Conditions for the formation of pure birnessite during the oxidation of Mn(II) cations in aqueous alkaline medium
Graphical abstract
Pathways of birnessite formation
Introduction
Birnessite is a mixed Mn(III)-Mn(IV) oxide constituted by layers of edge-sharing MnO6 octahedra separated by planes of hydrated cations (e.g. Na+, K+, Ca2+) and water molecules. It was found to be one of the most common and active occurring Mn oxide in soils and sediments [1], [2]. Jones and Milnes [3] proposed the formula Na0.7Ca0.3Mn7O14, 2·8H2O. This natural form presents a disordered structure [2], [4], [5]. Thereby, many studies were focused on ways to obtain birnessite. Besides the existing biogenic ways, the chemical methods could be divided in four groups based on the mechanism involved.
The first method is based on the Mn(II) oxidation in alkali media producing Mn(OH)2 and its oxidation by O2 bubbling to form buserite, the hydrated form of birnessite [6], [7]. To avoid hausmannite formation as by-product many authors studied the mechanism involved. Intriguingly, Yang and Wang [8] prepared pure birnessite by O2 oxidation of Mn(OH)2 precipitate that was prepared from deoxygenated NaOH and MnCl2 solutions. They suggested that the use of deoxygenated water prevented the presence of Mn(III) responsible of the hausmannite formation. Feng et al. [9] showed that the formation of hausmannite was avoided when NaOH and MnCl2 were mixed below 10 °C; this study also showed that an oxygen flow rate of 5 L min−1 during 5 h is required to produce pure birnessite. Cai et al. [10] proposed a variant of Giovanoli's method by replacing O2 by air and they pointed that, in that case, a flow rate of 24 L min−1 is essential to avoid hausmannite formation. Pure birnessite was also obtained by using H2O2 instead of O2 as oxidant [11], [12].
The second way to obtain birnessite relies on the reduction of MnO4- in concentrated HCl medium [13], [14]. Numerous organic reducing agents were used such as fumaric acid [15], sugars [16], [17], alcohols [12], [18], ethylene glycol [19] and more recently epoxypropane [20] and lactate [21]. This method could be constraining as it involved a relatively long time aging step [12], [18], a calcination step at temperature above 400–450 °C [16], [17] or a hydrothermal treatment [20].
The third method is based on a direct conversion of hausmannite to birnessite involving a dissolution/recrystallization mechanism [22] in alkaline medium. Birnessite was obtained for concentrations of OH- above 2 mol L−1. The reaction required several weeks to be complete and the dissolution of hausmannite was found to be the rate-limiting step in this reaction.
The fourth process is based on a redox reaction between MnO4- and Mn2+ in alkaline conditions. A manganese salt (i.e. MnCl2, MnSO4) and sodium or potassium permanganate were generally used as Mn(II) and Mn(VII) suppliers respectively while NaOH or KOH were used to provide alkaline medium. This method was first reported by Murray [23]; it consisted on adding slowly the MnCl2 solution to NaOH/NaMnO4 solution. The product presented a poor crystallinity similar to natural birnessite. Luo et al., [24] and Luo and Suib [25], studied the influence of many parameters (temperature, basicity, MnO4-/Mn2+ ratio, presence of magnesium and anion effect) and showed that pure birnessite could be obtained in strong alkaline conditions with a MnO4-/Mn2+ ratio of 0.28–0.36 and at 40–65 °C. The authors also pointed that feitknechtite (β-MnOOH) was an intermediate in birnessite formation. Villalobos et al. [26] followed this work and showed the presence of small amount of manganite (γ-MnOOH) in addition to birnessite.
The redox method gained more interest on the past decades as it overcomes the inconvenient of the other methods such as high consumption of O2, use of boiling solution with concentrated acid and strong oxidant and long reaction times. In spite of an extensive literature [27], [28], [29], [30] the role of dissolved oxygen on the redox method remains unclear. Actually a reactive medium with an average oxidation state (AOS) of manganese close to 3.25 (Mn(VII): Mn(II) molar ratio of 0.33) led to birnessite with an AOS of Mn equal to 3.53 [29]. This suggests that the oxidation of Mn(II) leading to birnessite is not related to a unique redox reaction between Mn(II) and Mn(VII) and that dissolved oxygen may intervene in it as already observed in other methods such as Giovanoli's studied by Yang and Wang [8]. Besides, the mixing order of the three solutions generally involved (i.e. manganese salt, permanganate and base) varied from one study to another [23], [29], [30] and to our knowledge, no study has focused on the influence that could have this order of mixing on the nature of the obtained products. Moreover, the occurrence and possible role of hausmannite (Mn3O4), which can be observed as a by-product, is not clear.
The goals of this study are: i) to optimize the experimental conditions to obtain pure Na-birnessite or K-Birnessite through the redox method and ii) to get an insight into birnessite formation mechanism. A special attention is paid to the role of dissolved oxygen and to the mixing order of the reagents to prevent the side reaction leading to hausmannite. The X-ray photoelectron spectrometry is used in order to gain a more in-depth understanding of the target reaction mechanism.
Section snippets
Chemicals
All chemicals were purchased from Sigma-Aldrich. Manganese(II) chloride tetrahydrate (MnCl2,4H2O, ACS reagent, ≥98%) was used as Mn2+ supplier, sodium permanganate monohydrate (NaMnO4,H2O, ACS reagent ≥97%) or potassium permanganate (KMnO4, ACS reagent, ≥99.0%) as MnO4- supplier and sodium hydroxide (NaOH, BioXtra, ≥98% pellets anhydrous) or potassium hydroxide (KOH, ACS reagent, ≥85%, pellets) to provide alkaline medium. Double distilled water (DDW, 18.2 MΩ cm) was used for all the experiments.
Synthesis of birnessite
Mechanism of birnessite formation
Table 1 gives the nature of the products identified by XRD for all prepared samples.
Conclusion
Na-birnessites with different chemical compositions were synthesized following three different methods based on the use of the same reagents, i.e. OH-, MnO4- and Mn2+ but differing from each other in the order of mixing the reagents. Among the three methods, only two give rise to the formation of birnessite as single phase. The third (oxidant-last method) leads to the formation of hausmannite, in addition to birnessite. Moreover, lowering the addition time of the oxidant solution decreases the
References (50)
- et al.
Structural characterization of terrestrial microbial Mn oxides from Pinal Creek, AZ
Geochim. Cosmochim. Acta
(2009) - et al.
Birnessite manganese dioxide synthesized via a sol-gel process: a new rechargeable cathodic material for lithium batteries
Electrochim. Acta
(1991) - et al.
Synthesis of well-crystallized birnessite using ethylene glycol as a reducing reagent
Mater. Res. Bull.
(2007) - et al.
A simple method to synthesize birnessite at ambient pressure and temperature
Geoderma
(2013) The surface chemistry of hydrous manganese dioxide
J. Colloid Interface Sci.
(1974)- et al.
Characterization of the manganese oxide produced by Pseudomonas putida strain MnB1
Geochim. Cosmochim. Acta
(2003) - et al.
Synthesis, structural characterization and Pb(II) adsorption behavior of K- and H-birnessite samples
Desalination
(2011) - et al.
Infrared absorption spectra and cation distributions in (Mn, Fe)3O4
Solid State Commun.
(1972) - et al.
Characterization of the thermal genesis course of manganese oxides from inorganic precursors
Thermochim. Acta
(1992) - et al.
Controlled synthesis of Mn3O4 nanocrystallites and MnOOH nanorods by a solvothermal method
J. Cryst. Growth
(2004)
Synthesis and long-term phase stability of Mn3O4 nanoparticles
J. Mol. Struct.
Hydrogen Bonding and Jahn – Teller Distortion in Groutite, α-MnOOH, and Manganite, γ-MnOOH, and Their Relations to the Manganese Dioxides Ramsdellite and Pyrolusite
J. Solid State Chem.
The role of tetraethylammonium hydroxide on the phase determination and electrical properties of γ-MnOOH synthesized by hydrothermal
Mater. Lett.
Characterization of Ni-rich hexagonal birnessite and its geochemical effects on aqueous Pb2+/Zn2+ and As(III)
Geochim. Cosmochim. Acta
Sorption behavior of heavy metals on birnessite: relationship with its Mn average oxidation state and implications for types of sorption sites
Chem. Geol.
Preparation, characterization and adsorption performance of cetyltrimethylammonium modified birnessite
Appl. Surf. Sci.
The association of manganese and cobalt in soils-further observations
J. Soil Sci.
Birnessite, a new manganese oxide mineral from Aberdeenshire, Scotland
Mineral. Mag.
Structure of synthetic monoclinic Na-rich birnessite and hexagonal birnessite: ii. Results from chemical studies and EXAFS spectroscopy
Am. Mineral.
Structure of synthetic monoclinic Na-rich birnessite and hexagonal birnessite: i. Results from X-ray diffraction and selected-area electron diffraction
Am. Mineral.
Über Oxidhydroxide des vierwertigen Mangans mit Schichtengitter. 1. Mitteilung: natriummangan (II,III) manganat (IV)
Helv. Chim. Acta
Crystal structure determinations of synthetic sodium, magnesium, and potassium birnessite using TEM and the Rietveld method
Am. Mineral.
Syntheses and characterization of well-crystallized birnessite
Chem. Mater.
Synthesis of birnessite from the oxidation of Mn2+ by O2 in alkali medium: effects of synthesis conditions
Clays Clay Min.
Preparative parameters and framework dopant effects in the synthesis of layer-structure birnessite by air oxidation
Chem. Mater.
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