Simultaneous wet desulfurization and denitration by an oxidant absorbent of NaClO2/CaO2.

The simultaneous wet removal performance of NO and SO2 was studied using the oxidant absorbent NaClO2/CaO2. The factors were studied including NaClO2 and CaO2 concentrations, reaction temperature, and gaseous components, such as SO2, NO, O2, and CO2. The products in liquid and solid phases were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and ion chromatography to determine the mechanism of simultaneous desulfurization and denitration by NaClO2/CaO2. The results indicated that the removal efficiency of SO2 was in the range of 98-99.9%, and the removal efficiencies of NO and NOx were 99.4% and 95.0%, respectively. The removal efficiencies of NO and NOx increased with the increase of NaClO2 and CaO2 concentration and reaction temperature. The gaseous components had a stronger effect on NOx removal efficiency, followed by NO removal efficiency, and SO2 removal efficiency. As SO2 concentration increased, the generation of sulfite species promoted the removal of NO and NOx. Competition for NO2 and SO2 absorption by absorbent inhibited the removal efficiencies of SO2 and NOx. The presence of O2 was beneficial for removing SO2, NO, and NOx, while the presence of CO2 was not. The main products in the liquid and solid phases were NO3-, NO2-, SO42-, and CaSO4. The reaction mechanism for simultaneous wet removal of SO2 and NO by NaClO2/CaO2 is proposed and discussed.

Comparative study on synergistic effects in co-pyrolysis of tobacco stalk with polymer wastes: Thermal behavior, gas formation, and kinetics.

Co-pyrolysis of tobacco stalk (TS) with different types of polymer wastes such as scrap tire (ST), polypropylene (PP) and polyvinyl chloride (PVC) was investigated. Thermogravimetric analyzer coupled with Fourier transform infrared spectrometer was carried out to examine the thermochemical properties, kinetics, and gas generation. The results of the co-pyrolysis showed a synergistic effect compared to the pyrolysis of the individual components. When using TS/ST co-pyrolysis, the reduction in char residue was about 6% (dry wt. basis) and the increase in organic gases exceeded 20%. It indicates that the addition of ST can increase both carbon conversion efficiency and volatiles yield. HCl from PVC underwent a complex physicochemical reaction with TS, increasing coke yield by 11-12% and inhibiting the gas release. In the main pyrolysis temperature range of ST, the activation energy is reduced by 40-80% by blending with TS; for PP this value is reduced by about 22%.