Effect of water vapor on lead adsorption by kaolinite at high temperatures

The effect of water vapor on lead adsorption by kaolinite at high temperatures was studied using a drop tube furnace. The lead was in the forms of PbO and PbCl₂. Firstly, effect of 0-20% water vapor was studied on adsorption of PbO (1100-1300 ℃) and PbCl₂ (800-1300 ℃) by kaolinite. Then, mechanism of high-temperature adsorption of kaolin was revealed according to the analysis of XRD, SEM and residual hydroxyl group fraction. The results showed that water vapor reduced the loss of hydroxyl groups on kaolinite surface at high temperatures, hindering PbO adsorption and promoting PbCl₂ adsorption. At the same time, due to production of inert mullite and collapse of pore structure of kaolinite at high temperatures, the optimal adsorption temperatures of PbO and PbCl₂ were 1200 and 1000 ℃, respectively.