A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Determination of the sorption mechanisms of sodium-alkalinized metakaolin-based geopolymers
Abstract Geopolymers (GP) are ceramic-like materials that can potentially be used in environmental applications to immobilize radionuclides (RNs) or toxic compounds. Although the literature reports that the sorption potential of a GP is influenced by its sorption capacity, especially for GPs produced from metakaolin (MK), the RN sorption mechanisms of these materials must be comprehensively studied together with their surface properties. In this study, the surface properties of a sodium-alkalinized MK-based GP (Na-MKGP), such as its surface protonation and cation exchange capacity (CEC), were characterized, and the sorption mechanisms of cesium (Cs+), strontium (Sr2+), and europium (Eu3+), which are important RNs for the safety assessment of high-level radioactive waste disposal, as functions of pH, ionic strength, and metal-ion concentration were investigated. The results were evaluated using the “two-site proteolysis no-electrostatics surface complexation/cation exchange (2SPNE SC/CE)” model by optimizing the selectivity coefficients and SC constants of the metal ions. Overall, this study provides a way to model the sorption of various cations to GP by a mechanistic model as is the case for clay minerals and makes the use of GP as a matrix of radioactive waste more attractive.
Highlights Cs+, Sr2+, Eu3+sorb on sodium alkalinized metakaolin-based geopolymer (Na-MKGP) by cation exchange and surface complexation, like as clay minerals. Silicate plays significant role on europium sorption. The distribution ratio of the sorbed metal ions modeled the selectivity coefficients and surface complexation constants are and optimized. Surface deprotonation trend showed the point of zero charge of Na-MKGP is approximately pH 5.3. Washing and drying improve the cation exchange capacity of Na-MKGP.
Determination of the sorption mechanisms of sodium-alkalinized metakaolin-based geopolymers
Abstract Geopolymers (GP) are ceramic-like materials that can potentially be used in environmental applications to immobilize radionuclides (RNs) or toxic compounds. Although the literature reports that the sorption potential of a GP is influenced by its sorption capacity, especially for GPs produced from metakaolin (MK), the RN sorption mechanisms of these materials must be comprehensively studied together with their surface properties. In this study, the surface properties of a sodium-alkalinized MK-based GP (Na-MKGP), such as its surface protonation and cation exchange capacity (CEC), were characterized, and the sorption mechanisms of cesium (Cs+), strontium (Sr2+), and europium (Eu3+), which are important RNs for the safety assessment of high-level radioactive waste disposal, as functions of pH, ionic strength, and metal-ion concentration were investigated. The results were evaluated using the “two-site proteolysis no-electrostatics surface complexation/cation exchange (2SPNE SC/CE)” model by optimizing the selectivity coefficients and SC constants of the metal ions. Overall, this study provides a way to model the sorption of various cations to GP by a mechanistic model as is the case for clay minerals and makes the use of GP as a matrix of radioactive waste more attractive.
Highlights Cs+, Sr2+, Eu3+sorb on sodium alkalinized metakaolin-based geopolymer (Na-MKGP) by cation exchange and surface complexation, like as clay minerals. Silicate plays significant role on europium sorption. The distribution ratio of the sorbed metal ions modeled the selectivity coefficients and surface complexation constants are and optimized. Surface deprotonation trend showed the point of zero charge of Na-MKGP is approximately pH 5.3. Washing and drying improve the cation exchange capacity of Na-MKGP.
Determination of the sorption mechanisms of sodium-alkalinized metakaolin-based geopolymers
Yıldırım, Anıl Can (author) / Toda, Kanako (author) / Saito, Takumi (author)
Applied Clay Science ; 251
2024-02-18
Article (Journal)
Electronic Resource
English
Metakaolin-Based Geopolymers : Design, Mechanisms and Performance
| Springer Verlag | 2024
Mechanical properties of sodium and potassium activated metakaolin-based geopolymers
| British Library Online Contents | 2012
Micromechanical characterization of metakaolin-based geopolymers
| Elsevier | 2013
Micromechanical characterization of metakaolin-based geopolymers
| British Library Online Contents | 2013
Metakaolin Effect on Geopolymers’ Properties
| Springer Verlag | 2024