Synthesis and characterization of two phases of manganese oxide from decomposition of permanganate in concentrated sulfuric acid at ambient temperature

Reaction Conditions and Aqueous Washing Process: Implications for Graphene Oxide Production and Its Applications

“…As each stage progresses, the oxygenated groups increase in the interlaminar space, exfoliating the layers, resulting in a decrease in the particle size. 37 In step 4, when 4% HCl is added, the intensity of the MnO 2 peaks decreases, but it also widens the peak that we have associated with the 002 of graphite. Step 5 is the same as step 4.…”

“…Step 2 has the same signals; that is, adding water does not structurally modify any of the solid compounds; in both cases, we see a series of peaks close to 24° 2θ, and we have associated it with graphite because the disturbance in its crystallinity at the original position of the peak may have changed. In step 3, H 2 O 2 has been added to neutralize KMnO 4 ; indeed, after this step, it is only possible to distinguish MnO 2 by the signals 110, 200, 220, 310, 211, 301, and 411 . In step 4, when 4% HCl is added, the intensity of the MnO 2 peaks decreases, but it also widens the peak that we have associated with the 002 of graphite.…”

“…The literature does not address the effect of washing in the samples, although there is a call to pay attention to this step. 28 The color changes of the first four steps (defined in Scheme 1) have been detailed in the literature 37 and are due to the reactions that take place between permanganate and sulfuric acid and then between permanganate and H 2 O 2 .…”

Characterization of an Inorganic Cryptomelane Nanomaterial Synthesized by a Novel Process Using Transmission Electron Microscopy and X-Ray Diffraction

“…A new, friendly green chemistry method has been developed to prepare the inorganic cryptomelane nanomaterial with the highest surface area~150 m 2 /g versus 130 m 2 /g! ever reported for this class of materials~Villegas Cheney et al, 2006Cheney et al, , 2007 The synthesis is based on the oxidation of MnSO 4 by permanganate ion in acidic conditions in the presence of about 2.5 ϫ 10 Ϫ4 MnO 2 at 608C in a closed reaction vessel and aging at 48C for 12 h. It was found that the aging time and concentration of O 2 affects the size of the crystals formed in the final product Cheney et al, 2006!. In the preliminary microstructure investigation of the nanosized cryptomelane, a fibrous structure with about 140-160 nm striations was identified by bright field transmission electron microscopy~BF-TEM!…”

“…In the past few years, nanomaterials have attracted great scientific interests owing to their small size, high surface area, and unique properties. A new, friendly green chemistry method has been developed to prepare the inorganic cryptomelane nanomaterial with the highest surface area (150 m 2 /g versus 130 m 2 /g) ever reported for this class of materials (Villegas et al, 2005; Cheney et al, 2006, 2007). The synthesis is based on the oxidation of MnSO 4 by permanganate ion in acidic conditions in the presence of about 2.5 × 10 −4 MnO 2 at 60°C in a closed reaction vessel and aging at 4°C for 12 h. It was found that the aging time and concentration of O 2 affects the size of the crystals formed in the final product (Cheney et al, 2006).…”