2002 Fiscal Year Final Research Report Summary
Development of pollution-free fining agent ; mechanism of fining reaction and redox eqilibrium
| Project/Area Number |
13450357
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
無機工業化学
|
|---|
| Research Institution | Ehime University |
|---|
Principal Investigator |
MAEKAWA Takashi Ehime University, Faculty of Engineering, Professor, 工学部, 教授 (50000873)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
YAMASHITA Hiroshi Ehime University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (00182501)
|
|---|
| Project Period (FY) |
2001 – 2002
|
| Keywords | Glass melts / Differential pulse voltammetry / Half-wave potential / Redox equilibrium / Multivalent metal ion / Non-alkali glass / Fining |
|---|
| Research Abstract |
1. Voltammetric Studies of Glass Melts
The differential pulse voltammetry was applied to investigate the Redox reaction of Fe, Sn, Ce and S ion in soda lime, phosphate, and non-alkali glass melts. Halfwave potential was computed from the peak position of current-potential curves, and discussed in relation with temperature and melt composition. It was seen that the concentration of reduced ions increases with an increase in temperature. In case of Fe ion in soda lime melt, it turns out that the Fe^<2+>/Fe^<3+> equilibrium is governed by the complex formation reaction Fe^<3+> ion and basicity of the melt. The equilibrium of Sn ion in nonalkali glass melt can be discussed by adding the amount of Na^+ ion in the melts and extrapolating the half wave potential to that of zero concentration of Na^+ ion.
2. The Spectroscopy of Glasses -- NMR study
By peak separation of ^<11>B, ^<27>Al and ^<29>Si NMR spectra of non-alkali glass(MO(M_2O)-SiO_2-Al_2O_3-B_2O_3), reactivity of alkali or alkaline earth oxides with SiO_2, Al_2O_3 and B_2O_3 was determined. The reactivity with B_2O_3 increase in order of K_2O>Na_2O>BaO>SrO>CaO>PbO>MgO>ZnO. The equilibrium constant, K, of the following reaction is applied to elucidate the experimental results. Si(Q_3)+B(Q_3)=Si(Q_4)+and B(Q_4) : K=[Si(Q_4)] [B(Q_4)] / [Si(Q_3)] [B(Q_3)]
3. Fining
The temperature dependence of Redox reaction of fining ions is important forclarifyingthe fining process. In the case of metal ion, it was important that [Ox]/[Red] concentration ratio is about unity in glass melting temperature, and it wasexpected that Sn ion is suitable for fining ion in non-alkali glass melts. In case of sulfur, irreversible decomposition of sodium sulphate contributes to fining process.
|
