Adsorptive removal of polyphenols from an alfalfa white proteins concentrate: Adsorbent screening, adsorption kinetics and equilibrium study

The objective of this work was to examine the effectiveness of adsorption for the removal of polyphenols from an alfalfa white protein concentrate to produce a protein purified fraction. Six commercial macroporous resins were tested for their polyphenols adsorption characteristics. The screening results showed that the adsorbent HP20 and the anion-exchange resin AER1 had the best adsorption characteristics with adsorption capacities of 54.62 mg/g and 48.18 mg/g, respectively. The effect of pH, contact time and adsorption isotherms were successively investigated on the two preselected resins. The process kinetics was evaluated by the pseudo-first-order, the pseudo-second-order, Elovich, intra-particle diffusion and the modified pseudo-first-order models. Batch kinetic data have been well described by the pseudo second order model. Meantime, the adsorption process close equilibrium was governed by intra-particle diffusion. The adsorption data were fitted well with the Langmuir isotherm model. It was found that the process is favourable. These results will be used in future studies for the design of column adsorption systems for the purification of the alfalfa protein concentrate and the recovery of phenolic compounds contained in the latter.