Efficient removal of Cs+ and Sr2+ from aqueous solution using hierarchically structured hexagonal tungsten trioxide coated Fe3O4

Efficient, irreversible capture of radioactive strontium and cesium from aqueous media remains a serious task for nuclear waste disposal and environmental protection. To address this task, an effective sorbent based on magnetic composites coated with the synthetic porous exchanger WO 3 was prepared by a facile method and characterized in detail. XRD analysis indicated that the WO 3 coating did not change the phase of the Fe 3 O 4 core, and TEM imaging further showed that Fe 3 O 4 @WO 3 particles were successfully obtained with nearly uniform size. A batch of experiments was carried out to investigate the efficiency of Fe 3 O 4 @WO 3 in removing Sr 2+ and Cs + under various environmental conditions. Experimental results showed that Fe 3 O 4 @WO 3 has higher adsorption capacity for Sr 2+ and Cs + in acidic aqueous solution in comparison to the previous literature. The theoretical maximum adsorption capacities of Fe 3 O 4 @WO 3 for Sr 2+ and Cs + are 44.178 and 53.175   mg   g −1 , respectively, as modeled by Langmuir isotherms. The adsorption process is fast and reaches equilibrium within 3   h, which is attributed to the good dispersion of WO 3 on the surface of Fe 3 O 4 and provided much more adsorption sites. Other than Ca 2+ and K + , coexisting electrolyte ions had no significant competition effects on the removal of Sr 2+ and Cs + by Fe 3 O 4 @WO 3 . In addition, the Fe 3 O 4 @WO 3 adsorbent remains stable in acidic solutions and may be repeatedly used 5 times without any noticeable loss in adsorption capacity; the used adsorbents can be easily separated from the aqueous solution using a magnetic method. The advantages of being nontoxic, highly stable, and resistant to acid, as well as having high adsorption capacity for Sr 2+ and Cs + , indicate that Fe 3 O 4 @WO 3 has significant potential for real radioactive wastewater treatment.