Efficient adsorption of La(III) by magnetic carbon nitride based ZIF-8 nanocomposites

The enrichment and recovery of low concentration rare earth ions from wastewater resources has become an important research direction to achieve high quality utilization of rare earth resources. In this experiment, graphitic carbon nitride was used as the substrate, which was firstly compounded with Fe 3 O 4 to become magnetic graphitic carbon nitride material by alcohol heat method, and then in situ compounded with ZIF-8 in aqueous phase at room temperature to form the composite g-C 3 N 4 /Fe 3 O 4 @ZIF-8. Finally, the composite was characterized. The adsorption performance of g-C 3 N 4 /Fe 3 O 4 @ZIF-8 and the control g-C 3 N 4 /Fe 3 O 4 and ZIF-8 for La(III) under various conditions was investigated by adsorption experiment. In addition, the types and mechanism of La(III) adsorption were discussed by kinetic, isothermal adsorption line and thermodynamic modeling studies. Finally, the stability performance and reusability of the composite were evaluated by regeneration experiments. The result show that g-C 3 N 4 /Fe 3 O 4 @ZIF-8 has good adsorption performance on lanthanide ions. g-C 3 N 4 /Fe 3 O 4 @ZIF-8 reached adsorption equilibrium at about 20 min. When pH is 6 and the solid–liquid ratio of adsorbent is 0.25 g/L, the adsorption amount was 176.68 mg/g. g-C 3 N 4 /Fe 3 O 4 @ZIF-8 had good selectivity for lanthanum(III), and it retains 81 % of initial adsorption performance after five times of reuse.