Differential Dissolution Analysis of Clays and its Application to Hawaiian Soils
Saved in:
| Title: | Differential Dissolution Analysis of Clays and its Application to Hawaiian Soils |
|---|---|
| Authors: | Hashimoto, Isao |
| Publisher Information: | University of Hawaii at Manoa |
| Publication Year: | 1961 |
| Collection: | ScholarSpace at University of Hawaii at Manoa |
| Subject Geographic: | Hawaii |
| Description: | Analyses of soil clays are carried out by several independent physical and chemical methods because each method has limitations. Differential dissolution methods are being developed based on crystal structure characteristics of minerals, the basis for mineral classification. Dissolution analysis provides not only a means of obtaining the chemical composition of labile minerals but also provides samples free of these materials for analysis of more resistant minerals. Development of dissolution techniques involves selection of specific reagents, establishment of optimal conditions for reaction, and recognition of their limitations. The objectives of this investigation were to develop a method for differential dissolution of amorphous constituents from soil clays and of the kaolinite plus halloysite components of crystalline soil clays. The results may be summarized as follows: Half normal HaOH solution was chosen because of its rapid and extensive dissolution of both silica and alumina, the two major constituents of clay minerals. Use of 2% Na2CO3 solution gave less complete dissolution. Boiling for as little as 2.5 minutes in the NaOH solution dissolved a large quantity of allophane-like materials and free silica and alumina from clays of some montmorillonite-rich soils of Hawaii, provided the ratio of clay to solution volume was kept less than 100 mg to 100 ml. Subsequent dithionite-citrate-bicarbonate treatment removed the released iron. Various typical allophane specimens were completely dissolved by this procedure. Reprecipitation of dissolved silica occurred with prolonged digestion or higher sample to solution ratio. Digestion for 80 minutes dissolved 50% of Georgia kaolinite and 25% of Wyoming montmorillonite, but only a small quantity of crystalline minerals dissolved during the short digestion period adopted. Halloysite specimens appeared somewhat unstable, however. Gibbsite dissolved very readily together with the amorphous constituents. Marked improvement of x-ray diffraction patterns of clays resulted ... |
| Document Type: | thesis |
| File Description: | application/pdf |
| Language: | English |
| Relation: | http://hdl.handle.net/10125/56318 |
| Availability: | http://hdl.handle.net/10125/56318 |
| Accession Number: | edsbas.8FEB8DDF |
| Database: | BASE |
Nájsť tento článok vo Web of Science | Abstract: | Analyses of soil clays are carried out by several independent physical and chemical methods because each method has limitations. Differential dissolution methods are being developed based on crystal structure characteristics of minerals, the basis for mineral classification. Dissolution analysis provides not only a means of obtaining the chemical composition of labile minerals but also provides samples free of these materials for analysis of more resistant minerals. Development of dissolution techniques involves selection of specific reagents, establishment of optimal conditions for reaction, and recognition of their limitations. The objectives of this investigation were to develop a method for differential dissolution of amorphous constituents from soil clays and of the kaolinite plus halloysite components of crystalline soil clays. The results may be summarized as follows: Half normal HaOH solution was chosen because of its rapid and extensive dissolution of both silica and alumina, the two major constituents of clay minerals. Use of 2% Na2CO3 solution gave less complete dissolution. Boiling for as little as 2.5 minutes in the NaOH solution dissolved a large quantity of allophane-like materials and free silica and alumina from clays of some montmorillonite-rich soils of Hawaii, provided the ratio of clay to solution volume was kept less than 100 mg to 100 ml. Subsequent dithionite-citrate-bicarbonate treatment removed the released iron. Various typical allophane specimens were completely dissolved by this procedure. Reprecipitation of dissolved silica occurred with prolonged digestion or higher sample to solution ratio. Digestion for 80 minutes dissolved 50% of Georgia kaolinite and 25% of Wyoming montmorillonite, but only a small quantity of crystalline minerals dissolved during the short digestion period adopted. Halloysite specimens appeared somewhat unstable, however. Gibbsite dissolved very readily together with the amorphous constituents. Marked improvement of x-ray diffraction patterns of clays resulted ... |
|---|