Ammonium molybdate phosphate functionalized silicon dioxide impregnated in calcium alginate for highly efficient removal of 137Cs from aquatic bodies

Abstract

In this study, silica functionalized with ammonium molybdate phosphate (AMP) impregnated in calcium alginate (SiO₂-AMP–Cal-Alg) was developed for the highly efficient removal of radioactive cesium from aquatic media. During the synthesis, a compact protective interlayer of silica was deliberately constructed to stabilize the AMP. The optimum composition of the SiO₂-AMP–Cal-Alg beads was evaluated as 6% AMP modified SiO₂ loaded into 4% calcium alginate. Because of high ion exchange capacity of the AMP functional layer, the SiO₂-AMP–Cal-Alg has high removal efficiency (>91%) of radioactive cesium from ¹³⁷Cs spiked solutions (3000–35 000 Bq L⁻¹) and contaminated seawater. Batch experiments revealed that adsorption equilibrium was rapidly achieved within 30 min and the maximum sorption capacity was up to 37.52 mg g⁻¹. Kinetic models and adsorption isotherm equations (Langmuir/Freundlich) were used to fit the experiment data for describing the sorption process. These SiO₂-AMP–Cal-Alg beads are proposed to hold great promise for the clean-up of radiocesium contaminated water around nuclear facilities after nuclear accidents.