Influence of supersaturation on structure of
sodium aluminate solutions with medium
concentration: a solution X-ray diffraction study
sodium aluminate solutions with medium
concentration: a solution X-ray diffraction study
(College of Chemistry and Chemical Engineering,
Central South University, Changsha 410083, China)
Central South University, Changsha 410083, China)
Abstract: Influence of supersaturation on the structure of a series of freshly prepared supersaturated sodium aluminate solutions with medium concentration was investigated by solution X-ray diffraction. Experimental results show that the basic Al-containing species in all kinds of supersaturated solution is four-coordinated ions. Opposite to Al—O distance contracted in highly concentrated solution, a little expand of the Al—O distance from 1.75℃ to 1.85℃ occurs with increasing supersaturation, which is consistent with the occurrence of oligomeric aluminate species. Meanwhile, O—O distance in the first shell of H2O—H2O(OH) in supersaturated sodium aluminate solution is obviously longer than in hydroxide sodium solution and becomes longer and longer with increasing supersaturation. Na—O bond length is about 2.4℃ and changes little with supersaturation. The reason for Al—O bond expanding with supersaturation and its influence on the stability of solution was discussed.
Key words: solution X-ray diffraction; sodium aluminate solution; structural property