[Catalytic dechlorination of 2, 4-D in aqueous solution by Fe3O4-stabilized nanoscale Pd/Fe]

Fe3O4-stabilized nanoscale Pd/Fe was used to dechlorinate 2,4-D in aqueous solution and achieved high dechlorination efficiency. The Fe3O4 dosage, pH, Pd loading, temperature and stirring rate were important factors for dechlorination of 2,4-D. The removal rate of 2,4-D increased with the increase of Fe3O4, dosage, and it reached 93.5% after 210 min when the Fe3O4 dosage was 4.0 g x L(-1), while only 47.3% 2,4-D was transformed using bare nanoscale Pd/Fe. Low pH enhanced dechlorination and 2,4-D was almost completely dechlorinated within 110 min when the pH ranged from 2.6 to 4.1. The dechlorination efficiency was significantly influenced by Pd loading. After 210 min, the different Pd loading, 0.25%, 0.50% and 0.75%, resulted in 2,4-D reduction efficiency of 51.4%, 93.5% and 99.9%, respectively. The removal rate was higher than 90.0% after 210 min in the temperature range of 16.5 degrees C to 30.0 degrees C, while it decreased significantly when the temperature rose to 35.0 and 40.0 degrees C. The dechlorination efficiency was improved with the increasing stirring rate. Fe3O4 prevented the aggregation of nanoscale Pd/Fe particles. In addition, Fe3O4 acted as a medium to promote the electron transfer from Fe(0) to H+ and 2,4-D, and thus enhanced the reductive dechlorination of 2,4-D.