Crude titanium dioxide is purified
via converting to titanium tetrachloride in the
chloride process. In this process, the crude ore
(containing at least *0% TiO2) is reduced with
carbon, oxidized with chlorine to give
titanium tetrachloride; i.e., carbothermal
chlorination. This titanium tetrachloride is distilled, and
re-oxidized in a pure oxygen flame or plasma at
***0–***0 K to give pure titanium dioxide while also regenerating
chlorine.[*9] Aluminium
chloride is often added to the process as a rutile
promotor; the product is mostly anatase in its
absence.
Another widely used process utilizes
ilmenite as the titanium dioxide source, which is
digested in sulfuric acid. The by-product
iron(II) sulfate is crystallized and filtered-off to
yield only the titanium salt in the digestion solution, which is
processed further to give pure titanium dioxide. Another method
for upgrading ilmenite is called the Becher Process.
One method for the production of titanium dioxide with relevance
to nanotechnology is solvothermal Synthesis of titanium
dioxide
