Strategies to enhance the stability of nanoscale zero-valent iron (NZVI) in continuous BrO3− reduction. (1st February 2019)

• Record Type: Journal Article
• Authors: Hamid, Shanawar; Abudanash, Damira; Han, Seunghee; Kim, Jong R.; Lee, Woojin
• Is Part Of: Journal of environmental management. Volume 231(2019)
• Page Start: 714
• Page End: 725
• Publication Date: 2019-02-01
• Subjects: Bimetallic catalyst -- Bromate reduction -- Catalyst stability -- NZVI -- NZVI-Cu-Pd; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2018.10.026
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: The reduction of bromate to bromide was successfully achieved by bimetallic catalysts with NZVI support in continuous-flow reactors. The stability of NZVI-supported bimetallic catalysts was enhanced by decelerating the iron corrosion and sequential rapid passivation of the iron-Cu-Pd ensembles under optimized reaction conditions. Thus >99% bromate removal can be continuously achieved for 11 h. The lifetime of the bimetallic catalyst was further enhanced and tested under different hydraulic retention time, catalyst loading, and initial bromate concentrations. At the optimized operation conditions, the catalyst showed a complete bromate reduction by 24 h and then the reactivity slowly decreased to 20% over the next 100 h. X-ray diffraction and X-ray photoelectron spectroscopy showed that the reactive NZVI support was oxidized to Fe(II) and Fe(III) along with Cu(0) oxidation to CuO, while the oxidation state of Pd did not change. Therefore, bromate reduction occurred on the surface of reactive NZVI support and Cu(0) particle, while Pd played a role as a hydrogenation catalyst that prolonged the lifetime of the bimetallic catalyst. Graphical abstract: Image 1 Highlights: An enhanced continuous reduction of BrO3 − to Br − was achieved by the catalysts. BrO3 − reduction stability was in the order of NZVI-Cu-Pd> NZVI-Cu>NZVI-Pd. Iron corrosion and sequential rapid passivation of the catalyst were decelerated. Complete BrO3 − removal was achieved for 24 h at optimized conditions.