| The high utilization of industrial lignin is a promising and challenging research field.This paper attempts to modify industrial sodium lignosulfonate(SL)and alkali lignin(AL)through hydrophobicity modification for pesticide controll release to expand its application in the field of agricultural sustainable development.Due to the strong polarity of lignin,its compatibility with pesticide was poor,which made it difficult to encapsulate pesticide effectively.In this paper,two different hydrophobic lignin-based materials were prepared by electrostatic self-assembling with cationic surfactant cetyltrimethylammonium bromide(CTAB)and acylated modifying by alkyl acyl chloride,respectively.These modified lignin were employed to encapsulate avermectin to make drug-loaded microspheres.Not only could these microspheres slow down the degradation rate of AVM,but also could help AVM against ultraviolet.The results of this study provide new materials and methods for the formulation of pesticide which is also a new attempt for the high value use of lignin.In this paper,a novel lignin-based microsphere was prepared.Through self-assembly,SL and CTAB aggregated into uniform colloidal spheres(SL-CTAB).SL-CTAB performed a reversible aggregation behavior and was used as the shell material to prepare microspheres to encapsulate AVM.Moreover,the microsphere(AVM@SL-CTAB)exhibited an uniform spherical structure.To reveal the excellent embedding capability of AVM@SL-CTAB,the controlled release and antiphotolysis performance for AVM were systematically investigated in this work.As a result,the encapsulation efficiency value of AVM@SL-CTAB reached to 62.58 ± 0.06%.The release of AVM from AVM@SL-CTAB was still going on after 70 h,and its cumulative release amount at that time was 49.96 ± 1.13%.The release process of AVM@SL-CTAB could be controlled by adjusting the doped proportion of SL-CTAB.The half-life of AVM in AVM@SL-CTAB under UV irradiation could be prolonged for 7.35 times that of uncoated AVM.The enhanced photoprotection and the controlled release of AVM implied that SL-CTAB possessed a great application prospect for efficient pesticide utilization.Alkali lignin was modified by acetyl chloride and benzoyl chloride respectively to improve the compatibility of alkali lignin with avermectin.By adjusting the hydrophobicity of the system,the acylated lignin gathered,during which avermectin was encapsulated inside to prepare the acetylated lignin-based drug-loaded microspheres AVM@ACAL and AVM@BZAL.SEM images revealed that the morphology of acylated lignin-based microspheres were spherical nanoparticles.By studying the drug-loading properties,sustained-release properties and anti-photolysis properties of alkali-lignin-based drug-loaded microspheres,it was found that benzoylated lignin demonstrated a better performance of controlled-release due to its steric hindrance and hydrophobic interaction between benzene ring and avermectin.The effect of phenolic hydroxyl content on the performance of drug-loaded microspheres was also studied.The results showed that the change of phenolic hydroxyl group could affect the hydrophobicity of the wall material,which iw related with the compatibility of the wall material with the core material.The better the compatibility is,the better the loading performance of the drug-loaded microspheres will be.Meanwhile,the higher the content of the phenolic hydroxyl group,the better the anti-photolysis performance will be.The performance of the drug-loaded microspheres prepared by SL,AL,SL-CTAB,ACAL and BZAL was compared.It was found that the hydrophobic modification of lignin was very essential for the encapsulation of avermectin.Comparing the sustained-release properties,SL-CTAB manifested a better performance.The optimal performance of the controlled release performance is closely related to the spatial structure of the wall material.The greater the steric hindrance of the wall material,the better the controlled release performance will be. |
PDF Full Text Request