Influence of flocculant–collector interactions on nanobubble stability in mineral-processing reagent systems

Collectors and flocculants are frequently co-dosed in flotation and dewatering circuits, where reagent interactions may alter gas dispersion and separation performance. However, their combined influence on nanobubble (NB) stability under controlled gas–liquid interfacial conditions relevant to mineral-processing reagent systems remains insufficiently understood. In this study, anionic polyacrylamide (APAM) and sodium oleate (NaOL), representative of reagents widely used in mineral processing operations, were employed to investigate flocculant–collector interactions and their impact on NB characteristics. Compared with single-reagent systems, the APAM–NaOL mixture generated smaller and more persistent NBs, accompanied by reduced surface tension, more negative interfacial charge, and enhanced interfacial viscoelasticity. These observations suggest the possible formation of a cooperative interfacial layer, which may arise from hydrophobic association, hydrogen bonding, and electrostatic interactions between polymer chains and oleate species, which may reduce bubble growth, coalescence tendency, and gas-transfer-related dissolution, thereby contributing to enhanced NB persistence. The results demonstrate that flocculant–collector interactions can significantly modify NB stability and interfacial properties, with potential implications for bubble–particle attachment and water removal efficiency. This work provides mechanistic insight into reagent synergy in integrated mineral processing circuits and supports reagent scheme optimization under realistic operating conditions.