Removal of reduced sulfur compounds from diluted gas streams by iron(III)EDTA in a trickling filter with in situ iron re‐oxidation. Issue 5 (27th February 2019)

• Record Type: Journal Article
• Authors: Kasper, Pernille L; Feilberg, Anders
• Is Part Of: Journal of chemical technology & biotechnology. Volume 94:Issue 5(2019)
• Page Start: 1593
• Page End: 1600
• Publication Date: 2019-02-27
• Subjects: hydrogen sulfide -- reduced sulfur compounds -- desulfurization -- FeEDTA -- oxidative absorption -- trickling filter; Biotechnology -- Periodicals; Chemistry, Technical -- Periodicals; Chemical engineering -- Periodicals; Industries -- Environmental aspects -- Periodicals; 660
• DOI: 10.1002/jctb.5926
• Languages: English
• ISSNs: 0268-2575

Abstract

Abstract: BACKGROUND: The relatively low solubility of reduced sulfur compounds can limit their removal in trickling filters treating large volumes of air at low residence times. This could be overcome by addition of an oxidizing agent. In this study, the oxidative absorption of reduced sulfur compounds – hydrogen sulfide (H2 S), methanethiol (CH3 SH) and dimethyl sulfide (CH3 S2 CH3 ) – in a high‐porosity trickling filter with added iron chelated by ethylenediaminetetraacetic acid (EDTA) was examined. The process was observed online by proton transfer reaction mass spectrometry (PTR‐MS). RESULTS: Removal efficiencies of H2 S remained in the range 80–99% for all combinations of operating parameters tested. The removal efficiency of CH3 SH was found to be limited compared to this, with removal efficiencies ranging from 10% to 74% and a strong dependence on gas flow rate and residence time was observed; CH3 S2 CH3 was found to be inactive. The FeEDTA solutions were prepared from ferrous chloride (FeCl2 ) as solutions of this compound were more stable than solutions prepared from ferric salts. Oxygen present in the gas stream allowed oxidation of Fe 2+ EDTA to Fe 3+ EDTA in situ, making regeneration prior to experimental runs unnecessary. To maintain high removal efficiencies during start‐up, pH should be kept above 7. CONCLUSION: Chelated iron catalysts could be effectively applied for H2 S removal in a one‐step trickling filter process treating low‐concentration (<3.5 ppm) and diluted waste gas streams, which are characteristic for environmental waste treatment facilities and livestock houses. However, removal of other reduced sulfur compounds important for deodorization was found to be limited. © 2019 Society of Chemical Industry