Experimental and kinetic study on Hg0 removal by microwave/hydrogen peroxide modified seaweed-based porous biochars

In this article, porous biochars (derived from the by-products of seaweed biomass pyrolysis) were synthesized by the combined treatment of microwave activation/hydrogen peroxide, and were used to control mercury emissions from flue gas. The effects of key factors on Hg-0 capture and the physicochemical properties of seaweed-based porous biochars were explored, respectively. The capture mechanism and adsorption kinetics were revealed. These results demonstrate that the treatment of microwave activation/hydrogen peroxide not only can improve surface morphology of materials, but also can increase the content of oxygen groups. The oxygen groups can act as main chemisorption sites, facilitating the removal of Hg-0. The porous biochars (SAM30 and ENM30) modified by 30% hydrogen peroxide show the best performance at 120 degrees C (reaching 90.86% and 86.33%, respectively) Besides, the Hg-0 capture on porous biochars can be accurately explained by the pseudo-second-order model, and the process of chemisorption is regarded as the main control step of Hg-0 capture over modified porous biochars. Capsule: Seaweed-based porous biochars jointly modified by microwave and H2O2 achieve efficient capture of Hg-0 from flue gas, and oxygen containing functional groups are key active sites. (C) 2021 Elsevier B.V. All rights reserved.