1987 Volume 1987 Issue 5 Pages 802-806
CO2 of atmospheric pressure containing saturated water Vapor reacted with ZnO fine particles at temperatures of 5, 10 and 20°C to form the following three kinds of basic zinc carbonates (zinc carbonate hydroxides): (1) at 20°C, the basic carbonate, whic h has the same composition ratio of metal, H20 and CO2 and the same X-ray diffraction pattern as rosasite (Cu, Zn) CO3(OH)2 (JCPDS 35-402), and the metal which consists of only Zn. (2) at 10°C, hydrozincite Zn5(CO3)2(OH)6 (JCPDS 19-1458). and (3) at 5°C, the basic zinc carbonate, which has a X-ray d iffraction pattern not ever reported and not listed in JCPDS and the composition ratio of 1:2 between CO2 and H20. All the above three kinds of basic zinc carbonates, when they were reacted fu rther under the respective conditions described above, finally changed to the neutral zinc carbonate ZnCO3, smithsonite (JCPDS 8-449). The thermal analyses of these four kinds of reaction products were carried out by DTA and TGA. The measurements of CO2-releasing properties upon heating, and their quantitative analyses were also carried out by FID gas chromatography. As the analyses have revealed that there exists a liqud phase between the solid and the gas phases in the reaction steps, the mechanism of the reaction was examined. This reaction, with its conditions precisely controlled, will be effective for adding new functions or reforming the surface of ZnO particles.
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