Color Variations Associated with Rapid Formation of Goethite from Proto-Ferrihydrite at pH 13 and 40°C
Color Variations Associated with Rapid Formation of Goethite from Proto-Ferrihydrite at pH 13 and 40°C
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在 pH 13 和 40°C 下，与原水铁矿快速形成针铁矿相关的颜色变化
DOI：
10.1346/ccmn.1992.0400515
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发表时间：
1992
影响因子：
2.2
通讯作者：
M. Senoo
中科院分区：
文献类型：
--
作者：
T. Nagano;S. Nakashima;S. Nakayama;K. Osada;M. Senoo
用比色法和光谱法研究了合成针铁矿从棕色到黄色的颜色变化。通过改变孵育时间，在pH 13和40°C下合成具有各种颜色的针铁矿。比色法显示，L*a*B* 颜色空间中的B* 值（淡黄色色度）是稀释样品颜色变化的定量指标。从UV-VIS-NIR光谱中，发现B* 值的增加是由于在500 nm附近形成针铁矿而导致的晶场衍射增加所引起的。B* 值是针铁矿在包括水铁矿的沉淀物中的相对比例的良好指标。X射线衍射和红外光谱表明，针铁矿的结晶与原水铁矿中的水的损失有关。
Color variations from brown to yellow of synthesized goethite have been studied colorimetrically and spectroscopically. Goethite with various colors was synthesized at pH 13 and 40°C by varying the incubation time. Colorimetry revealed that the b* value (yellowish chroma) in L*a*b* color space was a quantitative indicator of color variations of the diluted samples. From UV-VIS-NIR spectra, the increase in the b* value was found to be caused by the increase in crystal field absorptions due to goethite formation around 500 nm. The b* value was a good indicator of the relative proportion of goethite in the precipitates including ferrihydrite. X-ray diffraction patterns and infrared spectra revealed that crystallization of goethite was associated with loss of water from the proto-ferrihydrite.