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Published on: June 29, 2014
Inhibition of PCDD/Fs formation from dioxin precursors by calcium oxide
Wenbin Liu1, Minghui Zheng, Bing Zhang
1State Key laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, PR China.
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 degrees C when PCP was used as model precursor. When HCB and 2,3,4,5-T4CP 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.
Insights
Calcium oxide (CaO) effectively inhibits dioxin (PCDD/Fs) formation from precursors like chlorophenols. This research shows over 99% inhibition in open systems and over 90% in sealed systems, offering a promising pollution control method.
Area of Science:
- Environmental Chemistry
- Chemical Engineering
- Pollution Control
Background:
- Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are persistent organic pollutants.
- Their formation is a significant concern in industrial processes, particularly in Municipal Waste Incinerators (MWIs).
- Dioxin precursors include chlorophenols (CPs) and chlorobenzenes (CBs).
Purpose of the Study:
- To investigate the inhibitory effect of calcium oxide (CaO) on PCDD/Fs formation.
- To evaluate CaO's efficacy in both open and sealed reaction systems.
- To explore the potential of CaO as a dioxin pollution mitigation strategy.
Main Methods:
- Experiments were conducted in open and sealed systems using dioxin precursors.
- Calcium oxide (CaO) was introduced as an inhibitory agent.
- Pentachlorophenol (PCP), hexachlorobenzene (HCB), and 2,3,4,5-tetrachlorophenol (T4CP) were used as model precursors.
- Reaction products and precursor residues were analyzed.
Main Results:
- CaO demonstrated significant inhibition of PCDD/Fs formation in both open and sealed systems.
- In open systems, inhibition efficiency exceeded 99%, with PCDDs as the primary congeners.
- In sealed systems, inhibition efficiency surpassed 90% within a temperature range of 280-450°C, even with HCB and T4CP precursors.
Conclusions:
- Calcium oxide (CaO) is a highly effective inhibitor of dioxin formation from common precursors.
- Its non-toxic and non-volatile properties make it suitable for industrial applications.
- CaO presents a viable pathway for developing novel techniques to combat dioxin pollution in MWIs.
