Browsing by Author "Sahu, Rama Shanker"

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Boron-doped reduced graphene oxide-based bimetallic Ni/Fe nanohybrids for the rapid dechlorination of trichloroethylene
(2017-03-01)
Sahu, Rama Shanker
;
Bindumadhavan, Kartick
;
Doong, Ruey-an
;
環境工程研究所
;
Institute of Environmental Engineering
In this study, a simple chemical reduction method for the synthesis of novel and efficient graphene-based bimetallic Fe/Ni nanoparticles was developed for the rapid and effective dechlorination of trichloroethylene (TCE). Boron-doped reduced graphene oxide (B-rGO) was used as a support for the homogenous dispersion of Fe/Ni nanoparticles between the B-rGO nanosheets. The surface morphological results showed that the particle sizes of the bimetallic Fe/Ni nanoparticles were in the range of 10-50 nm with a mean diameter of 20 nm and the elements, including B, Fe and Ni, were homogenously distributed in the graphitic matrix. The Raman, X-ray photoelectron and electrochemical impedance spectra clearly indicated that the doped boron as well as the immobilized Fe/Ni increased the disordered structure of B-rGO. Conjointly, the interaction between the graphitic backbone and bimetallic nanoparticles resulted in fast and low-resistant electron transport in B-rGO/Fe/Ni for the enhanced dechlorination efficiency and rate of TCE. A rapid and complete hydrodechlorination of TCE by B-rGO/Fe/Ni, which followed the Langmuir-Hinshelwood kinetics, was observed between pH 4 and 7. In addition, the B-rGO-immobilized Fe/Ni could retain the high reactivity after 7 cycles of repeated injection of TCE. The results obtained in this study clearly demonstrate the efficiency, longevity and recyclability of B-rGO-immobilized Fe/Ni nanoparticles, which could pave a new way to prepare novel bimetallic Fe/Ni nanoparticles with high reactivity and long stability for the removal of environmental contaminants in water purification and waste-water treatment.
Unveiling the hydrodechlorination of trichloroethylene by reduced graphene oxide supported bimetallic Fe/Ni nanoparticles
(2018-02-15)
Sahu, Rama Shanker
;
Li, Dong-Lin
;
Doong, Ruey-an
;
環境工程研究所
;
Institute of Environmental Engineering
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 Fe-0 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.