Cadmium Removal by Chitosan/Magnetic Humic Acid/Cellulose Aerogel Globules with High Structure Stability

Humic acid (HA) based aerogel exhibits excellent adsorption capacity to heavy metal ions and cationic dyes owing to its multiple binding actions (ion-exchanging, chelating, and π–π interaction). However, the leakage of humic acid limits the wide application. In this work, simply dropping is used to prepare the HA-based aerogel with a core-shell structure. The skeleton of carboxymethyl cellulose (CMC) loaded by magnetic humic acid particles is in the center of the aerogel, and the outer layer is composed of chitosan (CS). The results show that the strong interactions between components (HA-Fe 3 O 4 , HA-CMC, HA-CS, and CMC-CS) endow the aerogel with remarkable structure stability. The maximum adsorption capacity toward cadmium ion is 490.2 mg/g, which indicates the aerogel has high adsorption ability. The adsorption kinetics, adsorption isotherms and reusability are investigated. These results show that the adsorption performance is consistent with a pseudo-second-order model and Langmuir adsorption model. According to thermodynamic equation, adsorption is a spontaneous endothermic process and the adsorption shows good reusability.