Enhanced dechlorination of 2,4-dichlorophenol by Pd/Fe-Fe3O4 nanocomposites

The Pd/Fe-Fe3O4 nanocomposites showed higher dechlorination efficiency of 2,4-dichlorophenol (2,4-DCP) rather than bare Pd/Fe nanoparticles in the batch dechlorination experiments. nFe(3)O(4) provided a convenient way to recycle the nanocomposites with an external magnetic field and significantly enhanced 2,4-DCP dechlorination. 2.0 g L-1 nFe(3)O(4) was the optimal dosage in the presence of 3 g L-1 Pd/Fe nanoparticles in our system, removing 76.4% 2,4-DCP within 5 h in the aqueous environment. This was much higher than bare Pd/Fe nanoparticles (35.8%), 1.0 g L-1 nFe(3)O(4) (58.0%) and 2.5 g L-1 nFe(3)O(4) (66.3%) employed under the same conditions. However, excessive nFe(3)O(4) (3.0 g L-1) partially overlapped on Pd/Fe nanoparticles to obstruct their contact with 2,4-DCP, and then 2,4-DCP removal efficiency was dropped to 7.4%. Efficiencies of dechlorination and phenol formations were increased significantly when the amount of Pd increased, whereas the highest 2,4-DCP removal efficiency was observed 98.2% at 0.20 wt% Pd loading. Moreover, SO42- would also inhibit the dechlorination while Cu2+, Ni2+ and Fe2+ enhanced the dechlorination of 2,4-DCP by Pd/Fe-Fe3O4 nanocomposites. The nanocomposites showed stable catalytic activity, fairly good mechanic stability, and promising to recycle during the process. (c) 2012 Elsevier B.V. All rights reserved.