Cationized lignocellulose-based composite aerogel features anisotropic and honeycomb-like structures for efficient removal of diclofenac sodium from water

Composite aerogels (CPA) constructed based on lignocellulose nanofibers (LCNF) with anisotropic and honeycomb-like three-dimensional network structures are excellent adsorbent materials. LCNF, as a core constituent of CPA, combines the advantages of cellulose nanofibers and lignin, which endows excellent adsorbent properties to the aerogels and shows great potential in the adsorption of aromatic pollutant diclofenac sodium (DS). Herein, a deep eutectic solvent (DES) and high-pressure homogenization strategy was employed to prepare cationized lignocellulose nanofibers (CLCNF) from industrial and agricultural waste bagasse, and cationized lignocellulose-based composite aerogels were prepared with polyvinyl alcohol (PVA) as crosslinking agent combined with directional freezing technique to efficiently remove DS from water bodies. The prepared CPA had a uniformly distributed honeycomb-like pore structure (porosity ≈ 98 %) and excellent mechanical properties (compressive strength up to 183.93 KPa). In addition, the CPA had a rapid adsorption response to DS with a theoretical maximum adsorption capacity of up to 298.51 mg/g. Its adsorption behavior was in accordance with the pseudo-second order kinetic and Langmuir isotherm model, which demonstrated that it was dominated via the monolayer chemical adsorption, and the main mechanism of the adsorption were electrostatic interactions and intermolecular interactions. Importantly, the CPA still had good stability and reusability after four cycles of use. Therefore, the CPA prepared in this study can be used as a desirable adsorbent for water remediation to achieve the effect of "treating pollution with waste". • Cationized lignocellulose composite aerogels (CPA) are prepared to remove DS. • CPA have anisotropic and honeycomb-like three-dimensional network structures. • LCNF as a core component combines the advantages of nanocellulose and lignin. • CLCNF are readily prepared via a DES-based strategy. • CPA show excellent adsorption performance, stability and reusability for DS.