Adsorption Of Hydrogen Sulfide Research Articles

Preparation of hydrogen sulfide adsorbent derived from spent Fenton-like reagent modified biochar and its removal characteristics for hydrogen sulfide

Hydrogen sulfide has serious harm to human health and equipment safety. Spent Fenton-like reagent poses a challenge to the environment. In this article, a cost-effective adsorbent was prepared from rice straw biochar modified with spent Fenton-like reagent, and was used to remove gaseous hydrogen sulfide. Effects of several parameters and gas components on hydrogen sulfide adsorption, and hydrogen sulfide adsorption mechanism were studied. Results show that spent Fenton-like reagent modification promotes the rise of active sites on biochar surface, but results in the decline of adsorbent specific surface area. The optimum calcination temperature of adsorbent is 300 °C, and the maximum adsorption capacity for hydrogen sulfide is up to 1000.6 mg/g at 120 °C, which is far more than similar adsorbents. Presence of gas components such as sulfur dioxide, nitric oxide or water vapor inhibits the desulfurization performance of adsorbent to varying degrees. Copper oxide is confirmed to be the key active substance for hydrogen sulfide adsorption on adsorbent, and copper sulphide, cuprous sulfide and elemental sulfur are found to be the main products of hydrogen sulfide removal on adsorbent. The study provides new ideas for utilization of spent Fenton-like reagent and development of cost-effective hydrogen sulfide adsorbent.

2D-MoSe2/0D-ZnO nanocomposite for improved H2S gas sensing in dry air ambience

In this paper, we report on a micro-sensor employing two-dimensional (2D)- zero-dimensional (0D) heterostructure based on MOSe2/ZnO (fabricated by a novel Complementary Metal Oxide Semiconductor (CMOS) compatible microwave-irradiation-assisted solvothermal route) as a receptor. Density Functional Theory (DFT) calculations show that the heterostructure is more favorable to the adsorption of hydrogen sulfide (H2S) gas than the pristine 2D nanosheets. Experimentally, the device demonstrates sensitivity in the ultra-low concentration H2S range (i.e. 200 ppb – 6.1 ppm), and response of as high as 9.08% (200 ppb) - 186.91% (6.1 ppm) could be obtained repeatably with decent signal-to-noise ratio and response/recovery time (~600 sec). The device stands well on various sensor parameter tests including absolute response percentage, lower limit of detection (LOD), repeatability, reproducibility, hysteresis error, etc. A sensing mechanism based on Wolkentein’s model is proposed to understand the detection behavior of the device.

Carbonaceous adsorbent from waste oil fly ash: surface treatments and hydrogen sulfide adsorption potential

Carbonaceous adsorbent from waste oil fly ash: surface treatments and hydrogen sulfide adsorption potential

Biogas purification by adsorption of hydrogen sulphide on NaX and Ag-exchanged NaX zeolites

Biogas is a cheap renewable and eco-friendly alternative energy to fossil fuels. However, biogas is made up of a mixture of gases including hydrogen sulphide (H2S), a corrosive and toxic gas. The current study was carried out to purify biogas by adsorbing H2S on NaX and Ag-exchanged NaX zeolites. Pure crystalline NaX zeolites were synthesized by microwave heating technique. NaX zeolites were then modified following Ag-exchange with various aqueous solutions of AgNO3 (11.5%, 34.1%, 71.6%, 76.7%, and 78.8%) at 40 °C for 2–12 h. Compositional and structural analyses of NaX and Ag-exchanged NaX zeolites were done using powder X-ray diffraction (XRD), elemental analysis, nitrogen adsorption porosimetry, and atomic absorption spectrometry. Anaerobic digestion (AD) was carried out by feeding the digesters with a mixture of 600 mL of dairy manure and 4.0 g L−1 NaX and Ag-exchanged NaX zeolites. An almost complete exchange of Na+ cations by Ag+ cations was observed. The Ag-exchanged zeolites exhibited type I isotherm features with no modification to the shape. A well-dispersed Ag+ ion in the zeolite framework was observed. More H2S was efficiently removed in Ag-exchanged NaX zeolites digesters when compared to that of NaX zeolite. Methane yield was significantly increased from 167.31 (control) to 215.33 (78.8% Ag/NaX) mL g−1 after 48 days. Ag-exchanged NaX zeolites in the current study is a promising adsorbent for H2S removal in biogas.

Core Shell Nanostructure: Impregnated Activated Carbon as Adsorbent for Hydrogen Sulfide Adsorption.

This study focuses on the synthesis, characterization, and evaluation of the performance of core shell nanostructure adsorbent for hydrogen sulfide (H2S) capture. Commercial coconut shell activated carbon (CAC) and commercial mixed gas of 5000 ppm H2S balanced N2 were used. With different preparation techniques, the CAC was modified by core shell impregnation with zinc oxide (ZnO), titanium oxide (TiO2), potassium hydroxide (KOH), and zinc acetate (ZnAC2). The core structure was prepared with CAC impregnated by single chemical and double chemical labelled with ZnAC2-CAC (single chemical), ZnAC2/KOH-CAC, ZnAC2/ZnO-CAC, and ZnAC2/TiO2-CAC. Then, the prepared core was layered either with KOH, TiO2, NH3, or TEOS for the shell. The synthesized adsorbents were characterized in physical and chemical characterization through scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) analyzers. Operation of the adsorber column takes place at ambient temperature, with absolute pressure at 1.5 bar. The H2S gas was fed into the column at 5.5 L/min and the loaded adsorbents were 150 g. The performance of synthesized adsorbent was analyzed through the adsorbent’s capability in capturing H2S gas. Based on the results, ZnAc2/ZnO/CAC_WOS shows a better adsorption capacity with 1.17 mg H2S/g and a 53% increment compared to raw CAC. However, the degradation of the adsorbents was higher compared to ZnAc2/ZnO/CAC_OS and to ZnAc2/ZnO/CAC_WS ZnAc2/ZnO/CAC_OS. The presence of silica as a shell has potentially increased the adsorbent’s stability in several cycles of adsorption-desorption.

Adsorption of Hydrogen Sulfide on 12.5% Ag-Graphene Substrate by Ti, Fe and Ti-Fe Co-Doped:A Dft Study

Adsorption of Hydrogen Sulfide on 12.5% Ag-Graphene Substrate by Ti, Fe and Ti-Fe Co-Doped:A Dft Study

A theoretical study of H2S adsorption and dissociation mechanism on defected graphene doped with Pt

The adsorption and dissociation of hydrogen sulfide (H2S) molecule on Pt or Pt4 cluster doped graphene with different vacancy (VG), as well as their geometric and electronic structures have been investigated by density functional theory (DFT). It has found that H2S and H atom are weakly adsorbed on Pt/Pt4-VG, while HS and S atom are strongly chemisorbed on different surfaces. By using climbing nudged elastic band method (CI-NEB), three elementary processes have been studied: (I) H2S(gas)→H2S(ads); (II) H2S(ads)→HS(ads) + H(ads); (III) HS(ads) → H(ads)+ S(ads). The energy barriers to break the first H–S bond in H2S on four different surfaces (Pt-MVG, Pt-DVG, Pt4-MVG, Pt4-DVG) are 1.69, 0.52, 0.01 and 0.24 eV respectively. In contrast, the energy barriers to break the second H–S bond in HS are 2.34, 1.08, 0.81 and 1.12 eV respectively. It is suggested that the control step of the complete dissociation of H2S is the second H–S bond rupture process. The trend shown in this study reveals that single Pt atom doped defected graphene is favored for adsorption of H2S, but is disadvantage for dissociation. Pt cluster doped defected graphene with bigger vacancy can successfully adsorb and easily eliminate H2S molecule, which is expected to be the ideal material for the adsorption and dissociation.

Adsorption of Hydrogen Sulfide (H2S) from Municipal Solid Waste by Using Biochars

The emission of hydrogen sulfide (H2S) from municipal solid waste is one of the environmental issues that raised the public’s attention and awareness. Exposure to H2S that brings a foul smell of rotten eggs will cause headaches, irritation, dizziness, fatigue, and even death if the concentration of H2S is too high. The study’s goals are to investigate the properties of biochars made from rice hulls, banana peels, and sawdust; to compare the biochars’ physical and chemical properties; and establish the H2S removal efficiency of the three biochars. Biochars derived from rice hull (RHB-500), banana peel (BPB-550), and sawdust (SDB-500) by pyrolysis were used as the adsorbents. The biochar yield, pH, ash content, surface functional group, and morphology of the biochars produced were investigated. In this study, H2S was synthesized by mixing food waste and soil in the experimental column. The H2S produced was reduced by the adsorption method. The removal efficiencies of H2S for each biochar were determined by allowing the synthetic H2S to flow through the two columns that were packed with sand (act as control) and biochars, respectively. All biochars were alkaline, and BPB-550 had the highest pH, followed by SDB-500 and finally RHB-500. The order for removal efficiency of H2S (>94%) is BPB-550 > SDB-500 > RHB-500. Overall, the biochars derived from biomass had a strong ability to act as the adsorbents for H2S removal.

Synthesis of zinc oxide nanoplates and their use for hydrogen sulfide adsorption

Synthesis of zinc oxide nanoplates and their use for hydrogen sulfide adsorption

Advances in Mechanism and Influencing Factors Affecting Hydrogen Sulfide Adsorption by Biochar

Hydrogen sulfide(H2S) is one of the most common gas products from modern industrial processes. It is highly toxic, corrosive, and polluting, and poses harm to both the natural environment and human health if it is not properly removed. Biochar has been widely applied for the treatment of environmental pollution due to its excellent adsorption ability, low cost, and wide choice of source materials. Currently, although studies on hydrogen sulfide adsorption by biochar have attracted increasing attention, the factors involved are complex and varied, leading to a necessity to review and summarize the available knowledge and advances. To bridge the research gap, this paper presents the advances in H2S adsorption by biochar, including properties, influencing factors(i.e., biomass feedstock, pyrolysis temperature, residence time, and particle size), control measures(i.e., humidity, adsorption temperature, operating conditions, and modification of biochar by activation), and adsorption mechanism. The work will provide further reference for the preparation and optimization of biochar adsorption conditions to realize a highly efficient removal of H2S.

Research Progress of Hydrogen Sulfide Adsorption Based on MOFs

AbstractAdsorption method is one of the main technologies for hydrogen sulfide treatment. Developing an adsorbent with good selectivity, large adsorption capacity, stability and good regeneration is the key to the removal of hydrogen sulfide by adsorption method. Compared with the traditional adsorbents, Metal‐organic frameworks (MOFs) have a large specific surface area, a variety of framework structures, adjustable pore sizes and functionality, showing significant advantages in the adsorption of hydrogen sulfide. In this paper, the research progress of hydrogen sulfide adsorption based on MOFs in recent years was summarized. The influences of pore structure and unsaturated metal sites on the hydrogen sulfide adsorption performance of MOFs were discussed, and the strategies of functionalized groups and preparation of composites were proposed to improve the hydrogen sulfide adsorption performance of MOFs. Finally, the problems and challenges in the future industrial application of MOFs as low concentration hydrogen sulfide adsorbents were pointed out.

Hydrogen sulfide occurrence states in China's coal seams

The occurrence states of hydrogen sulfide in coal seams are crucial in preventing and controlling hydrogen sulfide emission in coal mines and the safe development of coal bed methane. In this study, the research status of the occurrence states of free-state, adsorbed-state, and water-soluble hydrogen sulfide in coal seams was systematically analyzed. H2S anomaly areas in China's coal seams are mainly located in the Carboniferous-Permian and Jurassic series of northern, eastern, central, and northwest regions of China. Bacterial sulfate reduction accounts for most of the hydrogen sulfide anomalies of low-rank coal, while thermochemical decomposition thermal desorption spectroscopy and thermochemical sulfate reduction may also result in hydrogen sulfide anomaly in medium- and high-rank coal. In contrast, magmatism-induced hydrogen sulfide anomalies are rarely found. Absorbed-state hydrogen sulfide anomalies are prevailing, while water-soluble and free-state hydrogen sulfide anomalies are relatively scarce. Coal seam's porosity mainly controls the hydrogen sulfide adsorption, pressure, coalification degree, pore volume, and specific area, while water-soluble hydrogen sulfide is influenced by pressure, sulfate-reducing bacteria, burn, porosity, fractures, water temperature, and hydrodynamic conditions. The fractures in coal seams, their burial depth, coal quality, coal rank, roof, and floor lithology are the main factors controlling the free-state hydrogen sulfide preservation. The absorbed-state hydrogen sulfide in coal seams is mainly mitigated by varying the ventilation mode, increasing the ventilation capacity, spraying alkali fog into the air, and injecting alkali liquid into coal seams for governance.

Evaluation of the Impact of Different Natural Zeolite Treatments on the Capacity of Eliminating/Reducing Odors and Toxic Compounds.

Unlike odorants that mask odors, natural zeolite acts as a molecular sieve that captures and eliminates odors. Different treatment methods can be applied to influence the properties of the natural zeolites. To enhance the odor adsorption capacities of the natural zeolite two types of treatment methods were applied: chemical (acid, basic) and thermal. The initial natural zeolites and the activated one were characterized using X-ray diffraction (XRD) and scanning electron microscope (SEM-EDX). Two experiments were performed to establish the odor adsorption capacity of the activated natural zeolites. The best zeolite for the adsorption of humidity, ammonia and hydrogen sulfide was the 1–3 mm zeolite activated through thermal treatment. For the adsorption of PAHs, the best zeolite was the one activated through basic treatment, with an adsorption capacity of 89.6 ng/g.

A density functional theory study of molecular H2S adsorption on (4,0) SWCNT doped with Ge, Ga and B

The molecular adsorption of hydrogen sulfide has been investigated theoretically by using Density Functional Theory for gallium (Ga), germanium (Ge) and boron (B) doped (4,0) single-walled carbon nanotubes (SWCNTs). The method of B3LYP was utilized with basis sets of 6-31G(d,p) and LANL2DZ. Adsorption energy and adsorption enthalpy, HOMO and LUMO energy values, HOMO-LUMO energy gap, chemical hardness, chemical potential, electronegativity and Gibbs free energy values have been evaluated in this study. All doped SWCNT structures have negative Gibbs free energy and adsorption energy values which make these clusters promising for the removal of H2S by adsorption. However, Ge doped SWCNT cluster has the lowest HOMO-LUMO energy gap and chemical potential, highest electronegativity with minimum adsorption energy values when compared to other clusters. Furthermore, it is softer than other metal doped SWCNT clusters due to the lower chemical hardness value.

H2S adsorption on pristine and metal-decorated (8, 0) SWCNT: a first principle study.

Adsorption of hydrogen sulfide (H2S) on the surface of catalytic systems containing (8, 0) single-walled carbon nanotube decorated with Ni and Pd transition metals was investigated using plane-wave density functional theory. SWCNT was modified by adding Ni and Pd atoms to both inside and outside the nanotube and replacing carbon atoms with these metals. All structures were relaxed, and their structural and electronic properties were investigated before and after H2S adsorption and compared with pristine (8, 0) SWCNT properties. Obtained results showed that decorating CNTs with metals increases CNT efficiency for H2S adsorption. The most negative adsorption energies were observed when H2S was adsorbed on the surfaces of metal-decorated nanotube. Electronic properties like band structures and density of states indicated that systems containing Ni on SWCNT are more effective at adsorbing and sensing H2S molecules. Hydrogen sulfide adsorption also changed the magnetization of Ni-decorated structures. Moreover, adsorption of H2S from H side to Ni-decorated SWCNT leads to dissociation of H2S to HS and S atom. Obtained results showed that metal-decorated nanotubes are potentially good candidates for separating H2S from industrial waste gas streams and for its use in H2S sensors.

Molecular simulations of the adsorption and separation of hydrogen sulfide, carbon dioxide, methane, and nitrogen and their binary mixtures (H2S/CH4), (CO2/CH4) on NUM-3a metal-organic frameworks.

In this work, the adsorptions of carbon dioxide, methane, nitrogen, and hydrogen sulfide and the separation of their binary mixtures into NUM-3a Metal-Organic Framework (MOF) were studied through Grand Canonical Monte Carlo (GCMC) simulation method. The simulated pure gas uptakes using three generic force fields (UFF, Dreiding, and OPLS) at 298K were compared with the experimental values. The accuracy of the applied force fields for each gas was compared with the experimental isotherms and discussed. Our results show that OPLS has the best accuracy in the case of methane while Dreiding was the best for CO2 and N2. Simulated gas uptakes indicated that H2S was more adsorbed by NUM-3a than CO2, CH4, and N2. The calculated adsorption selectivity of NUM-3a for the binary mixtures of CH4 with H2S is larger than that of CO2. NUM-3a possess more affinity for H2S and CO2 than for CH4, where it may be a promising adsorbent material for separating carbon dioxide and hydrogen sulfide from methane. Furthermore, the most probable sites for the adsorption of the studied gases on the NUM-3a were investigated. The heats of adsorptions, as well as Henry's law constants, were also calculated, and it was in line with the observed gas adsorptions. The most preferred sites for the adsorption of carbon dioxide and hydrogen sulfide are the carboxyl groups and inside the channels and around the metal centers. However, methane and nitrogen are mainly accumulating in the channels' s apexes of NUM-3a around the metal center.

Impact of Na+ and Ca2+ Cations on the Adsorption of H2S on Binder-Free LTA Zeolites

Hydrogen sulfide is removed from natural gas via adsorption on zeolites. The process operates very effectively, but there is still potential for improvement. Therefore, in this article, the adsorption of hydrogen sulfide was investigated on eight LTA zeolites with different cation compositions. Starting with the zeolite NaA (4 A), which contains only Na+ cations, the Ca2+ cation content was gradually increased by ion exchange. Equilibrium isotherms from cumulative breakthrough curve experiments in a fixed-bed adsorber at 25°C and 85°C at 1.3 bar (abs.) were determined in the trace range up to a concentration of 2000 ppmmol. From a comparison of the isotherms of the different materials, a mechanistic proposal for the adsorption is developed, taking into account the specific positions of the cations in the zeolite lattice when the degree of exchange is increased. The shape of the isotherms indicates two energetically different types of adsorption sites. It is assumed that two mechanisms are superimposed: a chemisorptive mechanism with dissociation of hydrogen sulfide and covalent bonding of the proton and the hydrogen sulfide ion to the zeolite lattice and a physisorptive mechanism by electrostatic interaction with the cations in the lattice. As the degree of exchange increases, the proportion of chemisorption sites seems to decrease. Above an exchange degree of 50%, only evidence of physisorption can be found. It is shown that this finding points to the involvement of weakly bound sodium cations at cation position III in the chemisorption of hydrogen sulfide.

Influence of Surface Characteristics of Palm Shell Activated Carbon Modified with Nanostructured Nickel for Reactive Adsorption of Hydrogen Sulfide

ABSTRACT Hydrogen sulfide (H2S) is a colourless and toxic gas that could harms people and environment. Due to its acidic and toxic properties, H2S cannot be burnt directly, hence it is necessary to remove it. The aim of this work is to study the influence of surface characteristics of modified palm shell activated carbon (PSAC) with Nickel nanoparticles (Ni nps) towards H2S removal. Surface characteristics consist of a combination of various analysis on the adsorbent’s surface such as, surface morphology, surface area, surface porosity, and surface functional groups. The Ni nps were synthesized by using alkaline precipitation method at different synthesis parameters; pH (8 – 10), precipitant molarity (6.5M – 7.5M) and temperature (55◦C – 65◦C). To study the adsorption of H2S, the PSAC adsorbent was modified with the synthesized Ni nps at 400◦C for 3 hours. The performance of modified Ni nps with PSAC (Ni-PSAC) adsorbents were tested in a custom-design H2S scrubber for H2S removal application. The surface characteristics of modified Ni-PSAC adsorbent were analysed by using TGA, TEM, SEM, and FTIR. Among the impregnated adsorbents, Ni-PSAC with pH 10, 6.5 M of precipitant molarity and temperature of 65◦C gives the highest adsorption capacity (9.60 mg H2S/g Ni-PSAC) and breakthrough time (14 minutes) compared to the rest of adsorbents. The introduction of Ni nps in the PSAC adsorbent structures resulted in better H2S removal compared to unimpregnated PSAC adsorbent. The existence of Ni nps help to increase the availability of oxygen vacancies in the adsorbent with the aid of nanostructured added in the adsorbent.

Energetics and stability of hydrogen sulphide adsorption on defective carbon nanotube

Energetics and stability of hydrogen sulphide adsorption on defective carbon nanotube

Energetics and stability of hydrogen sulphide adsorption on defective carbon nanotube

We investigate a new design of the defective zigzag (10,0) carbon nanotube (CNT) as a hydrogen sulphide (H2S) sensor using density functional theory (DFT). Herein, the defective zigzag (10,0) CNT obtained by removing one to five carbon atoms from the pristine zigzag (10,0) CNT to create simultaneously one to five of the single vacancies located around the nanotube axis. The formation energy and the dissociation energy inform us that all defective zigzag (10,0) CNT systems are stable. Then, the adsorption energy shows that these defective systems can adsorb the H2S molecules. Furthermore, an unexpected finding has also been found in this study. The presence of the H2S molecules on the defective (10,0) CNT arises the band gap of these systems.