Salt induced polystyrene latex flocs investigated by neutron scattering

Studies with a model system consisting of polystyrene latex particles showed that the protein from seeds of Moringa trees adsorbs to the surface and causes flocculation as unusually dense aggregates. In this study, electrolytes sodium chloride (NaCl), ferric chloride (FeCl₃) and aluminium sulfate (Al₂(SO₄)₃) have been used to aggregate model polystyrene particles. The study augments previous work using neutron scattering on the flocculation of polystyrene latex with protein from seeds of Moringa trees that had indicated higher floc dimension, d_f, values as the concentration of particles increased. The measurements were made using ultra small-angle neutron scattering. Generally the fractal dimension, and thus the floc density, increased with particle concentration and salt concentration. Flocculation was apparent at much lower concentrations of FeCl₃ and Al₂(SO₄)₃ than of NaCl. The values of d_f were found not to simply scale with ionic strength for the three electrolytes studied with FeCl₃ being the most effective flocculating agent.