journal of environmental sciences 103 (2021) 279–287 Available online at www.sciencedirect.com w w w . e l s e v i e r . c o m / l o c a t e / j e s Simultaneous removal of CO 2 , NO x and SO x using single stage absorption column Sriram Valluri * , S. Komar Kawatra Department of Chemical Engineering, Michigan Technological University, Houghton, MI 49930, USA a r t i c l e i n f o Article history: Received 31 August 2020 Revised 2 November 2020 Accepted 3 November 2020 Available online 4 December 2020 Keywords: Carbon dioxide Nitric oxide Hydrogen peroxide Absorbance Kinetics a b s t r a c t Capturing fue gases often require multiple stages of scrubbing, increasing the capital and operating costs. So far, no attempt has been made to study the absorption characteristics of all the three gases (NO, SO 2 and CO 2 ) in a single stage absorption unit at alkaline pH conditions. We have attempted to capture all the three gases with a single wet scrubbing column. The absorption of all three gases with sodium carbonate solution promoted with oxidizers was investigated in a tall absorption column. The absorbance was found to be 100% for CO 2 , 30% for NO and 95% for SO 2 respectively. The capture effciency of sodium carbonate solution was increased by 40% for CO 2 loading, with the addition of oxidizer. Absorption kinetics and reaction pathways of all the three gases were discussed individually in detail. © 2020 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. Introduction Capturing CO 2 , NO x and SO x together has never been done be- fore, but capturing them separately incurs a huge plant cap- ital and operational costs. Capturing fue gases from power plants is a multi-step process. This is usually done in three stages: (1) Selective catalytic reduction (SCR) for the removal of NO x . (2) Flue gas desulfurization (FGD) for the capture of SO 2 and (3) CO 2 capture (Astarita et al., 1981; Barzagli et al., 2017; Deshwal et al., 2008a; Kawatra et al., 2011; Kawatra, 2020; Xie et al., 2015; Yang et al., 2008). Capturing CO 2 separately from other gases requires an additional 20% footprint for each capture unit operation (Berghout et al., 2015), making it diff- cult for power plants with space constraints and also increas- ing the capital and operational costs for each individual unit operation. If these processes could be combined into single capture column, the problems mentioned above could be re- solved. In a recent study conducted by Li et al. (2016) at 650- ∗ Corresponding author. E-mail: skvallur@mtu.edu (S. Valluri). MW coal fred power plant, concluded that total cost of fue gas removal could be reduced by 13.1% by just integrating FGD and CO 2 capture into single stage. If all the three processes can be combined into one step with the help of non-toxic reagents like sodium carbonate, further cost savings could be achieved, making fue gas removal more economical and environment friendly. To date, minimal attempts have been made to combine all three processes into a single step. Santos et al. (2016) have previously proposed a method to capture all the three gases through chemical absorption with ozone as the oxidizing agent, but they never reported any absorption effciencies for all the three gases. Few authors have previously studied the combined removal of NO x and SO x under acidic pH conditions (Chu et al., 2001; Deshwal and Hyung-Keun, 2009; Kouravand et al., 2018; Krzyzynska and Hutson, 2012; Santos et al., 2016). Deshwal and Hyung-Keun (2009) were able to achieve SO 2 and NO x removal effciencies of 100% and 70% respectively with the help of aqueous euchlorine, which is a signifcant removal, but only the addition of oxidant is not adequate for a system of fue gas with variable concentrations of CO 2 , SO 2 and NO x . https://doi.org/10.1016/j.jes.2020.11.006 1001-0742/© 2020 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.