人工合成绿锈GR1(CO32?)的氧化晶质过程、特点及主要影响因素

通过空气氧化法，采用电化学实时监测，结合X-射线衍射（XRD）、透射电镜（TEM）和溶液化学分析，探讨了 GR1(CO32-)的合成、氧化和晶质化特点。在合成阶段，当悬液pH降至最低或矿物中Fe2 含量升至最高时，GR1(CO32-)完全形成。在随后转化阶段，控制pH在6.5 ~ 10时，随pH增加，GR1(CO32-)的转化速率和氧化速率均减小，氧化产物由纤铁矿向针铁矿向磁铁矿变化，且针铁矿结晶尺寸随pH升高逐渐增加。控制温度在15 ~ 45 ℃时，随反应温度的增加，GR1(CO32-)的转化速率增加而氧化速率减小，氧化产物同样由纤铁矿向针铁矿向磁铁矿变化，且针铁矿粒径随温度升高而增大。控制空气流速在0 ~ 0.1 m3 h-1时，随着空气流速的增加，氧化速率增加，氧化产物中针铁矿含量逐渐减少而纤铁矿含量逐渐增加，且产物结晶度逐渐减弱。因此，在pH、温度和空气流速等影响GR1(CO32-)转化过程中，氧化速率是共同的决定因素，随着氧化速率的增加，产物由磁铁矿向针铁矿向纤铁矿变化，且产物结晶尺寸变小和结晶度减弱。

PROCESS AND CHARACTERISTICS OF OXIDATION-CRYSTALLIZATION OF SYNTHETIC GR1(CO32-) AND MAIN INFLUENCING FACTORS

By means of air oxidation electrochemical real-time monitoring, and X-ray diffraction (XRD), transmission electron microscope (TEM) and solution analysis, synthesis, oxidation and crystallization of hydroxycarbonate green rust GR1(CO32-) were investigated. At the synthesis stage when pH of the suspension drops to the lowest or the ratio of n(Fe2 )/n(Fetotal) in mineral rises to the highest, GR1(CO32-) is formed completely. At the transformation stage when pH is controlld within the range of 6.5 ~ 10 at 25 °C, with the rising pH, both the transformation rate and oxidation rate of GR1(CO32-) decreases, with its oxidate turning from lepidocrocite to goethite and magnetite, and the goethite crystallites increasing in size. When temperature of the suspension is controlled within the range of 15 °C ~ 45 °C, with the rising reaction temperature, the transformation rate of GR1(CO32-) increases while oxidation rate decreases, with its oxidate turning from lepidocrocite to goethite and magnetite, and the goethite crystallizes increasing in size. When airflow is controlled in the range of 0 ~ 0.1 m3 h-1 at 25 °C, with the increasing airflow rate, the oxidation rate increases, with its oxidate gradually turning from goethite to lepidocrocite and decreasing in crystallinity. Therefore, oxidation rate is a determining factor in the transformation of GR1(CO32-) under the influences of pH, temperature and airflow rate. With increasing oxidation rate, oxidate of the reaction turns from magnetite to goethite to lepidocrocite, and decreases in size of the crystallites and in crystallinity.