Preparation And Application Properties Of Pesticide Controlled Release Formulations Based On Hollow Silica

Food security serves as the foundation of people’s livelihoods.Pesticides are an important cornerstone for guaranteeing food security and a strong guarantee for improving food production and quality.However,the long-term inefficient use of conventional pesticides and the harm to environment have prompted the development of new nanopesticide delivery systems with high efficiency and low toxicity.Due to their environmentally friendly and unique porous hollow structure,hollow silica nanoparticle materials have attracted much attention as carriers to construct nanopesticide delivery systems.However,the complexity and high cost of the current preparation process of hollow silica nanoparticles limit their practical applications.Based on the above,we use Ca CO₃industrially prepared by high gravity technology as the hard-core templates to synthesize two kinds of hollow silica materials,namely,hollow silica nanoparticle（HSNs）and hollow mesoporous organosilica nanoparticles（HMONs）,using high-gravity technology and other ways.Furthermore,they were adopted as a carrier to construct nanopesticide delivery systems to enhance the efficiency of pesticide utilization.The main research contents and conclusions are as follows.1.HSNs were efficiently and controllably prepared using Ca CO₃nanoparticles as hard-core templates by high gravity technology.The effects of p H,flow rate of HCl,aging time and temperature,coating ratio,as well as high-gravity rotating speed and flow rate on the synthesis of HSNs were explored.The optimal process conditions were thus obtained.The as-preprared HSNs have an obvious hollow structure,uniform and controllable thickness,average size of 95 nm,and a BET surface area of662 m²/g.Compared with the traditional stirred tank reactor,the specific surface area of the product prepared by high gravity technology is larger and the reaction time is greatly shortened by 2/3,thereby greatly improving the synthesis efficiency.We further cooperated with an enterprise to establish a pilot equipment for the scale-up synthesis of HSNs with an annual output of ten tonnes.The prepared HSNs have an obvious hollow structure and the specific surface area of 525 m²/g,and the synthesis process has no obvious amplification effect.2.HSNs were used as pesticide carriers for loading abamectin（AVM）and cyantraniliprole（CNAP）to construct nanopesticides controlled-release systems（AVM@HSNs and CNAP@HSNs）.The corresponding drug loading,controlled-release performance,photolysis resistance were further investigated.The control of Chilo suppressalis and Panonychus citri was also evaluated in the field.The results indicated that the drug loading capability of CNAP@HSNs and AVM@HSNs were 40.33 wt%and 30.45 wt%,respectively.The half-life of AVM in AVM@HSNs（2.072h）was 7.73 times that of the AVM technical（0.2678 h）.The results of the field trials showed that CNAP@HSNs and AVM@HSNs were significantly better than the corresponding commercially available 10%cyantraniliprole dispersible oil suspension and 5%avermectin emulsifiable concentrate（AVM-EC）,respectively.At day 21 after spraying,AVM@HSNs was still more effective than the AVM-EC in controlling Panonychus citri at a low dose（50%reduction of active ingredient）.3.HMONs were further synthesized with co-hydrolysis and polycondensation method by using Ca CO₃ nanoparticles as hard-core templates,CTAB as a mesoporous pore director.A redox/near-infrared light dual-triggered insecticide delivery system（AVM@HMONs@PDA）,which was used for the control of Panonychus citri,was further constructed by loading AVM and coating a layer of polydopamine（PDA）.The as-obtained AVM@HMONs@PDA displayed a high pesticide loading capacity of 24.8 wt%,an excellent foliar affinity,and could release AVM rapidly under a redox environment or near-infrared light irradiation.The half-life of AVM in AVM@HMONs@PDA was 17.0-fold longer than that of the AVM technical.In the field trial,at day 28 after spraying,AVM@HMONs@PDA was significantly more control effective than AVM-EC in controlling the Panonychus citri,even at a 50%reduced dosage.4.A redox-and p H-triggered fluorescent smart nanopesticide delivery system（Boscalid@HMONs@ZnO）was constructed using HMONs as a carrier,Boscalid as a model pesticide,and ZnO quantum dots as a capping agent.The quantities of boscalid released under biostimulation associated with Botrytis cinerea were 81.4%（p H 3.0,without glutathione）and 55.5%（p H 7.4,with glutathione）,while the total release under natural conditions was 43.3%.For fungicidal activity,the median effective concentration of Boscalid@HMONs@ZnO was 40.4%lower than that of the technical.For the pot experiment,Boscalid@HMONs@ZnO was 1.27 times more effective than commercially available boscalid water-dispersible formulation from BASF in controlling the disease.In addition,Boscalid@HMONs@ZnO promoted the uptake of Boscalid in plants.