Study On The Emamectin Benzoate-HTlc Nanohybrids Controlled Release System

Nowadays in China, the second biggest country of pesticide producing, preparations forms are mainly powder, oil concentrate and suspension concentrate, which are irrational and large application. Pesticide has brought many ignorant effects such as air pollutions, environmental destroy, food safety and so on, which has baffled agricultural sustainable development. Now the hit research trends of pesticide forms in the world are focused on controlled-release formulations.Hydrotalcite-like compounds (HTIc), also called Layered double hydroxides (LDHs), consisting of divalent and trivalent metal ions and with the same layered crystal structure as hydrotalcite, are a class of layered materials which has been paid a great of attention in recent years. The interlayer region of HTIc may be considered as a microvessle, some pesticide and drug molecules may be intercalated into the gallery of HTIc to form pesticide/drug-HTIc nanohybrids. The nanohybrids may evidently inhibit the release of moleculars in the interlayer. So pesticide/drug-HTIc nanohybrids are greatly potencial controlled-release formulations.HTIc was chosen as host material and emamectin benzoate (MAAV) as guest species, have been successfully intercalated into HTIc using re-assemble method.The synthesis strategy and the properties of nanohybrids, released behavior, released mechanism and the relationship between structures and released behavior of nanohybrids were systematically studied. The main contents of this paper are as follows.One charge-neutral and poorly water-soluble pesticide, emamectin benzoate (MAAV), was first successfully intercalated into the gallery of Mg-Al hydrotalcite-like compounds (HTlc) by re-assemble method, to obtain MAAV-HTlc nanohybrids.The prepared samples were characterized by X-ray powder diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). Results showed that MAAV was successfully retained in the hydrophobic region of SDS-HTlc, corresponding to a distinct interlayer gallery increase. The thermal stability of MAAV-SDS-HTlc were investigated by thermogravimetry and differential thermal analysis (TG-DTA) showed that the modified HTlc increase the thermal stability of MAAV.The release kinetics of MAAV from the nanohybrids was investigated at different pH buffer solution. The nanohybrids can well control the release of MAAV, showing they are a potential pesticide controlled-release formulation. MAAV-SDS-HTlc nanohybrids exposed to pH 5.8 and 8.0 released MAAV more quickly. When the pH changed to 7.0, the rate of release decreased. It was found that the MAAV release kinetic processes of the nanohybrids can be described with pseudo-second-order model.Using particle size distribution and Zeta potential analysis of the different wetting and dispersing agents on the MAAV-SDS-HTlc hybrid materials suspended in the water performance. The results show that sodium alkyl naphthalene sulfonate condensation Morwet D-425 and MAAV-SDS-HTlc with modified can make hybrid materials stable suspension in water.The preparation method of the water dispersible granules of 26% emamectin benzoate-HTlc was studied. Through the test, we selected the suitable wetting agent, dispersant, disintegrant and binder and determined the optimum formula using the orthogonal test design. The new formulation included Emamectin benzoate-HTlc, wetting agent SDS+RS, dispersant MorwetD425, disintegrant urea, binder saccharose in mixture with mass fractions were 78%, 6%, 5%, 10% and 1%.The experimental results showed that the suspension rate of products was over 90%, the dispersion time was less than180 seconds and the decomposition rate of its active ingredient was less than 5% at (54±2)°C with 14 days, which conformed to the requirements of the formulation.