Removal of H 2 S and volatile organic sulfur compounds by silicone membrane extraction

BACKGROUND: This study explores an alternative process for the abatement and/or desulfurization of H 2 S and volatile organic sulfur compounds (VOSC) containing waste streams, which employs a silicone‐based membrane to simultaneously remove H 2 S and VOSC. An extractive membrane reactor allows the selective withdrawal of VOSC and H 2 S simultaneously from the waste stream, while preventing direct contact between the waste stream and the absorbing solution and/or the biological treatment system. The influence of the sulfur compounds, membrane characteristics, extractant and pH was studied. RESULTS: Sulfide and the VOCS studied, i.e. methanethiol (MT), ethanethiol (ET) and dimethylsulfide (DMS) were removed from the synthetic wastewater using a silicone rubber membrane. Methanethiol showed the highest (8.72 × 10 −6 m s −1 ) overall mass transfer coefficient ( k ov ) and sulfide the lowest k ov value (1.23 × 10 −6 m s −1 ). Adsorption of the VOCS into the silicone membrane reduced the overall mass transfer coefficient. The k ov when using Fe(III)EDTA − as extractant (5.81 × 10 −7 m s −1 ) for sulfide extraction was one order of magnitude lower than with anaerobic water (2.54 × 10 −6 m s −1 ). On the other hand, the sulfide removal efficiency with Fe(III)EDTA − was higher (84%) compared with anaerobic water (60%) as extractant. An additional mass transfer resistance was formed by elemental sulfur which remained attached to the membrane surface. CONCLUSIONS: Extraction of sulfide and VOCS from a synthetic wastewater solution through a silicone rubber membrane is a feasible process as alternative to the techniques developed to treat VOSC emissions. Optimizing the aqueous absorption liquid can increase the efficiency of extraction based processes. Copyright © 2008 Society of Chemical Industry