Fabrication of sulfonated cellulose nanocrystals/sodium alginate beads for adsorbents of matrine

Matrine is a type of alkaloid found in plants, exhibiting a wide range of biological and pharmacological activities. The process of separating and purifying matrine poses challenges due to its low concentration and frequent presence in mixtures during raw extraction. This work aims at synthesizing suitable adsorbents for efficient separation and purification of matrine from plant materials. The sulfonated cellulose nanocrystals/sodium alginate beads (SCNCs/SA) were synthesized by the ionic gelation method, characterized and investigated for the adsorption of matrine from water. The equilibrium adsorption capacity of SCNCs/SA beads for matrine at 298 K was approximately 55.66 mg/g. The adsorption enthalpy, entropy, and free energy of matrine on the SCNCs/SA beads were evaluated, indicating that the adsorption process was spontaneous, exothermic, and primarily driven by physisorption. 95 % of the adsorption equilibrium could be achieved within 60 min, and approximately 20 bed volumes of an 80 % (v/v) ethanol aqueous solution for effective recovery. The adsorption isotherms are analyzed using both Langmuir and Freundlich models, the kinetic of adsorption using the pseudo-first-order and pseudo-second-order models, and the breakthrough curves using four breakthrough models. These results suggested that the rapid adsorption and effortless regeneration render SCNCs/SA beads as promising adsorbents for the efficient adsorption and separation of matrine from plants.