The separation of the pyrethroid insecticide Fastac 10 EC by cationic pullulan derivatives

Pullulan derivatives with different content of tertiary amine groups have been evaluated, as flocculants, for the separation of pesticide Fastac 10 EC from model emulsions. The flocculation performance of the cationic polysaccharide samples at different conditions (Polycation dose, pH and pesticide concentration) was followed by UV-vis spectroscopy measurements. The results show similar values for the maximum removal efficiency (around 90%), irrespective of the ionic groups content and an increase (from 80% to more than 90%) with initial pesticide concentration increase (from 0.02% to 0.04%). The optimum polycation dose decreased with increasing substitution degree and decreasing the emulsion pH. The supernatant zeta potential dependence on the cationic polysaccharide dose indicated a charge neutralization mechanism for the flocculation of pesticide particles, that was supported by particle aggregates size measurements.