Fabrication of the Pesticide-Attapulgite composites regulated by mixed-surfactants

Abstract

The SB (DTAB, TTAB, CTAB, OTAB)-AP complex was obtained by modifying attapulgite (AP) with surfactant of SB (DTAB, TTAB, CTAB, OTAB). The structures were characterized by XRD, FT-IR, TGA/DTA and SEM. A new lamellar structure is formed by introducing surfactant. The basal spacing increases with the increase of alkyl chain length of cationic surfactants. Then, the beta-cypermethrin (BCT) composites of BCT/SB-AP, BCT/DTAB (TTAB, CTAB, OTAB)-SB-AP were prepared and investigated. The basal spacings of BCT composites were larger than those of SB-AP and the corresponding DTAB (TTAB, CTAB, OTAB)-AP. The existence of BCT and surfactants molecules into BCT composites was further confirmed. The BCT/DTAB (TTAB, CTAB, OTAB)-SB-AP have the smaller specific surface areas than DTAB (TTAB, CTAB, OTAB)-AP due to the increase of AP exfoliation in the presence of SB. Fabrication mechanism of BCT composites was put forward. Release behaviors of BCT were investigated and analyzed in different buffer solutions. The existence of mixed-surfactants influenced distinctly the release rates. BCT composites had the slow release property. The release behaviors were well fitted by pseudo second-order and parabolic diffusion models. This study provided a new approach to improve the utilization efficiency of pesticide and could be applied as a pesticide delivery system.