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1.
Todorokite is one of the common manganese ox-ides in manganese ore deposits, weathering product of manganese-bearing rocks, soils and sediments. It is also an important component in the abundant marine manganese nodules. Since todorokite was firstly found in Japanese Todoroki mine in 1934, its properties and origination have appeared to be very interesting to many researchers[1—3]. It has a stable structure similar to porous molecular sieves, constructed of triple MnO6 octahedral chains. Th…  相似文献   
2.
水钠锰矿吸附Pb2+亚结构变化的红外光谱研究   总被引:1,自引:0,他引:1  
利用红外光谱表征了吸附Pb2+前后的不同锰氧化度的水钠锰矿,结合二次求导退卷积方法确定实际的红外吸收带中心,分析了水钠锰矿红外吸收带的归属.结果表明,供试样品的899~920 cm-1红外吸收带源于八面体空穴处OH的弯曲振动,随着水钠锰矿锰氧化度的降低,空穴处与OH配位的Mn4+被Mn3+替代的数量增多,OH弯曲振动频...  相似文献   
3.
热液条件下钙锰矿的合成及其影响因素   总被引:5,自引:0,他引:5  
钙锰矿具有3×3的大隧道构造,广泛分布于大洋锰结壳和锰结核等环境中,其性质和成因倍受关注.以改进方法制备的水钠锰矿(birnessite)为前驱物,Mg2+交换后得到Mg水钠锰矿(或称布塞尔矿,buserite),经热液处理合成了结晶度高的单相钙锰矿(todorokite),采用X射线衍射(XRD)、透射电镜(TEM)和选区电子衍射(SAED)等技术探讨了热液温度、体系压力和处理时间等因素对钙锰矿合成的影响.结果表明:合成的钙锰矿与天然钙锰矿有相同的形貌和生长特征,呈纤维状,沿120°三连晶生长,平均化学组成为Mg0.16MnO2.07·0.82H2O.在实验条件下,热液温度和处理时间是影响钙锰矿合成的主要因素;而通过改变高压釜的填充度引起体系压力的变化对钙锰矿合成的影响较小,体系压力并不是钙锰矿形成的主要影响因素.热液温度越高,Mg水钠锰矿转化为钙锰矿的速率越快,完全转化为钙锰矿所需的处理时间越短.热液温度分别为120℃、160℃和200℃时,Mg水钠锰矿完全转化为钙锰矿所需的时间分别为6h、4h和2h;但热液温度高于160℃时,易生成水锰矿杂质.延长处理时间与提高热液温度具有相似的影响规律.这进一步明确了钙锰矿的生成条件,可为阐明钙锰矿的形成机制和促进其在材料科学中的应用提供理论依据.  相似文献   
4.
A recent early diagenetic banded iron-manganese mud has been forming underground in a closed lead-zinc mine for approximately 40 years. The processes leading to the banded structure of the precipitate were studied during a period of 2 years. Therefore, 19 physical and chemical parameters were measured regularly in short intervals. The resulting time series were analysed with respect to the data sets of the monthly chemical analyses of the descendent mine water, the daily rainfall and the mineral content. The results reveal that the precipitated material undergoes internal self-organization due to interaction of redox, colloid-chemical, microbial, electrical and ripening processes, and not exclusively produced by seasonal fluctuations of material input. Thus, the primary banding of the material, caused by externally forced fluctuations of the redox conditions within the mine water, is reorganized after a short time. The finally observed bands are controlled by non-linear coupling of reaction and transport processes within the mud. A genetic model for the banded mineralization was developed and verified by numerical simulation.  相似文献   
5.
Under the ever-present solar radiation, photosynthetic organisms on Earth evolved structurally-sophisticated photosynthetic systems. However, little attention has been paid to the inherent impact of sunlight illumination on the inorganic minerals widespread on the Earth surface. We discovered for the first time the solar energy conversion system of the “mineral coatings” on the Earth's surface (aka“mineral membrane”), which exerts potential oxygen-production and carbon-sequestration functions on the Earth surface. Our finding shed a light on the photoelectric effect and non-classical photosynthesis involving natural semiconducting minerals. In this contribution, we studied the semiconducting property and photoelectron energy of typical minerals in the “mineral membrane”, focusing primarily on the photoelectric effect in and oxygen-production/carbon-sequestration function of ferromanganese oxides, as well as relevant geological records. We propose that birnessite, goethite and hematite, the semiconducting minerals commonly found in the “mineral membrane”, can perform sensitive and stable photon-to-electron conversion under solar radiation. The non-classical mineral photosynthetic function we put forth is as follows: Solar energy utilization by inorganic minerals resembles photosynthesis in regarding to oxygen evolution and carbon fixing, and the “mineral membrane” may take part in both photocatalytic water-oxidation reaction and transformation of atmospheric CO2into marine carbonate. In addition, minerals might as well have promoted photosynthesis in photosynthetic organisms. During the water-oxidation reaction, the inorganic cluster Mn4CaO5of photosystem II cycles through redox intermediates that are analogous to birnessite both in structure and component. Thus, it is fair to postulate that birnessites could play a role in the initiation of the photosynthesis in cyanobacteria, as minerals could weaken the hydrogen bond strength and alter water properties, thus facilitating water oxidation and photosynthesis. This observation offers further insights into the molecular mechanism of mineral participation in photosynthesis in photosynthetic organisms.  相似文献   
6.
水钠锰矿氧化硫化物的过程与动力学研究   总被引:1,自引:0,他引:1  
水钠锰矿是表生环境中常见的氧化锰矿物之一,影响土壤溶液中硫化物的迁移、转化和归趋。本文考察了酸性水钠锰矿氧化硫化钠溶液的反应过程,采用分光光度法、离子色谱法分析S2-及其氧化产物的浓度和变化趋势,用XRD、SEM表征酸性水钠锰矿粉末反应前后的晶体结构和微观形貌,探讨了温度、pH值、矿物用量对S2-氧化速率的影响。结果表明,S2-的氧化产物主要为单质S,其氧化速率符合准一级动力学规律,且氧化速率随着温度升高、pH值降低和矿物用量增加而增大;酸性水钠锰矿首先被还原生成Mn(OH)2,Mn(OH)2在空气中与O2作用转化成Mn3O4,Mn3O4可进一步转化生成MnOOH。  相似文献   
7.
隧道构造的钙锰矿以其特殊的结构和理化性质在催化、吸附、二次电池正极材料等领域有广泛的应用,常以层状Na-布塞尔矿(Na-buserite)为前驱物进行人工合成。焦磷酸盐(pH=1~8)对Mn(Ⅲ)有很强的络合作用,经焦磷酸盐处理的Na-布塞尔矿向钙锰矿转化的特点可表征Mn(Ⅲ)在层状向隧道构造转化中的重要作用。常压回流条件下Na-布塞尔矿向钙锰矿的转化程度随着焦磷酸盐处理浓度的增加和处理时间的延长而逐渐减小,直至不能向钙锰矿转化。钙锰矿形成的难易与Na-布塞尔矿结构中Mn(Ⅲ)被络合数量成反比,用对Mn(Ⅲ)络合作用很弱的焦磷酸盐溶液(pH=10)处理的Na-布塞尔矿可在常压回流条件下完全转化形成钙锰矿。  相似文献   
8.
碱性介质中合成水钠锰矿的几个影响因素   总被引:8,自引:0,他引:8  
水钠锰矿是土壤和沉积物中常见的氧化锰矿物。较系统地研究了碱性介质中合成水钠锰矿几个影响因素的作用规律。结果表明,在实验条件下,反应液的流动速率和氧气流量是合成水钠锰矿的主要影响因素,在反应中使用机械搅拌,可以使水钠锰矿的合成简单易行;而反应前通氮气处理和反应温度对水钠锰矿的合成没有影响;实验合成单相水钠锰矿的条件为:OH-/Mn摩尔比为13.7,O2的流量2L/min,在常温和机械搅拌下氧化5h;其平均化学组成为Na0.25MnO2.07·0.66H2O。  相似文献   
9.
水钠锰矿、钙锰矿是土壤和沉积物中常见的氧化锰矿物。本文用改进的方法在碱性介质中合成了结晶度高的单相水钠锰矿 ,其平均化学组成为Na0 .2 5MnO2 .0 70 .6 6H2 O。合成在常温 2 5℃以及机械搅拌作用下进行 ,反应易于控制 ,没有黑锰矿、六方锰矿等其它矿相生成。合成的单相水钠锰矿经Mg2 + 交换、热液处理 ,完全转化为结晶良好、隧道构造为 3× 3的钙锰矿。生成的钙锰矿呈长短不一的纤维状 ,沿三个方向生长的晶体形成各交 12 0°角的三连晶结构 ,平均化学组成为Mg0 .1 6 MnO1 .570 .82H2 O  相似文献   
10.
地球上生物因受到太阳光辐射作用而进化出结构精致的光合作用系统。太阳光辐射对地球表面广泛分布的无机矿物的影响与响应机制长期未被重视与理解。我们新发现的地表“矿物膜”转化太阳能系统,具有潜在的产氧固碳作用,体现出自然界中固有的矿物光电效应与非经典光合作用。本文在总结自然界中矿物光电子能量特征,特别是地表“矿物膜”特征及其光电效应性能的基础上,重点探讨铁锰氧化物矿物表现出的光电效应、产氧固碳作用与地质记录。提出矿物享有光电效应特性,地表“矿物膜”富含水钠锰矿、针铁矿、赤铁矿等天然半导体矿物,在日光辐射下具有稳定而灵敏的光电转换性能,产生矿物光电子能量;提出矿物拥有非经典光合作用的性能,自然界无机矿物转化太阳能系统类似生物光合作用吸收转化太阳能的产氧固碳系统,地表“矿物膜”光催化裂解水产氧作用及其转化大气和海洋二氧化碳为碳酸盐矿物作用,孕育出“矿物光合作用”;提出矿物具有促进生物光合作用的功能,生物光合作用中心Mn4CaO5在裂解水产氧过程中产生成分和结构类似水钠锰矿的锰簇化合物结构体,初步认为水钠锰矿可能促使蓝细菌光合作用系统的起源,矿物影响与削弱水分子氢键以改变水的性质,可提高水的分解程度与光合作用效率,为进一步探索矿物促进生物光合作用机理提供科学技术突破的机遇。  相似文献   
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