Abstract
Novel composite magnetic nanoparticles (CuFe2O4) were synthesized from industrial sludge by acid leaching, chemical exchange, and ferrite processes in the laboratory. For the first time, these products were applied to investigate the Sr adsorption kinetics and the related thermodynamics in seawater. Rapidly enhanced Sr adsorption was observed when the solution pH changed from 2.61 to 10.25. The maximum adsorption capacity was 23.04 mg·g−1 at 318 K (pH 10.25). Sr adsorption decreased with the increase of the ionic strength from 0.01 to 0.5 mol·L−1 at pH 2.61–pH 10.25, indicating that the outer-sphere mechanism was involved in the Sr adsorption at the pH interval. This reaction is spontaneous and endothermic, as indicated by the negative change in the standard free energy (ΔG° = −5.68, −6.45, and −7.23 kJ·mol−1 at 298, 308, and 318 K, respectively) and positive ΔH° value (2.11 kJ·mol−1). The positive ΔS° (9.38 mol−1·K−1) further confirms that the randomness increased at the solid-solution interface during adsorption. These new results indicate that the composite magnetic nanoparticles can be used for the removal of radiogenic 90Sr nuclide in seawater that was released after the 3/11 earthquake offshore of Japan.
Highlights
IntroductionStrontium (Sr), the fifteenth most abundant element on Earth, is one of the major fission products present in the wastewater from nuclear power plants and spent nuclear fuel reprocessing [1,2]
Strontium (Sr), the fifteenth most abundant element on Earth, is one of the major fission products present in the wastewater from nuclear power plants and spent nuclear fuel reprocessing [1,2].In addition to 31 unstable isotopes, Sr has four major naturally occurring stable isotopes: 84 Sr, 86 Sr, 87 Sr, and 88 Sr
The structural characterization indicates that the crystalline pattern of the composite magnetic nanoparticles was
Summary
Strontium (Sr), the fifteenth most abundant element on Earth, is one of the major fission products present in the wastewater from nuclear power plants and spent nuclear fuel reprocessing [1,2]. In addition to 31 unstable isotopes, Sr has four major naturally occurring stable isotopes: 84 Sr, 86 Sr, 87 Sr, and 88 Sr. The longest-lived unstable isotope is 90 Sr, with a half-life of 28.9 years [3]. Sr has a variety of medical, commercial, and industrial applications [4]. Sr has been used in optical materials and as an oxygen eliminator in electron tubes. A high Sr concentration can be detected in seawater, industrial wastewater, and even in surface water because of improper Sr-bearing waste treatment
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