Cellulose-based hierarchical aerogels for dye-contaminated wastewater treatment

Abstract

The practical application of aerogels in environmental remediation is often constrained by their high cost, low adsorption efficiency, poor renewability, and insufficient performance in treating complex dye wastewater. To address these challenges, we developed a hierarchical porous aerogel by integrating biomass-derived 2,2,6,6-tetramethyl-1-piperidinyloxy-oxidized cellulose nanofibers (TOCNFs) and graphene oxide (GO) as the framework, and then functionalized with Zr-based metal–organic frameworks (UiO-66-NH₂). The composite aerogel (UiO-66-NH₂/TOCNFs/GO, abbreviated UTG) shows an optimized pore structure, high specific surface area, and outstanding dye adsorption capacities (up to 782.1, 327.1, 494.2, and 280.6 mg g⁻¹ for MB, CR, RB, and X-3b, respectively, at an initial concentration of 800 mg L⁻¹), surpassing many conventional aerogels. Adsorption kinetics followed a pseudo-second-order model, and the equilibrium data were well fitted by the Langmuir isotherm, indicating a monolayer adsorption process dominated by multiple interactions. Notably, the UTG aerogel maintained over 75% of its initial adsorption capacity after five consecutive regeneration cycles, demonstrating excellent recyclability. This design effectively addresses common limitations of traditional adsorbents, such as low adsorption capacity and poor cycling stability. This work provides an effective strategy for constructing durable and high-performance aerogels, which helps to overcome key limitations in dye wastewater remediation.