Home – Home – Jornals – Chemistry for Sustainable Development 2018 number 5

Dioscorea saponin isolated from the rhizome of Dioscorea nipponica Makino was investigated by performing grain size, SEM, XRD, FTIR and TG-DSC analysis. The sizes of D₅₀ for the Dioscorea saponin sample activated by AGO mill decreased to as low as 10.03 μm. According to SEM and XRD, the granularity and structures of Dioscorea saponin samples with and without mechanical activation significantly differed, and the crystalline of Dioscorea saponin was significantly converted into amorphous state after mechanical activation. On the basis of TG-DSC analysis, two endothermic peak of Dioscorea saponin after mechanical activation moved back 15 and 35 °C respectively, and it had 99 % weightlessness ahead of 100 °C due to the accelerated decomposition. According to thermal analysis kinetics, the average thermal decomposition activation energy of Dioscorea saponin after mechanical activation was increased 13.45 kJ/mol, and the dynamic mechanism function of Dioscorea saponin was f(α) = 6(1 - α)^2/3[1 - (1 - α)^1/3]^1/3, and this was regarded the mechanism of three-dimensional diffusion. With mechanical activation, the dynamic mechanism function was f(α) = 4(1 - α)^1/2[1 - (1 - α)^1/2]^1/2, and this was regarded the mechanism of two-dimensional diffusion. The result of transformation from three-dimensional to two-dimensional diffusion mechanism was consistent with XRD analytical result of transformation from original ordered crystalline structure to amorphous state after mechanical activation. None of the functional groups of the mechanically activated Dioscorea saponin disappeared, and no new functional groups appeared, which indicate that mechanical activation does not induce a chemical transformation of Dioscorea saponin.