Cesium immobilization by K-struvite crystal in aqueous solution: Ab initio calculations and experiments

A serious risk that harms the safe use of water and affects aquatic ecosystems is water pollution. This occurs when the water’s natural equilibrium is disrupted by an excessive amount of substances, both naturally occurring and as a byproduct of human activities, that have varied degrees of toxicity. Radiation from Cs isotopes, which are common components of radioactive waste and are known for their long half-lives (30 years), which are longer than the natural decay processes, is a major source of contamination. Adsorption is a commonly used technique for reducing this kind of contamination, and zeolite chabazite has been chosen as the best adsorbent for cesium in this particular situation. The purpose of this research is to investigate a composite material based on magnesium phosphate cement (MPC). Magnesium oxide (MgO), potassium dihydrogen phosphate (KH2PO4), and properly selected retarders are used to create the MPC. The optimal conditions for this composite material are investigated through the utilization of X-ray diffraction, scanning electron microscopy, BET surface area analysis, and atomic absorption spectroscopy. The principal aim is to enable innovations in the elimination of radioactive waste-contaminated water using effective cesium removal. The most promising results were obtained by using KH2PO4 as an acid, and MgO as a base, and aiming for an M/P ratio of two or four. Furthermore, we chose zeolite chabazite as a crucial component. The best adsorption abilities for Cs were found at Qads = 106.997 mg/g for S2 and Qads = 122.108 mg/g for S1. As a result, zeolite is an eco-friendly material that is a potential usage option, with many benefits, such as low prices, stability, and ease of regeneration and use.

Section: Xrd Analysissupporting

confidence: 84%

Section: Model Sample 1 Samplementioning

confidence: 99%

Advancing in Cesium Retention: Application of Magnesium Phosphate Cement Composites

Gharsallah,

Khitouni,

Mallah

et al. 2024

“…In the field of orthopedics, they are promising materials for accelerating bone regeneration, including calcium phosphate, magnesium ammonium phosphate and the latest potassium magnesium phosphate [ 3 ]. Moreover, they can be used for the stabilization/solidification of radioactive metal cations because of their excellent immobilization effects, great encapsulation properties and excellent resistance to acid attack and high temperature [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. Among various kinds of phosphate cements, magnesium potassium phosphate cement (MKPC) has drawn a great interest in research.…”

Section: Introductionmentioning

confidence: 99%

Effect of K+ Diffusion on Hydration of Magnesium Potassium Phosphate Cement with Different Mg/P Ratios: Experiments and Molecular Dynamics Simulation Calculations

Leng,

Fu,

et al. 2024

Self Cite

Magnesium potassium phosphate cement (MKPC) is formed on the basis of acid–base reaction between dead burnt MgO and KH2PO4 in aqueous solution with K-struvite as the main cementitious phase. Due to the unique characteristics of these cements, they are suitable for special applications, especially the immobilization of radioactive metal cations and road repair projects at low temperature. However, there are few articles about the hydration mechanism of MKPC. In this study, the types, proportions and formation mechanism of MKPC crystalline phases under different magnesium to phosphorus (Mg/P) ratios were studied by means of AAS, ICP-OES, SEM, EDS and XRD refinement methods. Corresponding MD simulation works were used to explain the hydration mechanism. This study highlights the fact that crystalline phases distribution of MKPC could be adjusted and controlled by different Mg/P ratios for the design of the MKPC, and the key factor is the kinetic of K+.

“…Struvite-K cement is a special cement with rapid curing and great developing strength, and it is usually used in emergency bridge or road repair works [28]. It is also used for the immobilization of radioactive nuclides [10,35]. Other related issues are the recovery of potassium and phosphorus from urines in the form of K-struvite [36][37][38][39][40][41], or the recovery of nitrogen and phosphorus from municipal sewage/sludge in the form of struvite [40,[42][43][44][45][46][47].…”

Section: Introductionmentioning

confidence: 99%

Cs+ Promoting the Diffusion of K+ and Inhibiting the Generation of Newberyite in Struvite-K Cements: Experiments and Molecular Dynamics Simulation Calculations

Leng,

Fu,

et al. 2024

Self Cite

Struvite-K cements, also called magnesium potassium phosphate cements (MKPCs), are applicable for particular applications, especially the immobilization of radioactive Cs+ in the nuclear industry. This work focuses on how Cs+ affects the hydration mechanism of struvite-K cements because newberyite and brucite in the hydration products are deemed to be risky products that result in cracking. Experiments and molecular dynamics simulations showed that Cs+ promoted the diffusion of K+ to the surface of MgO, which greatly facilitates the formation of more K-struvite crystals, inhibiting the formation of newberyite and brucite. A total of 0.02 M Cs+ resulted in a 40.44%, 13.93%, 60.81%, and 32.18% reduction in the amount of newberyite and brucite, and the Cs immobilization rates were 99.07%, 99.84%, 99.87%, and 99.83% when the ratios of Mg/P were 1, 3, 5, and 7, respectively. This provides new evidence of stability for struvite-K cements on radioactive Cs+ immobilization. Surprisingly, another new crystal, [CsPO3·H2O]4, was found to be a dominating Cs-containing phase in Cs-immobilizing struvite-K cements, in addition to Cs-struvite.