ABSTRACT
Heavy metal ions like cadmium, chromium(VI), lead, arsenic and mercury have high solubility in aquatic environments and they can be easily absorbed by aquatic organisms. Even in small concentrations, bioaccumulation of heavy metals can harm humans through through the food chain. It is even worse if the heavy metals are consumed beyond the permitted concentration, and hence the source of heavy metal pollution to the environment must be addressed and methods to stop them from being released need to be identified. In this chapter we propose the use of photocatalytic reduction of certain heavy metal ions, focusing on Cr(VI) as an example on ZrO2 nanotubes (ZNTs) as a photocatalyst. ZNTs can be fabricated on zirconium foil by anodic oxidation. In this chapter we provide a review first on the issue of heavy metal contamination, especially in Malaysia from the year 2012 to 2017, then on the applicability of ZNTs to remove them. We then elaborate on the fabrication process of ZNTs, aiming at giving insight on how to produce self-organized ZNTs by anodization.
