Efficient separation performance of suspended soil and strontium from aqueous solution using magnetic flocculant

This study aimed at magnetically separating suspended soil and Sr2+ from a soil suspension using a magnetic flocculant (MNP/IF). MNP/IF was prepared using the electrostatic interaction between the magnetite particles and the inorganic flocculant (IF) based on CaCO3 and Na2SO4. By analyzing the physical properties of MNP/IF, it was 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). Compared with raw IF, MNP/IF showed better flocculation performance to suspended soil for a shorter sedimentation time. 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. MNP/IF also showed excellent removal performance for Sr2+, exhibiting maximum Sr2+ adsorption capacities of 163.6 mg/g in the flocculation-sedimentation reaction of suspended soil. The Sr2+ adsorption process was consistent with the Langmuir model and followed the pseudo-second-order kinetics. These results provide that MNP/IF can be used for the simultaneous removal of suspended soil particles and Sr2+ from a radioactive soil suspension. [Display omitted] •MNP/IF was prepared using electrostatic attraction forces between MNPs and IF.•MNP/IF formed stable flocs with suspended soil, easily separated by magnetic force.•At low pH, flocculation-sedimentation of suspended soil by MNP/IF is more favorable.•IF plays a major role in Sr2+ adsorption by ion exchange of Ca2+ with Sr2+.