90Sr is considered a hazardous radionuclide due to its long half-life of 28.8 years, radiotoxicity, and potential to bioaccumulate in various organisms. In the environment, strontium typically exists as divalent cation Sr2+ or in different complexes, depending on the environmental physical and chemical factors. Despite its mobility, Sr2+ transport remains affected by adsorption from solid phases, such as soil and sediments. This research aimed to investigate the efficiency of a magnetic flocculant (MNP/IF) in separating suspended soil and Sr2+ from a soil suspension. MNP/IF was prepared via the electrostatic interaction between magnetite particles and an inorganic flocculant (IF) composed of CaCO3 and Na2SO4. Analysis of the physical properties of MNP/IF confirmed that MNP/IF was successfully imparted with magnetism and had excellent adsorption capacity for Sr2+. The optimal MNP/IF dosage for the sedimentation of suspended soil was determined to be 0.3 g/g (mass ratio of flocculant to soil). The lower the pH, the more favorable the flocculation-sedimentation process of the suspended soil by MNP/IF, since Ca2+ and Mg2+, which are the most common strong flocculators, were further eluted from IF under acidic conditions. Besides, MNP/IF exhibited outstanding removal performance for Sr2+, with maximum adsorption capacities of 163.6 mg/g observed during the flocculation-sedimentation reaction of suspended soil. The adsorption of Sr2+ exhibited consistency with the Langmuir model and followed pseudo-second-order kinetics. These findings suggest that MNP/IF can be used for the simultaneous removal of suspended soil particles and Sr2+ from a radioactive soil suspension.

• Hyun-Kyu Lee(Korea Atomic Energy Research Institute (KAERI)) Corresponding author
• Byung-Moon Jun(Korea Atomic Energy Research Institute (KAERI))
• Wooshin Park(Korea Atomic Energy Research Institute (KAERI))
• Hongrae Jeon(Korea Atomic Energy Research Institute (KAERI))