Formatbn of Manganese Complex in the Solutions of Ammonium Condensed Phosphates of Short Chain Lengths

Abstract

Liquid compound fertilizers containing cendensed phosphates have an ability to keep several heavy metals as trace elements in their solutions. In order to investigate the above character, the behavior of Mna2+ ien in the solution of ammonium condensed phosphates of short chain lengths has been studied mainly by using polarography and paper chromatography, Especially, differences of formation meehanism, stable zones, compositions of complex ion and precipitate of manganese among ertho-, pyro- and tripelyphosphate were investigated. The resultsobtained are summarized as follows:
In ammonium pyrophosphate solution, most of Mn2+ ion was precipitated in the same way as orthophosphate, but a small amount of the ion was kept as eomplex ion [Mn(P207)2]6- in the solution whose mole ratio of Mn2+/P205 was below O.5. The crystal phases precipitated in the solutions whose mole ratio being below and above 1.5 were different, and both were indicated by the same compesition expressed by (NH4)2Mng(P207)2.n H20 but n was different.
In the case of ammonium tripolyphosphate, the solubility of Mn2+ was large. Mn2+ ion was kept as complex ion [MnPsO10]3- in the solution of mole ratiobelow O.67 according to the formula (1), whereas the complex was decomposed and precipitated as NH4Mn2P3O10 n H2O in the solution of mole ratio above O.65 according to the formula (2).
Mn2+P30105- [MnP3O10] 3- (1)
[MnP3O10] 3-+Mn2+ NH M 2P801 H20 (2)