Transformation of Hexagonal Birnessite upon Reaction with Thallium(I): Effects of Birnessite Crystallinity, pH, and Thallium Concentration

Abstract

We examined the uptake of Tl(I) by two hexagonal birnessites and related phase transformations in laboratory experiments over 12 sequential additions of 0.01 M Tl(I)/Mn at pH 4.0, 6.0, and 8.0. The Tl-reacted Mn oxides were characterized for their structure, Tl binding, and morphology using X-ray diffraction, X-ray photoelectron and X-ray absorption spectroscopies, and transmission electron microscopy. Very limited Tl oxidation was observed in contrast to previous works, where equal Tl(I)/Mn was added in a single step. Instead, both birnessites transformed into a 2 × 2 tunneled phase with dehydrated Tl(I) in its tunnels at pH 4, but only partially at pH 6, and at pH 8.0 they remained layered. The first four to nine sequential Tl(I)/Mn additions resulted in lower residual dissolved Tl + concentrations than when the same amounts of Tl(I)/Mn were added in single steps. This study thus shows that the repeated reaction of hexagonal birnessites with smaller Tl(I)/Mn at ambient temperature triggers a complete phase conversion with Tl(I) as the sole reacting cation. The novel pathway found may be more relevant for contaminated environments and may help explain the formation of minerals like thalliomelane [Tl + (Mn 7.5 4+ Cu 0.5 2+ )O 16 ]; it also points to the possibility that other reducing species trigger similar Mn oxide transformation reactions.

Oxide– and Silicate–Water Interfaces and Their Roles in Technology and the Environment

“…For example, when Mn 2+ , Fe 2+ , or Tl + are added, the layered structure of birnessite (δ-Mn IV O 2 ) may be reduced to a Mn III oxide, partly dissolve and delaminate, , change its layer symmetry, or change to a tunneled Mn oxide. , The size of the resulting tunnels depends on the redox kinetics cycling . This cycling occurs with nanoparticulate birnessite, which may oxidize species that are stable under oxygenated conditions (such as Tl + ), suggesting higher oxidation potentials than oxygen, and therefore the possibility to oxidize water . Current related active research areas include both water oxidation , by birnessite and the electrochemical properties for processes such as water splitting to produce H 2 .…”

A Critical Review on the Multiple Roles of Manganese in Stabilizing and Destabilizing Soil Organic Matter

“…Mn­(II) can be oxidized to Mn­(III) by ROS (e.g., O 2 •– , 1 O 2 , OH • ) produced through abiotic pathways including Fe­(II) oxidation, nitrate photolysis, , illumination of humic substances, and illumination of metal oxides in desert varnish . Further Mn­(III) oxidation by ROS and/or disproportionation results in rapid Mn­(IV)-oxide formation. , Mineral surfaces, such as Fe-oxides and Mn-oxides, also catalyze Mn­(II) oxidation via interfacial catalysis and/or electrochemical reactions − at rates equivalent to or faster than biological oxidation. , Products of Mn­(II) oxidation and Mn-oxide phase transformations are highly dependent on pH conditions (e.g., SI Figure S1) and mineral surface properties (e.g., semiconductivity, particle size, ions). ,,− For instance, the presence of transition metals (e.g., Co and Ni), high concentrations of uranyl, and thallium have all been shown to mediate changes in Mn-oxide crystallinity or phase transformation.…”

“…44,45 Products of Mn(II) oxidation and Mn-oxide phase transformations are highly dependent on pH conditions (e.g., SI Figure S1) and mineral surface properties (e.g., semiconductivity, particle size, ions). 35,42,46−48 For instance, the presence of transition metals (e.g., Co and Ni), 49 high concentrations of uranyl, 50 and thallium 51 have all been shown to mediate changes in Mnoxide crystallinity or phase transformation.…”

The important role of the interaction between manganese minerals and metals in environmental remediation: a review

“…Based on the structural type, manganese minerals can be divided into tunnel structure, layered structure and low-valence unordered manganese mineral. Mutual transformation occurs between different types of manganese minerals under the certain conditions (Wang et al, 2018;Wu et al, 2019a;Ruiz-Garcia et al, 2021). The combination of the [Mn(III)O 6 ] octahedron and [MnO 6 ] octahedron leads to the transformation of the layered structure into the tunnel structure (Liang et al, 2020).…”

“…The synergistic or antagonistic effect resulted from the interaction in uence the puri cation of heavy metal and organism pollutant. Base on the synergistic effect of the interactions between manganese minerals with metals, Mn-based composites have been widely applied in the eld of environmental protection in recent years (Tarjomannejad et al, 2017;Ma et al, 2021;Ruiz-Garcia et al, 2021;Shaheen et al, 2022). The contribution of the synergistic effect between Mn and metal to environment puri cation has been con rmed (Chen et (Gao et al, 2019;Wang et al, 2019a).…”