Mass Transfer Characteristics during Ultrasound-Assisted Adsorption and Desorption of Aronia melanocarpa Anthocyanins on Fixed Bed Filled with Macroporous Resin

In this study, an ultrasound-assisted macroporous resin fixed-bed device was constructed for the purification of Aronia melanocarpa anthocyanins. Meanwhile, the effect of ultrasound on the mass transfer characteristics during the adsorption/desorption of anthocyanins on the fixed bed was investigated. The mass transfer patterns of total anthocyanins, total sugars, individual organic acids, individual anthocyaninic and non-anthocyaninic phenolics during fixed-bed purification were determined, and the effect of ultrasound on the physical properties of macroporous resins was analyzed. It was found that this fixed bed device could effectively remove impurities from the crude extract of A. melanocarpa. After purification, the purities of anthocyanin and polyphenol were 48.8% and 78.7%, respectively. During adsorption, ultrasound promoted the release of anthocyanins from the fixed bed. Specifically, in the fixed bed with a height of 2.5 cm, the breakthrough time of anthocyanin adsorption was reduced by 65.8% under sonication at 18.76 W/cm². Moreover, the mass transfer during anthocyanin desorption using a highly polar eluent was enhanced by ultrasound. When 25% aqueous ethanol was used as the desorption solvent, the amount of anthocyanins desorbed from the fixed bed after 48 min of elution was increased by 12.6% by 18.76 W/cm² ultrasound. Besides, ultrasound significantly increased the surface roughness of macroporous resin particles, but did not change the interior structure. In summary, ultrasound-assisted fixed bed treatment significantly improves the flowing of anthocyanins among resin particles during the adsorption/desorption, but has little effect on the interaction between single resin particles and anthocyanins.