Preparation Of PH-responsive Alkaline Lignin And Its Application In Pesticide Microcapsule

Alkaline lignin derived from alkaline pulping,no strong hydrophilic groups in the molecule,poor water solubility,recycling was extremely difficult,so in order to broaden the application of alkali lignin,to be its chemical modification,alkali lignin contains many active groups such as methoxy,phenolic hydroxyl,alcoholic hydroxyl,carbonyl,carboxylic acid,alkyl or aryl,etc.,which provided active sites for its modification.In this paper,AL was used as raw material,Na2SO3 as sulfonating agent and DETA as aminating agent.When the other conditions were constant,the isoelectric point of ASAL increased with the increase of the amount of aminating agent.When the other conditions were constant,the isoelectric point of ASAL decreased with the increase of sulfonating agent dosage.AL and ASAL were analyzed by elemental analysis and infrared spectroscopy.The results showed that ASAL was successfully synthesized,and the modified product was characterized in physicochemical behavior.The results show that the particle size of the modified lignin varied with the decrease of pH,which indicated that ASAL has obvious pH response.The preparation method of avermectin microcapsules was prepared by using the ASAL as the wall material and AVM as the core material.The preparation method was as follows: the ratio of core to wall(mass ratio)= 1/1,bagging pH = 7.5,glutaraldehyde dosage 5ml,wall material ASAL-10/50.The maximum drug loading was 42.85%,the highest encapsulation efficiency was 86.20%,and the sustained release time was prolonged from 94 hours to 6 hours.The performance of AVM microcapsules was characterized.The results showed that the prepared microcapsules had good release performance and were comparable to those of microcapsules.The SEM image showed that the surface of the AVM particles was smooth and the surface of the AVM microcapsules was rough,proving that the AVM particles are encapsulated by the aggregated ASAL.Morphology observation revealed that AVM-CS was irregularly granular,and the particle size was mainly distributed in(3.5±0.2)?m.The preparation of Cyhalothrin microcapsules by using the complex coacervation method with Cyhalothrin as the core material and ASAL as the wall material.Cyaphothrin was used as the core material to measure the drug loading and encapsulation rate.The preparation cost was as follows: CTAB was 5% Core material ratio),wall materials for the ASAL-10/50.Under the optimum preparation conditions,the drug loading and encapsulation efficiency of microcapsules were 33.72% and 64.66%,respectively.The performance of AVM microcapsules was characterized.The SEM images showed that the Cyhalothrin particles were smooth and Cyhalothrin microcapsules were rough,indicating that Cyhalothrin granules were encapsulated by aggregated ASAL.Morphological observation revealed that Cyhalothrin-CS was irregularly granular and its particle size distributedin(4.8±0.2)?m.The adsorption mechanism of Cyhalothrin microcapsule showed that the adsorption force between Cyhalothrin and the wall material was mainly the electrostatic attraction of the sulfonates of the CTAB quaternary ammonium and the ASAL sulfonates.Therefore,the addition of CTAB was the key to the embedding of Cyhalothrin microcapsules condition.