Abstract
In this paper, titanium–dioxide (TiO2) nanotubes (TNTs) are formed by anodic oxidation with a fluorinated glycerol–water (85% and 15%, respectively) electrolyte to examine the effect of fluoride ion concentration, time, and applied voltage on TNT morphologies and dimensions. For fluoride ion concentration, the surface etching increases when the amount of ammonium fluoride added to the electrolyte solution increases, forming nanotube arrays with a clear pore structure. At a constant voltage of 20 V, TNTs with an average length of ~2 µm are obtained after anodization for 180 min. A prolonged anodization time only results in a marginal length increment. The TNT diameter is voltage dependent and increases from approximately 30 nm at 10 V to 310 nm at 60 V. At 80 V, the structure is destroyed. TNTs formed at 20 V for 180 min are annealed to induce the TiO2 anatase phase in either air or nitrogen. When ethylenediaminetetraacetic acid is added as a hole scavenger, 100% hexavalent chromium removal is obtained after 120 min of sunlight exposure for nitrogen-annealed TNTs.
Highlights
In recent years, the application of TiO2 as a photocatalyst to reduce heavy metals such as hexavalent chromium [Cr(VI)] has gained academic attention
Anodization was conducted at 20 V for 90 min
The TNTs were formed by the anodic oxidation of Ti foil in a fluorinated glycerol–water electrolyte
Summary
The application of TiO2 as a photocatalyst to reduce heavy metals such as hexavalent chromium [Cr(VI)] has gained academic attention. Chrome plating is responsible for producing large amounts of wastewater containing Cr(VI) ions. The reduction of Cr(VI) to chromium [Cr(III)] is conducted to treat Cr(VI)-laden wastewater by photocatalysis [2]. This process is beneficial because, whereas Cr(VI) is mobile, corrosive, and toxic to humans, Cr(III) is non-toxic and an essential dietary element. Industrial activities such as metal finishing and chrome plating produce wastewater with large amounts of Cr(VI), which can contaminate water bodies and soil.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
