Preparation and SO2 Adsorption Behavior of Coconut Shell-Based Activated Carbon via Microwave-Assisted Oxidant Activation

A series of oxidants supported on coconut shell-based activated carbon (CAC) through microwave irradiation were prepared and characterized using scanning electron microscopy (SEM), N-2 adsorption/desorption analysis, and X-ray photoelectron spectroscopy (XPS). The SO2 adsorption capacities and rates were evaluated by adsorption tests performed in a fixed bed reactor with a simulated flue gas, and the adsorption isotherm models were validated against the experimental results. The findings revealed that the SO2 adsorption capacity decreased in the following order: MW-K2Cr2O7-CAC > MW-KMnO4-CAC > MW-H2O2-CAC > MW-CAC. The SO2 adsorption capacities and adsorption rates of the samples increased with an increasing oxidizability of the oxidants owing to the increment of mean pore size and oxygen-containing functional groups. In addition, a high initial SO2 concentration and a low bed temperature could positively affect the SO2 adsorption. Finally, the Langmuir model validated that SO2 was mainly adsorbed through chemical adsorption on the sample surfaces.