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- Title
Calcium elution from cement kiln dust using chelating agents, and CO2 storage and CaCO3 production through carbonation.
- Authors
Kim, Myoung-Jin; Jung, Sungsu
- Abstract
In this study, indirect carbonation was carried out by using cement kiln dust (CKD), an alkaline industrial by-product, and three chelating agents (citrate, malonate, and adipate salts) as solvents at the room temperature and atmospheric pressure. We derived the optimum conditions for eluting Ca from CKD, as well as those for storing CO2 and producing CaCO3 through carbonation. The most important factor affecting the Ca elution from CKD was the solvent concentration and that for the carbonation was the end-of-carbonation pH. Under the optimum conditions of Ca elution, the molar ratios of Ca and solvent in eluates were 1:1, 1:2, and 1:2, respectively, using citrate, malonate, and adipate solvents. Based on the results, we propose that one molecule of Ca ion and one molecule citrate that is tridentate are combined to form a complex. The bidentate malonate and adipate, on the other hand, form complexes by combining one molecule of Ca ion and two molecules of each solvent. It is essential to raise the pH while simultaneously minimizing the amount of free chelating agent in solution to produce more CaCO3 and prevent its dissolution. Besides, it is absolutely necessary to terminate the carbonation reaction at a pH of about 10.5 to improve the reuse efficiency of the chelating agent. CaCO3 produced through carbonation reaction started to dissolve at pH approximately 10.5. All of the CaCO3 produced was calcite with a purity of 98%. The efficiency of Ca elution from CKD using three solvents increased significantly with increasing stability constant of a Ca-ligand complex, but the efficiency of carbonation was the same for all solvents.
- Subjects
CARBONATION (Chemistry); CEMENT kilns; STABILITY constants; DUST; ATMOSPHERIC pressure; CALCIUM; CHELATING agents
- Publication
Environmental Science & Pollution Research, 2020, Vol 27, Issue 16, p20490
- ISSN
0944-1344
- Publication type
Article
- DOI
10.1007/s11356-020-08403-1