Structure and Property of Pesticide Intercalation into Laponite Assisted by Silane Coupling Agent

Abstract

The APTES-LAP was first prepared by silane coupling agent of 3-aminopropyltriethoxysilane (APTES) intercalation into laponite (LAP). The effect of m(APTES)/m(LAP) mass ratio and reaction time on the structure of APTES-LAP were investigated. The results showed that the interlayer distance of APTES-LAP was about 1.75 ∼ 1.89 nm as the mass ratio of m(APTES)/m(LAP) was between 0.5 and 2.0, reaction time was 24 h. Then, pesticides of beta-cypermethrin (BCT) and imidacloprid (IMP) were separately introduced into APTES-LAP to prepare BCT/ APTES-LAP and IMP/APTES-LAP composites. Their structures and thermal stabilities were characterized by powder X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), thermogravimetry/differen-tial thermal analysis (TGA/DTA), hydrogen magnetic resonance ( 1 H NMR) and scanning electron microscopy (SEM) techniques. Compared with APTES-LAP, the first diffraction peaks of BCT/APTES-LAP and IMP/APTES-LAP moved forward, and interlayer distance increased to about 2.2 nm. The existence of APTES and pesticide were further confirmed in the gallery. Furthermore, the release behaviors of pesticide from BCT/APTES-LAP and IMP/APTES-LAP in pH 5.0 and 6.8 buffer solutions were investigated and discussed. The pseudo-second-order and the parabolic diffusion models were used to fit the release data. This work was helpful to develop the application of composites in pesticide controlled release formulation.