Soluble colloidal manganese dioxide: Formation, identification and prospects of application

Abstract

1 EXPERIMENTAL Materials and MethodsAll chemicals used in this work were of reagent grade: KMnO 4 , Na 2 S 2 O 3 ⋅ 5H 2 O, MnSO 4 ⋅ H 2 O, KI were purchased from BDH, NaHCO 3 , H 2 SO 4 , NaCl, KCl, KBr, CuSO 4 , Al 2 (SO 4 ) 3 , HCOOH were pur chased from Merck. To prepare aqueous solutions, the double distilled water was used.The absorbance measurements and spectral analy sis were carried out by using a double beam UV Visible Abstract-Soluble colloidal MnO 2 was prepared by the reduction of KMnO 4 by three reducing agents as MnSO 4 , Na 2 S 2 O 3 and HCOOH in neutral aqueous solutions at 25°C. Under suitable conditions, these solu tions were dark brown in color and found to remain stable and transparent for several weeks. The obtained colloid was characterized by spectrophotometric and coagulation methods. The spectral behavior of soluble colloidal MnO 2 was studied. The λ max was 390 nm when MnO 2 was prepared by the reduction of KMnO 4 by MnSO 4 . Both the λ max and the molar extinction coefficient depended on the method of preparation of col loidal MnO 2 . The formation of MnO 2 was confirmed by the determination of the oxidation state of Mn species in MnO 2 . The behavior of as prepared colloidal solution obeys Beer Lambert law, if the concentrations of the colloidal particles are assumed to be equal to Both spectral analysis and that using Rayleigh's law con firmed the existence of colloidal MnO 2 . The observed coagulating efficiency depends not only on the concen tration of electrolyte but also on the charge carried by the cation of the electrolyte. Stability of the colloidal par ticles in the aqueous solutions is determined by the negative charge on the surface of the colloidal particles.

Soluble Colloidal Manganese Dioxide: Formation, Characterization and Application in Oxidative Kinetic Study of Ciprofloxacin

“…The oxidation state of manganese species in the colloidal solution was also determined iodometrically at 390 nm based on the previous report [46]. The determined oxidation state of Mn species in MnO2 was (+4.16), was confirming the formation of MnO2 [47].…”

Geochemical and Photochemical Constraints on S[IV] Concentrations in Natural Waters on Prebiotic Earth

“…We non-invasively tracked the evolution of the UV-Vis absorption spectra of the samples. These data are corroborative but not on their own definitive, because the potential products of S[IV] disproportionation are themselves UV absorbers (Beyad et al, 2014;Guenther et al, 2001;Islam & Rahman, 2008;Meyer et al, 1982). The UV-Vis monitoring is therefore secondary to the solution-phase analytics.…”

Geochemical and Photochemical Constraints on S[IV] Concentrations in Natural Waters on Prebiotic Earth

“…We non-invasively tracked the evolution of the UV-Vis absorption spectra of the samples. These data are corroborative but not on their own definitive, because the potential products of S[IV] disproportionation are themselves UV absorbers (Meyer et al, 1982;Guenther et al, 2001;Islam, 2008;. The UV-Vis monitoring is therefore secondary to the solution-phase analytics.…”