A pilot study on the regeneration of ferrous chelate complex in NOx scrubber solution by a biofilm electrode reactor
ABSTRACT A chemical absorption-biological reduction integrated process has been proposed for the removal of nitrogen oxides (NO(x)) from flue gases. In this study, we report a new approach using biofilm electrode reactor (BER) to regenerate Fe(II)EDTA via simultaneously reducing Fe(II)EDTA-NO and Fe(III)EDTA in NO(x) scrubber solution. Biofilm formed on the surface of the cathode was confirmed by Environmental Scan Electro-Microscope. Experimental results demonstrated that it was effective and feasible to utilize the BER to promote the reduction of Fe(II)EDTA-NO and Fe(III)EDTA simultaneously. The reduction efficiency of Fe(II)EDTA-NO and Fe(III)EDTA was up to 85% and 78%, respectively when the BER was continuously operated with electricity current at 30 mA. The absence of electricity induced an immediate decrease in reduction efficiency, indicating that the bio-regeneration of ferrous chelate complex was electrochemically accelerated. The present approach is considered advantageous for the enhanced bio-reduction in the NO(x) scrubber solution.
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ABSTRACT: Nitrogen oxides (NOx) are the cause of severe environmental problems such as acid rain, smog formation, an increase in ground-level ozone, depletion of the ozone layer, and global warming and can indirectly affect human and animal health. Considering its severe polluting aspects, many approaches have been utilized so far for the development of a technology that efficiently removes NOx from the industrial gaseous emissions. These control techniques can be broadly classified as primary and secondary techniques. Primary control techniques modify the existing combustion methods to limit the production of NOx, which includes various physical and chemical approaches, whereas the secondary NOx control techniques involve chemical reduction of NOx in flue gas using a chemical reducing agent such as ammonia or urea, reacting on a specially engineered catalyst surface or by absorption of the NOx into a special chelating liquid, and then reducing the chelate-NOx complex to regenerate the chelate using chemical and biochemical approaches, which involve compost biofilters, trickling bed biofilters, packed bed reactors, and several other types of bioreactors. The overall efficiency of the process depends on the absorption efficiency of the chelating agent, the denitrification capacity of the microorganism and the process parameters and physicochemical conditions. The authors highlight the essential features of various physicochemical and biochemical NOx control strategies and techniques. Further, extensive research and development efforts are recommended to improve existing technology for effective NOx control.Critical Reviews in Environmental Science and Technology 12/2013; 44(1):34-96. DOI:10.1080/10643389.2012.710430 · 3.24 Impact Factor
- Asian Journal of Chemistry 01/2013; 25(14). DOI:10.14233/ajchem.2013.14629 · 0.36 Impact Factor
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ABSTRACT: A chemical absorption–biofilm electrode reactor (CABER) integrated system was used for removal of nitrogen monoxide (NO) from flue gas. Effects of the electric current on NO removal efficiency, concentration of Fe(II)EDTA, and consumption rate of glucose in the stabilization phase were investigated. Results indicate that the optimum impressed current was 0.04 A [i.e., 66.7 A m–3 net cathodic compartment (NCC) of the current density]. Under this condition, the consumption rate of glucose was 0.462 g h–1. Performance evaluation of this new approach was investigated under optimum conditions as well. It is noted that minimum residence time was only 20 s, maximum oxygen tolerability was 10%, and maximum elimination capacity of NO was 104.2 g of NO m–3 h–1. The contribution of H2 and glucose in reduction of Fe(III)EDTA was also studied. The results indicated that increasing the H2 supply appropriately could reduce the consumption of glucose. This new approach showed a better performance on NO removal and a larger processing load than those of the chemical absorption–biological reduction (CABR) integrated system.Energy & Fuels 05/2014; 28(5):3332–3338. DOI:10.1021/ef500604d · 2.73 Impact Factor