Effect of Hydrochloric Acid on Sampling and Analysis of Semivolatile Organic Compounds in Incineration Flue Gas. 2. Polycyclic Aromatic Hydrocarbons

Abstract

The effect of hydrochloric acid (HCl) at 0.17, 2.05, and 5.53 mg/L in incineration flue gas on the recoveries of 16 polycyclic aromatic hydrocarbons (PAHs) from XAD-2 adsorbent of the MM5 (Modified Method 5) train was investigated. At constant concentrations of moisture (14%), carbon dioxide (7%), and oxygen (10%), 2.05 and 5.53 mg/L HCl decreased the recoveries of benzo[a]pyrene, perylene, anthracene, and acenaphthylene. At 5.53 mg/L HCl, only 6, 8, 32, and 46% of these PAHs, respectively, were recovered from XAD-2. The recoveries of other PAHs were 88-112% with relative standard deviations of 3-13% at all acid concentrations in flue gas. Acid effect occurred primarily during sampling of flue gas, and a smaller acid effect occurred during sample processing, in which the XAD-2 containing HCl, PAHs, and moisture was Soxhlet extracted using dichloromethane. The hypothesis is that these PAHs formed cation radicals in the presence of HCl, which was followed by subsequent reaction with water to yield quinones. The extraction of PAHs from synthetic acidic condensate and acidic ethylene glycol of the MM5 train was not dependent on pH. Extractions from various acidities of these combined solutions gave recoveries of 76-102% with relative standard deviations of 4-13%. The implications of all the above-mentioned effects on the selection of surrogates and interpretation of analytical results for MM5 sampling and analysis are discussed.

Effect of Hydrochloric Acid on Sampling and Analysis of Semivolatile Organic Compounds in Incineration Flue Gas. 3. Chlorobenzenes and Polychlorinated Biphenyls

“…All solvents have been specified earlier (2). Silica (Bio-Sil A, 100-200 mesh, Bio-Rad) was purified according to the previously reported procedure (3). Anhydrous sodium sulfate (Na 2SO4) was treated in the same manner as silica (3).…”

“…The acid effects on sampling and analysis of the 16 CPs (2) and the 16 PAHs (3) in incineration flue gas have been reported previously. When the concentrations of oxygen (10%), moisture (14%), and carbon dioxide (7%) are kept constant, HCl at 0.17 mg/L [an upper limit model of scrubbed flue gas (1)] does not affect the recoveries of CPs and PAHs from the XAD-2 of MM5 train (2,3). However, higher concentrations of HCl (2.05 and 5.53 mg/L) cause desorption of some CPs from the XAD-2 (2).…”

“…The CPs with a smaller number of chloro substituents are more affected by the acid (2). These higher HCl concentrations in flue gas also cause a decrease in the recoveries of some PAHs, i.e., benzo[a]pyrene, perylene, anthracene, and acenaphthylene (3). Only 6, 8, 32, and 46% of these PAHs, respectively, are recovered from XAD-2 after sampling of flue gas at 5.53 mg/L HCl (3).…”

“…These higher HCl concentrations in flue gas also cause a decrease in the recoveries of some PAHs, i.e., benzo[a]pyrene, perylene, anthracene, and acenaphthylene (3). Only 6, 8, 32, and 46% of these PAHs, respectively, are recovered from XAD-2 after sampling of flue gas at 5.53 mg/L HCl (3). PAHs are primarily affected on XAD-2 of MM5 train during sampling of flue gas, where they are continuously exposed to HCl, moisture, and oxygen (3).…”

“…Only 6, 8, 32, and 46% of these PAHs, respectively, are recovered from XAD-2 after sampling of flue gas at 5.53 mg/L HCl (3). PAHs are primarily affected on XAD-2 of MM5 train during sampling of flue gas, where they are continuously exposed to HCl, moisture, and oxygen (3). A smaller acid effect on PAH recoveries occurs during the Soxhlet extraction of organic compounds from XAD-2 using dichloromethane (3).…”