In Situ Ultrasonic Spectroscopy Study of the Nucleation and Growth of Copper Sulfate Pentahydrate Batch Crystallized from Supersaturated Aqueous Solutions
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- 作者：Eric Lyall ; Patricia Mougin ; Derek Wilkinson ; and Kevin J. Roberts
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2004
- 出版时间：August 4, 2004
- 年：2004
- 卷：43
- 期：16
- 页码：4947 - 4956
- 全文大小：255K
- 年卷期：v.43,no.16(August 4, 2004)
- ISSN：1520-5045
文摘
In situ ultrasonic attenuation spectroscopy is applied to the challenging case of monitoring thenucleation and growth of copper sulfate pentahydrate crystallized from supersaturated aqueoussolutions, a system not readily amenable to analysis via optical methods due to the intense bluecolor of the saturated crystallizing solution. In experiments in the 2.8-L rectilinear reactor of aspectrometer, crystallization and dissolution points are reliably detected from the measuredattenuation spectra. There are minor differences between data taken at 10 and 50 MHz, notablythe lower frequency data appearing to be more sensitive to the particle formation/dissolutionprocess. The nucleation data reveal that the material crystallizes fairly easily as characterizedby a metastable zone width of ca. 3-4 
C and a significantly cooling-rate-dependent nucleationorder of reaction of ca. 1.7 reflecting the fact that for high cooling rates the nucleation rate isless than that associated with supersaturation generation. The evolving crystal size distributionfollowing nucleation, calculated from ultrasonic attenuation spectroscopy measurements, revealswell-defined oscillations in the observed crystal sizes consistent with the break-up of crystalslarger than ca. 250 
m in this crystallizer. From dynamic measurements of changing particlesize and concentration during the crystallization process, apparent crystal mass growth ratesare calculated to be between 2.3 × 10-3 kg/m2·s at the maximum cooling rate of 0.55 C/minand 2.02 × 10-4 kg/m2·s at the minimum cooling rate of 0.2 C/min. On the basis of these dataand assuming a spherical particle model, the linear crystal growth rates are estimated to bebetween 2.0 × 10-6 m/s at the maximum cooling rate of 0.55 C/min and 1.8 × 10-7 m/s at theminimum cooling rate of 0.2 C/min.
C and a significantly cooling-rate-dependent nucleationorder of reaction of ca. 1.7 reflecting the fact that for high cooling rates the nucleation rate isless than that associated with supersaturation generation. The evolving crystal size distributionfollowing nucleation, calculated from ultrasonic attenuation spectroscopy measurements, revealswell-defined oscillations in the observed crystal sizes consistent with the break-up of crystalslarger than ca. 250 m in this crystallizer. From dynamic measurements of changing particlesize and concentration during the crystallization process, apparent crystal mass growth ratesare calculated to be between 2.3 × 10-3 kg/m2·s at the maximum cooling rate of 0.55 C/minand 2.02 × 10-4 kg/m2·s at the minimum cooling rate of 0.2 C/min. On the basis of these dataand assuming a spherical particle model, the linear crystal growth rates are estimated to bebetween 2.0 × 10-6 m/s at the maximum cooling rate of 0.55 C/min and 1.8 × 10-7 m/s at theminimum cooling rate of 0.2 C/min.