Desorption Of Sulfur Dioxide Research Articles

CHEMOSORPTION COMPOSITIONS BASED ON PHLOGOPITE FOR LOW-TEMPERATURE AIR PURIFICATION FROM SULFUR DIOXIDE

It is known that a large amount of sulfur dioxide is released into the atmosphere during the production of sulfuric acid, the combustion of metal sulfides at non-ferrous metallurgy enterprises, during the burning of coal containing sulfur, at thermal power plants, and in many other industries. In the air of industrial companies, its concentrations often significantly exceed the maximum allowable concentration (10 mg/m3 for the working area), despite the use of equipment for the sanitary treatment of exhaust gases. Therefore, there is a need to develop highly effective personal protection equipment of workers’ respiratory organs against sulfur dioxide in the form of respirators or gas masks. For their production, it is necessary to create cheap, affordable and reliable sorbents. A large number of methods for cleaning air and exhaust gases from sulfur dioxide are known. Among them, a special place is occupied by methods based on the use of nitrogen-containing bases, for example, urea, mono-, di- and triethanolamines, hydrazine, hydroxylamine, and hexamethylene tetramine (HMTA). Therefore, the use of aqueous solutions of nitrogen-containing bases as active components of sulfur dioxide chemosorbents is quite promising. However, their use in respiratory personal protection equipment, which would work according to the principle of using the absorption process, is quite difficult. Therefore, we made an attempt to impregnate a porous medium, as natural flagopite, with aqueous solutions of HMTA and NaOH. It was determined using X-ray phase analysis, that natural phlogopite, in addition to the main phlogopite phase, contains various impurities, such as diopside, vermiculite, clinochlore, and cordierite. To establish the type of adsorption, the adsorption and desorption of sulfur dioxide by natural phlogopite was studied. It has been proven that sulfur dioxide is weakly bound to the surface of natural phlogopite, that is, its physical adsorption mainly occurs. The perspective of using natural and chemically modified phlogopite for chemisorption neutralization of sulfur dioxide, provided its low concentration (150 mg/m3) in the air, is shown. It was established that monocomponent compositions based on NaOH and HMTA fixed on natural phlogopite absorb sulfur dioxide, but under the condition of their combined action at a certain ratio of components, a synergistic effect is observed, which is manifested in an increase in the time of the protective effect and adsorption capacity of the compositions.

Sulfur Dioxide Desorption Characteristics of Basic Alkali Aluminum Sulfate Desulfurization Rich Liquid by Falling Film Evaporation with a Spring Tube

This paper presented a novel technology for the desorption of SO2 in the basic aluminum sulfate solution (BASS) by falling film evaporator with spring tube. The liquid film falling along the internal surface of the evaporation tube was heated by the steam outside. The desorption performances of the vertical single falling film evaporators with spring tube and smooth tube were comparatively investigated. The film distribution on the inner surface of the two tubes were also analyzed through visualization experiments. Compared with the smooth tube, the spring tube was found to be much better in heat transfer and mass transfer. Thus, analysis on the operating parameters for the desorption of SO2 was performed only in the spring tube. The results showed that the flow rate of BASS rich in SO2, heating steam temperature, vacuum of the system, and initial concentration of SO32– played important roles in the desorption performance.

Guanidinium-based ionic liquids for sulfur dioxide sorption

Three guanidinium-based ionic liquids (GBILs) including [1,1,3,3-tetramethylguanidinium][phenol] ([TMG][PHE]), [1,1,3,3-tetramethylguanidinium][2,2,2-trifluoroethanol] ([TMG][TE]) and [1,1,3,3-tetramethylguanidinium][imidazole] ([TMG][IM]) were synthesized and their absorption and desorption of sulfur dioxide were investigated, respectively. The saturated molar ratio of SO 2 to GBILs varied from 2.24 to 3.16 at 40 °C with high absorption rate. The absorption mechanism might be that SO 2 reacts with the –NH 2 group on the cation and then a new –SO 2H group is formed. The new GBILs could absorb SO 2 by both physical and chemical interactions while physical absorption does play an important role at the experimental conditions under investigation.

A DFT study on the removal of adsorbed sulfur from a nickel(111) surface: Reducing anode poisoning

This report presents the results of our studies on the second step of the post-treatment of the solid-oxide fuel cells (SOFCs) that have been poisoned by sulfur from traces of H 2S in the fuel. The removal of strongly adsorbed atomic sulfur from a planar Ni(111) surface at 0.25 ML coverage is investigated in order to explore possible ways to regain the activity of SOFCs poisoned by sulfur deposition on the anode. The predominant reaction pathway studied consists of the adsorption and dissociation of molecular oxygen, followed by the formation and desorption of sulfur dioxide. Using periodic DFT calculations, preferred adsorption sites, energies, transition states and kinetic barriers are calculated for the resulting intermediate and product species, SO x ∗ ( x = 0 – 2 ) and ∗O. Generally, concurring with the limited experimental data available at temperature >750 K, our research illustrates the considerable exergonic nature that describes the formation and desorption of SO 2, and shows that the removal of the remaining 25% of sulfur after the first step of post-treatment of the fuel cell can be accomplished by means of high-temperature oxidation.

Sulfur dioxide absorption and desorption by water drops

A new model is developed for the absorption and desorption of sulfur dioxide by drops falling through air containing a low concentration of it. The model predictions are compared with published experimental results. We observe that whatever the type of absorption or desorption experiments is, the present model fits the experimental results.

Adsorption of sulfur dioxide by active carbon treated by nitric acid: II. Effect of preheating on the adsorption properties

The adsorption and desorption of sulfur dioxide by active carbon, treated by nitric acid and followed by heating at 200–1000 °C, were studied. The HNO 3 treated carbon has a higher adsorption capacity for sulfur dioxide, than the untreated carbon, in spite of its lesser basicity. This may be the result of interaction of the SO 2 with the oxygenated surface groups of acidic character. Water promotes the adsorption of SO 2. Heating results in a decrease of the carbon acidity because of decomposition of the surface oxygenated structures. It also leads to an increase of basicity resulting from the formation of basic sites. These changes of the carbon acid-base properties are particularly pronounced for the HNO 3 treated carbon due to higher concentration of the surface oxygenated groups. The increased basicity promotes adsorption of SO 2 and inhibits desorption by an acid-base mechanism different from the mechanism of adsorption on the carbon, which has not been preheated.

Manganese(II) Complexes Containing Polystyryl Diphenylphosphine Oxide as Ligand and their Reactivity with Sulfur Dioxide.

The ligand polystyryl diphenylphosphine oxide (L) and several manganese(II) complexes with empirical formulae MnLmX2·nH2O and MnLmSO4·3H2O (m = 2, 3; n=1-4; X=Cl, Br, I, NCS, NO3) have been synthesised and characterised. The absorption of sulfur dioxide by these complexes has been examined in the solid state, at room temperature and in the 230-30 °C temperature range, and also in SO2-saturated toluene suspensions. After the interaction between sulfur dioxide and metallic complexes some air-stable SO2 adducts of accurate formulae could be isolated. Nitrate complexes appear to exhibit distinct behaviour due to an additional reaction with SO2; viz. nitrate ions appear to be replaced by sulfate ions in the SO2 adducts. Sulfur dioxide desorption was studied for SO2 adducts by heating at 16O °C under reduced pressure for 1 h or at 300 °C for about 15 min at atmospheric pressure. © Acta Chemica Scandinavica 1997.

Adsorption of sulfur dioxide on coal reject-derived chars

Adsorption and desorption of sulfur dioxide onto coal reject-derived char particles are experimentally investigated using a TGA technique. Both equilib