Treatment of polycyclic aromatic hydrocarbons (PAHs) from aqueous solutions by flotation using colloidal gas aphrons

Abstract

Aqueous solutions contaminated with polycyclic aromatic hydrocarbons (PAHs) pose severe environmental risks, making their removal necessary. Flotation with colloidal gas aphrons (CGAs) has recently demonstrated high removal efficiencies for various pollutants present in aqueous solutions. This study determined the efficacy of CGAs in removing low-ring PAHs (naphthalene, fluorene, and phenanthrene) from aqueous solutions. CGAs were produced from different surfactants, such as anionic sodium dodecylbenzene sulfonate (SDBS), cationic hexadecyl trimethylammonium bromide (HTAB), and natural surfactant obtained from the leaves of Ziziphus spina-christi (ZSC). PAHs removal efficiency was studied by varying different parameters, such as type of surfactant, PAHs solution pH, CGAs flow rate, and PAHs and CGAs solution temperature. Results showed that at pH 5.6 and 25 °C, fluorene and phenanthrene were fully removed using CGAs (flow rate of 100 mL/min) derived from cationic HTAB surfactant, while naphthalene was removed to the extent of approximately 88.4% under similar conditions. These findings suggest that CGAs derived from cationic HTAB surfactant have a greater capacity for extracting low-ring PAHs from aqueous media.