间歇鼓泡碳化法制备立方形纳米碳酸钙工艺条件优化

Optimization of Processing Conditions for the Preparation of Cubic Nano-sized Calcium Carbonate by Intermittent Bubbling Carbonation

关键词:  纳米碳酸钙  间歇鼓泡碳化法  六偏磷酸钠  工艺优化

Key words:  nano-sized calcium carbonate  intermittent bubbling carbonization  sodium hexametaphosphate  process optimization

摘要:

[目的]探讨制备晶型均一且粒度分布窄的立方形纳米碳酸钙的最优工艺条件。[方法]采用改进的间歇鼓泡碳化法优化制备立方形纳米碳酸钙工艺,研究碳化温度、Ca (OH)₂浓度、CO₂流率、晶型控制剂(NaPO₃)₆用量及加入时间、搅拌速率等因素对碳化反应时间及纳米碳酸钙粒径的影响,并对所制备的纳米碳酸钙进行粒度分布、FESEM和XRD表征。[结果]合成立方形纳米碳酸钙的最优工艺条件:在碳化温度10℃,Ca (OH)₂初始浓度为3.8%(W/W),CO₂流率为300 mL·min^-1,搅拌速率800 r·min^-1,碳化反应开始后5 min加入2%(NaPO₃)₆(占CaCO₃理论产量的质量百分数)时,制备出粒径约为40 nm且粒度分布均匀的立方形纳米碳酸钙。XRD结果表明,所制备的纳米CaCO₃为方解石六方晶系。[结论]本方法操作简单且无需二次碳化,产品重复性好。

Abstract:

[Objective] The optimal process conditions were explored for preparing cubic nano-sized calcium carbonate with uniform morphology and narrow particle size distribution.[Methods] An improved intermittent bubbling carbonization method was adopted to synthesize cubic nano-sized calcium carbonate.Many significant operational conditions were investigated, including carbonation temperature, the initial concentration of calcium hydroxide, the injection flow rate of carbon dioxide, sodium hexametaphosphate addictive and the stirring rate which have important effects on the particle size and reaction time.In addition, size distribution, field emission scanning electron microscopy and X-ray diffraction were applied to characterize the particle.[Results] The optimum conditions were as follows:The carbonization temperature was 10℃, the initial Ca(OH)₂ concentration was 3.8%(W/W), the flow rate of CO₂ was 300 mL·min^-1, 2% sodium hexametaphosphate was added after 5 min of reaction time, and the stirring rate was 800 r·min^-1.The cubic nano-sized calcium carbonate was obtained with an average particle size of 40 nm.XRD results showed that the cubic nano-sized calcium carbonate was identified as calcite with hexagonal structure.[Conclusion] This method is simple with a stable and reliable quality of product.Moreover, there is no need for the secondary carbonation.Thus the research has a great significance to industrial production.