Journal of Chemical Technology and Biotechnology, Vol.84, No.1, 69-77, 2009
Removal of H2S and volatile organic sulfur compounds by silicone membrane extraction
BACKGROUND: This study explores an alternative process for the abatement and/or desulfurization of H2S and volatile organic sulfur compounds (VOSC) containing waste streams, which employs a silicone-based membrane to simultaneously remove H2S and VOSC. An extractive membrane reactor allows the selective withdrawal of VOSC and H2S 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 x 10(-6) m s(-1)) overall mass transfer coefficient (k(ov)) and sulfide the lowest k(ov) value (1.23 x 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 x 10(-7) m s(-1)) for sulfide extraction was one order of magnitude lower than with anaerobic water (2.54 x 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. (C) 2008 Society of Chemical Industry