铁酸盐
化学
吸附
齿合度
无机化学
铬酸盐转化膜
水溶液
离子强度
质子化
衰减全反射
傅里叶变换红外光谱
离子交换
红外光谱学
铬
物理化学
离子
金属
化学工程
有机化学
工程类
作者
Chad P. Johnston,Maria Chrysochoou
摘要
Chromate mobility, reactivity, and bioavailability in soil environments are affected by adsorption reactions on iron oxide minerals, but the adsorption mechanisms remain controversial. In this study, we employed in situ attenuated total reflectance Fourier transform infrared spectroscopy and theoretical frequency calculations to characterize chromate adsorption on 2-line ferrihydrite. The effects of pH, aqueous chromate concentration, ionic strength, and deuterium exchange were investigated. Results suggest the formation of monodentate and bidentate surface complexes. It was determined that monodentate complexes are dominant at low surface coverage and pH ≥ 6.5 and that bidentate complexes form at high surface coverage and pH < 6. Deuterium exchange experiments indicated that the inner-sphere complexes are not protonated. Difference spectra revealed that monodentate complexes are particularly susceptible to ionic strength effects under acidic conditions.
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