The role of particulate carbon in the de-novo synthesis of polychlorinated dibenzodioxins and-furans in fly-ash

Characteristics of Persistent Organic Pollutant Emissions from a Diesel-Engine Generator Fueled Using Blends of Waste Cooking Oil-Based Biodiesel and Fossil Diesel

“…The temperature of the combustion chamber of the generator when W40 was used exceeded that by when W20 was used, and carbon accounted for approximately 80% of all diesel engine particles (DEPs) (Chung et al, 2008;Tsai et al, 2010;, so the PCDD/Fs that were emitted using W40 contained more furan that was formed by de novo synthesis, yielding PCDFs/PCDDs > 1. The high PM with a high proportion of soot particles and de novo synthesis of furan occurs favorably on the small soot particles (Stieglitz et al, 1990). Hell et al (2000) claimed that at low trichlorophenol concentrations, PCDFs were formed mostly by de novo synthesis from the residual carbon of fly ash; moreover, as the trichlorophenol concentrations increased, the condensation reaction of 2,4,6-Cl 3 Ph to PCDD proceeded increasingly more strongly than the de novo reaction.…”

The formation of dioxins in combustion systems

“…Since the chlorination is assumed to take place before the release of the PCDD/F product, the dominant chlorine configuration is not 2378 as dictated by considerations of electrophilic aromatic substitution, i.e., if there was a preference for ortho and para substitutions. The group of Stieglitz [68,92,97,[118][119][120][121][122] investigated the mechanism of de novo formation by a program of annealing experiments. In one case an equimolar mixture of 12 C and 13 C (4%) with florisil to simulate flyash was used [122], with KCl added to provide chlorine and copper chloride as a catalyst.…”

Persistent Organic Pollutant Reductions from a Diesel Engine Generator Fueled with Waste Cooking Oil-based Biodiesel Blended with Butanol and Acetone

“…Stieglitz et al (1990) indicated that higher soot emission might lead to the formation of furans by de novo synthesis. Thus, the lower PM reflects fewer unburned carbon particles and lower PCDD/F formation in exhaust gas (Huang and Buekens, 1995).…”

“…The pyrolysis, elimination, and dechlorination of polychlorinated diphenyl ethers (PCDEs) and polycyclic aromatic hydrocarbons (PAHs) (Lindahl et al, 1980;Nito et al, 1997), as well as the condensations and recombination of fragments (PCDEs, CBs, and CPs) (Weber and Hagenmaier, 1999) have been reported as the major transformation mechanisms of these POPs in the gaseous phase. Nevertheless, de novo synthesis is the dominant heterogeneous reaction to form PCDFs (Stieglitz et al, 1990;Huang and Buekens, 1995). Weber and Kuch (2003) and Liu et al (2013b) indicated that the precursor reaction processes dominated over de novo synthesis for PCDD/F formation during combustion.…”