抄録
The practical application of clathrate crystals for the release control of biocide was investigated. The release of CMI (biocide) was controlled by the formation of clathrate crystals with TEP as the host. The CMI concentration released from TEP-CMI crystals increases with the amount of TEP-CMI clathrate crystals, however, it is limited. The appearance of the peak in the TEP concentration changes is related with the crystal structure change of TEP-CMI crystals. The release mechanism of CMI is cleared to be the combination of the dissolution of TEP-CMI crystal and the crystallization of the new solid phase (TEP-SOL (TEP·CH3OH·H2O)). The rate of the structural change remarkably depends on the amount of crystals. The crystal morphology is different between the TEP-CMI crystal and TEP-SOL crystal. The rate of the structural change also decreased with the increase of water composition.When the stirring is sufficiently intensive (450 rpm), the attained CMI concentration becomes higher than that at 250rpm with small magnetic bar. On the other hand, the attained TEP concentration at 450 rpm appeared to be lower than that at 250rpm. It was shown that at 450 rpm the true equilibrium was established between the crystals and the solutions, however, at 250 rpm both concentrations are under the qasi-equilibrium. This may be due to the disturbance of the diffusion of CMI molecule from TEP-CMI crystals by the TEP-SOL crystals which precipitate on the surface of the TEP-CMI crystals. The attained concentration was expressed as the function of the solvent composition. The abnormal concentration change of CMI and TEP was also observed by changing the stirring crate.
