Fabrication And Application Of Functionalized Controlled-release Nanopesticide Carrier

Pesticides are considered as the most effective way to control weeds,pests,and diseases in modern agriculture for the promotion of grain yield.However,traditional pesticides tended to enter atmosphere,water,and soil easily through runoff,volatilization,and leaching,leading to serious environmental issues and even hazards to human beings.In China,the annual consumption of pesticides reach up to one million tons,and the average utilization efficiency of pesticides is just about 30%.Consequently,it is urgent to develop new approaches to control the loss and improve the utilization efficiency of pesticide.In recent years,slow/controlled-release pesticide pesticides have attracted wide interests and made them possible to prolong duration,reduce application amount,and decrease the usage times of pesticide in comparison to conventional formulations.Studies have shown that most of the slow/controlled-release pesticides just exhibit slow release behavior rather than controlled release performance which could response to specific environmental stimulus.Therefore,on the basis of slow/controlled-release pesticide formulations,the development of new generation of "intelligent" controlled-release pesticide formulation with environmental response is of great significance to improve the utilization efficiency of pesticides and reduce environmental pollution.At the same time,it also provides effective technical support for the development of precision agriculture.Facing the problem of low utilization efficiency of pesticide and agricultural non-point source pollution caused by pesticide loss,this research developed a pesticide loss control technology and a stimuli-responsive intelligent nanopesticide system.This work provide a basic theory guidance for the development of new pesticide formulations,and a solution for the implementation of the "double reduction action",showing great practical significance to the construction of ecological civilization.This work mainly includes the following parts:(1)Porous calcium carbonate microspheres,fabricated through a facile coprecipitation method regulated by soluble starch,were used as carrier for prometryn,a typical herbicide,to prepare controlled-release prometryn nanopesticide.The influences of soluble starch concentration,reaction time and temperature on the morphology of calcium carbonate were investigated to obtain the optimal fabrication condition.The resulting calcium carbonate possessed a large specific surface area,a great number of functional groups and could efficiently load prometryn through electrostatic attraction and hydrogen bond.Compared with the commercial pesticide,this nanopesticide with good slow-release performance,could effectively control the migration of herbicide in soil.In addition,the nanopesticide possessed higher utilization efficiency,control efficacy on weeds and lower potential risk to environment,showing a potential application prospect in future.(2)In this work,a pH-responsively controlled-release chlorpyrifos(PRCRC)was developed using a nanosystem consisting of chlorpyrifos,polydopamine,attapulgite,and calcium alginate.Therein,chlorpyrifos was adsorbed in the nanonetwork-structured polydopamine-modified attapulgite to obtain chlorpyrifos-carrier through synergistic effect of adsorption,hydrogen bonds and electrostatic attraction.PRCRC spheres tended to collapse in alkaline solution and promoted the release of chlorpyrifos,thus displayed a good pH-responsively controlled release performance,which was proved by the control efficacy test on grubs.In addition,the system could effectively protect chlorpyrifos molecules from degradation under ultraviolet light.Besides,the hydrogel carrier has no poisoning effect on E.coli and foxtail millet,showing a high biosafety.The technology with advantages of low cost,high efficiency and friendly environment,could improve the utilization efficiency,prolong the duration,and provide effective technical support for reducing the pesticide usage amount,showing a huge potential application prospect.(3)In this work,we constructed a multifunctional nanopesticide system,a pH-responsively controlled-release pesticide(PRCRP)with magnetic collectability performance.Herein,herbicide(glyphosate)and pesticide(cypermethrin)were respectively loaded in the micro-nano pores of diatomite/Fe3O4,a magnetic nanocarrier,which was fabricated through in-situ deposition method.Afterwards,the resulting pesticide/diatomite/Fe3O4 was coated by chitosan which can be dissolved in acid condition so as to control the release of pesticide.The magnetism resulted from Fe3O4 endowed PRCRP a feasible magnetic collection performance.After the release of pesticide,PRCRP could be separated conveniently from water and soil with a high collection ratio.PRCRP displayed a high adhesion capacity on the weed surface and pest epidermis,a significantly controlled-release performance,a high utilization efficiency,an outstanding control efficacy on weed and pest,and potential collectability in practice.Therefore,this technology may have a promising application potential in reducing pesticide residue and risk to the environment.