Effect of Na₂CO₃, HF, and CO₂ Treatment on the Regeneration of Exhausted Activated Carbon Used in Sintering Flue Gas

Abstract

The method of continuous treatment with Na 2 CO 3 solution, HF solution, and CO 2 was proposed for the regeneration of the exhausted activated carbon (EAC) produced in the sintering flue gas purification process. In order to obtain the optimal operation conditions, the effect of key parameters such as Na 2 CO 3 solution concentration, HF solution concentration, and CO 2 activation temperature on the sulfur conversion rate and regeneration efficiency was analyzed. Also, the N 2 adsorption, Brunauer−Emmett−Teller analysis, scanning electron microscopy-energy dispersive spectrometry, X-ray diffraction, X-ray fluorescence, and Fourier transform infrared spectroscopy were adopted to investigate the deactivation reason and the change of the physical−chemical properties. The results showed that the deactivated EAC was mainly due to the deposition of inorganic compounds such as CaSO 4 , SiO 2 , and KCl to block the pores. Continuous treatment with Na 2 CO 3 solution and HF solution could remove the inorganic compounds effectively. CO 2 activation treatment further developed the blocked porosity and decreased the surface acidity. The optimal conditions for the regeneration of EAC were a Na 2 CO 3 concentration of 0.5 mol/L, an HF concentration of 0.8 mol/L, and a CO 2 activation temperature of 1073 K with the activation time of 1 h, corresponding to the specific surface area of 607.91m 2 /g. In the fourth regeneration cycle, the adsorption performance during the successive adsorption− regeneration process could still maintain a high level and the regeneration efficiency was 95.31%.

Effect of K-Modified Blue Coke-Based Activated Carbon on Low Temperature Catalytic Performance of Supported Mn–Ce/Activated Carbon

“…It could be seen from Figure that the infrared spectra of all samples were similar. There was a broad absorption band in the range of 3700–3200 cm –1 , and the maximum value was close to 3435 cm –1 , which could belong to the stretching vibration of the O–H. , The adsorption band at 2400–2300 cm –1 could be attributed to the CO 2 structure. , The weak band observed near 1632 cm –1 was designated as CC or CO stretching vibration. , The absorption band near 1100–1000 cm –1 was related to the C–O or C–O–C stretching vibration, and the peak at 1066 cm –1 was attributed to the C–O functional group . There were many kinds of functional groups on the surface of AC and M/AC, and the addition of K did not affect the types of functional groups of AC.…”