Microbial-induced synthesis of calcite based on carbon dioxide capture and its cementing mechanism

摘要

As a new type of green cementitious materials, inorganic minerals synthesized by microbial-induced mineralization could cement loose sand particles. Their advantages included efficient preparation pro-cess, easy control and environmental friendliness, and accordingly they could be used in desert treatment, fugitive dust control, foundation reinforcement, and slope stability. This study identified microbial growth under different conditions and obtained effective methods for the promotion of microbial growth were obtained. The enzyme protein expression was identified using an electrophoretic and gel imaging system, and the results indicated that the main enzyme protein in the bacterial solution was carbonic anhydrase. By means of X ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis, it was concluded that mineralization products were near spherical calcite with particle sizes of approximately 5 mm. The microstructure between the mineralization products and loose sand particles was analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the difference of cementing effect between different methods was determined. The feasibility of cementing sand by microbial-induced mineralization was demonstrated. Based on the analysis of interaction between the mineralization products and loose sand particles by fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR), it was found that the essential reason for cementing loose sand particles was the formation of intermolecular hydrogen bonds. Therefore, this study identified the mechanism of microbial-induced mineralization as the basis for the optimization and regulation of the whole process of mineralization and cementation. In this study, characteristics of the mineralization product and hydrogen bonding mechanism were investigated systematically. Carbon dioxide was used as a carbon source to synthesize mineralization products, and greenhouse gas was effectively utilized without toxic and harmful by-products. The research provided new ecological materials and technologies for environmental governance, which was expected to attract considerable attention. (C) 2020 Elsevier Ltd. All rights reserved.