牡蛎壳超细球霰石碳酸钙的制备与表征

Preparation and characterization of ultrafine vaterite calcium carbonate from oyster shells

以牡蛎壳为原料,经粉碎、乳酸溶提活性钙后,在胰蛋白酶调控下用碳化法制备超细碳酸钙,通过扫描电镜(scanning electron microscope,SEM)、红外光谱(infrared spectroscopy,IR)等表征分析产品特征。单因素结合正交试验研究了乳酸溶提牡蛎壳活性钙的工艺条件,结果表明,在1∶20的固液比体系(牡蛎壳质量∶乳酸溶液体积)下,当反应时间为30 min,乳酸浓度为2 moL/L,反应温度为50℃,搅拌速度为350 r/min时,牡蛎壳钙溶提率可达39.46%。在此基础上考察胰蛋白酶添加对乳酸溶提液碳化制备碳酸钙的影响,SEM、IR等表征结果显示,按3∶1胰钙质量比添加胰蛋白酶调控碳酸钙的碳化结晶,可制备出由纳米颗粒团聚而成的,大小较均一的(粒径为300~400 nm)键合胰蛋白酶的球霰石超细碳酸钙微球。

The active calcium was extracted from pulverized oyster shells by lactic acid prepared as ultrafine calcium carbonate by carbonization method under the regulation of trypsin.The features of ultrafine calcium carbonate were characterized by scanning electron microscopy(SEM)and infrared spectroscopy(IR).Through single-factor test and orthogonal experiment,the process conditions of lactic acid extracting active calcium from oyster shells were studied.The results showed that the calcium extraction rate of oyster shells could reach 39.46%under 1∶20 of the solid-liquid ratio system(oyster shell mass∶lactic acid solution volume),2 mol/L of lactic acid concentration,50℃of the extraction temperature,30 min of the extraction time and 350 r/min of the stirring rate.The effects of trypsin addition on the preparation of ultrafine calcium carbonate by the carbonation of the active calcium extracted from oyster shells by lactic acid were investigated.SEM,IR and other characterization results showed that the vaterite-type nano calcium carbonate agglomerated into 300-400 nm ultrafine microspheres with uniform size,could be prepared when the crystallization of calcium carbonate was controlled by adding trypsin at the ratio of 3∶1.The research is of great significance for the development and utilization of oyster shells and the preparation of new food-grade calcium preparations.