Rosin-based polymer@silica core–shell adsorbent: Preparation, characterization, and application to melanoidin adsorption

The pigments of sugarcane juice may be occluded within sugar crystals and impart a yellow or brown tint to sucrose, which causes a negative effect on the quality of white sugar. Adsorption is a useful method to remove color from sugarcane juice. In the present study, a novel rosin-based polymer@silica core–shell adsorbent (RP-Si-CA) bearing silica as a support, modified rosin as a cross-linking skeleton, and quaternary ammonium cations as a functional group was prepared and used as a decolorization agent for sugarcane juice. Synthetic melanoidin was used as a sugarcane juice colorant model to study the adsorption performance of RP-Si-CA. The equilibrium adsorption capacity of RP-Si-CA for melanoidins was 0.83 mg/g (experimental conditions: RP-Si-CA dosage, 0.30 g/mL; temperature, 333 K; pH, 7.0; initial melanoidin concentration, 270 mg/L), and the corresponding removal rate reached 92%. Studies on the kinetics, isotherms, thermodynamics, and interaction mechanisms of melanoidin adsorption by RP-Si-CA revealed that adsorption is mainly affected by chemisorption due to the interaction between the quaternary ammonium cations of RP-Si-CA and the carboxylate ions of the colorant. Moreover, adsorption occurred via an endothermic monolayer process and was spontaneous. Recycling experiments indicated that RP-Si-CA presents good regenerability.