title: The effect of pH on thiosulfate formation in a biotechnological process for the removal of hydrogen sulfide from gas streams.
abstract: In a biotechnological process for hydrogen sulfide (H2S) removal from gas streams, operating at natronophilic conditions, formation of thiosulfate (S2O3(2-)) is unfavorable, as it leads to a reduced sulfur production. Thiosulfate formation was studied in gas-lift bioreactors, using natronophilic biomass at [Na+] + [K+] = 2 mol L(-1). The results show that at sulfur producing conditions, selectivity for S2O3(2-) formation mainly depends on the equilibrium between free sulfide (HS(-)) and polysulfide (Sx(2-)), which can be controlled via the pH. At pH 8.6, 21% of the total dissolved sulfide is present as Sx(2-) and selectivity for S2O3(2-) formation is 3.9-5.5%. At pH 10, 87% of the total dissolved sulfide is present as Sx(2-) and 20-22% of the supplied H2S is converted to S2O3(2-), independent of the H2S loading rate. Based on results of bioreactor experiments and biomass activity tests, a mechanistic model is proposed to describe the relation between S2O3(2-) formation and pH.
authors.affiliation: Sub-department of Environmental Technology, Wageningen University, Bomenweg 2, P.O. Box 8129, 6700 EV Wageningen, The Netherlands. pim.vandenbosch@wur.nl
authors.forename: Pim L F
authors.initials: PL
authors.lastname: van den Bosch
authors.forename: Dimitry Y
authors.initials: DY
authors.lastname: Sorokin
authors.forename: Cees J N
authors.initials: CJ
authors.lastname: Buisman
authors.forename: Albert J H
authors.initials: AJ
authors.lastname: Janssen
mesh_terms: D018533:Biomass; D001709:Biotechnology; D006862:Hydrogen Sulfide / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D013885:Thiosulfates / Q000138:chemical synthesis*
chemical_list: D013885:Thiosulfates; D006862:Hydrogen Sulfide