Study on the complex formation of metal ions with humic substances by two-electrodes titration technique
| Project/Area Number |
18360451
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Nuclear engineering
|
|---|
| Research Institution | Tohoku University |
|---|
Principal Investigator |
TOCHIYAMA Osamu Tohoku University, Tohoku University, Institute of Multidisciplinary Research for Advanced Materials, Professor (70005479)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
KIRISHIMA Akira Institute of Multidisciplinary, Research for Advanced Materials, Assistant Professor (00400424)
|
|---|
| Project Period (FY) |
2006 – 2007
|
| Project Status |
Completed (Fiscal Year 2007)
|
| Budget Amount *help |
¥16,490,000 (Direct Cost: ¥15,200,000、Indirect Cost: ¥1,290,000)
Fiscal Year 2007: ¥5,590,000 (Direct Cost: ¥4,300,000、Indirect Cost: ¥1,290,000)
Fiscal Year 2006: ¥10,900,000 (Direct Cost: ¥10,900,000)
|
|---|
| Keywords | radioactive wastes / geological disposal / humic substances / complex formation / potentiometry / heterogeneous organic substances / polyelectrolyte |
|---|
| Research Abstract |
In the safety assessment of geological disposal of radioactive wastes, it is necessary to describe the ability of the concerned humic substance to form complexes with metal ions. In this study, the interaction of metal ions with humic substances was described by the following proposed equation, logK_<app>=logK+alogα-blog[Na^+]-mlog[M], for k_<app>=[ML]/([M][R]), where [ML] and [M] are the concentrations of bound and free metal ion, [R] is that of dissociated proton exchange site and a is the degree of dissociation (charges are omitted). The applicability of the model equation was verified by using the data on various metal ions and various humic substances reported in the literature. Moreover, to examine the individual dependency of the apparent stability constant on each term more precisely, the calcium-bindings of some humic substances were studied by potentiometry with using the Wallingford titrator which allowed to measure or control pH and pM simultaneously by using glass electrode and ion selective electrode. The model equation fairly well reproduced the apparent stability constants of the humate complexes with various cations (including proton) reported by other researchers, indicating the practical usefulness of the equation. The dependence of the apparent stability constants of calcium-humates on pH or pM obtained by keeping the other variables constant by using the two-electrode titration technique clearly indicated the effectiveness of the proposed model equation. The values of model parameter m were consistent with its meaning, the degree of heterogeneity or distribution of the complexation-strengths of the sites, indicating that the model is chemically reasonable.
|
Report
(3 results)
Research Products
(6 results)
