Flue Gas Desulfurization by Dielectric Barrier Discharge

There are many problems with flue gas desulfurization by traditional gas ionization discharge, including the large size of the plasma source, high energy consumption, and the need for a traditional desulfurization method. This paper introduces oxidization of SO₂ to sulfuric acid (H₂SO₄) in a duct by reactive oxygen species (O₂ ⁺, O₃) produced by strong ionization dielectric barrier discharge. The entire plasma reaction process is completed within the duct without the use of absorbents, catalysts, or large plasma source. The reactive oxygen species O₂ ⁺ reacts with gaseous H₂O in the flue gas to generate ·OH radicals, which can oxidize trace amounts of SO₂ in large volumes of the flue gas to produce H₂SO₄. Sulfuric acid is also produced by O₃ oxidation of SO₂ to SO₃, and SO₃ reacting with gaseous H₂O in the flue gas. Experimental results showed that with a gas temperature of 22 °C and reactive oxygen species injection rate of 0.84 mg/L, the SO₂ removal rate was 81.4 %, and the SO₄ ^2? concentration in the recovered liquid H₂SO₄ reached 53.8 g/L.     

Drawing Out the Structural Information About the First Hydration Layer of the Isolated Cl− Anion Through the FTIR-ATR Difference Spectra

The Fourier transform infrared-attenuated total reflectance (FTIR-ATR) difference spectra of aqueous MgSO₄, Na₂SO₄, NaCl and MgCl₂ solutions against pure water were obtained at various concentrations. The difference spectra of the solutions showed distinct positive bands and negative bands in the O–H stretching region, indicating the influences of salts on structures of hydrogen-bonds between water molecules. Furthermore the difference spectra of MgCl₂ solutions against NaCl solutions and those of MgSO₄ solutions against Na₂SO₄ solutions with the same concentrations of anions (Cl^? or SO ₄ ^2? , respectively) allowed extracting the structural difference of the first hydration layer between Mg²⁺ and Na⁺. Using SO ₄ ^2? as a reference ion, structural information of the first hydration layer of the Cl^? anion was obtained according to the difference spectra of MgCl₂ solutions against MgSO₄ solutions and those of NaCl solutions against Na₂SO₄ solutions containing the same concentrations of cations (Mg²⁺ or Na⁺, respectively). The positive peak at ~3,407 cm^?1 and negative peak at ~3,168 cm^?1 in these spectra indicated that adding Cl^? decreased the strongest hydrogen-bond component and increased the relatively weaker one.     

Single ion activities in aqueous sulfuric acid solutions: A new extra-thermodynamic assumption

Single ion activities in aqueous H₂SO₄ have been calculated from the mean ionic activity coefficients of H₂SO₄, the solubilities of PbSO₄ and the degrees of the second dissociation of H₂SO₄ in these solutions by employing a new extra-thermodynamic assumption. The hydrogen ion activities thus obtained are compared with the corresponding acidity function values based on different classes of acid-base indicators.     

Mass spectrometric study of SF6-N2 plasma during etching of silicon and tungsten

The reaction products in the SF₆-N₂ mixture rf plasma during reactive ion etching of Si and W have been measured by a mass spectrometric method. Two kinds of cathode materials were used in this work; they were stainless steel for the Si etching, and SiO₂ for the W etching. The main products detected in the etching experiments of Si and W included SF₄, SF₂, SO₂, SOF₂, SOF₄, SO₂F₂, NSF, NF₃, N₂F₄, N_xS_y, NO₂, and SiF₄. In the W etching with the SiO₂ cathode, additional S₂F₂, N₂O, and WF₆ molecules were also obtained. The formation reactions about the novel NSF compound and the sulfur oxyfuorides were discussed.     

Effects of Ions on the OH Stretching Band of Water as Revealed by ATR-IR Spectroscopy

The effects of various cations (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mn²⁺, Co²⁺, and Ni²⁺) and anions (Cl^?, Br^?, I^?, \( {\text{NO}}_{3}^{ - } \) , \( {\text{ClO}}_{4}^{ - } \) , \( {\text{HCO}}_{3}^{ - } \) , and \( {\text{CO}}_{3}^{2 - } \) ) on the molar absorptivity of water in the OH stretching band region (2,600–3,800 cm^?1) were ascertained from attenuated total reflection infrared spectra of aqueous electrolyte solutions (22 in all). The OH stretching band mainly changes linearly with ion concentrations up to 2 mol·L^?1, but several specific combinations of cations and anions (Cs₂SO₄, Li₂SO₄, and MgSO₄) present different trends. That deviation is attributed to ion pair formation and cooperativity in ion hydration, which indicates that the extent of the ion–water interaction reflected by the OH stretching band of water is beyond the first solvation shell of water molecules directly surrounding the ion. The obtained dataset was then correlated with several quantitative parameters representing structural and dynamic properties of water molecules around ions: ΔG _HB, the structural entropy (S _str), the viscosity B-coefficient (B _η ), and the ionic B-coefficient of NMR relaxation (B _NMR). Results show that modification of the OH stretching band of water caused by ions has quasi-linear relations with all of these parameters. Vibrational spectroscopy can be a useful means for evaluating ion–water interaction in aqueous solutions.     

Destruction of sodium lauryl sulfate in its aqueous solutions by contact glow discharge treatment

Degradation of the anionic surfactant sodium lauryl sulfate (C₁₂H₂₅SO₄Na, SLS) in its aqueous solutions with concentrations of 0.02–1.1 mmol/L acting as a liquid cathode of atmospheric-pressure dc discharge in air at a discharge current ranging within 20–100 mA has been studied. The products of degradation in the liquid phase have been identified, and the kinetic characteristics of their formation at an initial SLS concentration of 5 × 10^?3 g/L (～0.02 mmol/L) and a discharge current of 40 mA have been determined.     

Enthalpy changes of salting processes of hen-egg white lysozyme in various electrolyte solutions

The enthalpy changes of salting process of hen-egg white lysozyme in buffer acetate solutions (pH=4.25) as a function of concentration of following electrolytes: LiCl, KCl, K₂SO₄, Li₂ SO₄ and (NH₄)₂SO₄ are determined. Obtained data according to McMillan and Mayer’s approach, has been analyzed in the terms of the enthalpic pairwise interaction coefficients: lysozyme – lysozyme h_xx, and lysozyme – salt h_xy. The ability of cations to precipitate lysozyme solution in relation to the concentration of cations can be seen from the series as follows: Li⁺> Na⁺>K⁺>NH₄+⁺     

Ion-exchange selectivity of a sulfonic cation exchanger based on immobilized cis-tetraphenylcalix[4]resorcinolarene

The ion-exchange equilibrium of protons in SO₃H groups of a sulfonic cation exchanger based on immobilized cis-tetraphenylcalix[4]resorcinolarene with cations of Li⁺, Na⁺, Ag⁺, Cu²⁺, In³⁺, and protonated 1,3,5,7-tetraazaadamantane in aqueous solutions of electrolytes at 293 K was studied. The corrected coefficients of the cation exchange selectivity were calculated.     

Ion-exchange properties of microdispersed sintered detonation nanodiamond

The adsorption of transition metal cations and inorganic anions from aqueous solutions on microdispersed sintered detonation nanodiamond (MSDN) is systematically studied. The selectivity series Fe³⁺ > Al³⁺ > Cu²⁺ > Mn²⁺ > Zn²⁺ > Cd²⁺ > Co²⁺ > Ni²⁺ with maximum adsorption capacity between 2 and 5 µmol g^?1 is obtained. It is found that anions may significantly contribute to the adsorption of transition metal cations, so the adsorption of CH₃COO^?, Cl^?, B₄O₇ ^2?, ClO₄ ^?, I^?, SO₄ ^2?, C₂O₄ ^2?, PO₄ ^3? is also studied. For the first time, dominating adsorption of anions over cations is demonstrated for detonation nanodiamond. The maximum anion-exchange capacity of 50–150 µmol g^?1 is found for MSDN. Beside of electrostatic interactions, the formation of complexes with hydroxyl groups and interaction with metal impurities contribute to the adsorption of B₄O₇ ^2? and PO₄ ^3?, respectively. Therefore, anion exchange selectivity of MSDN is different from that observed for common anion exchange resins. In all cases, the adsorption on MSDN obeys Langmuir law. The pH effect on the adsorption of SO₄ ^2?, PO₄ ^3? and B₄O₇ ^2? is different from that observed for other anions due to specific interactions.     

Use of surfactant in aniline polymerization with TiO2 to PANI-TiO2 for supercapacitor performance

Polyaniline sulphate salt titanium dioxide composite (PANI-H₂SO₄·TiO₂) was synthesized by chemical in situ polymerization of aniline in the presence of TiO₂. The effect of anionic surfactant (sodium lauryl sulphate) in this reaction was also assessed. During the polymerization reaction, sodium lauryl sulphate (SLS) is converted to dodecyl hydrogen sulphate (DHS) in the presence of acidic medium and gets doped onto polyaniline along with sulphuric acid dopant, i.e. formation of polyaniline-sulphate-dodecyl hydrogen sulphate-titanium dioxide composite (PANI-H₂SO₄-DHS·TiO₂). In the PANI-H₂SO₄-DHS·TiO₂ composite, the presence of DHS is confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDAX) and TiO₂ is confirmed by XRD and EDAX results. In PANI-H₂SO₄-DHS·TiO₂ system, the nanoparticle of TiO₂ (10–20 nm) is uniformly embedded on nanofibres (20–60 nm) of PANI-H₂SO₄-DHS, and some part of PANI-H₂SO₄-DHS·TiO₂ forms core–shell morphology, wherein TiO₂ is in core and PANI-H₂SO₄-DHS in shell forms. Stability of PANI-H₂SO₄-DHS increases due to the incorporation of stable TiO₂. Utility of PANI-TiO₂ composite was carried out in supercapacitor cell system by performing cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopic techniques in 1 M H₂SO₄ solution. Very low values of solution resistance, charge transfer resistance and time constant are obtained between 0.2 and 0.6 V. Initial specific capacitance values for the cell carried out at low and high current densities are found to be 280 and 205 F g^?1, respectively, and after 1,700 charge–discharge cycles, its retention in the specific capacitance values is found to be the same (65–66 %) with coulombic efficiency of 98–100 %. A capacitor can work even at a high discharge rate. The efficiency of oxidizing and doping power increases with the use of a surfactant. Moreover, the use of a long chain surfactant dopant containing polyaniline as an electrode material plays an important role to increase the performance of the supercapacitor by allowing the electrolyte to easily enter and come out from PANI electrodes.     

Atmospheric Pressure Glow Discharges Generated in Contact with Flowing Liquid Cathode: Production of Active Species and Application in Wastewater Purification Processes

Miniaturized atmospheric pressure glow discharges (APGDs) were generated in contact with small sized flowing liquid cathode systems. As anodes a solid pin electrode or a miniature flow Ar microjet were applied. Both discharge systems were operated in the open to air atmosphere. Hydrogen peroxide (H₂O₂) as well as ammonium (NH₄ ⁺), nitrate (NO₃ ^?), and nitrite (NO₂ ^?) ions were quantified in solutions treated by studied discharge systems. Additionally, an increase in the acidification of these solutions was noted in each case. Emission spectra of the near cathode zone of both systems were measured in order to elucidate mechanisms that lead to the formation of active species in gas and liquid phases of the discharge. Additionally, the concentration of active species in the liquid phase (H₂O₂, NH₄ ⁺, NO₃ ^? and NO₂ ^?) was monitored as a function of the solution uptake rate and the flow rate of Ar. The suitability of investigated discharge systems in the water treatment was tested on artificial wastewaters containing an organic dye (methyl red), hardly removable by classical methods non-ionic surfactants (light Triton x-45 and heavy Triton x-405) and very toxic Cr(VI) ions. Preliminary results presented here indicate that both investigated flow-through APGD systems may successfully be applied for the efficient and fast on-line continuous flow chemical degradation of toxic and hazardous organic and inorganic species in wastewater solutions.     

Determination of inorganic acids by ion chromatography with n-tetradecylphosphocholine (zwitterionic surfactant) as the stationary phase and pure water as the mobile phase

A new ion chromatographic (IC) system, in which n-tetradecylphosphocholine (TDPC, a phosphobetaine type of zwitterionic surfactant) was used as the stationary phase, pure water as the mobile phase, and conductivity as the method of detection, has been developed for the determination of inorganic acids. Five model acids, HCl, HNO₃, HClO₄, H₂SO₄, and H₃PO₄, were separated to baseline and eluted in the order H₃PO₄ > HCl > HNO₃ > H₂SO₄ > HClO₄. When peak areas were plotted against the concentrations of the acids in samples, linear calibration curves were obtained. Ultimate determination limits were approximately 1 mmol L^–1, but the discrimination of the method between solutions of different concentration was better than 10 μmol L^–1 for those model analytes. Salts of divalent cations could also be separated, but they were eluted faster than the acids. No separation was observed for the salts of monovalent cations. This newly proposed approach is applicable to the simultaneous determination of the inorganic acids (produced by reactions of NO_x, SO_x, and HCl with water) in aerosols.     

A new tavorite LiTiPO<Subscript>4</Subscript>F electrode material for aqueous rechargeable lithium ion battery

Herein, we demonstrate a safe, inexpensive, and stable cycle-life aqueous rechargeable Li-ion battery system using tavorite LiTiPO₄F as anode and Li[Li_0.2Co_0.3Mn_0.5]O₂ as cathode in aqueous electrolyte using 2 M Li₂SO₄. These materials have been synthesized via a simple and an efficient method called RAPET (reaction under autogenic pressure at elevated temperature) method, and for the first time, we have evaluated the electrochemical properties of LiTiPO₄F in aqueous electrolyte. Structural and morphological features have been characterized using X-ray diffraction and scanning electron microscopy techniques, and the electrochemical studies have been investigated by using cyclic voltammetry, galvanostatic charge/discharge studies, electrochemical impedance spectroscopic technique, potentiostatic intermittent titration techniques, and galvanostatic intermittent titration techniques. In galvanostatic charge/discharge studies, the capacity, cycle life, and columbic efficiency of LiTiPO₄F have been tested in combination with Li [Li_0.2Co_0.3Mn_0.5]O₂ cathode. In particular, LiTiPO₄F shows capacity of 82 mA h g^?1, the capacity retention was maintained 90 % even after the 45th cycle.     

State of Platinum Group Metals and Gold in Mineral Acid Solutions and the Catalytic Activity of These Metals in the Oxidation of N-Methyldiphenylamine-4-Sulfonic Acid

The state of rhodium, iridium, platinum, and gold in HCl, HClO₄, H₂SO₄, and HNO₃ solutions was studied by capillary electrophoresis. The electrophoresis was performed in an acidic phosphate buffer solution using an unmodified fused-silica capillary. It was found that the catalytic activity of the metals in the reaction of N-methyldiphenylamine-4-sulfonic acid oxidation with periodates in weakly acidic solutions depends on the analyte speciation. It was found that rhodium and iridium cations formed upon the treatment of a sample with concentrated perchloric acid catalyze the above reaction; this is favorable for the selective determination of these cations in the presence of platinum and gold.     

On‐site sampling of inorganic contamination on the metal surface and analysis with capillary electrophoresis

Pipes are the primary structural elements used for transporting fluid in various industries. The most common damage mechanism is corrosion, which occurs in pipes surface of turbine. The corrosive compounds for pipes are inorganic ion (Na⁺, Cl^?, NH₄⁺, NO₃^?, etc.) and grinding oil. For rapid and quantitative detection of inorganic ions on site, more reliable and reproducible analytical methods are demanded. A highly efficient solid–liquid sampling collection system is introduced in this work. Papering on the sample surface, inorganic cations and anions were simultaneously collected and analyzed by capillary electrophoresis with indirect ultraviolet detection. As a result, five cations (Na⁺, K⁺, NH₄⁺, Ca²⁺, Mg²⁺) and three anions (Cl^?, NO₃^?, SO₄^2?) were completely separated. The efficiency of the sampling and ability of capillary electrophoresis analysis were presented by the determination of trace‐level (mg/m²) contaminants. The recoveries of cations and anions on the paper from metal surface were between 86.6 and 107.2%, and the relative standard deviations were less than 12.85%.     

Electrochemical behavior of Li[Li0.2Co0.3Mn0.5]O2 as cathode material in Li2SO4 aqueous electrolyte

Layered, lithium-rich Li[Li_0.2Co_0.3Mn_0.5]O₂ cathode material is synthesized by reactions under autogenic pressure at elevated temperature (RAPET) method, and its electrochemical behavior is studied in 2?M Li₂SO₄ aqueous solution and compared with that in a non-aqueous electrolyte. In cyclic voltammetry (CV), Li[Li_0.2Co_0.3Mn_0.5]O₂ electrode exhibits a pair of reversible redox peaks corresponding to lithium ion intercalation and deintercalation at the safe potential window without causing the electrolysis of water. CV experiments at various scan rates revealed a linear relationship between the peak current and the square root of scan rate for all peak pairs, indicating that the lithium ion intercalation–deintercalation processes are diffusion controlled. The corresponding diffusion coefficients are found to be in the order of 10^?8?cm²?s^?1. A typical cell employing Li[Li_0.2Co_0.3Mn_0.5]O₂ as cathode and LiTi₂(PO₄)₃ as anode in 2?M Li₂SO₄ solution delivers a discharge capacity of 90?mA?h g^?1. Electrochemical impedance spectral data measured at various discharge potentials are analyzed to determine the kinetic parameters which characterize intercalation–deintercalation of lithium ions in Li[Li_0.2Co_0.3Mn_0.5]O₂ from 2?M Li₂SO₄ aqueous electrolyte.     

Europium(III)-Sensitized Chemiluminescence Determination of Ibuprofen in Pharmaceutical Preparations and Biological Fluids

Abstract

Chemiluminescence reaction of the system containing europium(III) ion, KMnO₄, Na₂SO₃, and ibuprofen was investigated for the determination of ibuprofen. The introduction of Eu(III) ion into the system of KMnO₄-Na₂SO₃-ibuprofen caused a significant increase in the chemiluminescence signal. The increment of the chemiluminescence signal is proportional to ibuprofen concentration in the range of 5.0 × 10^?8–5.0 × 10^?6 g/ml with a detection limit of 1 × 10^?8 g/ml. The relative standard deviation for 1.0 × 10^?7 g/ml ibuprofen solution was 1.7% (n = 11). The proposed method was successfully applied to determine ibuprofen in tablets and human plasma.     

Effect of alkaline and alkaline–earth cations on the supercapacitor performance of MnO2 with various crystallographic structures

The electrochemical performances of the α-, γ-, and δ-MnO₂ with different crystallographic structures were systematically investigated in 0.5 mol/L Li₂SO₄, 0.5 mol/L Na₂SO₄, 1 mol/L Ca(NO₃)₂, and 1 mol/L?Mg(NO₃)₂ electrolytes. The results showed that the electrochemical performances of the manganese dioxides depended strongly on the crystallographic structures of MnO₂ as well as the cation in the electrolytes. Because the δ-MnO₂ consists with layers of structure and the interlayer separation is 7 Å, which is suitable for insertion/extraction of some alkaline and alkaline–earth cations, the δ-MnO₂ electrode showed the higher specific capacitance than that of α-MnO₂ and γ-MnO₂. We also found that the α-, γ-, and δ-MnO₂ electrodes in the Mg(NO₃)₂ electrolyte showed a higher specific capacitance, while all the α-, γ-, and δ-MnO₂ electrodes in the Li₂SO₄ electrolyte exhibited a better cycle life. The reason for the different behavior of Li⁺ and Mg²⁺ during the charge/discharge process can be ascribed to the charge effect of the cations in the electrolytes. The ex situ X-ray diffraction (XRD) and long-time cyclic voltammogram measurements were used to systematically study the energy storage mechanism of MnO₂-based electrodes. A progressive crystallinity loss of the materials is also observed upon potential cycling at the oxidized states. A reasonable charge/discharge mechanism is proposed in this work.     

Coefficient of ozone mass transfer during its interaction with an aqueous solution of formic acid in a bubble column reactor

A way of determining the coefficient of ozone mass transfer between the gas phase and liquid aqueous phase using a test compound (formic acid) is described. The values of ozone mass transfer coefficient (in aqueous solutions of 0.1–0.55 М HClO₄ and 0–1 М НСООН, and in 0.75 М H₂SO₄, 0.125 М KHSO₄, and 0–2 М НСООН) are determined along with the rate constants of the reaction of О₃ with undissociated НСООН molecules and formate ions at 21 ± 1°С.     

The Role of Alkali Cation Intercalates on the Electrochemical Characteristics of Nb2CTX MXene for Energy Storage

The intercalation of cations into layered-structure electrode materials has long been studied in depth for energy storage applications. In particular, Li⁺-, Na⁺-, and K⁺-based cation transport in energy storage devices such as batteries and electrochemical capacitors is closely related to the capacitance behavior. We have exploited different sizes of cations from aqueous salt electrolytes intercalating into a layered Nb₂CT_x electrode in a supercapacitor for the first time. As a result, we have demonstrated that capacitive performance was dependent on cation intercalation behavior. The interlayer spacing expansion of the electrode material can be observed in Li₂SO₄, Na₂SO₄, and K₂SO₄ electrolytes with d-spacing. Additionally, our results showed that the Nb₂CT_x electrode exhibited higher electrochemical performance in the presence of Li₂SO₄ than in that of Na₂SO₄ and K₂SO₄. This is partly because the smaller-sized Li⁺ transports quickly and intercalates between the layers of Nb₂CT_x easily. Poor ion transport in the Na₂SO₄ electrolyte limited the electrode capacitance and presented the lowest electrochemical performance, although the cation radius follows Li⁺>Na⁺>K⁺. Our experimental studies provide direct evidence for the intercalation mechanism of Li⁺, Na⁺, and K⁺ on the 2D layered Nb₂CT_x electrode, which provides a new path for exploring the relationship between intercalated cations and other MXene electrodes.