Study on adsorption mechanism of mercury on Ce-Cu modified iron-based biochar

Combined with sol-gel method and co-precipitation method, Ce-Cu is used to modify iron-based biochar, and the mercury adsorption performance of modified biochar is investigated with a fixed bed adsorption device. The mercury adsorption capacity and regeneration capacity of iron-based modified biochar under different Ce-Cu loading are explored. Pore structure and surface element valence of Ce-Cu modified iron-based biochar are investigated by BET and XPS. H-2-TPR and N-2-TPD are used to study the reaction path of metal active substances on the surface of modified biochar and the form of mercury on the biochar surface. The microscopic morphology of the biochar is explored by scanning electron microscope (SEM). At the same time, KOH and concentrated hydrochloric acid are used to study the effects of physical adsorption and chemical adsorption on mercury adsorption. The experimental results show that 4 % Ce2 % Cu-FeBC sample has the best mercury removal performance. The cumulative mercury adsorption per unit is 18025 ng center dot g(-1) in 3 hours, and the mercury removal efficiency remains above 90 %. The Ce-Cu modified biochar is mainly mesoporous, and the types of surface-active metals are abundant, which is conducive to the adsorption and oxidation of elemental mercury.(1) The main valence states of mercury on biochar surface are Hg2+, Hg-OM, HgCl2 and HgO are the main forms of existence. The regeneration performance of Ce-Cu modified iron-based biochar is superior, and the mercury removal performance does not decrease after regenerations twice. The rate-controlling step of mercury adsorption on biochar is chemical adsorption.

Automated summary

Ce-Cu modified iron-based biochar was used to adsorb mercury, and the mercury adsorption capacity under different loadings was studied. The porous structure and surface element valence of the modified biochar were investigated, along with the reaction path and form of mercury on the biochar surface. The experimental results showed that the 4% Ce2% Cu-FeBC sample had the best mercury removal performance, and the adsorption performance remained the same even after multiple regenerations.