Influence of Lignosulfonates on the Stability of Dimethomorph Water Based Suspension

Abstract

The dispersive effect of four lignosulfonates (Kinsperse126, sodium lignosulfonate, magnesium lignosulfonate and a modified lignosulfonate GCL4-1) on the stability of Dimethomorph (DMM) water based suspension with different particle sizes was investigated. DMM suspension without dispersant was unstable owing to the strong aggregation of particles, while the stability was increased after the addition of lignosulfonate (LS), which can be adsorbed on the particle surface and weaken the aggregation of particles. Moreover, the higher sulfonated degree of LS, the better the dispersible ability was. Compared with LS of high sulfonated degree which could improve the zeta potential of DMM, LS with high molecular weight had larger adsorption capacity and steric effect on the pesticide particles. Associated with the dispersive behavior of DMM suspension, the electrostatic repulsion was found to be the more important factor impacting the stability of DMM suspension by comparison with the steric effect.