Enhancing the selectivity of carboxylic acid surfactants in fluorite flotation via cation–π interaction coupling

Abstract The rapid depletion of high‐grade fluorite deposits has made the purification of fluorite from low‐grade ores increasingly critical. Traditional carboxylate surfactants face significant challenges in fluorite/calcite separation due to their similar affinity for both minerals. To address this limitation, we designed a novel surfactant 1‐(2‐octyldodecyl)‐1,2‐phenyl dicarboxylate (ODBD), containing phenyl groups, which exhibited superior flotation separation performance for fluorite and calcite compared to sodium oleate. X‐ray photoelectron spectroscopy, surface force measurements, and first‐principles calculations confirm that ODBD's carboxyl groups adsorbed onto fluorite and calcite in deprotonated forms, while its phenyl groups engaged in cation–π interactions with markedly higher affinity for fluorite surfaces. This dual adsorption mechanism created a pronounced synergistic effect, leading to superior selective adsorption of ODBD on fluorite. These findings demonstrate that coupling cation–π interactions with chemical interactions represents a viable strategy to significantly enhance surfactant selectivity, providing valuable insights for the optimization of traditional surfactants.