Microwave-assisted industrial wastes of fly ash and carbide slag as adsorbents for simultaneous desulfurization and denitrification

Abstract

In this paper, an efficient and low-cost desulfurization and denitrification adsorption technology was proposed by utilizing microwave-assisted fly ash and carbide slag as adsorbent with active coke (AC) as the catalytic adsorption media. The effect of different parameters on the removal of SO2 and NO using the prepared adsorbent was investigated. The optimal preparation and adsorption conditions were as follows: amount of AC 10 wt%, microwave-assisted power and time of 1000 W and 10 min, adsorption temperature of 150 °C. Under these conditions, the removal rates of T90% for SO2 and T80% for NO were 86 min and 30 min, respectively, whereas the maximum adsorption capacities of SO2 and NO were 0.57 mg/g and 0.07 mg/g, respectively. The reaction mechanism indicates that AC and oxygen would contribute to improving the adsorption activity and further facilitating the conversion of N2+ to N4+, and N5+, and S4+ to S6+. However, the generated sulfate and nitrate will poison the active sites of the adsorbent, which led to a decline in the adsorption capability of the proposed adsorbent.