Kinetic study of hydrogen sulfide absorption in aqueous chlorine solution

International audienceHydrogen sulfide (H2S) is currently removed from gaseous effluents by chemical scrubbing using water. Chlorine is a top-grade oxidant, reacting with H2S with a fast kinetic rate and enhancing its mass transfer rate. To design, optimize and scale-up scrubbers, knowledge of the reaction kinetics and mechanism is requested. This study investigates the H2S oxidation rate by reactive absorption in a mechanically agitated gas-liquid reactor. Mass transfer (gas and liquid sides mass transfer coefficients) and hydrodynamic (interfacial area) performances of the gas-liquid reactor were measured using appropriated physical or chemical absorption methods. The accuracy of these parameters was checked by modeling the H2S absorption in water without oxidant. A sensitivity analysis confirmed the robustness of the model. Finally, reactive absorption of H2S in chlorine solution for acidic or circumneutral pH allowed to investigate the kinetics of reaction. The overall oxidation mechanism could be described assuming that H2S is oxidized irreversibly by both hypochlorite anion ClO- (k = 6.75 106 L mol-1 s-1) and hypochlorous acid ClOH (k = 1.62 105 L mol-1 s-1)

Intensification of the temperature-swing adsorption process with a heat pump for the recovery of dichloromethane

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Kinetics study of H2S oxidation by NaOCl by chemical absorption in an agitated vessel

International audienceTo design precisely H2S chem. scrubbers working with sodium hypochlorite (NaOCl)​, the knowledge of the H2S oxidn. kinetics const. is indispensable. However, this kinetics remains unknown. The aim of this study is to det. this kinetics vs. the temp. by chem. absorption in an aq. soln. of NaOCl using a mech. agitated gas-​liq. vessel. This kind of reactor insures a perfectly mixed liq. phase to simplify the concn. profile and the math. treatment of the problem. This article presents the set-​up developed and the exptl. procedure that will enable to det. the kinetics. The procedure is based on the detn. of the gas (kGa0) and liq. (kLa0) side volumetric gas-​liq. transfer coeffs. and the interfacial area (a0) in given operating conditions (gas flow rate and pressure and agitation speed)​. Then, expts. in the pseudo first order configuration would enable to det. the kinetics const. This paper presents all the preliminary calcns. necessary to choose the operating conditions

Kinetics study of H2S oxidation by NaOCl by chemical absorption in an agitated vessel

International audienceTo design precisely H2S chem. scrubbers working with sodium hypochlorite (NaOCl)​, the knowledge of the H2S oxidn. kinetics const. is indispensable. However, this kinetics remains unknown. The aim of this study is to det. this kinetics vs. the temp. by chem. absorption in an aq. soln. of NaOCl using a mech. agitated gas-​liq. vessel. This kind of reactor insures a perfectly mixed liq. phase to simplify the concn. profile and the math. treatment of the problem. This article presents the set-​up developed and the exptl. procedure that will enable to det. the kinetics. The procedure is based on the detn. of the gas (kGa0) and liq. (kLa0) side volumetric gas-​liq. transfer coeffs. and the interfacial area (a0) in given operating conditions (gas flow rate and pressure and agitation speed)​. Then, expts. in the pseudo first order configuration would enable to det. the kinetics const. This paper presents all the preliminary calcns. necessary to choose the operating conditions