Study on the Adsorption Properties of Fe ₃ O ₄ @MnO ₂ @β‐Cyclodextrin Composite on Crystalline Violet and Mn (VII)

ABSTRACT Magnetic adsorption materials show great potential in wastewater treatment, but there are few relevant cases for the removal of crystalline violet (CV), while the removal of CV and heavy metal ions is even more of a challenge. In this experiment, Fe 3 O 4 microspheres are used as the core and hydrothermally wrapped with stacked clusters of MnO 2 on the outside to increase the specific surface area of the composite. Finally, the Fe 3 O 4 @MnO 2 composite is wrapped with β‐cyclodextrin (β‐CD) by cross‐linking grafting with the silane coupling agent KH‐560, bringing a large number of O atoms and epoxy groups to the adsorbent. The prepared Fe 3 O 4 @MnO 2 @β‐CD composite has a large specific surface area of 209.897 m 2 g −1 and has good removal of CV and Mn (VII). The effects of adsorbent type, initial concentration, temperature, and contact time on the adsorption performance were investigated. The results for the adsorption of CV and Mn (VII) show that the adsorption behavior follows a pseudo‐second‐order kinetic model and fits well with the Langmuir isotherm, indicating predominant monolayer adsorption, and the adsorption is governed by a combination of intraparticle and film diffusion mechanisms. Thermodynamic studies confirm its spontaneous and heat‐absorbing nature. Remarkably, after five reuse cycles, there is minimal loss in removal rate. The prepared Fe 3 O 4 @MnO 2 @β‐CD composite is a green and renewable adsorbent, which has a wide application prospect in the adsorption field.