Adsorption of rutin onto a food-grade styrene–divinylbenzene copolymer in a model system

Adsorption of quercetin-3-O-rutinoside (rutin) onto Amberlite® XAD 16HP was studied applying a modified D-optimal design. Temperature, pH value, rutin concentration and resin amount were studied as independent factors determining rutin adsorption. Using the mathematical model resulting from the analysis of the D-optimal design the optimal conditions for rutin adsorption onto the styrene–divinylbenzene copolymer were determined. Furthermore, the model equation was successfully applied to calculate the Langmuir and Freundlich isotherm parameters of this particular solute–sorbent system. In addition, the data obtained from the D-optimal design allowed the calculation of ΔG, ΔH and ΔS for the adsorption process. The results presented in this study are of utmost importance for a better understanding of adsorption phenomena. The more detailed knowledge of such sorbent systems is required to improve the cost-effectiveness of industrial processes for the recovery of secondary plant metabolites, such as polyphenols, based on resin adsorption technology.