title: Adsorption and destruction of PCDD/Fs using surface-functionalized activated carbons.
abstract: Activated carbon adsorbs polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs) from gas streams but can simultaneously generate PCDD/Fs via de novo synthesis, increasing an already serious disposal problem for the spent sorbent. To increase activated carbon's PCDD/F sorption capacity and lifetime while reducing the impact of hazardous waste, it is beneficial to develop carbon-based sorbents that simultaneously destroy PCDD/Fs while adsorbing the toxic chemicals from gas streams. In this work, hydrogen-treated and surface-functionalized (i.e., oxygen, bromine, nitrogen, and sulfur) activated carbons are tested in a bench-scale reactor as adsorbents for PCDD/Fs. All tested carbons adsorb PCDD/F efficiently, with international toxic equivalent removal efficiencies exceeding 99% and mass removal efficiencies exceeding 98% for all but one tested material. Hydrogen-treated materials caused negligible destruction and possible generation of PCDD/Fs, with total mass balances between 100% and 107%. All tested surface-functionalized carbons, regardless of functionality, destroyed PCDD/Fs, with total mass balances between 73% and 96%. Free radicals on the carbon surface provided by different functional groups may contribute to PCDD/F destruction, as has been hypothesized in the literature. Surface-functionalized materials preferentially destroyed higher-order (more chlorine) congeners, supporting a dechlorination mechanism as opposed to oxidation. Carbons impregnated with sulfur are particularly effective at destroying PCDD/Fs, with destruction efficiency improving with increasing sulfur content to as high as 27%. This is relevant because sulfur-treated carbons are used for mercury adsorption, increasing the possibility of multi-pollutant control.
authors.affiliation: Department of Civil and Environmental Engineering, University of Illinois, 205 N. Mathews Ave., Urbana, IL 61801, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Atkinson
authors.affiliation: Graduate Institute of Environmental Engineering, National Central University, Chongli City, Taiwan.
authors.forename: P C
authors.initials: PC
authors.lastname: Hung
authors.affiliation: Department of Civil and Environmental Engineering, University of Illinois, 205 N. Mathews Ave., Urbana, IL 61801, USA; State Key Laboratory of Heavy Oil Processing, Key Laboratory of Catalysis, CNPC, China University of Petroleum, Qingdao 266580, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Graduate Institute of Environmental Engineering, National Central University, Chongli City, Taiwan. Electronic address: mbchang@ncuen.ncu.edu.
authors.forename: M B
authors.initials: MB
authors.lastname: Chang
authors.affiliation: State Key Laboratory of Heavy Oil Processing, Key Laboratory of Catalysis, CNPC, China University of Petroleum, Qingdao 266580, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Yan
authors.affiliation: Department of Civil and Environmental Engineering, University of Illinois, 205 N. Mathews Ave., Urbana, IL 61801, USA. Electronic address: mrood@illinois.edu.
authors.forename: M J
authors.initials: MJ
authors.lastname: Rood
mesh_terms: D000327:Adsorption; D000393:Air Pollutants / Q000737:chemistry; D000397:Air Pollution / Q000517:prevention & control; D001572:Benzofurans / Q000737:chemistry*; D002606:Charcoal / Q000737:chemistry*; D005374:Filtration; D006256:Hazardous Waste / Q000032:analysis; D006859:Hydrogen / Q000737:chemistry; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D000393:Air Pollutants; D001572:Benzofurans; D006256:Hazardous Waste; D000072317:Polychlorinated Dibenzodioxins; D002606:Charcoal; D006859:Hydrogen
keywords: Activated carbon; Adsorption; Destruction; PCDD/Fs; Sulfur