CO2碳化法制备微米级球霰石型食品碳酸钙的研究

采用CO2碳化法制备了微米级球霰石型食品级碳酸钙,探讨了碳化温度、Ca2+浓度、混合气中CO2浓度等制备工艺参数对碳酸钙晶型和形貌的影响,探讨了氨水用量、碳化时间对碳酸钙产率的影响,并采用FT-IR、XRD和SEM对制备的碳酸钙进行了表征。结果表明,碳化温度升高、混合气中CO2浓度降低,制备的碳酸钙晶型由球霰石型转变为方解石型；Ca2+浓度增加,制备的碳酸钙颗粒尺寸增大,碳化时间增加,产率先增加后减小。最佳制备条件为碳化温度20℃,Ca2+浓度0.3 mol/L,混合气中CO2浓度30%,[氨水]/2[Ca2+]摩尔比为1.1,碳化时间为24 min,制备的微米级球霰石型碳酸钙颗粒分布均匀,平均粒径为3.79μm,产率>99%,重金属含量低于国家标准《食品添加剂GB1898-2007轻质碳酸钙》的要求。

Preparation of Micro-size Food-grade Vaterite CaCO3 by CO2 Carbonization Method

Micron-size food-grade vaterite CaCO3 were prepared by CO2 carbonization method. The effects of temperature, Ca2+ concentration and CO2 proportion in gas mixture on the morphology and polymorph of the CaCO3 crystals and influences of ammonia amount and carbonization time on the yield of CaCO3 were investigated. The microstructures and morphology of the prepared samples were systematically investigated by FT-IR, XRD and SEM. The crystal of prepared CaCO3 changed from vaterite to calcite with increasing carbonization temperature and decreasing the proportion of CO2 in gas mixture. The particle size of CaCO3 increased with increasing the concentration of Ca2+. The yield of the prepared CaCO3 increased and then decreased with prolonging the carbonization time. The average size of the prepared CaCO3 particles was 3. 79 μm with uniform particle distribution and the yield was higher than 99% at the carbonization temperature of 20 ℃, Ca2+ concentration of 0. 3 mol/L, CO2 proportion in gas mixture of 30%, [ammonia]/2[Ca2+] of 1. 1, the carbonization time of 24 min. Heavy metal content was lower than the limits of national standard "Food additive GB1898-2007 light calcium carbonate additive".