Influence of manganese, iron and pyrolusite blending on the physiochemical properties and desulfurization activities of activated carbons from walnut shell

• All loaded carbons exhibited higher sulfur capacity than blank activated carbon.
• The maximum sulfur capacity of activated carbon loaded by pyrolusite is 227.8 mg/g.
• Fe2O3-AC2 and pyrolusite-AC5 showed better texture properties.
• MnO2-AC10 and pyrolusite-AC5 presented higher content of functional groups.
• The synergistic effect of metals in pyrolusite is conducive to developing higher catalytic activity.

In this study, pyrolusite and its main metal oxide components, MnO2 and Fe2O3, were chosen to modify walnut shell-derived column activated carbon by blending method respectively. The desulfurization experiments showed that pyrolusite loaded carbons performed the best toward the removal of SO2. With the optimal dosage of additives, the maximum sulfur capacity of activated carbon loaded by pyrolusite, MnO2 and Fe2O3 were 227.8, 157.8 and 140.6 mg/g, which were 84.0, 27.5 and 13.6% higher than that of blank activated carbon, respectively. Physiochemical properties of all samples were studied by characterizing with BET, XRD, XPS and FTIR. The results indicated that the higher sulfur capacity of pyrolusite activated carbon was mainly attributed to the synergistic effect of metals mixture (manganese and iron) in pyrolusite which was conducive to the development of proper physicochemical characteristic and higher catalytic activity of activated carbon for desulfurization. It can be concluded that using pyrolusite to modify activated carbon by blending method is a low cost way for improving the sulfur capacity of activated carbon.