Nanoporous anodic Nb2O5 with pore-in-pore structure formation and its application for the photoreduction of Cr(VI)

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

doi:10.1016/j.chemosphere.2021.131231

Nanoporous anodic Nb₂O₅ with pore-in-pore structure formation and its application for the photoreduction of Cr(VI)

Chemosphere. 2021 Nov:283:131231. doi: 10.1016/j.chemosphere.2021.131231. Epub 2021 Jun 14.

Authors

Nurhaswani Alias¹, Zuhailawati Hussain¹, Wai Kian Tan², Go Kawamura³, Hiroyuki Muto⁴, Atsunori Matsuda³, Zainovia Lockman⁵

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. Electronic address: tan@las.tut.ac.jp.
³ Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi, 441-8580, Japan.
⁴ Institute of Liberal Arts and Sciences, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi, 441-8580, Japan; Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi, 441-8580, Japan.
⁵ School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300, Nibong Tebal, Pulau Pinang, Malaysia. Electronic address: zainovia@usm.my.

PMID: 34144283
DOI: 10.1016/j.chemosphere.2021.131231

Abstract

An anodic film with a nanoporous structure was formed by anodizing niobium at 60 V in fluorinated ethylene glycol (fluoride-EG). After 30 min of anodization, the anodic film exhibited a "pore-in-pore" structure; that is, there were smaller pores growing inside larger pores. The as-anodized film was weakly crystalline and became orthorhombic Nb₂O₅ after heat treatment. The energy band gap of the annealed nanoporous Nb₂O₅ film was 2.9 eV. A photocatalytic reduction experiment was performed on Cr(VI) under ultraviolet (UV) radiation by immersing the nanoporous Nb₂O₅ photocatalyst in a Cr(VI) solution at pH 2. The reduction process was observed to be very slow; hence, ethylenediaminetetraacetic acid (EDTA) was added as an organic hole scavenger, which resulted in 100% reduction after 45 min of irradiation. The photocatalytic reduction experiment was also performed under visible light, and findings showed that complete reduction achieved after 120 min of visible light exposure.

Keywords: And heavy metal removal; Anodization; Chromium(VI); Nanoporous Nb(2)O(5).

MeSH terms

Catalysis
Chromium
Nanopores*
Niobium*

Substances

Niobium
Chromium
chromium hexavalent ion