title: Application of ultraviolet, ozone, and advanced oxidation treatments to washwaters to destroy nitrosamines, nitramines, amines, and aldehydes formed during amine-based carbon capture.
abstract: Although amine-based CO(2) absorption is a leading contender for full-scale postcombustion CO(2) capture at power plants, concerns have been raised about the potential release of carcinogenic N-nitrosamines and N-nitramines formed by reaction of exhaust gas NO(x) with the amines. Experiments with a laboratory-scale pilot unit suggested that washwater units meant to scrub contaminants from absorber unit exhaust could potentially serve as a source of N-nitrosamines via reactions of residual NO(x) with amines accumulating in the washwater. Dosage requirements for the continuous treatment of the washwater recycle line with ultraviolet (UV) light for destruction of N-nitrosamines and N-nitramines, and with ozone or hydroxyl radical-based advanced oxidation processes (AOPs) for destruction of amines and aldehydes, were evaluated. Although <1000 mJ/cm(2) UV fluence was generally needed for 90% removal of a series of model N-nitrosamines and N-nitramines, 280-1000 mJ/cm(2) average fluence was needed for 90% removal of total N-nitrosamines in pilot washwaters associated with two different solvents. While AOPs were somewhat more efficient than ozone for acetaldehyde destruction, ozone was more efficient for amine destruction. Ozone achieved 90% amine removal in washwaters at 5-12 molar excess of ozone, indicating transferred dosage levels of ∼100 mg/L for 90% removal in a first-stage washwater unit, but likely only ∼10 mg/L if applied to a second-stage washwater. Accurate dosage and cost estimates would require pilot testing to capture synergies between UV and ozone treatments.
authors: Department of Chemical and Environmental Engineering, Yale University, Mason Lab 313b, 9 Hillhouse Avenue, New Haven, Connecticut 06520, USA.
authors: Amisha D
authors: AD
authors: Shah
authors: Ning
authors: N
authors: Dai
authors: William A
authors: WA
authors: Mitch
mesh_terms: D000447:Aldehydes / Q000302:isolation & purification*; D000588:Amines / Q000302:isolation & purification*; D000814:Aniline Compounds / Q000302:isolation & purification*; D002244:Carbon / Q000302:isolation & purification; D004867:Equipment Design; D009578:Nitrobenzenes / Q000302:isolation & purification*; D009602:Nitrosamines / Q000302:isolation & purification*; D010084:Oxidation-Reduction; D010126:Ozone / Q000737:chemistry; D014466:Ultraviolet Rays; D014865:Waste Disposal, Fluid / Q000295:instrumentation; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D000447:Aldehydes; D000588:Amines; D000814:Aniline Compounds; D009578:Nitrobenzenes; D009602:Nitrosamines; D014874:Water Pollutants, Chemical; D010126:Ozone; D002244:Carbon; C015384:nitramine