Modification of Carbon Nanotubes for H2S Sorption

Thermodynamic Characteristics of the Hydrogen Sulfide Sorption Process by Ferromanganese Materials

The work analyzes hydrogen sulfide sorption from model gas mixtures containing H₂S from 1.25 × 10^-3 to 1.28 × 10^-4 mol/L under static conditions at temperatures 253 and 298 K on the raw manganese ore of the Ulu-Telyak deposit (Bashkortostan, Russia), manganese(IV) oxide, and manganese(IV) and iron(III) oxide mixtures. The thermodynamic models for calculating the equilibrium constants and Gibbs energy changes were analyzed. The sorption isotherms were described by the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models. The value of enthalpy of hydrogen sorption on the ore was -68.98 ± 3.45 kJ/mol and those on model mixtures Mn₄ + Fe₂O₃ and MnO₄ were ±12.20 kJ/mol and -103.826 ± 5.19 kJ/mol, respectively, and the entropies of the hydrogen sulfide sorption process on three manganese materials at 253 K were calculated. The limiting capacity values of manganese materials at 253 and 298 K were obtained. The morphological analysis of the ore samples, Mn₄ + Fe₂O₃, and MnO₄, before and after hydrogen sulfide sorption, was carried out at 253 K. The obtained thermodynamic parameters determine the advantage of using the raw manganese ore over pure oxides, which characterizes its effective practical application in the desulfurization process.

Electrospun PU nanofiber composites based on carbon nanotubes decorated with nickel-zinc ferrite particles as an adsorbent for removal of hydrogen sulfide from air

This study focuses on the synthesis of carbon nanotubes decorated with nickel-zinc ferrites and fabrication of polyurethane (PU) nanofiber containing CNT-ferrite composites as highly efficient adsorbents for removal of hydrogen sulfide. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR) spectroscopy, and powder X-ray diffraction (PXRD) are used to perform microstructural and morphological characterization of the electrospun nanofibrous composites. To show the efficiency of the composite as an adsorbent, a breakthrough test is carried out. It is shown that the PU-CNT-ferrite composites are fabricated almost uniformly with an average fiber diameter of 320 nm and exhibit significant H₂S breakthrough capacity (498 mgH₂S/g) compared to both the pristine PU and PU-CNT nanofibers. These electrospun nanofibers based on CNT-ferrite composites, already studied for H₂S adsorption with promising results, open up new and interesting perspective into the design and fabrication of highly efficient membrane for practical application in the processes of air purification.

Effective removal of hydrogen sulfide using 4A molecular sieve zeolite synthesized from attapulgite

In this work, 4A molecular sieve zeolite was synthesized from attapulgite (ATP) in different conditions and was applied initially for H₂S removal. The sorbent was characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectra and N₂ adsorption/desorption. The effects of the synthesis condition and adsorption temperature were studied by dynamic adsorption experiment. The optimal adsorption temperature is 50°C. The H₂S adsorption results have showed that the optimal synthesis conditions are as follows: the ratio of silicon to aluminum and ratio of sodium to silicon are both 1.5, the ratio of water to sodium is 30, crystallization temperature and crystallization time is 90°C, 4h, respectively. The breakthrough and saturation sulfur sorption capacities of zeolite synthesized under optimum conditions are up to nearly 10 and 15mg/g-sorbent, respectively, and the H₂S removal rate is nearly 100%. The adsorption kinetics nonlinear fitting results show that the adsorption system follows Bingham model. These results indicate that 4A molecular sieve zeolite synthesized from attapulgite can be used for H₂S removal promisingly.