Studies of the Atrazine Aqueous Suspension Stability in the Presence of an Anionic Polymer—Influences of Polymer Molecular Weight and Solution pH

The influence of the molecular weight of sodium salt of styrene/methacrylic acid (SSMA) copolymers and solution pH value (range of 3–11) on the stability of the atrazine suspension was studied. SSMA with different molecular weights was synthesized by emulsion polymerization. Adsorption, zeta potential measurements, microscopy, and suspension stability measurements were carried out. The obtained results indicate that the adsorption of SSMA on the surfaces of atrazine particles decreases with the increase of the molecular weight, and the hydrogen bonding is the main adsorption force. The presence of SSMA improves the stability of the atrazine suspension. The stability of the atrazine suspension decreases with the increase of the molecular weight of SSMA. On the other hand, the stability of the atrazine suspension with SSMA increases firstly and then decreases with the increase in solution pH in the range of 3–11.