Adsorption/desorption, diffusion, and thermodynamic properties of anthocyanin from purple rice bran extract on various adsorbents

摘要

In the present study, the adsorption and desorption behaviors of anthocyanin in the aqueous solution of purple rice bran were investigated using amberlite XAD2, XAD4, XAD7, activated charcoal, and bentonite as adsorbents. The diffusion mechanisms of anthocyanin on adsorbents were also investigated. Amberlite XAD7 showed higher adsorption/desorption capacities and recovery of anthocyanin from purple rice bran extract over other adsorbents. The recovery of anthocyanin from XAD7 was 41.49% while adsorption and desorption capacities were 1.87 and 1.79 mg/g, respectively. The adsorption behavior of anthocyanin indicated that the process was better explained by pseudo-first-order kinetics than pseudo-second-order kinetics model. Adsorption isotherm behavior of anthocyanin on adsorbents was found to be homogeneous and more suitable for Langmuir (two parameters) and Redlich-Peterson (three parameters) isotherm models. The adsorption mechanisms of adsorbents were well explained by intra-particle diffusion model and indicated that XAD7 has the higher diffusion rate than the other adsorbents. In addition to that, the phytochemical profiling of the separated and concentrated bran extract was investigated using HPLC in terms of anthocyanins, cyanidin-3-glucoside, peonidin-3-D-glucoside, and phenolic acid content.