烟酸在水中的溶解度及介稳性质的研究

Study on solubility and metastable properties of nicotinic acid in water

介稳区宽度(MSZW)是结晶过程设计的重要参数,为了得到高纯度大颗粒的烟酸晶体,应将结晶条件控制在介稳区内。测定烟酸在293.15—323.15K下的溶解度,并用Apelblet经验方程关联,与实验值相比有较好的拟合效果,相对偏差在0.66%以下,平均偏差为0.27%;以溶解度数据为基础,计算了烟酸的溶解热力学参数。另外,通过聚焦光速反射测量(FBRM)技术测定烟酸的介稳区宽度,研究了降温速率、搅拌速率和晶种加入量对介稳区宽度的影响,研究发现,较小的降温速率、较大的搅拌速率以及加入晶种都会使介稳区宽度变窄;适当增大晶种数目,可以有效调节介稳区。溶解度及介稳区的测定,为生产过程工艺放大以及结晶器的设计提供数据支撑。

The metastable zone width (MSZW) was a vital parameter for design of crystallization processes. Crystallization conditions were controlled in the metastable zone to obtain nicotinic acid (NA) with high purity and a large granularity. The solubility of NA was determined experimentally in the temperature range from 293.15 K to 323.15 K. The experimental data are correlated by Apelblet empirical equation satisfactorily, and the calculation results show the relative deviation less than 0.66%, as well as the average deviation is just 0.27%. Meanwhile, based on solubility data, thermodynamic properties are calculated in dissolution. Moreover, MSZW of NA was determined by focus beam reflectance measurement (FBRM) technique. The effects of cooling rate, agitation rate, and seed addition quality on the MSZW were investigated. It is observed that the MSZW has a decrease with the lower cooling rate, the faster agitation rate and the increasing number of seed. These two parts of work should provide guidance for process magnification and crystallizer design.