Influence of initial calcium ion concentration on the precipitation and crystal morphology of calcium carbonate induced by bacterial carbonic anhydrase
Influence of initial calcium ion concentration on the precipitation and crystal morphology of calcium carbonate induced by bacterial carbonic anhydrase
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DOI：
10.1016/j.cej.2012.12.034
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发表时间：
2013-02-15
影响因子：
15.1
通讯作者：
Yu, Long-Jiang
中科院分区：
文献类型：
--
作者：
Li, Wei;Chen, Wei-Shan;Yu, Long-Jiang
碳酸钙（CaCO 3）的生物沉淀由于其在许多地质作用、地质与土木工程应用以及环境治理中的作用而受到广泛关注。从蜡状芽孢杆菌（Bacillus cereus）培养物中提取并部分纯化了胞外碳酸酐酶（carbonic anhydrase，CA），研究了CA对CaCO 3的催化沉淀作用。采用气相扩散法研究了不同初始Ca ~（2+）浓度（C-0（Ca ~（2+）条件下细菌CA催化碳酸钙沉淀的动力学。采用XRD、FTIR和FESEM对沉淀过程中得到的CaCO 3晶体的晶型和形貌进行了分析。结果表明，在细菌CA催化CaCO 3沉淀过程中，不同C-0（Ca 2+）下Ca 2+沉淀量的变化符合指数模型。在pH上升过程中，水对照组pH波动较大，而CA组pH上升较平稳。这可能与CA在pH调节中的作用有关。CaCO 3的沉淀率随C-0（Ca 2+）的增加而增加，但过高的C-0（Ca 2+）（100 mmol/L）对细菌CA催化CaCO 3沉淀有一定的负面影响。综合XRD、FTIR和FESEM分析结果表明，C-0（Ca 2+）对细菌CA作用下生成的CaCO 3晶体的晶型和形貌有较大影响。低的C-0（Ca ~（2+））有利于球文石的形成，而高的C-0（Ca ~（2+））有利于方解石的形成。(C)2012爱思唯尔有限公司版权所有。
Biogenic precipitation of calcium carbonate (CaCO3) has attracted much attention due to its role in many geological processes, applications of Geological and Civil Engineering as well as environmental treatments. The present paper focused on the biocatalytic precipitation of CaCO3 by the extracellular carbonic anhydrase (CA) extracted and partially purified from the culture of Bacillus cereus. The kinetics of CaCO3 precipitation catalyzed by the bacterial CA at different initial concentrations of Ca2+ (C-0(Ca2+)) was investigated through the gaseous diffusion system. The polymorph and morphology of CaCO3 crystals obtained in the precipitation process were also analyzed using XRD, FTIR and FESEM. The results showed that in the process of CaCO3 precipitation catalyzed by bacterial CA, the change in the amount of deposited Ca2+ at different C-0(Ca2+) fitted well with the exponential model. Greater fluctuation of pH occurred in the water control group during the rising process of pH, while in the CA group the pH increased more steadily. This may be related to the role of CA in pH regulation. The precipitation rate of CaCO3 increased with the increasing C-0(Ca2+), but overhigh C-0(Ca2+) of 100 mmol/L had a certain negative influence on CaCO3 precipitation catalyzed by bacterial CA. The integrated results of XRD, FTIR and FESEM analysis showed that the C-0(Ca2+) had greater effect on the polymorph and morphology of CaCO3 crystals formed in the presence of bacterial CA. The lower C-0(Ca2+) favored the formation of vaterite and the higher C-0(Ca2+) favored the formation of calcite. (C) 2012 Elsevier B.V. All rights reserved.