Center for Applied Energy Research, University of Kentucky , 2540 Research Park Drive, Lexington, Kentucky 40511, United States.
Department of Mechanical Engineering, University of Kentucky , 151 Ralph G. Anderson Building, Lexington, Kentucky 40506, United States.
Environ Sci Technol. 2017 Sep 19;51(18):10913-10922. doi: 10.1021/acs.est.7b02806. Epub 2017 Aug 28.
Nitrosamines generated in the amine solvent loop of postcombustion carbon capture systems are potent carcinogens, and their emission could pose a serious threat to the environment or human health. Nitrosamine emission control strategies are critical for the success of amine-based carbon capture as the technology approaches industrial-scale deployment. Waterwash systems have been used to control volatile and aerosol emissions, including nitrosamines, from carbon-capture plants, but it is still necessary to remove or destroy nitrosamines in the circulating waterwash to prevent their subsequent emission into the environment. In this study, a cost-effective method for selectively removing nitrosamines from the absorber waterwash effluent with activated-carbon sorbents was developed to reduce the environmental impact associated with amine-based carbon capture. The results show that the commercial activated-carbon sorbents tested have a high capacity and selectivity for nitrosamines over the parent solvent amines, with capacities up to 190 mg/g carbon, under simulated amine waterwash conditions. To further reduce costs, an aerobic thermal sorbent regeneration step was also examined due to the low thermal stability of nitrosamines. To model the effect of oxidation on the sorbent performance, thermal- and acid-oxidized sorbents were also prepared from the commercial sorbents and analyzed. The chemical and physical properties of nitrosamines, the parent amine, and the influence of the physical properties of the carbon sorbents on nitrosamine adsorption was examined. Key sorbent properties included the sorbent hydrophilicity and hydrophobicity, surface pK of the sorbent, and chemical structure of the parent amine and nitrosamine.
在燃烧后碳捕集系统的胺溶剂回路中生成的亚硝胺是强效致癌物质，其排放可能对环境或人类健康构成严重威胁。亚硝胺排放控制策略对于胺基碳捕集技术的成功至关重要，因为该技术正在接近工业规模部署。水洗系统已被用于控制碳捕集厂的挥发性和气溶胶排放，包括亚硝胺，但仍有必要去除或破坏循环水洗中的亚硝胺，以防止其随后排放到环境中。在这项研究中，开发了一种经济有效的方法，即用活性炭吸附剂从吸收器水洗废水中选择性地去除亚硝胺，以减少与胺基碳捕集相关的环境影响。结果表明，在所测试的商业活性炭吸附剂中，在模拟胺水洗条件下，对亚硝胺的容量和选择性高于母体溶剂胺，最高可达 190mg/g 碳。为了进一步降低成本，还研究了有氧热吸附剂再生步骤，因为亚硝胺的热稳定性较低。为了模拟氧化对吸附剂性能的影响，还从商业吸附剂中制备了热氧化和酸氧化的吸附剂，并对其进行了分析。考察了亚硝胺、母体胺的化学和物理性质，以及碳吸附剂的物理性质对亚硝胺吸附的影响。关键的吸附剂性质包括吸附剂的亲水性和疏水性、吸附剂的表面 pk 值以及母体胺和亚硝胺的化学结构。
