Substructural Transformation of Birnessite and Formation of Todorokite in Simulated Surface Environment
-
摘要: 水钠锰矿是土壤与沉积物中最为常见的氧化锰矿物, 依据其MnO6层对称特点分为六方和三斜两种亚结构类型.六方水钠锰矿在表生环境中可通过Mn2+的化学或生物氧化形成, 而环境中三斜水钠锰矿的形成及进一步转化为钙锰矿的途径尚不清楚.以两种六方水钠锰矿(酸性水钠锰矿和水羟锰矿)为前驱物, 采用X射线吸收光谱(EXAFS)、X射线衍射(XRD)、电镜(FESEM/TEM)及化学组成分析等技术方法模拟表生环境研究了水钠锰矿从六方向三斜的亚结构转化及生成钙锰矿的化学条件和矿物学机制.结果表明, 适当Mn(Ⅱ)浓度和弱碱性条件(pH≥8)可使六方水钠锰矿逐渐转化为三斜水钠锰矿, 继而经Mg2+交换、常压回流得到了长纤维状的钙锰矿, 其晶体生长以溶解-结晶为主.Mn(Ⅱ)与六方水钠锰矿MnO6八面体层内的Mn(Ⅳ)反应生成Mn(Ⅲ)并填充层内空位, 使水钠锰矿对称型由六方向三斜转变.与酸性水钠锰矿相比, 水羟锰矿结晶弱、层状堆积混乱度高, 与Mn(Ⅱ)反应迅速, 层结构向三斜水钠锰矿转化快.pH升高, 促进六方水钠锰矿对Mn(Ⅱ)的吸附和Mn(Ⅱ)与Mn(Ⅳ)间的反应, 六方水钠锰矿转化为三斜水钠锰矿的速率加快."六方水钠锰矿→三斜水钠锰矿"可能是环境中三斜水钠锰矿的重要来源, 及进一步形成钙锰矿的重要化学生成机制.Abstract: Birnessite, one of the most common Mn oxide minerals in soils and sediments, has two types of substructures, hexagonal and triclinic, on the basis of the MnO6 layer symmetrical features. In the surface environment, hexagonal birnessite is formed through the chemical or biological oxidation of Mn2+, but the formation pathway of triclinic birnessite and further transformation into todorokite are still not clear. In the simulated surface environment, the chemical conditions and mineralogy mechanism of hexagonal birnessite (acid birnessite and vernadite) transformation to triclinic birnessite, and then into todorokite were investigated by EXAFS, XRD, FESEM/TEM and chemical composition analyses. The results show that hexagonal birnessite can be converted into triclinic birnessite under appropriate Mn(Ⅱ) concentration and weak alkaline conditions (pH≥8), and triclinic birnessite can be further converted into todorokite which consists of long fibers after Mg2+ exchanged and refluxed under the atmospheric pressure. Long fibers of todorokite form mainly through a dissolution-recrystallization process. Reaction of aqueous Mn(Ⅱ) with Mn(Ⅳ) in the hexagonal birnessite MnO6 octahedral layers causes transformation of hexagonal birnessite into triclinic birnessite via filling of yielded Mn(Ⅲ) into vacancy sites in the layers. Compared with acid birnessite, the transformation of vernadite into triclinic birnessite was much easier due to weak crystallization and turbostratic structure of vernadite. Higher pH facilitates adsorption of Mn(Ⅱ) and reaction of Mn(Ⅱ) with Mn(Ⅳ), thus speeds up the transformation of hexagonal birnessite into triclinic birnessite. Therefore, one of the important sources of triclinic birnessite in nature can be denoted as: hexagonal birnessite → triclinic birnessite, which may be one of the important chemical formation mechanisms of todorokite in the surface environment.
-
Key words:
- birnessite /
- hexagonal birnessite /
- triclinic birnessite /
- todorokite /
- transformation /
- environmental geology
-
图 1 合成的酸性水钠锰矿和在16 mM Mn2+、pH 13条件下作用不同时间产物的XRD图谱
a.5°~75°2θ快速XRD图谱；b.5°~80°2θ粉晶XRD图谱；c.30°~40°2θ；d.60°~70°2θ
Fig. 1. Powder XRD patterns of acid birnessite and its products treated with 16 mM Mn2+ at pH 13 under different times
图 2 合成的酸性水钠锰矿和在12 mM Mn2+、pH13条件下作用不同时间产物的EXAFS图谱
Fig. 2. EXAFS date at the Mn-K edge and Fourier transforms of acid birnessite and its products treated with 12 mM Mn2+ at pH 13 under different times
图 3 合成的酸性水钠锰矿和在16 mM Mn2+、pH 13条件下作用不同时间产物的透射电镜图谱和扫描电镜图谱
Fig. 3. TEM、SEM images of acid birnessite and its products treated with 16 mM Mn2+ at pH 13 under different times a.HB; b.20 d; c.HB; d.1 d; e.6 d; f.20 d
图 4 合成的酸性水钠锰矿在不同pH条件以及不同Mn2+参与下的产物快速XRD图谱
F.六方水锰矿；H.黑锰矿
Fig. 4. Fast XRD patterns of acid birnessite at different pH values under different concentrations of Mn2+
图 5 合成的水羟锰矿和在7.5 mM Mn2+、pH9条件下作用不同时间产物的XRD图谱
a.5°~75°2θ快速XRD图谱；b.5°~75 °2θ粉晶XRD图谱；c.30°~°2θ；d.60°~70 °2θ
Fig. 5. Powder XRD patterns of vernadite and its products treated with 7.5 mM Mn2+ at pH 9 under different times
图 6 合成的水羟锰矿(a)和在7.5 mM Mn2+、pH9条件下作用20 d产物(b)的扫描电镜图谱
Fig. 6. SEM images of vernadite (a), its product treated with 7.5 mM Mn2+ at pH 9 for 20 d (b)
图 7 TB(HB)经Mg2+交换后回流不同阶段生成产物的粉晶XRD图谱
Fig. 7. Powder XRD patterns of intermediate products at the different stages of reflux after TB exchanged with Mg2+
图 8 TB(HB)经Mg2+交换后回流不同阶段生成产物的SEM形貌
Fig. 8. SEM images of intermediate products at the different stages of reflux after TB(HB) exchanged with Mg2+ a.2 h; b.6 h; c.12 h; d.24 h
图 9 钙锰矿的粉晶XRD图谱
图谱a.T(HB)－酸性水钠锰矿转化形成的钙锰矿、T(V)－水羟锰矿转化形成的钙锰矿、T(syn)－回流合成的钙锰矿；图谱b.120 ℃加热处理不同时间钙锰矿T(V)的X-射线衍射图谱
Fig. 9. Powder XRD pattern of the todorokite
表 1 酸性水钠锰矿和在16 mM Mn2+、pH 13条件下不同转化阶段产物的理化性质分析
Table 1. Physicochemical properties of acid birnessite and its products treated with 16 mM Mn2+ at pH 13 under different times
样品 平均化学组成 Mn AOS SSA(m2/g) HB Na0.253MnO2.052·nH2O 3.85 33.78 转化1 d Na0.308MnO1.959·nH2O 3.61 20.55 转化6 d Na0.318MnO1.989·nH2O 3.66 21.15 转化20 d Na0.292MnO1.986·nH2O 3.68 20.95 
下载: 导出CSV
-
[1] Bargar, J.R., Fuller, C.C., Marcus, M.A., et al., 2009. Structural Characterization of Terrestrial Microbial Mn Oxides from Pinal Creek, AZ. Geochimica et Cosmochimica Acta, 73: 889-910. doi: 10.1016/j.gca.2008.10.036 [2] Bish, D.L., Post, J.E., 1989. Thermal Behavior of Complex, Tunnel-Structure Manganese Oxides. American Mineralogist, 74: 177-186. http://www.researchgate.net/publication/236552007_Thermal_behavior_of_complex_tunnel-structure_manganese_oxides [3] Bodeï, S., Manceau, A., Geoffroy, N., et al., 2007. Formation of Todorokite from Vernadite in Ni-Rich Hemipelagic Sediments. Geochimica et Cosmochimica Acta, 71: 5698-5716. doi: 10.1016/j.gca.2007.07.020 [4] Buatier, M.D., Guillaume, D., Wheat, C.G., et al., 2004. Mineralogical Characterization and Genesis of Hydrothermal Mn Oxides from the Flank of the Juan, the Fuca Ridge. American Mineralogist, 89: 1807-1815. doi: 10.2138/am-2004-11-1227 [5] Cai, J., Liu, J., Suib, S.L., 2002. Preparative Parameters and Framework Dopant Effects in the Synthesis of Layer-Structure Birnessite by Air Oxidation. Chemistry of Materials, 14: 2071-2077. doi: 10.1021/cm010771h [6] Chukhrov, F.V., Drits, V.A., Gorshkov, A.I., et al., 1987. Structural Models of Vernadite. International Geology Review, 29: 1337-1347. doi: 10.1080/00206818709466228 [7] Drits, V.A., Silvester, E., Gorshkov, A.I., et al., 1997. Structure of Synthetic Monoclinic Na-Rich Birnessite and Hexagonal Birnessite: I. Results from X-Ray Diffraction and Selected-Area Electron Diffraction. American Mineralogist, 82: 946-961. doi: 10.2138/am-1997-9-1012 [8] Drits, V.A., Lanson, B., Gaillot, A.C., 2007. Birnessite Polytype Systematics and Identification by Powder X-Ray Diffraction. American Mineralogist, 92: 771-788. doi: 10.2138/am.2007.2207 [9] Fendorf, S.E., Sparks, D.L., Franz, J.A., et al., 1993. Electron Paramagnetic Resonance Stopped-Flow Kinetic Study of Manganese (Ⅱ) Sorption-Desorption on Birnessite. Soil Science Society of America Journal, 57: 57-62. doi: 10.2136/sssaj1993.03615995005700010011x [10] Feng, X.H., Liu, F., Tan, W.F., et al., 2004a. Synthesis of Todorokite by Refluxing Process and Its Primary Characteristics. Science in China(Ser. D), 47: 760-768. doi: 10.1360/03yd0511 [11] Feng, X.H., Tan, W.F., Liu, F., et al., 2004b. Synthesis of Todorokite at Atmospheric Pressure. Chemistry of Materials, 16: 4330-4336. doi: 10.1021/cm0499545 [12] Feng, X.H., Tan, W.F., Liu, F., et al., 2005. Hydrothermal Synthesis of Todorokite and Its Influencing Factors. Earth Science—Journal of China University of Geosciences, 30(3): 347-352 (in Chinese with English abstract). http://en.cnki.com.cn/Article_en/CJFDTOTAL-DQKX200503011.htm [13] Feng, X.H., Zhu, M.Q., Ginder-Vogel, M., et al., 2010. Formation of Nano-Crystalline Todorokite from Biogenic Mn Oxides. Geochimica et Cosmochimica Acta, 74: 3232-3245. doi: 10.1016/j.gca.2010.03.005 [14] Giovanoli, R., 1980. Vernadite is Random-Stacked Birnessite. Mineralium Deposita, 15: 251-253. [15] Golden, D.C., Chen, C.C., Dixon, J.B., 1987. Transformation of Birnessite to Buserite, Todorokite and Manganite under Mild Hydrothermal Treatment. Clays and Clay Minerals, 35: 271-280. doi: 10.1346/CCMN.1987.0350404 [16] Grangeon, S., Lanson, B., Miyata, N., et al., 2010. Structure of Nanocrystalline Phyllomanganates Produced by Freshwater Fungi. American Mineralogist, 95: 1608-1616. doi: 10.2138/am.2010.3516 [17] Jiang, X.J., Yao, D., Lin, X.H., 2009. Role of Sodium Ion on Stability of the Crystal Structure of Marine 10 Å Manganates. Earth Science —Journal of China University of Geosciences, 34(3): 392-398 (in Chinese with English abstract). doi: 10.3799/dqkx.2009.043 [18] Kijima, N., Yasuda, H., Sato, T., et al., 2001. Preparation and Characterization of Open Tunnel Oxide α-MnO2 Precipitated by Ozone Oxidation. Journal of Solid State Chemistry, 159(1): 94-102. doi: 10.1006/jssc.2001.9136 [19] Lanson, B., Drits, V.A., Silvester, E., et al., 2000. Structure of H-Exchanged Hexagonal Birnessite and Its Mechanism of Formation from Na-Rich Monoclinic Buserite at Low pH. American Mineralogist, 85: 826-838. doi: 10.2138/am-2000-5-625 [20] McKenzie, R.M., 1971. The Synthesis of Birnessite, Cryptomelane and Some Other Oxides and Hydroxides of Manganese. Mineralogical Magazine, 38: 493-502. doi: 10.1180/minmag.1971.038.296.12 [21] McKenzie, R.M., 1989. Manganese Oxides and Hydroxides. In: Dixon, J.B., Weed, S.B., eds., Minerals in Soil Environments (2nd Edition). Soil Science Society of America, Madison, Wisconsin, 439-465. [22] Post, J.E., 1999. Manganese Oxide Minerals: Crystal Structures and Economic and Environmental Significance. Proceeding of the National Academy of Sciences of the United of America, 96: 3447-3454. doi: 10.1073/pnas.96.7.3447 [23] Potter, R.M., Rossman, G.R., 1979. The Tetravalent Manganese Oxides: Identification, Hydration, and Structural Relationships by Infrared Spectroscopy. American Mineralogist, 64: 1199-1218. http://ammin.geoscienceworld.org/content/64/11-12/1199 [24] Qian, J.C., 1998. Study on Structural Stability of 1 nm Manganates. Acta Oceanologica Sinica, 20(3): 56-63 (in Chinese with English abstract). [25] Saratovsky, I., Gurr, S.J., Hayward, M.A., 2009. The Structure of Manganese Oxide Formed by the Fungus Acremonium sp. Strain KR21-2. Geochimica et Cosmochimica Acta, 73: 3291-3300. doi: 10.1016/j.gca.2009.03.005 [26] Shen, Y.F., Zerger, R.P., Suib, S.L., et al., 1993. Manganese Oxide Octahedral Molecular Sieves: Preparation, Characterization and Application. Science, 260: 511-515. doi: 10.1126/science.260.5107.511 [27] Takematsu, N., Khaben, H., Saton, Y., et al., 1988. Todorokite Formation in Seawater by Microbial Mediation. Journal of the Oceanographic Society of Japan, 44: 235-243. doi: 10.1007/BF02303427 [28] Tan, W.F., Liu, F., Li, Y.H., et al., 2000. Methodological Study of Identifying Manganese Minerals in Fe-Mn Nodules of Soils. Acta Mineralogica Sinica, 20(1): 63-67 (in Chinese with English abstract). [29] Tebo, B.M., Bargar, J.R., Clement, B.G., et al., 2004. Biogenic Manganese Oxides: Properties and Mechanisms of Formation. Annual Review of Earth and Planetary Sciences, 32: 287-328. doi: 10.1146/annurev.earth.32.101802.120213 [30] Toyoda, K., Tebo, B.M., 2013. The Effect of Ca2+ Ions and Ionic Strength on Mn(Ⅱ) Oxidation by Spores of the Marine Bacillus sp. SG-1. Geochimica et Cosmochimica Acta, 101: 1-11. doi: 10.1016/j.gca.2012.10.008 [31] Tu, S.H., Racz, G.J., Goh, T.B., 1994. Transformations of Synthetic Birnessite as Affected by pH and Manganese Concentration. Clays and Clay Minerals, 42(3): 321-330. doi: 10.1346/CCMN.1994.0420310 [32] Villalobos, M., Lanson, B., Manceau, A., et al., 2006. Structural Model for the Biogenic Mn Oxide Produced by Pseudomonas Putida. American Mineralogist, 91: 489-502. doi: 10.2138/am.2006.1925 [33] Villalobos, M., Toner, B., Bargar, J., et al., 2003. Characterization of the Mn Oxide Produced by Pseudomonas Putida Strain MnB1. Geochimica et Cosmochimica Acta, 67: 2649-2662. doi: 10.1016/S0016-7037(03)00217-5 [34] Wadsley, A.D., 1950. Synthesis of Some Hydrated Manganese Minerals. American Mineralogist, 35: 485-488. [35] Webb, S.M., Dick, G.J., Bargar, J.R., et al., 2005a. Evidence for the Presence of Mn(Ⅲ) Intermediates in the Bacterial Oxidation of Mn(Ⅱ). Proceeding of the National Academy of Sciences of the United of America, 102: 5558-5563. doi: 10.1073/pnas.0409119102 [36] Webb, S.M., Tebo, B.M., Bargar, J.R., 2005b. Structural Characterization of Biogenic Mn Oxides Produced in Seawater by the Marine Bacillus sp. Strain SG-1. American Mineralogist, 90: 1342-1357. doi: 10.2138/am.2005.1669 [37] Yang, D.S., Wang, M.K., 2002. Syntheses and Characterization of Birnessite by Oxidizing Pyrochroite in Alkaline Conditions. Clays and Clay Minerals, 50: 63-69. doi: 10.1346/000986002761002685 [38] Yin, H., Tan, W.F., Zheng, L.R., et al., 2012. Characterization of Ni-Rich Hexagonal Birnessite and Its Geochemical Effects on Aqueous Pb2+/Zn2+ and As(Ⅲ). Geochimica et Cosmochimica Acta, 93: 47-62. doi. org/10.1016/j. gca. 2012.05.039 doi: 10.1016/j.gca.2012.05.039 [39] Zhu, M.Q., Matthew, G.V., Sanjai, J.P., et al., 2010. Cation Effects on the Layer Structure of Biogenic Mn-Oxides. Environmental Science Technology, 44: 4465-4471. doi: 10.1021/es1009955 [40] 冯雄汉, 谭文峰, 刘凡, 等, 2005. 热液条件下钙锰矿的合成及其影响因素. 地球科学——中国地质大学学报, 30(3): 247-252. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX200503011.htm [41] 姜学钧, 姚德, 林学辉, 2009. 钠离子对于海洋成因10 Å水锰矿结构稳定性的影响. 地球科学——中国地质大学学报, 34(3): 392-398. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX200903001.htm [42] 钱江初, 1998.1 nm锰矿相结构稳定性的研究. 海洋学报, 20(3): 56-63. doi: 10.3321/j.issn:0253-4193.1998.03.009 [43] 谭文峰, 刘凡, 李永华, 等, 2000. 土壤铁锰结核中锰矿物类型鉴定的探讨. 矿物学报, 20(1): 63-67. doi: 10.3321/j.issn:1000-4734.2000.01.012 -
点击查看大图
计量
- 文章访问数: 3354
- HTML全文浏览量: 151
- PDF下载量: 474
- 被引次数: 0
