Effect of nature and structure of synthetic anionic food dyes on their sorption onto different sorbents: Peculiarities and prospects

In this paper, results of a comparative study on sorption of synthetic anionic food dyes onto different sorbents are represented. Five anionic food dyes (3 sulfoazo dyes - E-102, E-110, E-124; a quinophthalone dye - E-104; and a triphenylmethane dye - E-143) and four different sorbents (silica-C16, hypercrosslinked polystyrene, alumina, and polyurethane foam) were examined. Effects of pH, ionic strength were evaluated. Quantitative characteristics of the dye sorption were calculated and effectiveness of different sorbents toward the dyes was assessed. Optical properties of the dyes on the sorbent surface were estimated and compared. Possible mechanisms of the sorption were proposed. Effects of the structure of dyes and the nature of sorbents on efficiency of the sorption were revealed. Based on this study, recommendations regarding sorption isolation and preconcentration of anionic food dyes have been made and a method for direct determination of the dyes by diffuse reflectance spectroscopy on sorbent surface after flow-based preconcentration has been developed.