Photoreduction of Cr(VI) in wastewater by anodic nanoporous Nb2O5 formed at high anodizing voltage and electrolyte temperature

Nurhaswani Alias; Zuhailawati Hussain; Wai Kian Tan; Go Kawamura; Hiroyuki Muto; Atsunori Matsuda; Zainovia Lockman

doi:10.1007/s11356-022-20005-7

Photoreduction of Cr(VI) in wastewater by anodic nanoporous Nb₂O₅ formed at high anodizing voltage and electrolyte temperature

Environ Sci Pollut Res Int. 2022 Aug;29(40):60600-60615. doi: 10.1007/s11356-022-20005-7. Epub 2022 Apr 15.

Authors

Nurhaswani Alias¹, Zuhailawati Hussain¹, Wai Kian Tan², Go Kawamura³, Hiroyuki Muto^{2

3}, Atsunori Matsuda³, Zainovia Lockman⁴

Affiliations

¹ School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300, Nibong Tebal, Pulau Pinang, Malaysia.
² Institute of Liberal Arts and Sciences, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi, 441-8580, Japan.
³ Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi, 441-8580, Japan.
⁴ School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300, Nibong Tebal, Pulau Pinang, Malaysia. zainovia@usm.my.

PMID: 35426025
DOI: 10.1007/s11356-022-20005-7

Abstract

In this study, nanoporous anodic film was produced by anodization of niobium, Nb in a fluoride ethylene glycol electrolyte. The effect of anodization voltage and electrolyte temperature was studied to find an optimum condition for circular, ordered, and uniform pore formation. The diameter of the pores was found to be larger when the applied voltage was increased from 20 to 80 V. The as-anodized porous film was also observed to comprise of nanocrystallites which formed due to high field-induced crystallization. The nanocrystallites grew into orthorhombic Nb₂O₅ after post-annealing treatment. The Cr(VI) photoreduction property of both the as-anodized and annealed Nb₂O₅ samples obtained using an optimized condition (anodization voltage: 60 V, electrolyte temperature: 70 °C) was compared. Interestingly, the as-anodized Nb₂O₅ film was found to display better photoreduction of Cr(VI) than annealed Nb₂O_5. However, in terms of stability, the annealed Nb₂O₅ presented high photocatalytic efficiency for each cycle whereas the as-anodized Nb₂O₅ showed degradation in photocatalytic performance when used continually.

Keywords: Anodization; Cr(VI); Nanoporous; Nb2O5; Photocatalyst; Reduction.

Abstract

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