The coprecipitation of magnesium hydroxoaluminate hydrates from aqueous solution with ammonium hydroxide: Precipitate compositions and coprecipitation mechanisms

Abstract

Magnesium liydroxoalurniiiate hydrates were coprecipitatetl from different mixed metal cation solutions a t Mg/Al, ratiticv froin 1 t o 4 by ammonium hydroxide, The coprecipitations were monitored by potentiornetric titration and the final precipitate compositions were exainiiied by chemical analysis, X-ray diffraction, infra-red spectrophotornetry and tliernial analysis. The process of coprecipitation was similar to that for coprecipitation with sotliurn hydroxide but large excess of ammonium hydroxide was required for cornplete reaction a t pHs from about 8 to 10.At Mg/Al, = I , the main phase was probably Mg(H,O)h [Al(0H),l2; at Mg/Al, = 2 , the rimin phase was probably Mg,(H,O), [Al,(OH),,]; at Mg/A12 = 4, the main phase was probably (MgOH,) (H20)* [A12(OH)J.

Immobilization of imidazolium ionic liquids on hydrotalcites using silane linkers: retardation of memory effect

“…3c). What we observe instead is consistent with either meixnerite (a layered structure with hydroxyl groups in the interlayer) 37,38 or a very poorly crystalline HT phase. The lack of high angle reections in PXRD patterns (Fig.…”