Study On The Effects Of Pesticide Adjuvant On The Evaporation, Deposition And Rebouncing For Droplet On Typical Biointerface

The interaction between droplet and target crop leaf surfces have a significantly influence on the pesticide utilization and pest control efficiency.We explore the effects of pesticide adjuvant on the evaporation,deposition and rebouncing for droplet on typical biointerface and concluded as follows:The evaporation kinetics for droplet of solution and suspension system on rice,cotton and cabbage leaves is studied respectively.We found that the evaporation time and evaporation mode is significantly influenced by surfactant concentrations and surface characterastics.For solution system,the evaporation time is increased firstly and then decreased when surfactant concentrations above CMC on rice leaves which is the very opposite on cotton leaves.It mainly showed a CCR mode during the droplet evaporation.For suspension system,on cabbage leaves,the evaporation time is gradually decreased when surfactant concentrations above CMC and after 1500s it changed from CCR mode to Mix mode.Besides,the concentrations of SiO₂ in our experiement has little influence on droplet evaporation time and evaporation mode.The deposition pattern for suspension liquids of SiO₂?MSN?MSN-TA and MSN-DF?on rice?cabbage and polytetrafluoroethylene membrane is studied.Surfactant of SDS,Tween80 and a combine of two of them is adding to the suspension liquid respectively.We found that on cabbage leaves,the deposition pattern is influenced by surfactant concentrations.The spreading area is small with relatively lower concentrations of surfactant.A coffee ring depositon is approximately formed which is characterized by particles deposition on the edge of the droplet.However,with concentrations above CMC,a uniform pattern is achieved.For rice leaves,no significant effect can be observed for surfactant concentrations to the deposition pattern and spreading area.It may be induced by the superhydrophobicity of the rice leaf surfaces.When SiO₂?MSN?is positive charged as MSN-TA,the deposition area is slightly reduced.Besides,for MSN-DF which is synthesised by loading difenoconazole on SiO₂?MSN?,the deposition area is slightly increased.The rebouncing for suspension liquids same as what is used in deposition is studied on rice and cabbage leaves.The result showed that the rebouncing can be inhibited with concentrations above CMC on cabbage leaves.Whereas,on hydrophobic rice leaf surfaces,the rebouncing is easily to happen for droplet of all liquids.We also studied the dilational rheological viscoelasticity properties of the suspension liquids.We also found that with the surfactant of SDS and the combine of both SDS and Tween80,a sudden decrease of the ultimate value of dilatational elasticity happened just at the point of no rebouce occurred on cabbage leaves.It reflected that the stability of interfacial layer of the droplet may have an effect on the rebouncing of the droplet.We explore the evaporation,deposition and rebouncing for droplet on crop leaves aiming to provide theoretical data to improve the efficiency of pesticide and reduce pesticide loss.