基于红外光声光谱的蒙脱石-黄原糖复合体界面层特征研究

CHARACTERIZATION OF THE INTERFACE OF MONTMORILLONITE-XANTHAN COMPLEX USING FOURIER TRANSFORM INFRARED PHOTOACOUSTIC SPECTROSCOPY

黏土矿物-有机物复合体在土壤中具有重要的作用,而土壤黏土矿物-多糖复合体是黏土矿物-有机物复合体形成的前体,有利于复合体的形成和转化,但其具体的作用机制尚不清楚。本研究制备了蒙脱石-黄原糖模型复合体,采用X-衍射分析了复合体的结构信息,并利用傅里叶转换红外光声光谱原位逐层扫描功能,探测了蒙脱石-黄原糖复合体表面下不同深度的光谱信息。结果表明,蒙脱石与黄原糖的相互作用主要发生在蒙脱石的表面,并形成表面界面层;该界面层具有明显的红外光声光谱特征,所形成的复合体有更强的持水能力,且表层与亚表层的光谱信息明显不同;红外光声光谱逐层分析表明,蒙脱石-黄原糖复合体界面层厚度大约在2.05～6.47μm之间。本结果为揭示复杂的矿物-有机物复合体形成过程及其影响因素提供了定量依据。

Organo-mineral complexes play an important role in soil. Clay mineral-polysaccharide complex is a precursor, contributing to the formation of clay Organo-mineral complexes, but its specific functions remain unclear. Montmorillonite-xanthan complex was prepared and analyzed for its structure with X-diffraction and spectra at various depths with a Fourier transform infrared photoacoustic spectroscop （FTIR-PAS） that has the function of insitu depth-profiling. Results show that the interaction between montmorillonite and xanthan occurred mainly on the surface of montmorillonite, and subsequently formed an interfacial layer, which featured a distinct infrared photoacoustic spectrum; the formed complex demonstrated stronger water-holding capacity than montmorillonite, and its surface differed significantly from its subsurface in spectrum, and the interracial layer of the montmorillonite-xanthan complex was approximately 2.05 - 6.47 μm thick according to the depth-profiling with FTIR-PAS.