Three methods of synthesizing hydrotalcite (HT) have been developed using magnesium from seawater and dolomite (MgCa(CO3)2). In the first process, 1.0 M Na2CO3 solution was added to calcium ion free artificial seawater containing AlCl3 with an initial Mg/Al molar ratio of 2.0 to approximately 3.7 until a pH of 10 was obtained. The solution was then continuously stirred for 1 h at 60 °C. CO32--HT was precipitated as a single phase, and the initial Mg/Al molar ratio, which each recovery of Mg2+ and Al3+ from the solution was above 98%, was 2.0-2.3. In the second process, a Ca(OH)2 slurry was added to artificial seawater containing AlCl3 with an initial Mg/Al molar ratio of 1.0 to approximately 5.0 until a pH of 10.5 was obtained, and then was stirred for 1 h at 60 °C. HT was also precipitated as a single phase with initial Mg/Al molar ratio 2.0-4.0. The initial Mg/Al molar ratio, which each recovery of Mg2+ and Al3+ from the solution was above 98%, was 2.2 to approximately 3.3, but SO42- and Cl- were contained in the precipitated HT. When HT was produced using initial Mg/Al molar ratio of 3.0 at 25 °C, SO42- and Cl- in the HT were ion-exchanged with CO32- in a 0.05 M Na2CO3 solution for 24 h at 25 °C, and SO42- and Cl- content of the HT were decreased to 0.5 and 0.05 wt%, respectively. In the third process, dolomite calcined at 1000 °C was added to an AlCl3 solution with an initial Mg/Al molar ratio of 1.0 to approximately 2.0, and the solution was stirred for 1 to approximately 4 h at 25 to approximately 90 °C. HT was precipitated with the smallest amount of MgO and Mg(OH)2 when the initial Mg/Al molar ratio was 1.5 and the solution was stirred for 4 h at 90 °C.
|Number of pages||6|
|Journal||Molecular Crystals and Liquid Crystals Science and Technology Section A: Molecular Crystals and Liquid Crystals|
|Publication status||Published - 2000|
|Event||10th International Symposium on Intercalation Compounds (ISIC 10) - Okasaki, Jpn|
Duration: 1999 May 30 → 1999 Jun 3
ASJC Scopus subject areas
- Condensed Matter Physics