Synthesis of modified sludge biochar for flue gas denitration: Biochar properties, synergistic efficiency and mechanism

Abstract

Biochar has been recommended as a carbon material with high porosity, rich functional groups, and low cost for flue gas denitration. In this study, five different biochar materials, including original sludge biochar (SC), the KOH-impregnated biochar (SCK), the biochar of SCK washing by ultra-water (SCK-W), the H2SO4-impregnated biochar (SCS), and the biochar of SCS washing by ultra-water (SCS-W), prepared using a one-step activation method were applied to remove NO from flue gases, acting as both reductants and catalysts. The results indicate that the SCK-700 can lead to the highest NO conversion of 100% at 325 °C, and can suppress the acidic gas generation compared with SCS. The order of reduction capacity at 300–400 °C was SCK-700 > SCK-W-700 > SC-700 > SCS-700 > SCS-W-700. Furthermore, the kinetics indicated that adsorption capacity enhanced with the rise in temperature, and that SCK-700 had the largest adsorption capacity, reaching 337.15 mg/g at 400 °C.