Which is greater, the formation rate of CaCO3 or the production rate of Mg(OH)2?
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This post was last edited by sunjl1981 on 2013-1-6 20:12. Thank you all for your advice! # ， ， &
Under conditions where the temperature is appropriate, the production rate of Mg(OH)2 is high, allowing it to be produced in an instant； The formation rate of CaCO3 is greatly influenced by temperature; at around 50 degrees, the reaction is completed in about 30 minutes.
Do you know the reaction mechanism? Just put it in more detail
Of course, magnesium is faster; it’s very simple – you can do experiments to see for yourself.:L
Magnesium hydroxide has low solubility, so it dissolves quickly naturally
Optimization of the process conditions for preparing CaCO3 whiskers: The main factors affecting the growth of CaCO3 whiskers include reaction temperature, stirring speed, CO2 flow rate, and promoters. Among the promoters that can influence whisker growth, phosphates and MgCl2 are the most significant. First, experiments were conducted to examine the effects of these two promoters on CaCO3 whiskers. The results show that the whisker content is extremely low when phosphoric acid is used as a crystal form control agent, indicating that the conditions for whisker formation under these circumstances are quite stringent. When MgCl2 is used as a crystal form control agent, aragonite-type whiskers are more easily formed, and the conditions are easier to control; therefore, it is selected as a whisker growth promoter. Based on the results of the orthogonal experiments conducted earlier in this study and the analysis of the influence trends of various factors on performance, optimization experiments were carried out on the conditions for preparing CaCO3 whiskers. XRD testing was performed on the products obtained through these optimizations to determine the content of CaCO3 whiskers, while the aspect ratio of the whiskers was measured using polarizing microscope images. The results are shown in Table 1. Table 1 Optimized experimental conditions and properties Magnesium chloride concentration/(mol·L-1) Reaction temperature/°C Stirring speed CO2 flow rate Initial pH value Whisker mass fraction, average length-diameter ratio % 0.5 904 001 9.09 7.21 8.30 0.68 04001 8.09 8.01 7.20 0.59 4250 19.09 4.51 9.30 0.59 04001 9.09 6.71 7.6 Note: Stirring speed is in r/min; CO2 flow rate is in mL/min.