摘要
在利用旋转产生的模拟超重力环境中 ,以Ca(OH) 2 CO2 为反应物系 ,H3 PO4作为晶形控制剂 ,控制气体流量 10 0～ 30 0L/h ,液体流量 6 0 0～ 10 0 0L/h ,旋转床转速 6 0 0～ 12 0 0r/min ,碳化反应温度为 4 0～ 80℃ ,H3 PO4相对于Ca(OH) 2 完全反应所生成CaCO3 质量分数为 5 %～ 30 % ,采用反应结晶法制备出了平均短轴为 80～ 2 5 0nm、长径比为 10～ 2 5的微细晶须碳酸钙 .制备等量的晶须碳酸钙 ,超重力环境中所需碳化时间约为文献值的 1/ 36～ 1/ 18.同时 ,利用TEM、XRD、TG DTA及元素分析等手段对产品粒子进行了表征 .结果表明 ,所合成微细晶须碳酸钙为结晶态 ,文石型含量达到 97.77% ,初始分解温度较常重力场中下降了 4 0 2℃ .
Ultra-fine whiskers of calcium carbonate were successfully synthesized by reactive precipitation in high-gravity field generated by the rotating packed bed (RPB). In the experiment Ca(OH) 2 and CO 2 were as reactants and H 3PO 4 was used as the morphology-control additive. Synthesizing the same amount of CaCO 3 whiskers, the needed carbonation time in the high-gravity field is 1/36～1/18 of that by the traditional technology reported in the literature. The ultra-fine CaCO 3 whiskers can be synthesized and well-controlled under the following conditions: the volumetric flow rate of gas 100～300 L/h and that of liquid 600～1000 L/h, rotating speed of RPB 600～1200 r/min, reaction temperature between 40～80℃ and concentration of H 3PO 4 5.0%～30%.The calcium carbonate whiskers have the mean shaft diameter of 80～250 nm and the average aspect ratio of 10～25 with the narrow distribution of both the mean shaft diameter and the aspect ratio. The properties of the product are characterized by means of TEM, electron diffraction, XRD, TG-DTA and elementary analysis. Electron diffraction analysis shows that the synthesized calcium carbonate whiskers have crystalline structure, while XRD analysis indicates that aragonite structure accounts for 97.77% in content of the final CaCO 3 whisker product. And TG-DTA analysis shows that the obtained product decomposes at 423℃, which is 402℃ lower than that of the CaCO 3 obtained in the normal gravity.
基金
ProjectsupportedbytheNationalNaturalScienceFoundationofChina (2 0 2 36 0 2 0 )
OutstandingYouthScientistFoundationofBeijingCity (95 5 810 35 0 0 )
andNanoMaterialsTechnologyPte .Ltd .
Singapore
关键词
碳酸钙
晶须
微细
超重力
合成
表征
Calcium carbonate, Whisker, Ultra-fine particles, High-gravity, Synthesis, Characterization
