The adsorption thermodynamics and kinetics of three dispersants(Morwet D-425

GYD-1252 and LG-3)onto pesticide imidacloprid particle surface were studied in order to compare adsorption properties.Adsorption data of three dispersants onto imidacloprid were fitted with Langmuir and Freundlich isotherm equations

and the former fitted better.The thermodynamic parameters:ΔH<0

ΔG<0

ΔS>0

indicated that the adsorption was a spontaneous exothermic process.Theoretically

higher temperature was not beneficial to adsorption process

|ΔH|<40 kJ·mol-1 indicated that the adsorption process was physical adsorption.The conclusion obtained by comparing adsorption properties showed that Morwet D-425 had higher adsorption stability and was not susceptible to temperature effects

LG-3 had lower adsorption stability and was susceptible to temperature effects

adsorption stability of GYD-1252 was in between.The adsorption process followed the pseudo-second-order with a good correlation coefficient.The step of adsorption process included the external diffusion and adsorption onto particle surface

without intraparticle diffusion.Descending order of adsorption rate was Morwet D-425

GYD-1252 and LG-3.The result of adsorption layer thickness by XPS showed that Morwet D-425 had smaller adsorbed layer thickness which changed little with increasing temperature due to higher adsorption stability. GYD-1252 and LG-3 had larger adsorbed layer thickness which decreased significantly with increasing temperature due to weak adsorption stability.