CHARACTERIZATION OF PYROLUSITE-MODIFIED ACTIVATED CARBON PREPARED FROM WALNUT SHELL AND THE APPLICATION OF FLUE GAS DESULFURIZATION

摘要

A novel columnar activated carbon was prepared from agricultural waste walnut shell and applied for flue gas desulfurization. The pyrolusite was blended with the walnut shell chars as a catalyst in the process of CO_2 activation. The produced activated carbons were characterized using Brunauer-Emmett-Teller (BET), Scanning electron microscope-Energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD) and X-ray photoelectron spec-troscopy (XPS), in order to evaluate the effects of pyrolusite addition on the properties of activated carbon. The BET results indicated that the activated carbon with 5 wt.% pyrolusite addition had the highest BET value of 687 m~2/g and total pore volume of 0.45 cm~3/g, which were 21.6% and 18.4%, respectively, higher than the blank sample. The XRD and XPS results showed that the manganese oxide in pyrolusite was evenly dispersed in the activated carbon's matrix. Compared to the blank activated carbon (137 mg/g), the pyrolusite-modified activated carbon with 5 wt.% pyrolusite achieved 243 mg/g of sulfur adsorption capacity. This could be attributed to the improvement of carbon porous structures during the activation of pyrolusite-modified activated carbon and to the catalytic oxidation of SO_2 in desulfurization process.