Biomineralization has emerged as a novel and eco-friendly technology for artificial mineral formation utilizing the metabolism of organisms. Due to its highly efficient urea degradation ability, Sporosarcina pasteurii(S. pasteurii) is arguably the most widely investigated organism in ureolytic biomineralization studies, with wide potential application in construction and environmental protection. In emerging, large-scale commercial engineering applications, attention was also paid to practical challenges and issues. In this review, we summarize the features of S. pasteurii cells contributing to the biomineralization reaction, aiming to reveal the mechanism of artificial mineral formation catalyzed by bacterial cells. Progress in the application of this technology in construction and environmental protection is discussed separately. Furthermore, the urgent challenges and issues in large-scale application are also discussed, along with potential solutions. We aim to offer new ideas to researchers working on the mechanisms, applications and challenges of biomineralization.

Biomineralization Induced by Cells of Sporosarcina pasteurii: Mechanisms, Applications and Challenges

In nature, biomineralization is a common phenomenon, which can be further divided into authigenic and artificially induced mineralization. In recent years, artificially induced mineralization technology has been gradually extended to major engineering fields. Therefore, by elaborating the reaction mechanism and bacteria of mineralization process, and summarized various molecular dynamics equations involved in the mineralization process, including microbial and nutrient transport equations, microbial adsorption equations, growth equations, urea hydrolysis equations, and precipitation equations. Because of the environmental adaptation stage of microorganisms in sandy soil, their reaction rate in sandy soil environment is slower than that in solution environment, the influencing factors are more different, in general, including substrate concentration, temperature, pH, particle size and grouting method. Based on the characteristics of microbial mineralization such as strong cementation ability, fast, efficient, and easy to control, there are good prospects for application in sandy soil curing, building improvement, heavy metal fixation, oil reservoir dissection, and CO2 capture. Finally, it is discussed and summarized the problems and future development directions on the road of commercialization of microbial induced calcium carbonate precipitation technology from laboratory to field application.

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Research status and development of microbial induced calcium carbonate mineralization technology

ABSTRACT Carbamic acid (NH2COOH) plays an important role in microbial induced carbonate precipitation. However, investigations on the reaction mechanisms of NH2COOH elimination and hydrolysis are still lacking. In this work, the transformation mechanism of NH2COOH elimination and hydrolysis in neutral and basic conditions was investigated by quantum chemical calculation. The results showed that NH2COOH mainly existed in the form of trans-NH2COOH configuration in the liquid phase at room temperature. In the neutral condition, the catalysis of NH3 or H2O could reduce the reaction energy barrier of NH2COOH elimination and hydrolysis, and NH2COOH tended to carry out the elimination reaction catalysed by NH3 to generate NH3 and CO2. In the basic condition, reaction energy barriers of NH2COOH elimination and hydrolysis increased and decreased significantly, respectively, indicating that the basic condition was unfavourable for the NH2COOH elimination reaction but rather favourable for the NH2COOH hydrolysis reaction. NH2COOH in the basic condition tended to carry out the hydrolysis reaction to generate NH3 and H2CO3. The transformation mechanism of NH2COOH elimination and hydrolysis in different conditions was examined in this work, which would provide the theoretical guidance for the better healing ability of microbial self-healing concrete in practical engineering.

Transformation mechanism of carbamic acid elimination and hydrolysis reaction in microbial self-healing concrete

There are abundant sea-sand resources on the earth. Traditional sea-sand concrete faced various problems relating to insufficient anticorrosion ability. In this paper, artificial seawater, sea sand, industrial waste, steel fiber, and polycarboxylate superplasticizer were used to prepare ultra-high-performance polymer cement mortar (SSUHPC). At the same time, freshwater river-sand ultra-high-performance polymer cement mortar (FRUHPC) with the same mixing ratio was prepared for comparative study. The compressive strength of SSUHPC reached 162.1 MPa, while the that of FRUHPC reached 173.3 MPa, which was slightly higher. Meanwhile, SSUHPC showed excellent anticorrosion characteristics in terms of carbonization, frost resistance and chloride resistance, and especially for sulfate resistance. The composition of SSUHPC was separated into three parts: mortar, pore and steel fiber, and the performance difference mechanisms of SSUHPC and FRUHPC were investigated by X-ray computed tomography (X-CT), mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The hydration degree of mortar in SSUHPC was higher, with higher content of CSH and CH, and its better optimized gel pore characteristics gave SSUHPC better corrosion resistance. The mechanical properties of SSUHPC were slightly poor due to the uneven dispersion of steel fibers and air pores, with an- air pore porosity of 1.52% (above 200 μm) that was twice that of FRUHPC (0.6%). In this paper, the mechanics and anticorrosion performance of ultra-high-performance polymer cement mortar prepared with seawater sea sand were comprehensively evaluated, and the mechanism of performance difference between SSUHPC and FRUHPC was revealed, conducive to the targeted improvement of sea sand concrete.

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The Mechanism of Anticorrosion Performance and Mechanical Property Differences between Seawater Sea-Sand and Freshwater River-Sand Ultra-High-Performance Polymer Cement Mortar (UHPC)

To understand the hydration inhibition mechanism of gypsum (CaSO4·2H2O) on tricalcium aluminate (C3A), the very early hydration process of C3A in the presence of CaSO4·2H2O was investigated by Reax...

Hydration inhibition mechanism of gypsum on tricalcium aluminate from ReaxFF molecular dynamics simulation and quantum chemical calculation

To provide theoretical guidance for better healing ability of microbial self-healing concrete, the mechanism of urea decomposition catalyzed by Sporosarcina pasteurii urease in Microbial Induced Ca...

Chunmei Tang

Papers

Mechanism of urea decomposition catalyzed by Sporosarcina pasteurii urease based on quantum chemical calculations