Removal of antracene and benzo[a]pyrene from soil-washing synthetic emulsions by Fenton and solar photo-Fenton oxidation

Abstract

This study examines the treatment of polycyclic aromatic hydrocarbons (PAHs) aqueous emulsions, equivalent to those obtained from soil-washing, using Fenton and solar photo-Fenton oxidation for pollutant removal and surfactant recovery in water treatment applications. PAHs, persistent contaminants in industrial wastewater, require sustainable treatment approaches. Soil was contaminated with anthracene (ANT) and benzo[a]pyrene (BaP) and washed with sodium dodecyl sulfate (SDS) at a mass liquid-to-soil ratio of 2:1, with SDS concentrations ranging from 2500 to 10,000 mg L−1. A synthetic emulsion (SDS: 4500 mg L−1, ANT: 5 mg L−1, BaP: 5 mg L−1) was prepared and treated using low oxidant (H₂O₂: 60–240 mg L−1) and catalyst (Fe: 2.5–10 mg L−1) dosages to optimize reagent consumption. The Fenton process (pH = 3) achieved complete PAHs removal, with BaP fully degraded under all conditions and ANT requiring higher oxidant (H₂O₂, 240 mg L−1) and catalyst (Fe, 10 mg L−1) concentrations. The solar photo-Fenton process achieved up to 70 % ANT and 85 % BaP removal at near-neutral pH using ferrioxalate complexes (120 mg L−1 H2O2, 10 mg L−1 Fe). Minimal SDS degradation and negligible mineralization support surfactant recovery and reuse, enhancing process sustainability. These findings highlight the viability of light-assisted advanced oxidation processes for selective pollutant degradation in engineered water systems, supporting the development of cost-effective and environmentally friendly remediation technologies.