对苯二甲酸锌初级成核过程研究

Primary nucleation process of zinc terephthalate

为研究对苯二甲酸锌的成核过程,实验采用平衡法测量对苯二甲酸锌在苯二甲酸钠溶液中的溶解度计算成核过程的过饱和度;298.15 K下用聚焦光束发射测量仪在线监测对苯二甲酸锌反应结晶过程中诱导期,并计算临界成核半径和临界成核自由能与过饱和度的关系。结果表明:过饱和度越大,诱导期时间越短;根据经典成核理论,在过饱和度S大于8.16时,发生的是均相成核过程,过饱和度S小于6.66时,发生的是非均相成核过程;其中在均相成核中,临界成核半径和临界成核自由能都是随着过饱和度的增加不断减小。因此,提高过饱和度使成核过程更加容易进行。

To analyze the nucleation process of zinc terephthalate, balancing method was used to investigate the solubility of zinc terephthalate in sodium terephthalate solution. The induction period of zinc terephthalate reaction- crystallization process was measured by FBRM at 298.15 K. The relationship of critical nucleation radius and free energy with supersaturation was calculated. The results show that the induction period decreases with the supersaturation increasing. According to the classical theory of primary nucleation, homogeneous nucleation process occurs at the supersaturation S 〉 8. 16, and heterogeneous nucleation process happens at S 〈 6. 66. In the homogeneous nucleation process, the critical nucleation radius and free energy decrease with the supersaturation increasing. Therefore, the increasing of supersaturation make it more available for the nucleation process.