Spectra of sodium aluminate solutions
(1. Laboratory of Green Process and Engineering, Institute of Process Engineering,
Chinese Academy of Sciences, Beijing 100080, China;
2. Graduate University of Chinese Academy of Sciences, Beijing 100039, China)
Chinese Academy of Sciences, Beijing 100080, China;
2. Graduate University of Chinese Academy of Sciences, Beijing 100039, China)
Abstract: The UV spectra of sodium aluminate solutions were obtained in the sodium oxide concentration range from 59 to 409 g/L and the caustic ratio range from 1.5 to 4.0 to reveal the structure characteristics of them. It is found that a new peak appears at about 370 nm besides peaks at about 220 and 266 nm in all solutions. The new peak is strongly favored by high hydroxide concentration and high caustic ratio. And it only appears when the solutions are prepared by dissolving sodium hydroxide and aluminum hydroxide. In addition, the IR and Raman spectra of sodium aluminate solutions with high alkali concentration and high caustic ratio were measured, and the UV spectra of aqueous solutions of and were measured as well. According to the crystal field theory in coordination chemistry as well as the above spectra characteristics, this new peak at about 370 nm is determined as the evidence of a new species of aluminate ion with a coordination number of 6.
Key words: sodium aluminate solution; UV spectrum; IR absorption; Raman spectrum; aluminate ion