Encapsulation complex of chlorine dioxide in α-cyclodextrin: Structure characterization and release property

This paper investigated the encapsulation complex (EC) of chlorine dioxide (ClO₂) in α-cyclodextrin. The encapsulation process was evaluated with varying molar ratios of ClO₂ to α-cyclodextrin; the structure of the EC was characterized using FTIR, XRD, and microscopy imaging; and the release and retention of ClO₂ was measured using UV–vis spectrophotometry. Results showed that high ClO₂ loading and EC yield were achieved using appropriate ClO₂/α-cyclodextrin ratio. Characterization analyses showed that α-cyclodextrin was oxidized by ClO₂ and agglomerated into larger particles with modified crystallinity. The retention of ClO₂ at −20 °C was stable for at least 3 months. The release of ClO₂ followed an anomalous transport process in which diffusion played an important role. The release rate was relatively slow compared to some ClO₂ releasing systems reported in the literature, suggesting this EC had potential for applications requiring an extended releasing period.