Removal of Cesium and Strontium Ions from Aqueous Solutions by Thermally Treated Natural Zeolite

Abstract

The radionuclides of cesium (Cs) and strontium (Sr) are dangerous products of nuclear fission that can be accidentally released into wastewater. In the present work, the capacity of thermally treated natural zeolite (NZ) from Macicasu (Romania) to remove Cs+ and Sr2+ ions from aqueous solutions in batch mode was investigated by contacting different zeolite quantities (0.5, 1, and 2 g) of 0.5–1.25 mm (NZ1) and 0.1–0.5 mm (NZ2) particle size fractions with 50 mL working solutions of Cs+ and Sr2+ (10, 50, and 100 mg L−1 initial concentrations) for 180 min. The concentration of Cs in the aqueous solutions was determined by inductively coupled plasma mass spectrometry (ICP-MS), whereas the Sr concentration was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The removal efficiency of Cs+ varied between 62.8 and 99.3%, whereas Sr2+ ranged between 51.3 and 94.5%, depending on the initial concentrations, the contact time, the amount, and particle size of the adsorbent material. The sorption of Cs+ and Sr2+ was analyzed using the nonlinear form of Langmuir and Freundlich isotherm models and pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models. The results indicated that the sorption kinetics of Cs+ and Sr2+ on thermally treated natural zeolite was described by the PSO kinetic model. Chemisorption dominates the retention of both Cs+ and Sr2+ by strong coordinate bonds with an aluminosilicate zeolite skeleton.

Hydrothermal Synthesis of Cancrinite from Coal Gangue for the Immobilization of Sr

“…The results are presented in Table 1 and Figure 1. employed natural zeolite as an adsorption material to effectively remove Sr 2+ and Cs + ions from aqueous solutions, yielding positive outcomes [20]. Cancrinite, an exceptional zeolite, exhibits an open framework structure comprising hexagonal rings of SiO4 and AlO4 tetrahedra stacked along the hexagonal c-axis [21][22][23].…”

“…The essence of its solidification treatment is to form a certain solid solution of the radionuclides in high-level liquid waste with the corresponding salts in the hightemperature phase, thereby encapsulating the radionuclides in the solid phase and creating a thermodynamically stable solidified matrix [16][17][18][19]. Researchers have employed natural zeolite as an adsorption material to effectively remove Sr 2+ and Cs + ions from aqueous solutions, yielding positive outcomes [20]. Cancrinite, an exceptional zeolite, exhibits an open framework structure comprising hexagonal rings of SiO 4 and AlO 4 tetrahedra stacked along the hexagonal c-axis [21][22][23].…”

Properties and applications of natural zeolites

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