Pickering Emulsions Stabilized by TEMPO-Oxidized Acacia mearnsii Bark Cellulose for Effective Matrine Adsorption

TEMPO-oxidized Acacia mearnsii bark cellulose (OABC), pretreated using deep eutectic solvents (DES), was employed to prepare Pickering emulsions, which served as an efficient adsorbent for matrine. The adsorption of matrine from aqueous solutions was systematically characterized and evaluated using an OABC-stabilized Pickering emulsion (OABCPE). At 298 K, the equilibrium adsorption capacity of matrine on OABCPE was determined to be 44 mg g–1. Furthermore, investigations into the Gibbs free energy, entropy change, and enthalpy increment of the adsorption process indicated that the process is exothermic, spontaneous, and predominantly driven by physisorption. During the first 20 min, a noticeable increase in the adsorption rate is observed, with equilibrium being reached after 60 min. Dynamic adsorption studies revealed that equilibrium could be reached within 200 min, with 70% of the adsorbed matrine being desorbed using 70% alcohol. The adsorption isotherms were fitted to both the Langmuir and Freundlich models. The pseudo-first-order and pseudo-second-order models were employed to analyze the adsorption kinetics. Four breakthrough models (Adams–Bohart, Thomas, Clark, and Yoon–Nelson) were applied to analyze fixed-bed adsorption. The rapid adsorption and facile preparation of OABCPE endow it with significant potential for matrine adsorption and exhibit good stability and reusability under varying industrial conditions.