Titanium dioxide

Question 1

Special properties of Titanium dioxide

Answer 1

Highest opacifying power - high refractive index and scattering
high brightness
very small round particles

Question 2

is titanium dioxide polymorphic?.

Answer 2

Yes
Anatase - purer square organisation
Rutile - most common - linear organisation

Question 3

production process of titanium dioxide

Answer 3

2 processes sulphite or chloride
sulphite:
Ilmenite
grinding
washing and drying
sulfuric acid and oleum to form cake
hydrolysis
calcined
suspension and milling
Chloride process:
Natural rutile
chlorination
distililation

Question 4

Explain titanium dioxide production using chlorination process

Answer 4

Natural rutile
chlorination
distillation

Question 5

Explain titanium dioxide production using sulphite process

Answer 5

ilmenite
grinding
washing and drying
sulfuric acid and oleum to form cake
hydrolysis
calcined
suspension and milling

Question 6

is titanium dioxide hydrophilic/phobic

Answer 6

hydropillic - easy to disperse but need to stop agglomeration

Question 7

what is the challenge with titanium dioxide

Answer 7

it is hard to retain!! Add retention aids but these cause flocculation which lowers optical efficiency.
Causes significant decrease in reflectance at lower wavelengths, have high absorption below 400nm making it hard to use with OBA’s

Question 8

Why is it hard to use OBA and Titanium dioxide

Answer 8

TiO2 has high absorption below 400nm which is where OBA’s absorb from, so competition