluminum hydroxide consisted of pure and uniform tabular particulates with average 100 nm in thickness and 1 mm in diameter.

Key words: solventing-out method, sodium aluminate, methanol, solubility, aluminium hydroxide