The influence of ammonia and selected amines on the characteristics of calcium carbonate precipitated from calcium chloride solutions via carbonation

The precipitation of calcium carbonate was carried out by passing a gaseous mixture of carbon dioxide and air into a calcium chloride solution. The selected compounds enhancing carbon dioxide absorption were used as additives which promote the formation of carbonate ions in the solution. The additives were ammonia, monoethanolamine, triethylamine and triethanolamine. The resulting calcium carbonate particles varied in polymorphic composition and the particle size depending on the used absorption promoter. When absorption occurred quickly in ammonia or monoethanolamine solutions, the obtained calcium carbonate particles were mainly vaterite. Calcium carbonate particles were precipitated as calcite in triethylamine or triethanolamine solutions, while the rate of carbon dioxide mass transfer from gas to liquid phase was much slower. All precipitated calcium carbonate particles had monomodal particle size distributions. Smaller particles of vaterite were produced in the monoethanolamine solution and of calcite in the triethylamine solution. (C) 2017 Elsevier B.V. All rights reserved.