Mechanochemical route for synthesizing nitrate form of layered double hydroxide

This paper introduces a mechanochemical process for synthesizing a nitrate compound, Mg–Al–(NO3) (Mg:Al = 3:1), which is a layered double hydroxide (LDH) from three kinds of starting materials, Mg(OH)2, Al(OH)3 and Mg(NO3)2.6H2O. The operation was attempted by one-and two-step milling operations, and the former is to grind the three kinds of samples simultaneously, while the latter is to mill two kinds, Mg(OH)2 and Al(OH)3, followed by further milling with Mg(NO3)2.6H2O. Characterizations by XRD, FT-IR, and TG-DTA indicate that the latter step operation is superior to the former one in terms of the formation of the target material, nitrate form of LDH. This form could be taken as a potential candidate for slow-release fertilizer, where the release of the nitrate from the synthesized LDH has been held back due to the intercalation into the LDH structure.

Figure optionsDownload as PowerPoint slideA two-step milling operation with two hydroxides milled first and Mg nitrate hydrated added as source of water and nitrate allows the successful formation of nitrate form of layered double hydroxide without elaborate effort to avoid carbonation.