Industrial & Engineering Chemistry Research, Vol.39, No.2, 335-341, 2000
Fixation of lead chloride on kaolinite and bentonite at temperatures between 550 and 950 degrees C
Vaporization of lead chloride (PbCl2) on sorbents was carried out at linearly rising temperatures in flowing nitrogen with the use of a thermogravimetric apparatus. A modeling method has been proposed to depict the vaporization rate of lead chloride and to calculate the fraction of lead chloride fixed on sorbents during heat-up. The results revealed that dehydrated kaolinite (metakaolinite) had a moderate ability to fix lead chloride while fresh kaolinite showed a significantly increased fixation ability. The lead component formed by reaction with kaolinite or dehydrated kaolinite could hardly volatilize, even at a temperature up to 1200 degrees C. Bentonite also showed the moderate effectiveness for capturing lead chloride. However, at least part of the components or reaction products adsorbed on bentonite appeared to be thermally unstable and could volatilize gradually with a prolonged heating time at elevated temperatures. It was seen that during dehydroxylation of kaolinite, part of the chloride was released in the form of hydrochloric acid. Chemically bound water in kaolinite appeared to dramatically promote ita reaction with lead chloride.