Removal Of Hydrogen Sulfide Research Articles

Use of chicken feathers as potential adsorbent for the reclamation of industrial lean methyl diethanolamine solutions

ABSTRACT Sweetening units using methyl diethanolamine (MDEA) solvent are instrumental in removing hydrogen sulfide and carbon dioxide from natural gas. However, over time MDEA degrades and loses its scavenging efficiency due to the formation of heat-stable salts (HSS) that are hard to remove. Chicken feathers (CFs), a poultry waste by-product, are rich in functional groups that could help to remove HSS from alkanolamine solutions. CFs were characterized using XRD, SEM-EDX, TGA, DSC, and BET. FTIR spectroscopy analysis confirmed the presence of hydroxyl and amide groups that were responsible for the total organic acid (TOA) anions adsorption. The Freundlich model best fitted the equilibrium adsorption data with a maximum uptake capacity of 525 mg/g at 298 K. Kinetic analysis showed that the Pseudo-Second-Order model best fitted results with a rate constant of 0.0006 min−1. The equilibrium thermodynamic study showed that the biosorption process was spontaneous. CFs exhibited good recyclability and high TOA uptake capacity even after five cycles using absolute ethanol as the eluent, maintaining 88% of the adsorption ability. The results demonstrated that CFs could be employed as a low-cost alternative to commercial activated carbon absorbents that are currently used to clean industrial lean MDEA aqueous solutions from their HSS contaminants.

A Retrospection of Hydrogen Sulphide Removal Technologies in Biogas Purification

A Retrospection of Hydrogen Sulphide Removal Technologies in Biogas Purification

Effective removal of hydrogen sulfide using Mn-based recovered oxides from recycled batteries

The use of clean and environmentally friendly renewable energy as well as the minimization of waste disposal are fundamental aspects to be considered nowadays in a circular economy approach. In this way, the development of efficient systems for sulfur removal in biomass and waste gasification is of key relevance and the use of recycled materials will provide an opportunity to combine the reduction of waste‘s production and the application of circular economy principles.Sorbents from waste powder of recycled batteries have been prepared at laboratory scale. Subsequently, their potential application to syngas cleaning is evaluated specifically for H2S removal. Lab-scale tests at 400°C, 10 bar and space velocity of 3500 h−1 were carried out using first a simplified gas mixture of 0.9% H2S in N2 and then a more complex one consisting of 20% H2, 40% CO and 0.45% H2S/N2 to investigate the effect of reducing components, CO and H2 co-existing with H2S in any syngas. Sorbent utilization values as high as 80% (w/w, %) were obtained when tested under realistic syngas composition. XRF, XRD, XPS, TEM and textural characterization results of fresh and sulfided samples showed that those materials with higher Mn contents showed higher H2S removal capacity although the Mn/Zn ratio demonstrated to play a crucial role in their selectivity to form sulfides. Additionally, plausible mechanisms for H2S removal are discussed where the influence of composition, structure and morphology of the recovered binary metal oxides on sulfur removal efficiency is analysed.

Hydrogen sulfide removal technology: A focused review on adsorption and catalytic oxidation

The principal technologies for H2S removal are reviewed herein. Two technologies in particular, adsorption and catalytic oxidation, are considered as promising for desulfurization in terms of process simplicity, H2S removal performance, and operational cost. Nanoporous materials such as activated carbons, zeolites, mesoporous silicas, and metal organic frameworks are extensively used as sorbents because their porous characteristics are suitable for efficient diffusion and capture of H2S. To improve the H2S adsorption performance, these materials are frequently modified with functional groups or doped with various metal oxides. For example, representative metal oxide-based catalysts (e.g., vanadium, magnesium, and iron oxides) have been investigated for the selective oxidation of H2S to elemental sulfur. In this context, the dispersion of active metals onto supports, or the addition of modifying metals, are reasonable strategies for inhibiting catalyst deactivation and enhancing catalytic activity. Emerging studies based on the combination of adsorption and catalytic oxidation have introduced the syntheses of dual-function materials, such as metal nanoparticle-dispersed or metal-free porous carbons. In conclusion, comprehensive research into catalyst synthesis and performance evaluation must continue in order to develop the most promising technology for H2S removal.

Simultaneous hydrogen sulfide removal and wastewater purification in a novel alum sludge-based odor-gas aerated biofilter

A novel alum sludge-based odor-gas aerated vertical flow biofilter (Al-OAF) was developed, which aims to removal the pollutants in wastewater and simultaneously to eliminate H2S generated from wastewater treatment facility. Three lab-scale parallel columns were operated in batch model while intermittently aerated with 200 ppm H2S (Al-OAF), air (Al-AF) and unaerated (Al-F, as blank), respectively. The pollutants in wastewater and the effluent H2S concentration from Al-OAF were monitored regularly. Results showed that three columns presented a high removal efficiency (>98%) of total phosphorus (TP) and a completed removal of H2S (100%) in Al-OAF. Al-OAF and Al-AF could enhance the removal efficiency of chemical oxygen demand (COD) of 94.3 ± 3.0, 94.8 ± 1.9%, and total nitrogen (TN) of 86.2 ± 14.2, 91.6 ± 5.4%, respectively. In particular, there was no significant difference regarding the COD, TN removal performances between the “H2S driven” Al-OAF and the “air driven” Al-AF. The H2S removal mechanism lies in the alum sludge ability of H2S adsorption and the reaction by the biofilm in the biofilter. This demonstrates that the novel Al-OAF (aerated with waste gas) would be a promising “wise choice” for intensified biofilter with dual-goals of simultaneous wastewater purification and H2S elimination.

A simple model for estimating hydrogen sulfide solubility in aqueous alkanolamines in the high pressure-high gas loading region

Hydrogen sulfide is essentially removed from the raw natural gas to meet the process, health, safety and environmental standards. Alkanolamine based absorption process remains the prevalent technique for hydrogen sulfide removal due to ease of operation and economic considerations. The design of such gas separation systems is a critical factor in meeting the stringent process requirements and optimizing operations. To achieve precise design, determination of vapor–liqid equilibrium for the system is indispensable while maintaining efficacy and simplicity. This study presents a simple model for estimating hydrogen sulfide solubility in aqueous alkanolamines and their blends in the high pressure-high gas loading region. The model equation is developed by considering and combining amine protonation and bi-sulfide formation reactions, assuming ideal liquid properties. Satisfactory correlated values of hydrogen sulfide loadings (0.21–3.15 mol gas/mole solvent) are obtained over a wide range of temperature (298.15–393.15 K), pressure (60–7027 kPa) and alkanolamine concentration (1.12–14.27 molal). Parameters are given for the hydrogen sulfide solubility in aqueous solutions of monoethanolamine, diethanolamine, N-methyldiethanolamine, 2-amino-2-methyl-1-propanol, piperazine, diglycolamine, di-isopropylamine, 1-amino-2-propanol and their selected blends. The model shall be useful for the design of alkanolamine based natural gas sweetening systems, operating at high pressure and high hydrogen sulfide gas loadings.

Simultaneous phosphorus recovery, sulfide removal, and biogas production improvement in electrochemically assisted anaerobic digestion of dairy manure

Anaerobic digestion (AD) produces renewable biogas from organic-rich waste streams, but the resultant digestate has to be subject to further nutrient recovery processes for better valorization. In this study, an electrochemical treatment unit using stainless steel mesh electrodes was integrated with an up-flow anaerobic sludge blanket (UASB) reactor to treat liquid dairy manure for simultaneous phosphorus (P) recovery, methane production improvement, and hydrogen sulfide (H2S) removal. The 36-d batch AD trial showed that a large portion of total P and reactive P were removed from the liquid dairy manure and were recovered mainly on the cathode deposits in the form of phosphate-bearing minerals. In the continuous USAB trial with an applied voltage of 1.0 V, 65.1% of the total P in the feeding manure was removed, of which 96.7% was achieved by sludge bed accumulation and 3.3% in the cathode deposit. Increases in both biogas production rate (13.0%) and methane yield (10.9%) were observed in the electrochemically assisted UASB system as compared to the one without electrochemical treatment. The electrochemical assistance helped decrease the H2S concentration in biogas by 20.8% at an applied voltage of 0.5 V and by 50.3% at 1.0 V. This electrochemically assisted UASB system can produce more biogas with less H2S content and recover P-enriched sludge in the sludge bed and the cathode deposit.

Effect of pH on the performance of an acidic biotrickling filter for simultaneous removal of H2S and siloxane from biogas.

Acidic biotrickling filters (BTF) can be used for simultaneous removal of hydrogen sulfide (H2S) and siloxane from biogas. In this study, the performance of a BTF under different acidic pH conditions was investigated. The removal profile of H2S showed that 90% of H2S removal was achieved during the first 0.4 m of BTF height with down-flow biogas. Decamethylcyclopentasiloxane (D5) removal decreased from 34.5% to 15.6% when the pH increased from 0.88 to 3.98. Furthermore, the high partition coefficient of D5 obtained in under higher pH condition was attributed to the higher total ionic strength resulting from the addition of sodium hydroxide solution and mineral medium. The linear increase in D5 removal with the mass transfer coefficient (kL) indicated that the acidic recycling liquid accelerated the mass transfer of D5 in the BTF. Therefore, the lower partition coefficient and higher kL under acidic pH conditions lead to the efficient removal of D5. However, the highly acidic pH 0.9 blocked mass transfer of H2S and O2 gases to the recycling liquid. Low sulfur oxidation activity and low Acidithiobacillus sp. content also deteriorated the biodegradation of H2S. Operating the BTF at pH 1.2 was optimal for simultaneously removing H2S and siloxane.

Valorization of Raw and Calcined Chicken Eggshell for Sulfur Dioxide and Hydrogen Sulfide Removal at Low Temperature

Chicken eggshell (ES) is a waste from the food industry with a high calcium content produced in substantial quantity with very limited recycling. In this study, eco-friendly sorbents from raw ES and calcined ES were tested for sulfur dioxide (SO2) and hydrogen sulfide (H2S) removal. The raw ES was tested for SO2 and H2S adsorption at different particle size, with and without the ES membrane layer. Raw ES was then subjected to calcination at different temperatures (800 °C to 1100 °C) to produce calcium oxide. The effect of relative humidity and reaction temperature of the gases was also tested for raw and calcined ES. Characterization of the raw, calcinated and spent sorbents confirmed that calcined eggshell CES (900 °C) showed the best adsorption capacity for both SO2 (3.53 mg/g) and H2S (2.62 mg/g) gas. Moreover, in the presence of 40% of relative humidity in the inlet gas, the adsorption capacity of SO2 and H2S gases improved greatly to about 11.68 mg/g and 7.96 mg/g respectively. Characterization of the raw and spent sorbents confirmed that chemisorption plays an important role in the adsorption process for both pollutants. The results indicated that CES can be used as an alternative sorbent for SO2 and H2S removal.

Performance and mechanism of hydrogen sulfide removal by sludge-based activated carbons prepared by recommended modification methods

The sludge-based activated carbons (SACs) were prepared by sewage sludge and corn straw and modified by ferric nitrate. The H2S removal performance and the desulfurization mechanism of the modified SAC were studied. Results showed that breakthrough sulfur capacity and saturation sulfur capacity of the SAC prepared by recommended modification were 27.209 mg/g and 48.098 mg/g, which were as 4.68 times and 7.02 times larger as those before modification, respectively. Additionally, results showed that the desulfurization products of unmodified SAC were mainly sulfur, while that of modified SAC were mainly sulfate. These results indicated that ferric nitrate modification changed the way of hydrogen sulfide removal by SAC: the desulfurization process of unmodified SAC can be expressed as S2- → S0 → S4+ → S6+, and the oxidative active component was dominated by O*, while that of modified SAC can be expressed as S2- → S0 → S6+, and the oxidative active components are both Fe3+ and O*.

Fabrication of coral-like Mn2O3/Fe2O3 nanocomposite for room temperature removal of hydrogen sulfide

In this study, coral-like Mn2O3/Fe2O3 nanocomposite was synthesized by a surfactant-mediated co-precipitation method. The XRD patterns confirmed the formation of a nanocomposite of Mn2O3/Fe2O3 with no trace of MnFe2O4. The surface area of the nanocomposite was 6.18 m2 g−1. The metal oxide adsorbents were studied for the adsorptive removal of H2S gas at ambient conditions. The Mn2O3/Fe2O3 nanocomposite showed the highest adsorption capacity of 11.97 mg g−1 for 0.75 g of adsorbent and 0.2 L min−1 of H2S flowrate. The XPS analysis confirmed the presence of sulfur majorly in the form of sulfate ions with elemental sulfur and sulfide ions as minor contributors. The XRD pattern showed complete disappearance of Mn2O3 with the evolution of new peaks for two spinel phases with possible S2− doping. The study confirmed that the transition metal oxide nanocomposite could be used for removal of H2S at room temperature.

Corrosion of Sulfur Removal Tanks Used in the Processing of Landfill Gas

Stainless steel tanks used in processing landfill gas experienced significant, accelerated corrosion leading to their sudden removal from service and unplanned operational downtime. A root cause investigation limited to visual and microscopic examination and EDS analysis was conducted on sections of the tank walls and confirmed under-deposit corrosion was the primary corrosion mechanism. Non-regenerable H2S removal media was used to remove hydrogen sulfide from the landfill gas and had direct contact with the tank walls, creating crevice-like regions where localized corrosion could take place. The corrosion mechanism was driven by sulfur, despite the presence of chloride in the H2S removal media. Corrosion products containing high levels of sulfur confirmed that hydrogen sulfide combined with moisture in the landfill gas formed an aggressive, corrosive environment that led to the formation of pits.

Study on the removal of hydrogen sulfide from natural gas by titanosilicite zeolite

The presence of hydrogen sulfide in natural gas will reduce the calorific value of natural gas, so hydrogen sulfide in natural gas needs to be removed. Titanosilicalite zeolite is a stable porous material with good catalytic effect and has attracted much attention due to its excellent catalytic oxidation performance in the system composed of it and hydrogen peroxide. Therefore, in this paper, the removal of hydrogen sulfide in natural gas was studied by using titanosilicalite zeolite as catalyst and hydrogen peroxide as oxidant, and the mixture of hydrogen sulfide and nitrogen gas was used as the simulated gas of natural gas. The experimental results show that the titanosilicite zeolite has a good catalytic effect on hydrogen sulfide. The influence of the concentration of hydrogen peroxide, reaction temperature and pH of the initial solution in the process of removing hydrogen sulfide by titanosilicalite zeolite was studied.

Key parameters influencing hydrogen sulfide removal in microaerobic sequencing batch reactor

In industry, microaeration is often used for the removal of hydrogen sulfide (H2S) from biogas in full-scale biogas plants. This strategy is very successful when applied in a continuous stirred tank reactor (CSTR), but, due to the fluctuating concentration of H2S in biogas, it is challenging to achieve consistently high H2S removal in an sequencing batch reactor (SBR) or intermittently mixed and/or fed CSTR. To optimize air/oxygen dosing, key parameters influencing the biochemical removal of H2S under microaerobic conditions must be quantified. Here, a lab-scale microaerobic SBR was operated under mesophilic conditions to assess these parameters. In parallel, a mathematical model describing the kinetics of sulfur transformation was developed in AQUASIM software. The experimental data were used to calibrate the model. Subsequent sensitivity analysis identified the liquid-to-gas mass transfer coefficient and biofilm area as the key parameters. We show that the optimization of these parameters is crucial if microaeration is to be successfully utilized for H2S removal from biogas in intermittently mixed reactors.

Fabrication of Cu(BDC)0.5(BDC-NH2)0.5 metal-organic framework for superior H2S removal at room temperature

A mixed ligand Cu-based MOF, Cu(BDC)0.5(BDC-NH2)0.5 was synthesized by a rapid ultrasonication method for the adsorptive removal of hydrogen sulfide (H2S) gas at room temperature. The MOF has a sheet-like morphology with 100 nm thickness crystallized in the monoclinic symmetry (a = 11.27 Å, b = 14.82 Å, c = 7.95 Å, β = 110.8°) with C2/m space group. The surface area and pore volume was 19.4 m2 g−1 and 0.024 cm3 g−1, respectively. The XPS analysis confirmed a near equal proportion of Cu(I) and Cu(II)-sites in the MOF. The MOF showed the H2S adsorption capacity of 128.4 mg g−1 for 500 ppm of H2S flowing at a rate of 100 mL min−1, which is among the highest values reported for Cu-based MOFs. The spent MOF was regenerated by a methanol and UV-irradiation method, which significantly improved the adsorption capacity. The H2S adsorbed onto the MOF by breaking Cu-carboxylate bonds with the formation of covellite CuS nanoparticles and sulfates. The spectroscopic analysis predicted a Cu(OH)-type sites after UV-irradiation along with increased surface area, which were responsible for an enhanced adsorption capacity of the regenerated sample.

Synthesis and characterization of physicochemical properties of imidazolium-based ionic liquids and their application for simultaneous determination of sulfur compounds

Three types of imidazolium-based ionic liquids (IMILs) were synthesized and characterized by 13C and 1H NMR, FT-IR, and elemental analysis. Thermal stability and physicochemical properties of prepared IMILs were measured in the temperature range of 283.15 to 363.15 K. The physicochemical results revealed the entirely temperature-dependent properties and quietly decreasing through increasing the temperature. Electrochemical studies of the IMILs were also performed at the surface of screen-printed electrode cells. Consideration of these properties and determining the unique abilities of IMILs will help researchers through modern applications like liquid-liquid extraction, particular tasks of scavenging and removal of hydrogen sulfide and thiols from petroleum matrices.

A solid oxide fuel cell fuelled by methane recovered from groundwater

This study investigates the feasibility of electricity production in a solid oxide fuel cell using methane recovered from groundwater as the fuel. Methane must be removed from groundwater for the production of drinking water to, amongst others, avoid bacterial regrowth. Instead of releasing methane to the atmosphere or converting it to carbon dioxide by flaring, methane can also be recovered by vacuum stripping and served as a fuel. However, the electrical efficiency of currently used combustion-based technologies fuelled with methane-rich gas is limited to 35% due to the low heating value of the recovered gas (70 mol. % methane) and power derating due to the presence of carbon dioxide (25 mol.%). We propose to use a solid oxide fuel cell to use the methane-rich gas as fuel. Solid Oxide Fuel Cells are fuel-flexible and potentially attain higher electrical efficiencies up to 60%. To this end, specific gas processing, including cleaning and methane reforming, is required to allow for durable operation in a solid oxide fuel cell. We assessed whether electricity could be generated by a solid oxide fuel cell using methane recovered from a full-scale drinking water treatment plant as a fuel. The groundwater had a methane concentration of 45 mg∙L-1, and the recovered gas by vacuum towers contained 70 mol% methane. We used a gas cleaning reactor with impregnated activated carbon to remove hydrogen sulfide traces from the methane-rich gas. Thermodynamic calculations showed that additional steam is required to achieve a high methane reforming. The added steam and the carbon dioxide content in the recovered gas simultaneously contribute to the methane reforming to prevent carbon deposition. The measured open circuit potential corresponded with the theoretical Nernst voltage, implying high methane reforming in the solid oxide fuel cell. The achieved power density of the cell fuelled with the methane-rich gas (mixed with steam) was 27% less than the hydrogen-fuelled cell. Ultimately, 51.2% of the power demand of the plant can be covered by replacing the gas engine in a drinking water treatment with a 915 kW solid oxide fuel cell system fuelled by the methane recovered from the groundwater, while the greenhouse gas emission can be reduced by 17.6%.

Hydrogen sulfide removal from natural gas using membrane technology: a review

In this review, the H2S/CH4 separation properties of polymer membranes are presented and a new upper bound is proposed. In view of the existing problems and development prospects of various membranes, the corresponding opinions and advices are given.

Hydrogen sulfide removal from wastewater using hydrogen peroxide in-situ treatment: Case study of Moroccan urban sewers

Problems of sewers corrosion and odor release are always associated to sulfide presence in waste water. This inorganic compound can occur under different oxidative states such as HS−, S2− SO42− and H2Sliq. However, the emission of hydrogen sulfide is due to the presence of H2SLiq only. The purpose of this paper is to study the effect of peroxide treatment on sulfide abatement in Moroccan sewage in Casablanca city. A field study was carried out to evaluate the oxidation of hydrogen sulfide by hydrogen peroxide (35%) in two sewer lines. The dosage was intermittent; sulfide concentration in both gaseous and aqueous form was monitored as well as COD. The main findings report that hydrogen peroxide decreases remarkably the hydrogen sulfide emission to achieve 4 and 7 ppm in sewer line 1 and sewer line 2, respectively. As for sulfide in aqueous phase, its concentrations reached 0.3 and 1.7 mg S/l in sewer line 1 and sewer line 2, respectively. COD removal efficiency is around 30%. However, it is worth mention that an additional amount of peroxide may be needed during pumping events.

Catalytic Conversion for Hydrogen Sulfide

In this study, a series of transition metal mono-substituted heteropoly compounds H7PMo11MO39 (M = Co2+, Mn2+, Ni2+ and Zn2+) (HPMo11M) and single-absent heteropoly compounds H3PMo11O39 (HPMo11) were prepared for highly effective removal of hydrogen sulfide (H2S) from gas stream. The heteropoly compounds were characterized Fourier transform infrared spectroscopy (FT-IR), elemental analysis and scanning electron microscopy (SEM). The results confirmed that the transition metal ions successfully replaced the Mo atom. H7PMo11CoO39 showed that the outstanding desulfurization capacity and the H2S removal efficiency can reach more than 90% for 3 h. Besides, after regeneration, the desulfurization capacity of H7PMo11CoO39 towards H2S only a drop of 5.11% of the initial desulfurization capacity. Optimization experiments demonstrated that H7PMo11CoO39 had the ideal desulfurization performance under the condition of low H2S concentration or high dosage of H7PMo11CoO39. An appropriate temperature of 25°C is necessary for high removal efficiency. The optimum pH value for desulfurization is 5. The kinetic data can be well described by pseudo-first-order kinetic model. The desulfurization products were proved to be S and SO42– based on X-ray photoelectron spectroscopy (XPS) characterization results.