To develop an advanced desulfurization process that can be carried out under mild conditions without pressurized hydrogen or catalysis that has been evaluated for the extraction of thiophenic sulfur ...from a model fuel using the ionic liquids, 1-alkyl-3-alkyl imidazolium alkyl sulfate at room temperature was investigated. Six types of halogen-free ionic liquids with different alkyl chain lengths were prepared. The extraction yield of dibenzothiophene was higher than that of diphenylsulfide and diphenyldisulfide. The extraction yield of dibenzothiophene increased linearly with an increase in the length of alkyl chains and the mass ratio of the ionic liquid to the model fuel. The effect because of the change in the type of solvent was not appreciable, and dibenzothiophene was efficiently removed regardless of whether tetralin, benzene, or n-dodecane was used as the solvent.
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•The effect of ultrasound and LMNO on reduction of Au3+ to Au NPs are determined.•Au NPs are successfully deposited on a 5-V-class cathode material using ultrasound.•Ultrasound is ...superior to stirring for dispersing Au NPs on LMNO/C.•Au NP deposition using ultrasound improves the electronic conductivity of LMNO/C.
LiNi0.5Mn1.5O4 (LMNO) has attracted considerable attention as a Li-ion battery cathode material, owing to its high discharge voltage of 4.7 V (vs. Li/Li+) and high energy density. However, the electronic conductivity of LMNO is low, resulting in a low discharge capacity at high current density. To overcome this limitation, we deposited Au nanoparticles (NPs), which have a high conductivity and chemical stability at high battery voltages, on carbon-coated LMNO (LMNO/C) using ultrasound irradiation. Consequently, Au NPs that are ∼16 nm in size were deposited on LMNO/C, and ultrasound irradiation was reported to disperse the NPs on LMNO/C more effectively than stirring. Furthermore, the deposition of Au NPs on LMNO/C using ultrasound irradiation improved its electronic conductivity, which is related to an increase in the discharge capacity due to the reduction of Ni4+ to Ni2+ in LMNO/C at a high current density.
Adsorption of mercury from aqueous solution on sulfur-impregnated adsorbent has been studied. Raw coal was mixed with K
2S powder, and then heated at 800–1000
°C for 30
min in nitrogen to produce ...sulfur-impregnated adsorbent. The sulfur content and specific surface area of the adsorbent were determined, and the ability of the adsorbent to adsorb mercury in aqueous solution was examined. With increasing temperature of sulfur-impregnation, specific surface area of the adsorbent increases, while sulfur content of the adsorbent is almost constant. The adsorbent obtained at 900
°C shows the highest and fastest adsorption of mercury from aqueous solution at 25
°C, and the elution extents of adsorbed mercury are negligible in distilled water and 10% in 0.1
M HCl solution, respectively. Adsorption kinetics was tested for pseudo-first order and pseudo-second order reactions, and the rate constants of adsorption for these kinetic models were calculated. Adsorption experiments demonstrate that the adsorption process corresponds to pseudo-second-order kinetic model than pseudo-first-order model. With increasing temperature of aqueous solution, the kinetics of adsorption becomes faster and the amount of mercury adsorbed on the adsorbent increases. The thermodynamic values, Δ
G
0, Δ
H
0 and Δ
S
0, indicated that adsorption was an endothermic and spontaneous process.
► Sulfur-impregnated adsorbent prepared from coal with K
2S. ► application of mercury removal from aqueous solution. ► Adsorption of mercury is highest and fastest for the adsorbent prepared by pyrolysis at 900 °C. ► the adsorbent strongly retains mercury in the adsorbent. ► adsorption of mercury ions increased with an increase in temperature of the solution.
Abstract
We report the desorption of carbon dioxide CO
2
(g) from monoethanolamine (MEA) solution via the addition of calcium chloride (CaCl
2
) into a CO
2
-absorbed MEA solution (0.2 M, pH 8.2) ...under ultrasound treatment (28 kHz, 200 kHz) and stirring (1500 rpm). Ultrasound at 28 kHz had a higher CO
2
(g) desorption ratio than either ultrasound at 200 kHz or stirring after 1 min 9.2% (28 kHz), 6.2% (stirring), and 5.8% (200 kHz). Treatment with ultrasound at 28 kHz resulted in the highest Ca recovery ratio, 89.1%, at 1 min treatment time. The desorption of CO
2
(g) from the MEA solution using 28 kHz ultrasound started immediately after the initiation of CaCO
3
formation. Furthermore, it was found that the average particle size of CaCO
3
obtained by ultrasound treatment at 28 kHz and a treatment time of 1 min was 0.91
μ
m, with a narrow particle size distribution.
Ultrasound can desorb CO2 from dissolved CO2 gas CO2(aq) in a low-concentration monoethanolamine (MEA) solution (0.2 M) at a low temperature (25 °C). However, it is difficult to desorb CO2 using ...ultrasound at pH >8.2 because CO2 mainly exists as HCO3− and not as CO2(aq). We investigated the increment of the CO2 gas desorption ratio on the synthesis reaction of CaCO3 by the shift in the CO2 equilibrium in the direction of the increase of CO2(aq) by the decrease of pH from 8.2 with an increase in the H+ concentration in the MEA solution. Results indicated that a high Ca recovery ratio of 93.1% was observed by CaCl2 addition and ultrasound irradiation. Compared with the desorption ratio of CO2 gas using ultrasound irradiation without the addition of CaCl2, the CO2 gas desorption ratio increases from 2.2% to 9.8% using ultrasound with a low concentration of CaCl2 (Ca/MEA molar ratio 0.026).
•Effect of reaction temperature on ultrasound synthesis was studied.•Particles obtained at 90°C were non-homogeneous.•Scorodite particles synthesized at 90°C was smaller than that at 70°C.•Ultrasound ...oxidation contributed to scorodite synthesis at low temperature.
Synthesis of scorodite (FeAsO4·2H2O) using dynamic action agglomeration and the oxidation effect from ultrasound irradiation was investigated. The effect of different reaction temperatures (90, 70, 50, and 30°C) on the size and morphology of scorodite particles synthesized under O2 gas flow and ultrasound irradiation was explored because the generation of fine bubbles depends on the solution temperature. At 90°C, the size of scorodite particles was non-homogeneous (from fine particles (<1μm) to large particles (>10μm)). The oxidation–reduction potential (ORP) and yield at 90°C showed lower values than those at 70°C. The scorodite particles, including fine and non-homogeneous particles, were generated by a decrease in the oxidation of Fe(II) to Fe(III) and promotion of dissolution caused by the generation of radicals and jet flow from ultrasound irradiation. Using ultrasound irradiation in the synthesis of scorodite at low temperature (30°C) resulted in the appearance of scorodite peaks in the X-ray diffraction (XRD) pattern after a reaction time of 3h. The peaks became more intense with a reaction temperature of 50°C and crystalline scorodite was obtained. Therefore, ultrasound irradiation can enable the synthesis of scorodite at 30°C as well as the synthesis of large particles (>10μm) at higher temperature. Oxide radicals and jet flow generated by ultrasound irradiation contributed significantly to the synthesis and crystal growth of scorodite.
Abstract
Oil sand contains about 15 wt% bitumen which contains approximately 5 wt% sulfur. Bitumen must be extracted from sand and desulfurized before use as a fuel. Currently, bitumen is recovered ...from sand using hot water (80 °C) and sulfur is removed via hydrodesulfurization (200 °C–450 °C), which consumes large amounts of energy. Therefore, we investigated the separation of bitumen from sand and the oxidative desulfurization of bitumen using ultrasound and n-pentane at 20 °C. We successfully extracted 94 wt% bitumen from sand and removed 66.1% of the sulfur via oxidative desulfurization using 15 wt% H
2
O
2
and 5 mol l
−1
NaOH.
In this study, we performed electrochemical reduction of H2O2 (H2O2 + e− = OH. + OH−, H2O2 + 2e− = 2OH−) that was generated by ultrasound irradiation and oxidation of As(III) using OHcenterdot and ...H2O2. Electrochemical reduction was conducted using a Pb electrode, which was immersed in 10 ppm of As(III) solution containing 20 mM of KCl and 10 ppm of H2O2, and applied electrical potential of −0.5 V versus Ag/AgCl for 30 min in Ar atmosphere. After electrochemical reduction, the pH increased from 4.8 to 9.3. The concentration of As(V), which was oxidized from As(III) by H2O2, increased from 0 to 6.2 ppm. The precipitate of Pb, β-PbO, and Pb5O8 was obtained by ultrasound irradiation in the presence of the Pb electrode at −0.5 V, and the concentration of As deceased from 10 to 1.2 ppm. The precipitate adsorbed As(V) after oxidation of As(III) by OHcenterdot and H2O2.
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