New Blue Pigments with Reduced Content of Harmful Cobalt

  • Author: ChemistryViews.org
  • Published: 18 January 2020
  • Copyright: Wiley-VCH Verlag GmbH & Co. KGaA
  • Source / Publisher: ACS Omega/ACS Publications
  • Associated Societies: American Chemical Society (ACS), USA
thumbnail image: New Blue Pigments with Reduced Content of Harmful Cobalt

Cobalt blue (CoAl2O4) is used as an intensely blue, easy-to-synthesize, and stable pigment. However, cobalt is toxic and environmentally harmful. Synthesizing alternative pigments with lower toxicity but a similar color and intensity has been challenging so far.


M. A. Subramanian and colleagues, Oregon State University, Corvallis, USA, have synthesized a new class of intensely blue inorganic pigments, called "hibonite blues". The team mixed and heated CaCO3, Al2O3, CoCO3, and TiO2 to obtain CaAl12ā€“2xCoxTixO19 (0 < x ā‰¤ 1). The compounds crystallize in a hibonite (CaM12O19) structure. The hue of the pigments can be tuned by changing the value of x. This tunability is rare in blue pigments. The researchers attribute the compounds' colors to a strong dā€“d transition of tetrahedrally coordinated Co2+.


In contrast to cobalt blue, which contains 33 % of Co by mass, the hibonite blues have Co contents as low as 4 % by weight. This makes them less harmful to human health and the environment, as well as cheaper to produce. The team also found that the compounds are stable in both strongly acidic and basic environments.


 

 

Article Views: 967

Sign in Area

Please sign in below

Additional Sign In options

Please note that to comment on an article you must be registered and logged in.
Registration is for free, you may already be registered to receive, e.g., the newsletter. When you register on this website, please ensure you view our terms and conditions. All comments are subject to moderation.

Article Comments - To add a comment please sign in

Bookmark and Share

If you would like to reuse any content, in print or online, from ChemistryViews.org, please contact us first for permission. more


CONNECT:

ChemistryViews.org on Facebook

ChemistryViews.org on Twitter ChemistryViews.org on YouTube ChemistryViews.org on LinkedIn Sign up for our free newsletter


A product of ChemPubSoc Europe (16 European Chemical Societies)published by Wiley-VCH