265 / 2022-03-31 20:59:39

微生物作用下碳酸盐矿物形成过程中溶液PH值及主要阳离子变化

carbonate minerals, aerobic, moderately halophilic bacteria, changes in pH, changes in cations

The synthesis of carbonate minerals mediated by microorganisms provides some insight into the “dolomite problem.” In this paper, under the mediation of aerobic and moderately halophilic bacteria, carbonate was synthesized in solutions with Mg/Ca ratios of 3, 5, and 7, and the pH of the synthetic mineral solution was recorded every 24 hours, and changes in the main cations in the solution were analyzed. Understanding the changes observed in the solution pH and cation concentrations is of great significance for understanding the process and mechanism of carbonate mineral synthesis under the action of microorganisms. The experimental results show that the synthesized minerals are mainly calcium carbonate monohydrate, calcite, and protodolomite. The pH of the three solutions decreased significantly in the first four days, and the solution was acidic. The rate of pH decline decreased after four days, and the pH slowly increased after 10 days to nearly neutral or weakly alkaline. Both Ca²⁺ and Mg²⁺ concentrations showed a tendency of first decreasing and then slightly increasing. The slight increase in Ca²⁺ and Mg^{2 +} concentrations in the later stage may be due to the fact that Ca²⁺ and Mg²⁺ were no longer consumed after the bacterial activity decreased, and cations such as H⁺, Na⁺, and K⁺ in the solution replaced some of the Ca²⁺ and Mg²⁺ adsorbed on the culture medium by cation exchange and adsorption. In the three solutions, the consumption of Ca²⁺ decreased with an increase in the Mg/Ca ratio, while the consumption of Mg²⁺ increased with an increase in the Mg/Ca ratio. Changes in the Sr²⁺ concentration were consistent with the overall trends observed for Ca²⁺ and Mg²⁺ concentrations, but there was a much better correlation with Ca²⁺, which may be related to the fact that Sr²⁺ more easily replaces Ca²⁺ than Mg²⁺ when it enters the carbonate lattice.