Tetrabutyl titanate (10 mL), acetic acid (2 mL) and DEHP (1.2 mL) were respectively dissolved in 13 mL of anhydrous ethanol, and then the as-prepared cadmium sulfide (0.041 g) was dispersed in above solution to obtain the solution A.
This is because that in the process of fabrication of MIP-CdS/TiO2, template DEHP has bound with monomer tetrabutyl titanate via hydrogen bond, so that DEHP has been fixed in MIP-CdS/TiO2.
Tetrabutyl titanate was mixed with absolute alcohol and hydrochloric acid, and the mixture solution was added into the slurry of kaolin and deionized water in thermostatic water baths.
The obtained [TiO.sub.2]-coated kaolin particles arc influenced by various factors, including tetrabutyl titanate dosage, slurry concentration, pH value, hydrolysis temperature, aging time, calcination temperature, and calcination time.
The effect of tetrabutyl titanate dosages on whiteness and oil absorption value is shown in Figs.
When the slurry concentration is increased, the whiteness of compound pigments is improved from 92.2% to 93.0%, and the oil absorption value decreases from 41 mL/100 g to 40 mL/100 g with gradual hydrolysis of tetrabutyl titanate. However, when the slurry concentration is further increased, it is too high to stir evenly, and the hydrolysis product of tetrabutyl titanate cannot (or not totally) coat on the surface of slurry.
When tetrabutyl titanate is hydrolyzed at a pH value of 7.0, it hydrolyzes tetrabutyl titanate so fast that [TiO.sub.2] particles are deposited on the surface of kaolin flakes by hetero-flocculation (flocculation of dissimilar particles that have already formed).
However, when the temperature is elevated to 40[degrees]C, the hydrolysis reaction of tetrabutyl titanate is promoted by the outer temperature, and the elevated temperature quickens the formation of [TiO.sub.2] particles on the surface of kaolin.
By using single-factor tests such as those above, the process of creating [TiO.sub.2]-coated kaolin compound pigments is confirmed with the optimum parameters as follows: a tetrabutyl titanate dosage of 6 mL/20 g kaolin, a slurry concentration of 11.0%, a pH value of 3.0, hydrolysis temperature at 40[degrees]C, an aging time of 16.0 h, calcination temperature at 800[degrees]C, and a calcination time of 3 h.