| Montmorillonite(MMT)is a layered material with positive and interlayer with anions,and it has a large specific surface area,lamellar with a negative charge,with superior adsorption capacity and good biocompatibility,which is an ideal slow release drug carrier.Using an amphoteric surfactant(ZS)to modify the MMT by electrostatic action to form a ZS-MMT composite,and the pyrethroid pesticide is further introduced to prepare a pesticide hybrid.Meanwhile,the intercalation of surfactant can improve the interlayer hydrophobicity,induce the intercalation of pesticides,boost the loading and prolong the time of pesticides release and reduce the environment contamination.In this paper,firstly,studied amphoteric surfactants(dodecyldimethylcarboxybetaine(DCB),dodecyldimethylsulfonabetaine(DSB),3-sulfopropylhexadecyldimethyl beet)Structural properties of alkali(SB16)and dodecyldimethylammonium oxide(OA)intercalated MMT.Secondly,the pesticide cyhalothrin C and beta-cypermethrin BC loaded on the hybrid ZS-MMT respectively by the micelle method,which was used to study the structure and sustained release properties of the drug-loaded complex.The main research contents are as follow:1.Preparation and Characterization of Amphoteric Surfactant(ZS)intercalated into MMT.ZS-MMT,prepared by ion exchange method,which characterized by XRD,FT-IR,TGA/DTA techniques.We studied the effect of surfactant concentration and p H on the preparation has been investigated in detail.Within a certain concentration range,the results show that the interlayer spacing of MMT increases with the increase of surfactant concentration.When the mass of DCB increased from 0.15 g to 0.6g,the DCB-MMT layer spacing is increased from 2.03 nm to 3.35 nm,and the preparation is not affected by the p H environment;when the OA mass increased from 0.3g to 0.6g,OA-The MMT layer spacing is expanded from 2.98 nm to 3.05 nm,and the optimal p H environment is p H 7-9.When the mass of DSB increased from 0.2 to 0.75 g,the DSB-MMT layer spacing is expanded from 1.60 nm to 2.29 nm.The optimal is p H 4-5 and 9;when the mass of SB16 is increased from 0.15 g to 0.75 g,the SB16-MMT layer spacing is increased from 2.19 nm to 4.41 nm,and the preparation is not affected by the p H environment.2.The Preparation and release properties of C/DCB-MMT and BC/SB16-MMT intercalated materials.Micellar C/DCB and BC/SB16 was introduced into the precursors DCB-MMT(4)(4 represents the p H environment at the time of preparation,the same below),DCB-MMT(6),DCB-MMT(9) and SB16-MMT(4),SB16-MMT(6),SB16-MMT(9) by micellar method,respectively.The structure and thermal stability of intercalated materials are characterized by XRD,FT-IR,TGA/DTA and SEM.The release experiments were carried out in p H 5.0 and 6.8 buffer solution,and the release data were kinetically fitted.The layer spacing of the composites C/DCB-MMT(4),C/DCB-MMT(6),C/DCB-MMT(9)was 3.35 nm.This indicates that the micelles C/DCB have successfully entered the precursor hybrid.In addition,The study found that the sustained release time of these three samples was about 2h,and the sample C/DCB-MMT(4)was slowly released for 2.7h in the p H 5.0 buffer environment,and released for 2.2h at p H6.8 buffer environment.and the sustained release rate was 59% and 61.5%,separately.And the release behavior of those three composites are highly fitted to the second-order kinetic equation and the parabolic diffusion model.The layer spacing of the composites BC/SB16-MMT(4),BC/SB16-MMT(6),BC/SB16-MMT(9)was 4.61 nm.This showed that the micelles of BC/SB16 have successfully entered the precursor hybrid.In addition,The study found that the sustained release time of these three samples was about 2h,and the sample BC/SB16-MMT(6)was slowly released for 3h both in the p H 5.0 and p H6.8 buffer environment,and the sustained release rate was 59% and 61.5%,separately.And the release behavior of the six composites coincides with the second-order reaction model and the parabolic diffusion model. |
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