Chitosan composite aerogels doped with oilfield drill cuttings for arsenic removal: A combined experimental and...

A composite aerogel of chitosan and thermally treated drill cuttings (TTDC-CA) was developed via a green and straightforward process for arsenic removal. The results showed that the composite aerogels have a honeycomb porous structure and exhibit anisotropic properties. TTDC improved the specific surface area and tolerance to acidic environments of TTDC-CA by modulating the pore structure and providing cross-linking sites. The adsorption properties and mechanism of the composite aerogels for arsenic adsorption were systematically investigated using experimental and density functional theory (DFT) methods. The maximum Langmuir adsorption capacities of the 3 wt% TTDC-doped composite aerogels at room temperature were notably 8.09 mg·g^-1 for As(III) and 13.23 mg·g^-1 for As(V), significantly higher than those of the pure chitosan aerogels. Kinetic studies showed that the adsorption was very fast (about 10 min). Quantum chemical calculations revealed that hydrogen bonds play a dominant role in the adsorption process, with the interaction between protonated chitosan and arsenic species being stronger than that of chitosan. Specifically, the -NH₃⁺ groups serve as the primary functional sites in protonated chitosan for interacting with H₃AsO₃ and H₂AsO₄^-.