Constraint of Nanometer-Sized Pyrite Crystals on Oxidation Kinetics and Weathering Products
Constraint of Nanometer-Sized Pyrite Crystals on Oxidation Kinetics and Weathering Products
复制标题
纳米黄铁矿晶体对氧化动力学和风化产物的约束
DOI：
10.1166/jnn.2017.14508
复制
发表时间：
2017
影响因子：
--
通讯作者：
Zhou Yuefei
中科院分区：
文献类型：
--
作者：
Xu Liang;Xie Qiaoqin;Chen Tianhu;Li Ping;Yang Yan;Zhou Yuefei
研究了中国长江中下游成矿带胶体黄铁矿（CPy）的氧化行为和氧化产物，并与正常黄铁矿（NPy、大晶黄铁矿）进行了对比，以评价胶体黄铁矿的相对环境影响。CPy是黄铁矿的隐晶形式，具有纳米和亚微米大小的晶体。通过x射线衍射（XRD）和扫描电镜（SEM）对新鲜和氧化样品的分析表明，在环境条件下，CPy的氧化分两个阶段进行，没有冲洗。第一阶段的特征是形成铁（II）氧化产物，如菱长石和黑钨矿，而第二阶段的特征是形成铁（III）硫酸盐，如菱长石和菱长石。通过氧化动力学实验研究了CPy的尺寸控制氧化速率，结果表明，CPy在水溶液中的氧化可以用零级动力学模型来描述，其氧化速度比NPy快36.8倍。CPy的高反应活性归因于纳米尺寸的晶体和高比表面积，这反过来决定了氧化产物的形态。由于纳米效应，CPy的氧化比NPy的氧化对矿山环境的破坏更大。
The oxidation behavior and oxidation products of colloidal pyrite (CPy) from the middle-lower Yangtze River metallogenic belt in China are investigated and compared with normal pyrite (NPy, macrocrystalline pyrite) in order to evaluate the relative environmental impact of CPy. CPy is a cryptocrystalline form of pyrite with nanometer- and submicrometer-sized crystals. Analysis of fresh and oxidized samples by X-ray diffraction (XRD) and scanning electron microscopy (SEM) reveals that the oxidation of CPy proceeds in two stages under ambient conditions without flushing. The first stage is characterized by the formation of Fe(II) oxidation products such as rozenite and melanterite, whereas the second stage is characterized by the formation of Fe(III) sulfates such as rhomboclase and romerite. The oxidation kinetic experiments were designed to investigate the size-controlled oxidation rate of CPy and the results show that the oxidation of CPy in aqueous solution can be described by a zero-order kinetic model, proceeding 36.8 times faster than for NPy. The higher reactivity of CPy is attributed to the nanometer-sized crystals and high specific surface area, which in turn determines the speciation of oxidation products. Due to the nano effect, the oxidation of CPy is more destructive to the mine environment than that of NPy.