Ultrasound-assisted removal of organochlorine pesticide chlordecone from aqueous matrices

Chlordecone (CLD) is a persistent organochlorine pesticide that causes adverse human health effects and remains widespread in certain regions, such as the French West Indies. Despite its hydrophobicity, CLD is detected in surface and groundwater, sometimes at concentrations exceeding regulatory standards. Interestingly, this same hydrophobicity makes chlordecone a suitable candidate for removal via sonolysis. Sonolysis, which is based on the creation and collapse of cavitation bubbles in a liquid phase, has been proven effective in removing organochlorine pesticides. This study is the first to demonstrate that sonolysis can effectively remove CLD from both deionized spiked water and natural surface water at environmentally relevant CLD concentrations (0.4 to 4 µg L -1 ). Approximately 74% of CLD is degraded within 120 minutes, regardless of whether the water matrix is synthetic or natural. Removal proceeds slightly faster in surface water samples, likely due to the suspended solids on which CLD tends to bind, which catalyze the formation and growth of cavitation bubbles. This highlights that the likely mechanism for removal is the thermal breakdown of CLD at the bubble interface rather than oxidation in the bulk. The performance, evaluated through the Electrical Energy per Order (EEO) figure of merit, shows that sonolysis outperforms photolysis (444 kW h m -3 vs 1,600 kW h m -3 ), although the CLD concentration differs. The EEO decreases – hence, energy efficiency increases with increasing CLD concentration. Future studies should focus on determining the maximum concentration of CLD before reactive sites become saturated – a prerequisite for scaling up sonolysis. • Chlordecone (CLD) is a persistent organochlorine pesticide • Sonolysis removed 72-78% of CLD from groundwater and spiked deionized water • 20% higher removal rate at 4 µg/L CLD vs. 0.4 µg/L • Groundwater colloids may enhance bubble nucleation and the CLD removal rate