Sorption of food dyes on polyurethane foam and aluminum oxide

Abstract

The sorption of food dyes Sunset Yellow (E-110), Tartrazine (E 102), Ponceau 4R (E-124), Fast Green FCF (E-143) on polyether-based polyurethane foam, and α-Al2O3 from water solutions has been studied. It has been found that the maximum sorption is observed in the range of 0.2 M HCl-pH 2 on polyurethane foam and at pH 2–4 on aluminum oxide. Under the optimal conditions the recoveries on polyurethane foam and α-Al2O3 are 20–30% and 70–80%, respectively. It has been shown by diffuse reflectance spectroscopy that, for all dyes except for Fast Green FCF, only one form of the dye that dominates under these conditions in the aqueous solution is extracted on the sorbents in the range of 0.5 M HCl, pH 8.0. Possible models of the interaction between the dyes and the sorbent surface are proposed.