Efficient removal of thallium from flow gas using manganite‐based catalysts by gas–solid‐phase catalytic oxidation at low temperature

Abstract

Thallium (Tl) is a highly toxic heavy metal, for which its removal from aqueous environments has gained increasing attention. However, removal of Tl from the gas phase is yet to be addressed, especially at low temperature. Herein, we synthesized and characterized a manganite‐based active carbon (Mn–AC) catalyst via an impregnation method process. The Mn–Ac catalyst was then used for elemental Tl removal from simulated flow gas in a laboratory‐scale fixed‐bed reactor. Tl(I) was adsorbed by the AC and oxidized by active Mn, resulting in Tl(III). In addition, experiments were performed at varying temperatures and different Mn dosages to evaluate the efficiency of Tl removal in various conditions. The Mn–AC catalysts were shown to oxidize Tl(I) to Tl(III) on their surface with Tl removal efficiency decreasing with increasing temperature, reaching a removal rate of 90% over 8 h at 25°C. Further, increasing Mn content led to a decrease in surface area and a convolution of the AC morphology. Mn(10%)–AC was shown to have the highest gas‐phase Tl removal efficiency (≥90%, over 8 h).

Mn/Ce@HKUST-1 for Efficient Removal of Gaseous Thallium: Insights from Kinetic and Experimental Studies

“…Interestingly, the presence of CO 2 or NO 2 did not hinder Tl removal by these catalysts, as shown in Figure S4. Although Tl removal efficiency was slightly affected (decreased by 5%) in the presence of SO 2 , it was significantly lower compared to the results from a previous study (over 15% Tl removal decrease was observed with SO 2 ) . Due to the small pore volume of MOFs, the catalyst prevented impurity molecules from taking up the active sites, improving the TOF .…”

“…Although Tl removal efficiency was slightly affected (decreased by 5%) in the presence of SO 2 , it was significantly lower compared to the results from a previous study (over 15% Tl removal decrease was observed with SO 2 ). 13 Due to the small pore volume of MOFs, the catalyst prevented impurity molecules from taking up the active sites, improving the TOF. 34 Furthermore, introducing CO 2 made no difference in the efficiency of Tl removal (see Figure S4).…”

“…Surface adsorption on porous materials, metal catalytic oxidation, biocatalysis, and non-metal catalytic oxidation are mostly reported in Tl control ,− (Table S1). These methods aim to efficiently capture and degrade gaseous Tl species, contributing to the remediation of Tl-contaminated environments.…”

“…Furthermore, the study of Tl oxidation on Aspergillus niger biomass was explored by Sangvanich, which showed low removal efficiency and required a long residence time . The gaseous Tl catalytic oxidation on manganese-modified active carbon is investigated, demonstrating a favorable removal rate despite limited working hours . Copper ferrocyanide-functionalized mesoporous silica is applied to the selective capture of cesium and Tl from natural waters by Yantasee .…”

“…17 oxidation on manganese-modified active carbon is investigated, demonstrating a favorable removal rate despite limited working hours. 13 Copper ferrocyanide-functionalized mesoporous silica is applied to the selective capture of cesium and Tl from natural waters by Yantasee. 18 Even sawdust and sugar beet pulp are green and economical sorbents for Tl removal.…”