In Situ Adsorption‐Reduction Removal of Cr(VI) Using Magnetic Fe 3 O 4 @SiO 2 @Zr‐PDC Composite From Aqueous Solution

A new magnetic Zr‐based MOF composite, Fe 3 O 4 @SiO 2 @Zr‐PDC (where PDC = pyridine‐3,5‐dicarboxylate), was constructed via a facile layer‐by‐layer wet‐loading approach and used for removing Cr(VI) by means of adsorption‐reduction mechanism from aqueous solution. Cr(VI) removal efficiency was investigated through batch experiments under different conditions. The optimal dislodgment performance (32.62 mg/g or 98.56%) was obtained under the following experimental conditions: pH = 3; Volume ( V ) = 50 mL; mass = 60 mg; C 0 (Cr(VI)) = 100 mg/L; T = 25°C; and t = 90 min. The isotherm and kinetic data were well fitted by Langmuir and pseudo‐second‐order (PSO) models, respectively. And the efficient removal of Cr(VI) can be primarily attributed to chemisorption between the solid and liquid interfaces. Moreover, the composite achieved the ultrafast separation (within only 5 s) from aqueous solution and reusability (at least 5 cycles), demonstrating the great potential of the adsorbent for mitigating Cr(VI) pollution.