Release kinetics of ethylene gas from ethylene-α-cyclodextrin inclusion complexes

Ethylene was included into α-cyclodextrin (α-CD) by molecular encapsulation. Characterisation of the ethylene-α-CD inclusion complexes (ICs) using X-ray diffractometry (XRD) and scanning electron microscopy (SEM) confirmed their crystalline structures. Release kinetics of ethylene gas from the ICs was investigated. Release characteristics experiments were carried out at various relative humidities (RH) (52.9%, 75.5%, and 93.6%) and temperatures (45, 65, 85, and 105°C). The Power Law and Avrami's equations were used to analyse release kinetics. The latter showed better fit for ethylene release. Kinetics analysis based on Avrami's equation showed that the release of ethylene was accelerated by increases in RH and temperature. For humidity treatments, the release parameter n represented a diffusive mechanism at 52.9% and 75.5% RH and a first-order mode at 93.6% RH. However, a diffusive mechanism was found in all temperature experiments. Release rate constants increased as a function of increasing temperature. Temperature coefficient (Q₁₀), activation energy (E_a) and half-life release of ethylene gas were also analysed.