Boron incorporation into precipitated calcium carbonates affected by aqueous pH and boron concentration
Boron incorporation into precipitated calcium carbonates affected by aqueous pH and boron concentration
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DOI：
10.1016/j.jhazmat.2019.121183
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发表时间：
2020-02-05
影响因子：
13.6
通讯作者：
Wang, Shan-Li
中科院分区：
文献类型：
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作者：
Kobayashi, Kazuki;Hashimoto, Yohey;Wang, Shan-Li
本研究的目的是研究在共沉淀过程中B在沉淀碳酸钙（PCC）中的掺入量，并确定不同pH和B浓度下沉淀碳酸钙中特定的矿物相（方解石或水晶石）和B的配位模式（三角形或四面体）。在pH为8 ~ 12的范围内，随着水溶液中B （B-aq）浓度的增加，PCC中B的掺入量也随之增加。当pH为10，B-aq浓度在30 ~ 50 mM之间时，PCC对B的去除率达到最大（约200 mmol kg(-1)）。当pH为8和10时，B-aq的增加促进了水晶石向方解石的转变，而过量的水（聚）硼酸阴离子浓度（100 mM）抑制了方解石的晶体生长。通过B- k边x射线吸收精细结构光谱测定，在B-aq < 75 mM时，B在PCC中的配位优先为四面体（B- iv, 55-70%），而不是三角形（B- iii, 30-45%）。相反，在高B浓度（即100 mM）的溶液中，没有观察到B- iv在PCC中的优先结合。在高B-aq浓度下，B的掺入量、PCC的形态和PCC中B的配位发生了显著变化。
The objectives of this study were to investigate the amount of B incorporation into precipitated calcium carbonate (PCC) in the coprecipitation process, and to determine specific mineral phases (calcite or vaterite) and the mode of B coordination (trigonal or tetrahedral) in PCC under different pH and B concentrations. The amount of B incorporation into PCC increased in general with increasing aqueous B (B-aq) concentrations in the pH range from 8 to 12. The B removal by PCC reached maximum (similar to 200 mmol kg(-1)) at pH 10 with B-aq concentrations between 30 and 50 mM. The transformation of vaterite to calcite was promoted with increasing B-aq at pH 8 and 10, whereas an excess concentration of aqueous (poly)borate anions (100 mM) inhibited crystal growth of calcite. As determined by B K-edge X-ray absorption fine structure spectroscopy, the coordination of B incorporated in PCC was preferentially tetrahedral (B-IV, 55-70%) over trigonal (B-III, 30-45%) at B-aq < 75 mM. In contrast, the preferential incorporation of B-IV into PCC was not observed in the solution with a high B concentration (i.e., 100 mM). The amount of B incorporation, the morphology of PCC and B coordination in PCC were remarkably changed in high B-aq concentrations.