Study on Optimization Control of Hydrogen Sulfide Concentration in Coal-fired Boilers

H2S is an important element to high-temperature corrosion for the water-cooled wall of coal-fired boilers, thus, it is an effective means to prevent high-temperature corrosion through reducing the concentration of H2S near the boiler wall. Since the concentration of H2S in the boiler is closely related to the concentration of O2 and CO, the research on the distribution of H2S atmosphere in the boiler furnace was conducted in this paper. With the air distribution regulation as the means, local O2 concentration is increased, to avoid the accumulation of H2S near the wall and reduce high-temperature corrosion.

Effect of abiotic factors on sulfidogenic activity of bacteria Desulfuromonas sp.

Sulfur-reducing bacteria are promising agents for the development of new methods of wastewater treatment with the removal of ions of heavy metals and organic compounds. Study of the effect of various environmental factors on the growth and sulfidogenic activity of sulfur-reducing bacteria allows one to investigate the adaptability of these microorganisms to stress factors. The paper deals with the effect of рН, different concentrations of elemental sulfur, hydrogen sulfide and presence of various electron acceptors on the growth and sulfidogenic activity of bacteria Desulfuromonas sp. YSDS-3. The calculation of C/S ratio for sulfur-reducing bacteria Desulfuromonas sp. YSDS-3 was made, with the comparison with similar parameters of sulfate-reducing bacteria. In the medium with elemental sulfur, concentration of hydrogen sulfide increased with the concentration of elemental sulfur. Bacteria Desulfuromonas sp. YSDS-3 accumulated their biomass in the most effective way at the concentration of elemental sulfur of 10–100 mM. In the medium with polysulfide form of sulfur at the neutral pH, bacteria produced hydrogen sulfide and accumulated biomass the best. Hydrogen sulfide at the concentration of 3 mM did not inhibit the bacterial growth, but further increase in the hydrogen sulfide concentration inhibited the growth of bacteria. The bacteria did not grow at the hydrogen sulfide concentration of 25 mM and above. As the concentration of elemental sulfur and cell density increases, sulfidogenic activity of the bacteria grows. Presence of two electron acceptors (S and K2Cr2O7, S and MnO2, S and Fe (III)) did not affect the accumulation of biomass of the bacteria Desulfuromonas sp. YSDS-3. However, under such conditions the bacteria accumulated 1.5–2.5 times less hydrogen sulfide than in the test medium. After 12–24 h of cultivation, different concentrations of elemental sulfur had a significant effect on the sulfidogenic activity. However, during 3–16 days of cultivation, the percentage of effect of elemental sulfur concentration decreased to 31%, while the percentage of effect of cell density increased threefold. Presence in the medium of the electron acceptors (Cr (VI), MnO2, Fe (III)) alternative to elemental sulfur led to a significant decrease in the content of hydrogen sulfide produced by sulfur-reducing bacteria.

Hydrogen Sulfide Removal Using Various Metal Oxide Nanocomposite from Drilling Fluid: Optimization, Kinetic and Adsorption Isotherms

In a drilling operation, the existing hydrogen sulfide in oil and gas reservoirs can be solved in drilling fluid and cause some environmental problems and life-threatening situations to personnel. Therefore, hydrogen sulfide removal of drilling fluid is so important. In this work, in order to hydrogen sulfide removal from drilling fluid, zinc oxide nanoparticle, silica nanoparticle and silica/zinc oxide nanocomposite with different ratio were synthesized by precipitation and sol-gel method and characterized by x-ray diffraction, fourier-transform infrared spectroscopy, Field emission scanning electron microscopy, energy dispersive x-ray and brunauer–emmett–teller. The Design Expert software, I-optimal, was used to design the experiments and the optimum condition for hydrogen sulfide removal was determined. Also, the effect of nanomaterial concentration, hydrogen sulfide concentration, contact time, pH and type of nanomaterial on removal of hydrogen sulfide was investigated. the results show, the optimization of removal at nanoparticle concentration, 0.1 and 0.9 wt.%, hydrogen sulfide concentration, 800 ppm, contact time, 3 min., pH, 12 and ZnO/SiO2 nanocomposite with 3:1 ratio is about 92.6 and 97.2%. investigation of the reaction kinetic showed that hydrogen sulfide removal had a very high rate, so that time parameter has a low impact on the removal process. Also, the kinetic adsorption was pseudo-first order. Adsorption of hydrogen sulfide followed Freundlich isotherm model and multilayer adsorption. The reusability of nanocomposite is four cycles for hydrogen sulfide removal more than 50%, which was significant in industrial processes.

Measurement of Hydrogen Sulfide Concentration by use of Carbon Nanotubes and 1-allyl-3-Methylimidazolium Bromide

Objective: In this research, carboxylated multi-walled carbon nanotubes were used to construct working and counter electrodes of the electrochemical gas sensor. The 1-allyl-3- methylimidazolium bromides which is a hydrophilic room temperature ionic liquid was used as the electrolyte. Finally, the sensor was used to measure hydrogen sulfide and carbon monoxide in the air. Methods: The electrochemical method was used to measure the hydrogen sulfide concentration. To record sensor response, chronoamperometry was performed. Also, impedance spectroscopy of screen printed electrodes modified with MWCNTs-COOH was done. The working electrode was characterized by field emission scanning electron microscopy (FESEM), Energy-Dispersive X-Ray Spectroscopy (EDX) and Fourier-Transform Infrared (FTIR) spectroscopy. Results: In the range of 0.6 ppm to 10 ppm, the sensor had a linear behavior and its sensitivity was 0.3716 µA / ppm. The results of the FESEM, EDX and FTIR analysis confirm the desired structure of the working electrode. Impedance spectroscopy shows that by using ionic liquid electrolyte the impedance is less than the case of the sulfuric acid electrolyte. Conclusion: The use of ionic liquid as an electrolyte can increase the sensor sensitivity about 141% with respect to sulfuric acid as the electrolyte, in 0.6 ppm to 10 ppm concentration range of H2S gas. Also, the sensor response to hydrogen sulfide is more than one thousand times greater than its response to carbon monoxide per 1 ppm of gas.

A ratiometric fluorescent chemosensor for the convenient monitoring of hydrogen sulfide concentration by the dual fluorescence fluctuation mode of two distinct emission bands in living cells and zebrafish

An interplaying ICT-FRET-based chemosensor with two response sites having differentiated sensitivities to H2S was engineered to conveniently determine the concentration of H2S by the dual fluorescence fluctuation mode of two distinct emission bands.