Carbon capture utilization and storage (CCUS) is known as an important technology that can be applied to minimize CO2 emissions and reduce global warming. In post-combustion carbon capture, nitrosamines are one of the degradation products that formed from the reaction of NOx in flue gas with secondary amines. In the coming years, further adaptations to the technology in power plants can bring critical concerns of nitrosamines formation and emissions. These carcinogenic degradation products can be removed from amine-based carbon capture systems by first capturing them using a circulating waterwash, followed by adsorption using activated carbon. Generally, nitrosamines adsorbed onto activated carbon are immobilized with limited potential to leach back into the solution, suggesting a very stable physical adsorption. However, it is important to fully characterize the leaching potential using standard leaching protocols. The leaching behavior of adsorbed nitrosamines from the activated carbon at various pH was investigated and evaluated using Environment Protection Agency reviewed method (EPA 1313), Standard Toxicity Characteristic Leaching Procedure (TCLP 1311), and ASTM American Society for Testing and Materials Standard Test Method (ASTM D3987). The aqueous solubility of many chemical species depends on the pH of the contacting solution. Leaching studies were conducted with the N-Nitrosopyrolidine (NPYR) and N-Nitrosodiethylamine (NDEA) adsorbed activated carbon to check the stability of the adsorbed nitrosamines under relevant disposal conditions. The total concentration of nitrosamine adsorbed onto the activated carbon was determined by comparing the initial and final concentrations of the nitrosamine solution used for adsorption. The percentage of N-Nitrosopyrolidine (NPYR) and N-Nitrosodiethylamine (NDEA) leached at various pH was determined by analyzing the samples post leaching using LCTOF-MS. After leaching, the concentration of nitrosamines extracted in DCM was determined by GC-MS and compared to the concentration of nitrosamine initially adsorbed onto the activated carbon. Nitrosamine leaching from activated carbon is pH-dependent, with more leaching at lower pH values (pH &lt; 5). The minimal amount of NDEA leached back from activated carbon, indicates good stability of the adsorbed nitrosamine.

Stability of adsorbed nitrosamines on packed activated carbon bed to reduce environmental impact from amine-based CO2 capture

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