Research on the Reaction Mechanism between Struvite Crystals and Cesium Ions

As a strategic element, efficient
extraction technology
for cesium
holds significant importance. This study investigates the reaction
process between Cs+ and struvite (MgNH4PO4·6H2O). Fitting reveals that this reaction
follows a pseudo-second-order kinetic model, while the thermodynamic
equilibrium process adheres to the Temkin isothermal model (R2 = 0.990). The thermodynamic parameter ΔG° < 0 indicates a spontaneous entropy-increasing
reaction process. By combining the characterization of intermediate
products M1–M4 and reaction evolution analysis, the reaction
mechanism between struvite and Cs+ is intuitively demonstrated.
The reaction mechanism is proposed as follows: macroscopically, it
manifests as an ion exchange process with chemical adsorption characteristics;
microscopically, it involves dissolution and recrystallization. This
finding provides theoretical support for process design in Cs+ adsorption by struvite.