Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
Appl Spectrosc. 2011 Oct;65(10):1162-9. doi: 10.1366/11-06236.
The adsorption of alginic acid on a TiO(2) particle film from aqueous solution was investigated by attenuated total reflection infrared (ATR-IR) spectroscopy. ATR-IR spectra recorded at different pHs confirmed that alginate adsorption to TiO(2) is favored at pH 3.0 and no significant adsorption occurs above pH 5.0. Upon adsorption the carboxylic acid groups of alginic acid are converted to the carboxylate form and bind to surface Ti(IV) ions via bridging bidentate structures. Spectral analyses of the carboxylic acid and carboxylate stretching vibrations indicated that about three in four -COOH groups are converted to -COO(-) groups as they bind coordinately to TiO(2). Additionally, the spectral data at pH 8.0 showed specific interactions of Ca(2+) ions with the free COO(-) groups of the polysaccharide backbone of adsorbed alginic acid.
采用衰减全反射红外光谱（ATR-IR）研究了从水溶液中吸附到 TiO(2) 颗粒膜上的褐藻酸。在不同 pH 值下记录的 ATR-IR 光谱证实，褐藻酸盐在 pH 3.0 时有利于吸附到 TiO(2)上，而在 pH 值高于 5.0 时则没有明显的吸附作用。吸附后，褐藻酸的羧酸基团转化为羧酸盐形式，并通过桥联双齿结构与表面 Ti(IV)离子结合。羧酸和羧酸盐伸缩振动的光谱分析表明，当它们与 TiO(2)配位结合时，大约有四分之三的 -COOH 基团转化为 -COO(-)基团。此外，在 pH 8.0 时的光谱数据显示，Ca(2+)离子与吸附褐藻酸多糖主链上的游离 COO(-)基团之间存在特定的相互作用。
