title: PCDD/Fs' suppression by sulfur-amine/ammonium compounds.
abstract: Three distinct -S and -NH2 or NH4(+) containing compounds, including ammonium thiosulfate, aminosulfonic acid and thiourea, were studied as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) inhibitors. All these three -S and -N containing compounds tested show strong suppression of PCDD/Fs formation, especially for thiourea which has not been studied before. With a (S+N)/Cl molar ratio of only 0.47, thiourea could inhibit 97.3% of PCDD/Fs and even 99.8% of I-TEQ. At an unusually high de novo test temperature (650 °C), the PCDD/Fs' formation was still very low but also the inhibition capacity of thiourea was weak, with an efficiency of 59% for PCDD/Fs when with a (S+N)/Cl molar ratio of 1.40. The results also revealed that the inhibition capability of the combined -S/-NH2 or -S/NH4(+) suppressant was strongly influenced by both the nature of the functional group of nitrogen and the value of the molar ratio (S+N)/Cl. The amine functional group -NH2 tends to be more efficient than ammonium NH4(+) and within a certain range a higher (S+N)/Cl value leads to a higher inhibition efficiency. Moreover, the emission of gases was continuously monitored: the Gasmet results revealed that SO2, HCN and NH3 were the most important decomposition products of thiourea. Thiourea is non-toxic, environment-friendly and can be sprayed into the post-combustion zone in form of powder or aqueous solution. The cost of thiourea at least can be partially compensated by its high inhibition efficiency. Therefore, the application of thiourea in a full-scale incinerator system is promising and encouraging.
authors.affiliation: State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, China. Electronic address: meiguishuier@163.com.
authors.forename: Jian-Ying
authors.initials: JY
authors.lastname: Fu
authors.affiliation: State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, China.
authors.forename: Xiao-Dong
authors.initials: XD
authors.lastname: Li
authors.affiliation: State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, China.
authors.forename: Tong
authors.initials: T
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, China.
authors.forename: Xiao-Qing
authors.initials: XQ
authors.lastname: Lin
authors.affiliation: State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, China.
authors.forename: Alfons
authors.initials: A
authors.lastname: Buekens
authors.affiliation: State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, China.
authors.forename: Sheng-Yong
authors.initials: SY
authors.lastname: Lu
authors.affiliation: State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, China.
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Yan
authors.affiliation: State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, China.
authors.forename: Ke-Fa
authors.initials: KF
authors.lastname: Cen
mesh_terms: D001572:Benzofurans / Q000737:chemistry*; D004147:Dioxins / Q000737:chemistry*; D004785:Environmental Pollutants / Q000737:chemistry*; D012037:Refuse Disposal / Q000379:methods*; D013451:Sulfonic Acids / Q000737:chemistry*; D013885:Thiosulfates / Q000737:chemistry*; D013890:Thiourea / Q000737:chemistry*
chemical_list: D001572:Benzofurans; D004147:Dioxins; D004785:Environmental Pollutants; D013451:Sulfonic Acids; D013885:Thiosulfates; C005741:sulfamic acid; C035309:ammonium thiosulfate; D013890:Thiourea
keywords: Aminosulfonic acid; Ammonium thiosulfate; Inhibition; Model fly ash; PCDD/Fs; Thiourea