Departmental Bulletin Paper Optimization of the Preparation Method of K–Selective Manganese Oxide for Assessing the Availability of Soil K

Matsuda, Ayumi  ,  Mori, Yuki  ,  Wada, Shin-Ichiro  ,  Wada, Shinichiro

61 ( 1 )  , pp.189 - 193 , 2016-02-29 , Faculty of Agriculture, Kyushu University
Heating mixed solutions containing manganese sulfate, ammonium peroxodisulfate and ammonium sulfate at a molar ratio of 1:1:5 at 150°C gave NH_4–cryptomelane. The higher the starting manganese concentration, the higher the purity of the products. At a concentration of 0.5 mol/L any products other than NH_4– cryptomelane was detected. Column washing with 6 mol/L nitric acid was found to be suitable for exchanging NH_4^+ with H^+. The H–exchanged cryptomelanes were highly selective for K and the K adsorption capacity increased as the volume of nitric acid used for washing increased. The maximum adsorption capacity achieved in this study was about 800 mmol/kg.

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