Abstract:

As the core product of microbially induced calcium carbonate precipitation (MICP) reaction, the precipitation characteristics of calcium carbonate have an important influence on the engineering properties of MICP-treated materials. The effects of calcium acetate (CA) concentration, bacterial solution (BS) concentration, and pH of initial solution on the precipitation characteristics of calcium carbonate induced by Klebsiellaaerogenes were investigated by full factor experiments, X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). When the concentration of calcium acetate was 0.5 mol/L, the concentration of bacterial solution was OD_nature, and the initial solution pH was 10, the amount of calcium carbonate precipitation was the largest. When the CA was 0.25—0.5 mol/L, calcite and vaterite coexisted; when the CA was 1.0 mol/L, calcium carbonate crystals had the polymorph of vaterite. When the CA was 0.25 mol/L, the BS concentration and pH of initial solution had a major impact on the polymorphs of calcium carbonate. The crystal size of calcium carbonate ranged from 7.6 μm to 15.1 μm; the calcite crystals had rhombohedral and lamellar shapes, and vaterite crystals had spherical and fusiform shapes. The average elastic modulus of vaterite is 15.9 GPa, and calcite is 22.7 GPa. The three main environmental factors can regulate the precipitation amount, polymorph, and morphology of calcium carbonate crystals induced by Klebsiellaaerogenes while the pH of initial solution plays a prominent role in regulating the particle size of calcium carbonate. This provides theoretical support for regulating the MICP process and establishing the relationship between the microscopic properties of calcium carbonate crystals and the engineering properties of the processed materials.

Key words: MICP, Klebsiella aerogenes, vaterite, calcite, environmental factors

摘要：

作为微生物诱导碳酸钙沉淀（MICP）反应的核心产物，碳酸钙的沉淀特性对其所处理材料的工程性能具有重要的影响。采用全因子实验、X射线衍射仪（XRD）、扫描电子显微镜（SEM）和原子力显微镜（AFM）表征，研究了乙酸钙浓度、菌液浓度和初始溶液pH对克雷白氏杆菌诱导碳酸钙沉淀特性的影响。结果表明，乙酸钙浓度为0.5 mol/L、菌液浓度为OD_nature、初始溶液pH=10时，碳酸钙沉淀量最大。乙酸钙浓度为0.25~0.5 mol/L时，方解石和球霰石共存；乙酸钙浓度为1.0 mol/L时，碳酸钙晶体均为球霰石。乙酸钙浓度为0.25 mol/L时，菌液浓度和初始溶液pH对碳酸钙晶型的影响较大。碳酸钙晶体粒径为7.6~15.1 μm，方解石为菱面体状和片状，球霰石为球状及纺锤状。球霰石的平均弹性模量为15.9 GPa，方解石的平均弹性模量为22.7 GPa。三个主要环境因素对克雷白氏杆菌诱导生成的碳酸钙晶体沉淀量、晶体类型和晶体形貌具有调控作用；初始溶液pH对碳酸钙晶体粒径调控作用明显。这对于调控MICP过程及建立碳酸钙晶体的微观性能与其所处理材料的工程性能之间的关系提供了理论支撑。

关键词: 微生物诱导碳酸钙沉淀, 克雷白氏杆菌, 球霰石, 方解石, 环境因素