Environmental catalysis and materials

Effects of amine, amine salt and amide on the behaviour of carbon dioxide absorption into calcium hydroxide suspension to precipitate calcium carbonate

Wittaya Chuajiw , Mitsuru Nakano , Kazumasa Takatori , Toshiya Kojima , Yoshiki Wakimoto , Yoshiaki Fukushima


Received January 06, 2013,Revised March 07, 2013, Accepted , Available online November 29, 2013

Volume ,2013,Pages 2507-2515

The amount of carbon dioxide (CO2) absorption and calcium ion (Ca2+) concentration besides the pH of aqueous solution were observed during the CO2 absorption to precipitate calcium carbonate (CaCO3) from calcium hydroxide (Ca(OH)2). A reaction rate-limiting effect of an amount of CO2 absorption without any organic additives in the early stage of the precipitation was observed, which was attributed to an interruption effect of bicarbonate ion (HCO3-) on the precipitation of CaCO3. The improvement for the reaction rate was achieved not only by amine additives but also by neutral additives such as ε-caprolactam or amine salt. When the hexamethylene diamine was dissolved in the solution, successive change of crystal forms of CaCO3 aragonite to calcite in aqueous suspensions, confirmed by Ca2+ concentration change and X-ray diffraction, was concluded that a local environment around the amine group in aqueous solution and an interaction of the diamine with precipitated CaCO3 particles were important factors for these reactions.

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