Effect of mixing on reductive dechlorination of persistent organic pollutants by Fe/Pd nanoparticles

: Herein, we report the comparison of two different mixing methods for reductive dechlorination of gamma-hexachlorocyclohexane (γ-HCH), aldrin, and p, p'-dichlorodiphenyl-trichloroethane (p, p'-DDT), using iron/palladium (Fe/Pd) bimetallic nanoparticles. A noticeable enhancement of the reaction rate was found when the reductive dechlorination reaction was carried out in an ultrasound bath as compared with a platform shaker. These enhancements could be attributed to (a) the continuous cleaning and chemical activation of the surfaces of nanoscale Fe/Pd bimetallic nanoparticles by the combined chemical and physical effects of acoustic cavitation; and (b) the accelerated mass transport rates of target POPs to the surfaces of the Fe/Pd nanoparticles. Finally, the degradation intermediates and final products were determined by gas chromatography/mass spectrometry (GC/MS) analysis and the plausible degradation pathways for γ-HCH, aldrin, and p, p'-DDT by Fe/Pd bimetallic nanoparticles were proposed. PRACTITIONER POINTS: Exposure to POPs is a resilient global environmental and health issue. Fe/Pd bimetallic nanoparticles demonstrated > 90 % removal of POPs in the first 30 minutes of the reaction via ultrasonic mixing. GC-MS analyses provided verification of POPs degradation intermediates and final products.