Inhibition of PCDD/Fs formation from dioxin precursors by calcium oxide

Abstract

Research aimed at understanding the inhibition effect of CaO on polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) formation form dioxins precursors, such as chlorophenols (CPs) and chlorobenzenes (CBs). The results indicated that a clear dioxin inhibition effect occurred both in open and sealed system when CaO was used. In the open system, PCDDs were the main congeners and the inhibition efficiency was all over 99% in the experiments. In the experiments with CaO, less than 0.1% of the initial PCP was detected in the absorption tube and only about 1% of the initial PCP was examined as calcium pentachlorophenate in the reaction tube. In the sealed system, the inhibition efficiency was over 90% at temperature range between 280 and 450°C when PCP was used as model precursor. When HCB and 2,3,4,5-T 4 CP replaced PCP, significant inhibition effect was also observed. As CaO has the advantageous properties of non-toxicity and non-volatile nature, it is our hope that the result will contribute to the development of a new technique to cope with the problem of dioxin pollution in MWIs.

Suppression of PCDD/Fs by Raw Meal in Cement Kilns

“…The reaction time and temperature largely affect the suppressing ability of CaO. The suppression efficiency of PCDD/Fs by CaO surpassed 90% in a range of 280-450°C and a reaction time of 2 h using pentachlorophenol as a model precursor (Liu et al, 2005).…”

Concentrations and Profiles of Polychlorinated Dibenzo-p-Dioxins and Dibenzofurans in Air and Soil Samples in the Proximity of a Municipal Solid Waste Incinerator Plant

“…Exposure to PCDD/Fs is of great concern because of their toxicity, which may induce hormonedependent cancers and reproductive effects in humans and wildlife (Liu et al, 2005;Wang et al, 2010). Thermal or combustion processes, chemical-industrial sources, and reservoirs are the three important categories of dioxin sources.…”

Synergetic inhibition of PCDD/F formation from pentachlorophenol by mixtures of urea and calcium oxide

“…Toluene, n-hexane, and dichloromethane (all pesticide grade) were obtained from Fisher Scientific (Waltham, Massachusetts, USA). 13 C-labeled PCDD/Fs were obtained from Cambridge Isotope Laboratories (USA). PCCD/F impurities were removed from PCP (purity 99%) as follows.…”

“…However, the suppressing efficiencies of them is CaO ≈ BaO > MgO. Liu et al [13] also reported that CaO can efficiently inhibit the formation of PCDD/Fs from dioxin precursors. Nitrogen-containing compounds, including NH 3 , urea, and dimethylamine, also effectively inhibit PCDD/F formation [15][16][17][18][19].…”

“…Vallejo et al [12] reported that toxic PCDD/Fs could be formed during remediation of 2-chlorophenol via Fenton oxidation. Liu et al [13] found that PCDDs, especially OCDD, were the mainly formed congeners during inhibition of PCDD/Fs formation from PCP by calcium oxide. Therefore, suppression of PCDD/F formation from chlorophenol precursors could be significant in the thermal processes.…”