Abstract: Dispersion stability of pesticide suspensions has a great impact on their application performance. The adsorption of dispersing agent on pesticide particles is the key factor of determining the stability of the suspension systems. In order to explore the action of dispersant adsorption on the physical and chemical properties of pesticides and help to develop new dispersants, the adsorption performance of common dispersant sodium lignosulfonate (SLS) on dimethomorph (DMM) was investigated, and the zeta potential and contact angle changes after adsorbing SLS on DMM particles were measured. The results showed that when the concentration of SLS was 0-10 g/L, a double-layer absorption occurred on DMM surface. With low concentration of 0-1.0 g/L, the adsorption isotherm was agree with Langmuir equation. The adsorption of SLS on the surface of DMM is a spontaneous, exothermic process, and the interaction between SLS and DMM included hydrophobic interaction, van der Waals force and hydrogen bond. The zeta potential of DMM particles was improved after adsorbing SLS and the higher sulfonated degree of SLS, the greater of this zeta potential improvement. With the increasing of SLS concentration, the contact angle of DMM in water solution reduced firstly and then increased to 70º-80º.

Key words: Adsorption, Lignosulfonate, Dimethomorph, Pesticide, Dispersant