Correlation of X-ray, Infrared, Dta (Differential Thermal Analysis), Dtga (Differential Thermogravimetric Analysis), and Cec (Cation-exchange Capacity) Observations on Synthetic and Natural Aluminum-hydroxy Interlayers

NORMAN LARRY MEYERS, Purdue University

Abstract

Hydroxy interlayers in smectites are common in acid soils and have been of interest in soil science for a number of years. Detection of interlayer material has generally been accomplished by X-ray diffraction and is often confounded by pretreatments for the removal of organic matter and free iron oxides. This study serves to correlate data obtained on X-ray diffraction, IR, DTA, DTGA, CEC, and aluminum analysis using synthetically produced Al-hydroxy interlayers in an effort to better evaluate naturally occuring soil interlayers. Al-hydroxy interlayers were prepared using 4, 8, 16, and 20 meq.of Al per gram of clay with NaOH added to effect a final OH/Al ratio of 1.5. Preparations were aged for periods of one week and four months. X-ray diffraction reveals increasing resistance of the clay to collapse on K-saturation and heating with increasing amounts of inter-cm-1 layer. The IR reveals an absorption band in the 3700 cm region which is attributed to the OH stretching mode of the interlayer. Deuteration of some clay crystal OH and interlayer OH is possible at 100°C but does not allow differentiation between the two. However, an OD band always appears when interlayers are present and thus provides a sensitive technique for the detection of Al-interlayers,

Degree

Ph.D.

Subject Area

Agronomy

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