Effect of H₂O, SO₂ and CO₂ on PbO adsorption in CaO surface during sewage sludge combustion

The effect of flue gas components on the adsorption of PbO on the surface of CaO(001) during sewage sludge combustion was studied by DFT (Density Functional Theory). The calculation results show that O apex on the surface of CaO(001) is the active site of the adsorption of PbO molecules, H₂O molecules, SO₂ molecules and CO₂ molecules. The presences of H₂O molecules, SO₂ molecules and CO₂ molecules increase the adsorption energy of PbO molecules on the surface of CaO(001) by 71.42, 19.589 and 46.431 kJ/mol, respectively. OH group and local Ca(OH)₂ surface structure formed by H₂O molecules during the adsorption process are conducive to the adsorption of PbO molecules. Density of state orbitals of O_S atom in SO₂ molecule and O_surf atom on the surface of CaO(001) overlap with the orbitals of Pb atom, making the adsorption of PbO molecules on the surface more stable. CO₃ group formed by CO₂ molecules pre-adsorbed on the surface of CaO(001) has a strong adsorption effect on PbO molecules, making PbO molecules more stable adsorption on the surface of CaO(001).