Preparation of Diatomite Based Porous Slow-Release Materials and its Adsorption-Release Properties on Phoxim

Abstract

Slow-release materials have the property of controlling the slow-release of drugs. At present, polymer slow-release materials have been widely studied, but the stability is poor and the release effect of components is difficult to control. The diatomite mineral is light in weight, small in volume and stable in physical and chemical properties. A series of diatomite based porous slow-release materials were prepared to explore the adsorption-release performance. The prepared slow-release materials have excellent porous structure and adsorption-release properties. The adsorption process of phoxim onto slow-release materials accorded with Freundlich model. The maximum adsorption capacity reached 217.86 mg g-1 at 25 ºC. In addition, the release effect of phoxim from slow-release materials was obvious under acid or high temperature conditions. The limit release amount was 60.04 and 80.2% respectively. The slow-release time was up to 25 days which will reduce the phoxim residues efficiently. According to the fitting results of Ritger-Peppas model, the release process was controlled by Fick diffusion mechanism.

Keywords: diatomite, adsorption, adsorption isotherm, slow-release, Ritger-Peppas