Formation of CaCO_3 from calcium sources with different anions in single process of CO_2 capture-mineralization

摘要

The single process CO(2)capture-mineralization approach integrates methods of CO(2)absorption using aqueous solvents and mineral carbonation technology to not only remove carbon dioxide quickly, but also to simultaneously produce precipitated calcium carbonate (PCC). To develop a more sustainable process, it is important to extract calcium from inexpensive raw materials such as industrial by-products. The extractant has a significant effect on the quality of the calcium carbonate produced because it determines the anion paired with the calcium cation. In this work, several calcium sources with different anions (Propionate, Acetate, Nitrate and Chloride) were applied in the single process CO(2)capture-mineralization method, and their influence on the polymorph of the obtained CaCO(3)was investigated. The CaCO(3)produced with inorganic calcium sources predominantly exhibited a calcite structure, while the CaCO(3)produced with organic calcium sources had a structure in which vaterite and calcite coexist. This result was in good agreement with our DFT calculations, which indicated the adsorption energy of the organic anions (Propionate and Acetate) were lower than the inorganic anions on the surface of vaterite. Except for chloride with its non-polar nature, in most cases, there was a strong correlation between the polymorph and the adsorption energy calculated for each surface. A mechanism for the polymorph CaCO(3)formation in our single process CO(2)capture-mineralization method was proposed after observing crystal formation at low concentration.