Facile preparation of cucurbituril-modified magnetic chitosan microspheres for efficient removal of Cr(VI) and MB from wastewater: Adsorption experiments, statistical optimization, and mechanistic insights.

In this study, a magnetic microsphere (CB/MCS) based on magnetic chitosan and cucurbituril (CB) was successfully prepared for efficient removal of methylene blue (MB 2968.6 mg/g) and hexavalent chromium (Cr(VI) 297.3 mg/g) from water. CB/MCS combined the fast magnetic separation performance of magnetic chitosan and the excellent adsorption capacity of CB to realize the efficient removal of MB and Cr(VI), and it is noteworthy that the adsorption capacity of Cr(VI) was significantly enhanced in the presence of MB. The synthesis conditions of CB/MCS were optimized by response surface methodology and Box-Behnken Design experimental design. The results of the adsorption experiments showed that the adsorption process of CB/MCS on MB and Cr(VI) conformed to the quasi-secondary kinetic model and Langmuir isotherm model, indicating that the adsorption process was mainly controlled by chemisorption and there was a strong interaction between the adsorbent and adsorbate. In addition, CB/MCS demonstrated excellent removal efficiencies in different aqueous environments, reaching 93.2 % and 91.4 % for Cr(VI) and MB, respectively, even in complex industrial wastewater. The results of the cycling experiments further confirmed the stability and reusability of CB/MCS. In summary, CB/MCS can be used as an excellent adsorbent for the removal of Cr(VI) and MB from wastewater.