Currently, industrial wastes are typically combusted at
incineration plants, and the resulting ashes are sent to landfill. This
practice raises issues, such as potential toxicity of the leachate to the
environment, as well as the loss of valuable metals left in the waste.
Therefore, from both economic and environmental standpoints, it is
becoming increasingly important to recover valuable metals from
industrial waste. In this work, a transformative recovery of vanadium
(conversion nearly 100%) from leaching solutions of carbon black waste
(metal leaching efficiency > 97%) which originates from oil refineries in
Singapore, has been systematically studied. Interestingly, three distinctive
alkaline earth vanadate nanomaterials were successfully synthesized from
the leaching solutions by a facile hydrothermal process, that is, singlecrystal calcium vanadate nanorods (Ca10V6O25) oriented along the [001]
direction, strontium vanadate nanorods with ellipsoid-like assembly
(Sr10V6O25), and barium vanadate polyhedral nanoparticles (Ba3V2O8). Importantly, we have demonstrated that this facile
metal recovery route enables the morphology control of vanadate nanomaterials without templates in the system. Moreover, the
vanadate nanomaterials obtained are potential wide band gap semiconductors for electronic devices and semiconducting glasses.