科研之友
微信
新浪微博
Facebook
分享链接
摘要
By using a specially contrived experimental technique, crude terephthalic acid (TPA) crystals have been aged in their own saturated 90 mass % acetic acid + 10 mass % solution at 467, 477, 487, 497, and 507 K. The time evolution of crystal size distribution, as well as contents of the contaminant 4-carboxybenzaldehyde (4-CBA) in both solid and liquid phases, has been experimentally measured. Experimental results reveal the following: (1) The effect of stirring rate on the aging of crude TPA crystals is negligible under the conditions of this study. (2) The crystal size distribution is observed to broaden with time, accompanied by a decrease in number and an increase in averaged crystal size during aging. The aging rate increases with the increasing of temperature. (3) Under the conditions of this study, substantial purification occurs during aging. The rate of purification increases as the temperature increases. The Ostwald ripening mechanism is proposed to model the effect of aging on crystal size distribution. A purification model based on Ostwald ripening and molecular diffusion of 4-CBA in TPA crystal is proposed to simulate the effect of aging on the purification of crude TPA by crystal aging. The model parameters have been determined in a nonlinear optimization. The fit of the simulated results is fairly good.
- 出版日期2007-10-24
- 单位浙江大学
