Chemical, HR-XRD and spectroscopic approaches to short-time dissolution behavior of kaolinitic soils
- Univ. of California, Berkeley, CA (United States)
Batch experiments were conducted at varying proton concentrations on a representative tropical soil in order to investigate its dissolution behavior over a 12h period. The release kinetics of Al, Fe, Si and C were investigated over a 2 to 6 pH range. The pH-dependence exhibited a point of minimum dissolution at pH {approx} p.z.n.c. Light scattering measurements on supernatant solutions indicated that colloids were dispersed mainly at pH > p.z.n.c. These results suggested a two-pathway dissolution process, with organic matter playing a role in both pathways. High-resolution X-ray diffraction as well as electron spin resonance and diffuse reflectance spectroscopies, were applied to characterize solid-phase transformations in the course of dissolution. With the exception of quartz, all mineralogical phases (kaolinite, and minor phases such as Fe-, Al- and Ti-oxides) remained unchanged or were slightly affected. A significant loss of quartz (about 10% by mass) was observed after a 12h dissolution at pH 2. Minor phases might have played an important role in stabilizing kaolinite, and dissolved silica may have hindered the dissolution of minor phases.
- OSTI ID:
- 501015
- Report Number(s):
- CONF-960401--; ISBN 1-55899-335-5
- Country of Publication:
- United States
- Language:
- English
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