The synthesis methods used to produce todorokite (10 Å manganate, OMS-1) and birnessite (7 Å manganate), which are abundant in marine manganese nodules, have been studied to confirm whether pure mineral phases can be obtained and to compare their physicochemical characteristics. The physicochemical characteristics of todorokite and its precursor Na–birnessite can vary widely based on the precursors used during their synthesis. Birnessite can be synthesized via three mechanisms, i.e., the oxidation of Mn²⁺, a redox reaction between Mn²⁺ and MnO₄⁻, or the reduction of MnO₄⁻. Herein, four precursors are used to synthesize birnessite using different methods before being transformed into todorokite. The characteristics of the birnessite and todorokite synthesized using different methods are investigated via X-ray diffraction (XRD), chemical analysis, Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and field emission scanning electron microscopy (SEM). Based on the method used, birnessite and todorokite exhibit distinct physicochemical features, including crystallinity, crystal structure, specific surface area, oxidation state of manganese, thermal stability, and morphology. Thus, the characteristics of birnessite and todorokite are closely correlated, indicating the importance of designing suitable methods to synthesize them for specific applications.

中文翻译：

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多种方法合成的水钠锰矿和钙锰矿的理化特性

研究了用于生产锰锰矿中丰富的锰锌矿（10Å锰酸盐，OMS-1）和水钠锰矿（7Å锰酸盐）的合成方法，以确定是否可以获得纯矿物相并比较其理化特性。 。钙钛矿及其前体钠水钠锰矿的理化特性可根据其合成过程中使用的前体而有很大差异。水钠锰矿可通过三种机制，即合成的，Mn的氧化²⁺，锰的氧化还原反应²⁺和MnO ₄ ^- ，或MnO的还原₄ ^-。在此，在将四种前体转化成钙锰矿之前，使用不同的方法来合成水钠锰矿。通过X射线衍射（XRD），化学分析，Brunauer-Emmett-Teller（BET），X射线光电子能谱（XPS），热重分析（TGA）和不同的方法研究了使用不同方法合成的水钠锰矿和钙锰矿的特性。场发射扫描电子显微镜（SEM）。基于所使用的方法，水钠锰矿和钙锰矿显示出独特的物理化学特征，包括结晶度，晶体结构，比表面积，锰的氧化态，热稳定性和形态。因此，水钠锰矿和钙锰矿的特性密切相关，这表明设计适合特定应用的合成方法的重要性。