Chlorobenzene Formation from Fly Ash: Effect of Moisture, Chlorine Gas, Cupric Chloride, Urea, Ammonia, and Ammonium Sulfate

Abstract

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are formed jointly with numerous products of incomplete combustion during waste incineration. Chlorobenzenes (CBz) are often cited as surrogates or precursors of PCDD/Fs. Experiments were conducted to investigate the effect of some key parameters on CBz formation, including moisture (H 2 O), chlorine gas (Cl 2 ), cupric chloride (CuCl 2 ), urea [(NH 2 ) 2 CO], ammonia (NH 3 ), and ammonium sulfate [(NH 4 ) 2 SO 4 ]. Cl 2 and CuCl 2 promoted CBz formation from fly ash, increasing the chlorination degree. In addition, Cl in cupric compound was more active than chlorine atom of Cl 2 , and chlorine type significantly affected the chlorination process. Less CBz yield was detected after S-and N-containing compounds [(NH 2 ) 2 CO, NH 3 , and (NH 4 ) 2 SO 4 ] were added into reactive ash. High content of moisture in gas prevented CBz synthesis and reduced chlorination. These experimental results are useful to optimize CBz emission control and realize the mechanism of the correlation between CBz and PCDD/Fs.

Formation, Reduction and Emission Behaviors of CBzs and PCDD/Fs from Cement Plants

“…Because of general inhomogeneity, the other solid samples were collected by fully mixed multipoint sampling. Pre-treatment of CBzs is depicted in detail by Yan et al (2012). GC-ECD (GC 6890N, Agilent, USA) with a DB-5 column (30 m × 0.25 mm × 0.25 µm) is used to analyze CBzs (DBz to HCBz).…”

Optimizing the Elimination of Dioxin-Like Compounds (PCDD/Fs and PCBs) Through Effective Combustion Practices in the Flue Gas in the Medical Waste Incineration Facility

“…Calibration solutions of the seventeen regulated 2,3,7,8chloro-substituted PCDD/Fs (CSL-CS4), EPA-1613, and twelve PCBs (CS1-CS6), WP-CVS, containing the corresponding 13 C12-labelled compounds in nonane, were obtained from AfriFusion (Pty) Ltd (Midrand) for quantification purposes. The calibration solutions of PCDD/Fs and PCBs covered a concentration range from 0.1 to 400 ng mL -1 and between 0.1 and 200 ng mL -1 , respectively.…”

“…A quartz fiber filter and a glass cartridge with polyurethane foam (PUF) were used for collecting particle phase and gas-phase compounds, respectively. A known amount of PCDD/Fs isotopically labeled surrogate standards ( 37 Cl4-2,3,7,8-TeCDD, 13 C-1,2,3,4,7,8-HxCDD, 13 C-2,3,4,7,8-PeCDF, 13 C-1,2,3,4,7,8-HxCDF, and 13 C-1,2,3,4,7,8,9-HpCDF) was spiked into the cartridge before field sampling in order to estimate the collection efficiency of the sampling train. The sampling flow rate was set to 0.225 m -3 min -1 ±10%.…”

“…Combustion conditions have been investigated for the formation of PCDD/Fs, yet the impact of these operating parameters during waste combustion is indistinct, bringing about confounded interrelationships [12]. The role of chlorine on the formation of PCDD/Fs is debatable, some studies showed correlation between chlorine sources and PCDD/Fs formation [13,14] while others show minimal correlation [15,16]. Wang et al [17] found that the amounts of highly chlorinated PCDD/Fs (i.e., octa-PCDD/Fs) does not necessary formed from high chlorine input, but they may form from presence of precursors such as chlorobenzenes (CBzs), chlorophenols (CPhs) and polycyclic aromatic hydrocarbon (PAHs) as they share similar formation mechanisms.…”

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

“…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]. Kasai et al [17] reported that the addition of urea did not significantly affect the concentration of NO x in the stack gas.…”