Chitosan-Cross-Linked Graphene Oxide/Carboxymethyl Cellulose Aerogel Globules with High Structure Stability in Liquid and Extremely High Adsorption Ability

Graphene oxide (GO) exhibits excellent adsorption ability to remove organic dyes from liquid; therefore, fabricating GO-based adsorbents has attracted increasing interest from researchers. However, it is still challenging to prepare the GO-based adsorbents with high structure stability while simultaneously maintaining its high adsorption ability. In this work, a novel one-step fabrication method combining exfoliating and micro-cross-linking simultaneously was proposed to prepare the GO composite aerogel globules, in which GO was exfoliated by carboxymethyl cellulose (CMC) in the globule center, whereas the globule was micro-cross-linked by chitosan (CS) on the surface. The results showed that there were strong interactions between components, and the composite aerogel globule exhibited multiscale porous structures on the globule surface and the highly porous structure in the globule center. The composite aerogel exhibited high structure stability in liquid. The adsorption measurements toward methylene blue (MB) showed that the CS-GO/CMC composite aerogel had extremely high adsorption capacity, and the maximum adsorption capacity was 3190 mg/g for the CS-GO/CMC-1/1 composite aerogel, which was the highest adsorption capacity reported in the literature. The adsorption kinetics, adsorption isotherms, and the adsorption thermodynamics were comparatively investigated. The results showed that the adsorption of MB obeyed a pseudo-second-order model and Langmuir adsorption model, and the adsorption was a spontaneous process. Furthermore, the composite aerogel also showed excellent removal ability for Cr(VI), and the adsorption capacity was 127.4 mg/g. The extremely high adsorption abilities toward MB and Cr(VI) and high structural stability in liquid endow the CS-GO/CMC composite aerogel with potential applications in wastewater treatment.