Reaction mass of calcium disilicide and calcium silicide

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption

Remarks:

adsorption

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Data source

Reference

Reference Type:

publication

Title:

Silicate and Phosphate Adsorption on Gibbsite Studied by X-ray Photoelectron Spectroscopy Angular Distributions

Author:

Alvarez, Robustiano., Charles S. Fadley, and James A. Silva

Year:

1980

Bibliographic source:

Soil Sci Soc Am J 1980 44: 422-425.

Materials and methods

Test guideline

Qualifier:

no guideline followed

Type of method:

batch equilibrium method

Media:

other: synthetic gibbsite

Test material

Test material information

Constituent 1

Reference substance name:

Tetrahydroxysilane

EC Number:

233-477-0

EC Name:

Tetrahydroxysilane

Cas Number:

10193-36-9

IUPAC Name:

orthosilicic acid

Study design

Batch equilibrium or other method

Analytical monitoring:

not required

Details on test conditions:

The adsorbent chosen for this study was solid A1(OH)3 powder with a surface area of 9.7 m2/g as measured by the BET method. The adsorbates were aqueous solutions of Si(OH)4 (75 ppm Si) CaSiO3 (75 ppm Si), , Ca(NO3)2 (0.005M), and Ca(H2PO4)2 (0.01M). The gibbsite was
shaken with unbuffered solutions of the adsorbates for three hours and allowed to equilibrate for 8 hours then was separated by filtration through a Buchner funnel, and the remaining solid leached with a relatively large volume of water [solid to water ratio = 1:50]. Most of the more
weakly bonded adsorbate species would be removed from the gibbsite surface by this leaching. The solid samples were then dried for eight hours at 55°C at atmospheric pressure and subsequently pressed into small wafers. Examination of the surfaces of these wafers was carried out with a
Hewlett Packard 5950A ESCA spectrometer capable of an instrumental resolution of —0.5 eV. The pressure in the spectrometer chamber during these measurements was ~10"8 torr.

Duration of adsorption equilibration

Duration:

11 h

Applicant's summary and conclusion

Executive summary:

Summary of observations:

1) No Si was detected on the A1(OH)₃ surface in the Si(OH)₄ treatment which suggests weak adsorption of Si on gibbsite in the absence of Ca.

2) When CaSiO₃ was the adsorbate, both Ca and Si were detected on the adsorbent surface with an approximate Ca/Si ratio of 1/8.

3) Ca and P were both present on the adsorbent after Ca(H₂PO₄)₂ treatment.

4) Atomic concentration ratio estimates calculated from peak intensities, kinetic energies, and photoelectron cross-sections, showed that Ca/Si exceeds Ca/P on the alumina surface.