Photocatalytic removal of elemental mercury via Ce-doped TiO2 catalyst coupling with a novel optical fiber monolith reactor

Abstract

Reduction of mercury emission from coal combustion is a serious task for public health and environmental societies. Herein, Cedoped TiO 2 (Ce/TiO 2 ) catalyst coupling with a novel optical fiber monolith reactor was applied to efficiently remove elemental mercury (Hg 0 ) from coal-fired flue gas. Under the optimal operation condition (i.e., 1.5 mW/cm 2 UV light, 90°C), above 95% of Hg 0 removal efficiency was attained over the optical fiber monolith reactor coating with 3.40 g/m 2 Ce/TiO 2 catalyst. The effects of flue gas compositions on Hg 0 removal performance were clarified systematically. Gaseous O 2 replenished the surface oxygen, hence maintaining the production of free radicals and promoting the removal of Hg 0 . SO 2 , HCl, and NO inhibited Hg 0 removal in the absence of O 2 due to the competitive adsorption and consumption of free radicals. However, SO 2 and HCl significantly enhanced Hg 0 removal with the participation of O 2 , while NO exhibited obviously inhibitory effect even with the assistance of O 2 . H 2 O also decreased the Hg 0 oxidation capacity owing to the competitive adsorption and reduction of HgO. The optical fiber monolith reactor exhibited much superior Hg 0 removal capacity than the powder reactor. Utilization of Ce/TiO 2 catalyst coupling with an optical fiber monolith reactor provides a cost-effective method for removing Hg 0 from coal-fired flue gas.

Experimental and Kinetic Analysis of H2O on Hg0 Removal by Sorbent Traps in Oxy-combustion Atmosphere

“…52,53 The enriched H 2 O inhibits the oxidation ability of Hg 0 through supplying additional electrons (e − ) on the surface of sorbent traps, and the additional electrons can eliminate Hg 2+ and form Hg 0 by reaction R5. 54,55 The existence of mercury compounds on the spent adsorbent surface can be obtained by the TPD experiment. As shown in Figure 5, HgO is the dominating speciation on the spent adsorbent surface.…”

“…The OH radical can oxidize Hg 0 to HgO, which promotes the removal of mercury. Reactions and are the related reaction equations. , The presence of oxygen may form the OH group through reactions and and react with Hg 0 . − Thus, a low concentration of H 2 O can promote the adsorption of mercury. However, the existence of 20% H 2 O will compete with mercury for the adsorption and oxidation active sites, leading to a decrease of the mercury adsorption capacity. , The enriched H 2 O inhibits the oxidation ability of Hg 0 through supplying additional electrons (e – ) on the surface of sorbent traps, and the additional electrons can eliminate Hg 2+ and form Hg 0 by reaction . , The existence of mercury compounds on the spent adsorbent surface can be obtained by the TPD experiment. As shown in Figure , HgO is the dominating speciation on the spent adsorbent surface. …”

Impacts of environmental issues on health and well-being: a global pollution challenge

“…Jia-Qian Jiang (UK) spoke about water and wastewater treatments using double hydroxide materials (Wang et al 2019 ; Jiang and Lloyd 2002 ), Shin Takahashi (Japan) delighted us with a presentation about the persistence of organic pollutants in the Asia Pacific Region (Monirith et al 2003 ; Anh et al 2019 ), and Jose Luis Gomez-Ariza (Spain) captivated us with a talk combining analysis and health problems in relation to metallomics and metabolomics in environmental metal toxicity assessment (Rodriguez-Moro et al 2020 ; Gómez-Ariza et al 2000 ). Making this edition even more extraordinary was the presence of outstanding keynote speakers, namely Ana Luisa Fernando (Portugal) (Souza and Fernando 2016 ), Erika Kothe (Germany) (Haferburg and Kothe 2007 ), Binoy Sarkar (UK) (Sarkar et al 2010 ), Yongchun Zhao (China) (Xin et al 2020 ), Jerzy Jozef Zajac (France) (Muller et al 2019 ), Tamara Garcia Barrera (Spain) (Callejón-Leblic et al 2020 ), Michael Gochfield (USA) (Gochfeld 2003 ; Burger et al 2020 ), and Elisabete Oliveira (Portugal) (Marcelo et al 2020 ; Oliveira et al 2018 ), who explained their research covering topics as diverse as nanoparticles and food, antibiotic resistance and heavy metals, environmental clean-up applications of clay minerals, power plant wastewater metal analysis, metabolomics and the role of selenium, mechanisms of mercury and selenium toxicity, and the use of mesoporous nanomaterials and chemosensors for removing toxic agents and emerging contaminants. The picture was completed by the participation of close to 170 research fellows from five continents, contributing 70 oral talks, 20 “shotgun” presentations by young researchers, and more than 40 poster communications.…”