Unveiling the hydrodechlorination of trichloroethylene by reduced graphene oxide supported bimetallic Fe/Ni nanoparticles

Abstract

Reduced graphene oxide (rGO) is a promising support for electrochemical and environmental applications. However, the role of rGO in dechlorination of chlorinated hydrocarbon by zerovalent iron-based nanoparticles remains unclear. Herein, the rGO-supported bimetallic Fe/Ni nanocomposites were fabricated by chemical reduction method and the microstructures as well as the electrochemical properties of rGO/Fe/Ni, were investigated to elucidate the dechlorination behaviors of trichloroethylene (TCE) under various environmental conditions. Results show that the 10–60 nm Fe/Ni nanoparticles with average particle size of 32 nm are homogeneously dispersed onto the rGO surface. The rGO/Fe/Ni exhibits excellent dechlorination efficiency and rate of TCE is 2.4 times higher than that of free Fe/Ni nanoparticles. Cyclic voltammetric curves and electrochemical impedance spectra indicate that the superior dechlorination activity is attributed to the strong interaction between Fe/Ni and rGO, low internal resistance and rapid diffusion rate of electrons and ions. In addition, the capacitive behavior of rGO can store and transfer 2.7–3.4 electrons produced from Fe0 to the adsorbed TCE more readily, and then converts TCE to non-toxic ethane via hydrodechlorination in the presence of Ni nanoparticles. The rGO/Fe/Ni can be recycled for at least 8 times to effective dechlorinate TCE. Moreover, the reaction rate of TCE dechlorination can be enhanced 1.26–1.49 times when 5–10 mg L−1 humic acid are added. Results obtained in this study have clearly unveiled the role of rGO in hydrodechlorination of TCE and can provide a new insight into the development of rGO−supported bimetallic Fe/Ni nanoparticles for the enhanced removal of chlorinated pollutants in water and wastewater treatment.