Synthesis of Fe₃O₄ nanocomposites for efficient separation of ultra-small oil droplets from hexadecane–water emulsions

Abstract

Eco-friendliness and low cost are critical when investigating new oil-water separation agents with high separation efficiencies for the treatment of emulsified oily wastewater in industrial applications, including crude oil exploitation. Treatment methods specifically suited to wastewater containing ultra-small oil droplets are lacking and urgently required. This study investigated the one-pot synthesis of humic acid and polydimethyldiallylammonium chloride coated Fe₃O₄ nanoparticles. A low dosage of the nanoparticles (375 μg mL^-1) exhibited excellent separation efficiency (nearly 100%) and reusability when applied to hexadecane-water emulsions containing ultra-small droplets (200-300 nm). Electrostatic interactions and the strong interfacial activity of the nanoparticles played essential roles in achieving oil-water separation. This study provided an efficient extraction material synthesized by a facile and cheap method for separating ultra-small oil droplets from emulsions.