A New Method of Preparation and Some Interesting Transformations of Colloidal Manganese Dioxide.

Abstract

Within the last few years several papers on the formation of colloidal manganese dioxide have appeared. Thus far, however, the intermediate formation of colloidal manganese dioxide in the ordinary oxidations of organic compounds with potassium permanganate has not been reported. The following paper is a report of some observations on this subject. In the course of the experiments it was found that the gelatinous form of colloidal manganese dioxide first obtained is slowly and automatically converted into a limpid colloidal solution. This transformation was studied somewhat more in detail and was found to be readily influenced (I) by the temperature a t which the gel form was prepared, (2) by the concentration of the reacting solutions, (3) by the temperature to which the gel was subjected during the transformation, and (4) by the varia-4 Dissertation, Heidelberg (1907). G. Bredig and A. Marck, "Ueber kolloides MnOz sol und sein Verhalten gegen # 2 0 2 ; "

A Review of Porous Manganese Oxide Materials

“…This dependence on template ion is clearly the case for OMS-1 materials 2 and for RUB-7, as discussed later. 6 The formation of structures up to the 3 × 3 todorokite has been established for quite some time, however, stabilization of larger pore sizes and asymmetric tunnel 7) containing Rb + cations in the tunnels as well as an unknown, but presumably layered phase (RUB-8). 6 The material was prepared via hydrothermal treatment of Rb birnessite with Rb(OH) in a gold ampule at 350 °C and 2 kBar of pressure for 2 days.…”

“…2 Such adsorption capacity rivals zeolitic type materials and has been recognized for natural manganese nodules. [1][2][3][4][5][6][7][8][9][10][11][12][13] The porosity of other materials already discussed were not reported, however, structural properties suggest that they should be porous. [15][16][17][18][19][20]…”

“…Such routes frequently result in formation of a sol or gel. Although the initial report of manganese oxide jellies was made over 80 years ago, it was not until 1990 that such routes were re-examined for formation of microporous manganese oxides. − Very recently, Ching and co-workers have investigated the synthesis of the 2 × 2 material, cryptomelane (hollandite) and birnessite, by sol-gel routes. , …”

Syntheses of Birnessites Using Alcohols as Reducing Reagents: Effects of Synthesis Parameters on the Formation of Birnessites

“…36 We report here the synthesis of OL-1 materials using alcohols as reducing agents. E. J. Witzemann summarized reactions between permanganate and organics in neutral, acidic, and basic media, 37 and the focus of that research was to obtain amorphous manganese oxide colloids. Experiments described here are systematic investigations of the synthesis parameters in monoalcohol systems to understand and optimize crystallization of OL-1.…”

Manganese oxide thin films prepared by nonaqueous sol–gel processing: preferential formation of birnessite

“…Ching and Suib later developed sol-gel routes to birnessite-type manganese oxide using aqueous sol-gel reactions between KMnO 4 or NaMnO 4 and saccharides (such as glucose and sucrose) as well as other polyalcohols (such as ethylene glycol and glycerol) [8,9]. This work was built on much earlier observations of "manganese dioxide jellies" reported by Witzemann in 1915 [10]. With potassiumcontaining gels, there was an additional discovery that partial extraction of K + from the gel matrix led to formation of cryptomelane rather than birnessite [9,11,12].…”