Study on the modulation mechanism of calcium lignosulfonate-modified Ca(OH)2 and its application in flue gas desulfurization

Calcium lignosulfonate, an important natural anionic surfactant widely used in chemical, agricultural and construction applications, was employed to enhance the desulfurization performance of Ca(OH) 2 by adjusting its crystal growth at the atomic level. In the digestion of CaO, calcium lignosulfonate was selectively adsorbed onto the 101 surface of Ca(OH) 2 crystal by the interaction between the sulfonic acid group of calcium lignosulfonate and Ca(OH) 2 surface. The specific adsorption was proved to inhibit the growth of the 101 crystal surface owing to the steric hindrance and electronic interactions. DFT calculations show that the adsorption energy is −1.70 eV, and the change in free energy is negative, indicating spontaneous adsorption. By XRD and SEM characterization results and DFT simulation results, while boost the Ostwald ripening of the 001 surface to form the ultrathin nanosheets with a thickness of 16–21 nm. PDOS simulation results testified that the transferring of lone pair electrons from 2p orbital to the empty 3d-orbitals of calcium and the formation of Ca-O bond because of 0.08 Ha blue shift and broadening of the 2p-orbitals of oxygen. Additionally, the calcium lignosulfonate (CLS) modified Ca(OH) 2 exhibited the increase of BET surface area by 62 % from 30.09 m 2 /g to 48.76 m 2 /g and developed a mesoporous structure with the pore volume of 0.248 cm 3 /g. Consequently, the sulfur capacity of Ca(OH) 2 –15.62 mg/g in comparison to pristine Ca(OH) 2 without CLS, while the penetration times for desulfurization experiments increased from 3300 s to 7600 s.