Design and synthesis of a macro-porous chitosan-sodium alginate aerogel adsorbent for efficient adsorption of SDBS from aqueous solutions

• An environmentally friendly chitosan-sodium alginate aerogel was successfully synthesized by an internal sol–gel strategy. • A ternary solvent system of acetic acid/water/tetrahydrofuran was used for the formation of macro-porous structure. • The synthesized aerogel adsorbent exhibited remarkable adsorption performance on Sodium dodecylbenzene sulfonate (SDBS). • The adsorption of SDBS on the adsorbent was controlled by chemisorption through ion exchange and electrostatic interaction. • The synthesized adsorbent demonstrated excellent regeneration ability and recyclability. The treatment of wastewater containing surfactants is an increasingly serious issue that requires immediate remediation. Adsorption is an effective way to treat wastewater containing surfactants. However, for the adsorption of macromolecular substances like surfactants, adsorbents typically require a macro-porous structure to ensure efficient adsorption of surfactants. In this study, a macro-porous aerogel adsorbent was successfully fabricated with renewable biopolymers of chitosan (CS) and sodium alginate (SA) by a novel internal gelation strategy with a ternary solvent system of acetic acid/water/tetrahydrofuran (THF). The as-prepared adsorbent was systematically characterized by XRD, FT-IR, SEM, and XPS. Equilibrium adsorption experiments were conducted to investigate the effects of pH, adsorbent dosage, contact time, initial concentration, and temperature on the Sodium dodecylbenzene sulfonate (SDBS) adsorption performance. At the optimal pH of 3.0, the maximum adsorption capacity reached 254.83 mg/g at 308 K with 50 mg/L initial concentration and 0.20 g/L adsorbent dosage. The macro-porous structure of the adsorbent facilitated the diffusion of SDBS and exposed more adsorption sites, which enabled the adsorption of SDBS in aqueous solutions. The adsorption process conformed to the pseudo-second-order kinetic model and the Freundlich isotherm model. Thermodynamic results indicated that the adsorption process was spontaneous and endothermic. Moreover, the synthesized adsorbent demonstrated excellent reusability after five cycles. The fixed-bed adsorption experiments further showed the potential of the synthesized adsorbent as an efficient adsorbent for continuous removal of SDBS. This study offers a feasible strategy for the development of macro-porous aerogel materials and demonstrates the as-prepared adsorbent for SDBS removal.