Interaction and stabilization of organic radioactive waste in geopolymer

2021 Fiscal Year Research-status Report

• Project/Area Number: 21K04207
• Research Institution: Hokkaido University
• Principal Investigator: Y Elakneswaran 北海道大学, 工学研究院, 准教授 (60769090)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: Cement chemistry / Geopolymer / Radioactive waste / Oil

Outline of Annual Research Achievements

This year of research focused on analyzing surface functional groups of minerals and organic components. We have selected two types of oil for the analysis and measured the zeta potential in various pH solution. The oils show negative zeta potential which is independent of pH. Moreover, surface electrical properties of quartz, calcite, and kaolinite were determined. Measured zeta potential of quartz, calcite, and kaolinite becomes more negative with increasing pH. However, the absolute value for kaolinite was much higher than that of calcite at equivalent pH values. In addition, calcite exhibited positive zeta potential under alkaline pH conditions, unlike kaolinite or quartz. The interaction of H+ and OH- with minerals influences the zeta potential in addition to the ionic strength. A triple-layer surface complexation model built-in PHREEQC was applied to quartz-, calcite-, and kaolinite-solution interface, and the modelling results were verified with experimental data. Moreover, the determined equilibrium constants for protonation and deprotonation of calcite, kaolinite and quartz were consistent with literature values. The surface electrical properties will be used to evaluate the interaction of oils with minerals, which will be used to select the most suitable geopolymer composite.

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

The research is going smoothly as proposed. I have achieved some important results in the first year of work and plan to present at an international conference.

Strategy for Future Research Activity

FY 2022; WP 2: Geopolymer properties and emulsification characteristics
WP 2.1: Synthesis and characterisation of geopolymers
Metakaolin and ground granulated blastfurnace slag will be used as source materials, and potassium silicate will be used as activating solution for geopolymer preparation.
WP 2.2: Emulsification of polymers and crude oil in the activating solution
The formation and stability of emulsion will be examined by changing the oil to
solution ratio and the concentration of the solution.

Causes of Carryover

We did a little bit less experiment than planned. In addition, we could not travel to present due COVID situation. So, we plan to use it next year.