Absorption of H<sub>2</sub>S in NaOCl caustic aqueous solution

Chen, Liming; Huang, James; Yang, Chaoyu

doi:10.1002/ep.670200313

Cited by 52 publications

(49 citation statements)

References 8 publications

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“…For pH > 10.5, the absorption rate increasing with the pH is less sensitive since the E values are so large that the liquid resistance is almost negligible. This conclusion is in accordance with the results reported by Chen et al (2001) [6].…”

Section: Study Of the Recombination With Ho -Reactionsupporting

confidence: 94%

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Overview of mass transfer enhancement factor determination for acidic and basic compounds absorption in water

Biard

Couvert

2013

Chemical Engineering Journal

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Absorption or gas-liquid mass transfer is a fundamental unit operation useful in many fields, particularly gas treatment (wet scrubbing). Absorption of basic or acidic compounds, even hydrophobic, in water can be achieved successfully due to the mass transfer enhancement linked to proton transfer reactions in the liquid film. The absorption rate takes this phenomenon into account through the enhancement factor E, which depends on many parameters: nature (irreversible or reversible), kinetics and stoichiometry of the reaction, reagents and products diffusion coefficients and concentrations. This article gives an overview of the enhancement factor determination for acidic and basic compounds transfer in water. Modeling is performed for three compounds of interest, hydrogen sulfide H 2 S, methyl mercaptan CH 3 SH and ammonia NH 3 , for different scenarii to assess the influence of the pH. The results demonstrate that recombination with HO -and protonation reactions are respectively the two preponderant reactions for respectively acidic and basic compounds. They enable to reach large values of the enhancement factor at appropriated pH and to reduce the mass transfer resistance in the liquid film. Furthermore, the simulations highlight that, in many cases, knowledge of the reaction kinetics is not necessary since the reaction can be considered as instantaneous compared to mass transfer.

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Section: Study Of the Recombination With Ho -Reactionsupporting

confidence: 94%

“…This is typically the case for hydrogen sulfide (H 2 S) [6]. The mass transfer enhancement factor, E, must be quantified to determine the absorption rate of the gas phase reactant and to achieve a proper scrubber design [7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Overview of mass transfer enhancement factor determination for acidic and basic compounds absorption in water

Biard

Couvert

2013

Chemical Engineering Journal

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“…4, the removal efficiency of H 2 S in the current study has been compared with a packed bed scrubber from the study of Chen et al [26]. It can again be seen that the F L /F G ratio is lower in the present work.…”

Section: Resultssupporting

confidence: 53%

Removal of Gas Pollutants of a Thermal Oxidizer with a Dynamic Scrubber

2007

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The absorption of gas pollutants including CO 2 , CO, NO, NO 2 , SO 2 , and H 2 S from the exhaust of a paint recuperative oxidizer into NaOH solution has been studied using an industrial scale dynamic scrubber. Experimental results show the influence of the absorbent concentration on the pollutant removal efficiency. The best removal efficiencies of CO 2 , CO, NO, NO 2 , SO 2 , and H 2 S were 79, 80, 80, 100, 75 and 88 %, respectively, with 2 % NaOH as the absorbent. A comparison of these results with previous studies shows that the liquid-to-gas flow rate ratio (F L /F G ) in this dynamic scrubber is much smaller than for traditional NaOH scrubbers and spray dryers. IntroductionAir pollution has a widespread affect on the world. It threatens the health of human beings and other living things on our planet. Although often invisible, pollutants in the air create smog and acid rain, cause cancer or other serious health problems, diminish the protective ozone layer in the upper atmosphere, and contribute to the potential for world climate change.Nitrogen oxides (NO and NO 2 ) are produced largely by industry. Nitrogen oxides can also originate in the atmosphere by reactions which combine reactive oxygen containing molecules with nitrogen from the atmosphere [1]. Nitrogen oxides (NO x ) play a major role, together with volatile organic compounds (VOC), in the atmospheric reactions that produce ozone and acid rain, and may affect both terrestrial and aquatic ecosystems [2,3] 1) . They can also cause increased breathing difficulty for asthmatics. The US Environmental Protection Agency (EPA) uses NO x as one of the 'criteria pollutants' to indicate air quality [4].Carbon monoxide (CO) is a product of incomplete combustion. Its main sources are combustion processes involving vehicles, heating, coal-fired power generation, and biomass burning. It is emitted from the exhausts of motor vehicles and engines where there is incomplete combustion of fossil fuels [1]. Carbon monoxide (CO) interferes with the body's ability to carry oxygen, thus impairing perception and thought, slowing reflexes and causing drowsiness. Prolonged exposure to high levels of CO can cause unconsciousness and even death [5].Sulfur dioxide (SO 2 ) is produced by the burning of coal, vehicle emissions and emissions from oil/gas fields and refineries. Sulfur dioxide in high concentrations, with or without exercise, is a respiratory irritant, provoking airflow limitations. Ambient SO 2 may contribute to acid aerosol (H 2 SO 4 ) formation. In some studies, SO 2 , sulfates, and acid aerosols have been associated with increased emergency visits and hospitalizations for asthmatics [1,6].Hydrogen sulfide (H 2 S) is produced by many industrial processes, and by the decomposition of oil or dead vegetation. Clinical and research findings indicate that the nervous system is a target of H 2 S. At high concentrations, exposure can cause loss of consciousness or death. Breathing H 2 S at greater than 500,000 ppb can affect the brain's respiratory center, leading to...

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“…The effectiveness of the packed scrubber for removal of H 2 S has been proven by several studies [28][29][30][31][32] . The alkali mixtures of NaOH and NaOcl as absorption liquid has good efficiency for H 2 S removal in a packed scrubber 4) .…”

Section: Discussionmentioning

confidence: 99%

“…The maximum allowable exposure for prolonged periods is 10 parts per million (ppm), the peak concentration for 10 minutes exposure is 50 ppm, and exposure to concentrations greater than 300 ppm for 30 min is fatal 4) .…”

Section: Introductionmentioning

confidence: 99%

Application of Local Exhaust Ventilation System and Integrated Collectors for Control of Air Pollutants in Mining Company

Shahna

Farasati

2012

Ind Health

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Abstact: Local exhaust ventilation (LEV) systems and integrated collectors were designed and implemented in a mining company in order to control emitted air pollutant from furnaces. The LEV was designed for capture and transition of air pollutants emitted from furnaces to the integrated collectors. The integrated collectors including four high efficiency Stairmand model cyclones for control of particulate matter, a venturi scrubber for control of the fine particles, SO 2 and a part of h 2 S to follow them, and a packed scrubber for treatment of the residual h 2 S and So 2 were designed. Pollutants concentration were measured to determine system effectiveness. The results showed that the effectiveness of LEV for reducing workplace pollution is 91.83%, 96.32% and 83.67% for dust, So 2 and h 2 S, respectively. Average removal efficiency of particles by combination of cyclone and venturi scrubber was 98.72%. Average removal efficiency of SO 2 and h 2 S were 95.85% and 47.13% for the venturi scrubber and 68.45% and 92.7% for the packed bed scrubber. The average removal efficiency of SO 2 and h 2 S were increased to 99.1% and 95.95% by the combination of venturi and packed bed scrubbers. According to the results, integrated collectors are a good air pollution control option for industries with economic constraints and ancient technologies.

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Absorption of H₂S in NaOCl caustic aqueous solution

Cited by 52 publications

References 8 publications

Overview of mass transfer enhancement factor determination for acidic and basic compounds absorption in water

Overview of mass transfer enhancement factor determination for acidic and basic compounds absorption in water

Removal of Gas Pollutants of a Thermal Oxidizer with a Dynamic Scrubber

Application of Local Exhaust Ventilation System and Integrated Collectors for Control of Air Pollutants in Mining Company

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Absorption of H2S in NaOCl caustic aqueous solution

Cited by 52 publications

References 8 publications

Overview of mass transfer enhancement factor determination for acidic and basic compounds absorption in water

Overview of mass transfer enhancement factor determination for acidic and basic compounds absorption in water

Removal of Gas Pollutants of a Thermal Oxidizer with a Dynamic Scrubber

Application of Local Exhaust Ventilation System and Integrated Collectors for Control of Air Pollutants in Mining Company

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Absorption of H₂S in NaOCl caustic aqueous solution