Solvent Decomposition Research Articles

Decomposition of Waste Organic Solvents by Liquid-Phase Atmospheric Pressure Microwave Plasma Generated Using Carbon Felt Pieces Impregnated with NaCl

Abstract The decomposition of organic solvents was divided into three periods: LPSD, LPAPMP, and APMP. We found that the generation behaviors of LPAPMP were different due to the relative permittivity of the solvents, however, LPAPMP generation is effective for decomposing each of the organic solvents.

Use of low temperature solvothermal reactions in the synthesis of nanocrystalline tantalum nitrides including nanorods

Solvothermal reactions of TaCl5 with LiNH2 or Mg3N2 lead to amorphous products at temperatures up to 500 °C. Post-reaction annealing under nitrogen yields crystalline products with Ta3N5 (LiNH2) and TaN (Mg3N2) structures. When these reactions are carried out with LiNH2 in refluxing mesitylene, rods of Ta3N5-structured material are obtained. Using commercial LiNH2 these have dimensions of ∼5 × 200 nm but are contaminated with LiTaO3. With high purity LiNH2 a black oxide-free but carbon-containing material presents as rods of 20–50 nm length. Higher temperature reactions in an autoclave lead to isotropic nanocrystals of ca. 10 nm diameter of a nitrogen-deficient or carbide-substituted Ta3N5-type material. Carbon incorporation is attributed to solvent decomposition at the temperatures required for the reactions. The TaN derived from reactions with Mg3N2 consists of nanoparticles of 6–8 nm in diameter.

High‐Field Scanning Probe Lithography in Hexadecane: Transitioning from Field Induced Oxidation to Solvent Decomposition through Surface Modification

High field scanning probe lithography in hexadecane leads to two different chemical reactions depending on surface hydrophilicity. On a hydrophilic surface, oxidation of the sample occurs; a hydrophobic surface, results in solvent decomposition and nanoscale deposition of etch resistant material. The features are characterized with photoelectron emission microscopy and are carbonaceous in nature with a highly cross-linked bonding network. Tone reversal in a fluorinated etch is achieved.

Multibubble plasma production and solvent decomposition in water by slot-excited microwave discharge

Intense microwaves are injected from a slot antenna into water partly filling a metal vessel. When the vessel is evacuated to saturated vapor pressure (∼5×103Pa) of water, microwave breakdown gives rise to plasmas in many bubbles in the boiling water. Gas bubbling technique enables production of multibubble plasmas in water even at atmospheric pressure. Optical emissions from the exited species are investigated to identify radical species in water. In order to demonstrate application to purification of polluted water, methylene blue and trichlorethylene solution in 8l water were observed to rapidly decrease with multibubble plasma treatment.

Proton and hydrogen formation by cyclohexyl benzene during overcharge of Li-ion batteries

This study provides experimental evidence for proton and hydrogen formation caused by the anodic electropolymerization of cyclohexyl benzene (CHB), which is a popular electrolyte additive for overcharge protection of lithium-ion batteries (LIBs). It is found that considerable H 2 evolution is observed in overcharged LiCoO 2/graphite cells, especially when CHB is included as an electrolyte additive. In order to confirm the proton generation during the CHB oxidation, Pt/Pt-rotating ring disc electrode (RRDE) measurements are performed in 1 M Li(C 2F 5SO 2) 2N ethylene carbonate/ethyl methyl carbonate (1/2, v/v) solutions with and without CHB. The cathodic ring current is intimately correlated to the anodic disc current, and the cathodic reaction at the ring is determined to be the reduction of the proton. The proton generation efficiency during the CHB oxidation is as high as 90%. Proton liberation is also observed during the anodic decomposition of the electrolyte solvents, although it occurs in a much less stoichiometric way compared with that during the CHB oxidation.

Degradation of pentachlorophenol with zero-valence iron coupled with microwave energy

The objective of this research is to study the degradation of pentachlorophenol with zero-valence iron (Fe 0) coupled with the use of microwave energy. The sample containing 1000 mg/L PCP solution was dosed with 0.5 g Fe 0 and then subject to 700 W microwave energy for 10 s; 85% pentachlorophenol was noted to be removed. If the microwave treatment time was increased to 30 s, the pentachlorophenol removal efficiency exceeded 99% with end products including H 2O, CO 2, HCl, etc. Using Fe 0 as a medium, the microwave treatment is made an efficient method for degrading pentachlorophenol. The time needed to achieve a satisfactory treatment is also reduced leading to significant savings of energy consumption to make this method cost-effective. Since this technology applies Fe 0, which is amenable to natural environment, to speed up the decomposition of an industrial solvent, it is not only cost-effective but also environmental friendly for the industry to pursuit sustainable development.

Surface film formation on electrodes in a LiCoO 2/graphite cell: A step by step XPS study

In this paper, we report on a study of the electrode/electrolyte interfaces of a LiCoO 2/C cell using XPS (X-ray photoelectron spectroscopy). The originality of our work lies in detailed investigations step by step during the first cycle. The results have shown that the formation process of the SEI takes place in different successive stages that are dependent on the potential of the cell. It clearly appears that SEI formation continues in the potential range where lithium ion intercalation proceeds in the carbon electrode. Salt degradation products are formed after solvent decomposition ones. Concerning the LiCoO 2/electrolyte interface, the results obtained have shown the formation of a very thin film on the active material but not on the binders. In all cases, the novel XPS approach applied in the lab, combining core peaks and valence band analyses, allows a precise characterization of the main chemical species of the interface layers. On the basis of these results and in conjunction with literature data, the degradation mechanisms have been discussed.

SEI Layer Formation on Amorphous Si Thin Electrode during Precycling

The morphological and compositional changes of the solid electrolyte interphase (SEI) layer formed on the surface of Si thin electrodes during precycling were investigated. At the beginning of charging, the native layer ( and silanol) covering the surface of the Si thin electrode is readily destroyed and a new SEI layer is formed by the decomposition of both organic solvents and anions. At this stage, the interfacial resistance decreases to a minimum level. Thereafter, the interfacial resistance increases with charging due to the growth of an SEI layer, which is mainly originated from the decomposition of organic solvents. During the discharging process, an SEI layer was formed mainly by the decomposition of anions.

Electrochemical performance of nano-Pt-supported carbon anode for lithium ion batteries

A nano-Pt-supported carbon anode was prepared by supporting Pt nanoparticles onto carbon powder. Ultrafine Pt nanoparticles could be well distributed on the surface of carbon particles. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), cyclic voltammetry (CV), FTIR, and impedance spectroscopy were used to study on the electrode structure and electrochemical performance. Nano-Pt-supported carbon anode enhanced the Li discharge reaction and suppressed the solvent decomposition reaction, which are favorable for lithium batteries.

Solid-State NMR Characterization of Electrolyte Breakdown Products in Nonaqueous Asymmetric Hybrid Supercapacitors

We report the direct observation of solid phase electrolyte products resulting from decomposition of the acetonitrile solvent on the mesoporous activated carbon positive electrode of a nonaqueous asymmetric hybrid supercapacitor by 13 C, 1 H, and 15 N solid-state nuclear magnetic resonance (NMR). At least two of the observed NMR signals can be assigned to acetamide and a lithium-based carbon derivative, which suggests that the Li-salt interacts with the acetonitrile solvent, leading to accumulation of the decomposition products on the electrode particle surface. These results may find practical applications in evaluating the design and performance of high-voltage electrochemical double layer capacitors and lithium-ion batteries.

Influence of the lithium salt nature over the surface film formation on a graphite electrode in Li-ion batteries: An XPS study

The formation of a passivation film (solid electrolyte interphase, SEI) at the surface of the negative electrode of full LiCoO 2/graphite lithium-ion cells using different salts (LiBF 4, LiPF 6, LiTFSI, LiBETI) in carbonate solvents as electrolyte was investigated by X-ray photoelectron spectroscopy (XPS). The analyzes were carried out at different potential stages of the first cycle, showing the potential-dependent character of the surface film species formation and the specificity of each salt. At 3.8 V, for all salts, we have mainly identified carbonated species. Beyond this potential, the specific behavior of LiPF 6 was identified with a high LiF deposit, whereas for other salts, the formation process of the SEI appears controlled by the solvent decomposition of the electrolyte.

Ultrasound in polymer chemistry: Revival of an established technique

AbstractThe history of ultrasound in polymer chemistry goes back a long way. Initially, its uses were limited to being an alternative method of initiating radical polymerizations through the decomposition of solvents to form radicals or through the breakage of polymers leading to macroradicals. Recently, the raw power of ultrasound has been focused through the use of weak linkages in polymer chains, which enables the production of well‐defined macroradicals and coordinatively unsaturated metal complexes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5445–5453, 2006

Intercalation into and film formation on pyrolytic graphite in a supercapacitor-type electrolyte (C 2H 5) 4NBF 4/propylene carbonate

Highly oriented pyrolytic graphite (HOPG) in a solution of (C 2H 5) 4NBF 4 in propylene carbonate (PC) was investigated as a model system for the electrochemical double-layer capacitor (EDLC) negative electrode. For the first time the intercalation of (C 2H 5) 4N + into HOPG could be monitored by means of in situ atomic force microscopy (AFM). In analogy to the behavior in Li + containing solution the formation of a surface film on the negative electrode could be detected. The question is addressed if this film might serve as a solid electrolyte interphase preventing sustained solvent decomposition.

Venting of a runaway organic peroxide decomposition in viscous solvents on pilot scale

AbstractRunaway reactions continue to occur in polymerization reactors, which are widely used in the chemical industry. Those of greatest concern include highly viscous multiphase mixtures. Considerable uncertainties exist in the design of emergency pressure‐relief systems for such reactors because there are only limited experimental data available on the flow of such fluids in relief systems.Venting experiments are reported here that have been carried out in a 350 L pilot‐scale reactor for the runaway decomposition of an organic peroxide in xylene solvent, with batch volumes of 150 and 200 L and with a range of concentrations of polystyrene dissolved in the xylene to modify the viscosity. Measurements were made of pressures in the reactor, vent line, and catch tank; temperatures at different levels in the reactor and in the vent line and catch tank; viscosity in the reactor; mass in the catch tank; and two‐phase density in the vent line.Analysis of the results shows that the venting behavior of a high‐viscosity reaction system is complex. There is no simple relationship between maximum pressure and viscosity. The results indicate that the flow regime in the reactor is influenced by the fluid viscosity and that this is of primary importance in explaining the effects on maximum pressure. © Crown Copyright 2006. Published with the permission of the Controller of HMSO and the Queen's printer for Scotland. Process Saf Prog, 2006

Cryo-electrochemistry in tetrahydrofuran: The electrochemical reduction of a phenyl thioether: [(3-{[trans-4-(Methoxymethoxy)cyclohexyl]oxy}propyl)thio]benzene

Abstract Cryo-electrochemistry in tetrahydrofuran (THF) with cyclic voltammetry and microdisc chronoamperometry has been applied to the reductive cleavage of the phenyl thioether: [(3-{[trans-4-(methoxymethoxy)cyclohexyl]oxy}propyl)thio]benzene, (RSPh) and has allowed the number of electrons participating in the reaction to be deduced from potential step experiments. Characteristic cyclic voltammograms and microdisc chronoamperometric experiments have been used to identify the products of the electrochemical reduction as trans-1-(methoxymethoxy)-4-propoxycyclohexane, (RH) and thiophenolate, (PhS−) which upon oxidation, rapidly dimerises to form diphenyl disulfide, (PhSSPh). In addition, preparative electrolysis confirms the proposed mechanism of reduction of RSPh as being a simultaneous two-electron reduction to give the products: trans-1-(methoxymethoxy)-4-propoxycyclohexane, (RH) and thiophenolate, (PhS−). Both chronoamperometric and voltammetric analyses performed at low temperature proved significantly advantageous over room temperature analyses. In particular, voltammetric waves and peaks were better resolved from the solvent window allowing accurate step potentials to well-defined steady-state plateaus used in chronoamperometric experiments, with voltammetric potential sweeps reversed without significant scanning into the solvent decomposition window.

Suppression of Co-intercalation on the Carbon Anode by MA Addition in a PC-base Electrolyte

Propylene Carbonate (PC) has the interesting properties of being able to dissolve and dissociate lithium salts, thus leading to highly conducting electrolytes even at low temperatures. Moreover, electrolytes that contain PC are stable against oxidation at voltages up to ~5 V. However, it is known that, when lithium is intercalated into graphite in pure PC based electrolytes, solvent co-intercalation occurs, leading to the destruction of the graphite structure. (i.e., exfoliation). The objective of this study was to suppress PC decomposition and prevent exfoliation of the graphite anode by co-intercalation. Electrochemical characteristics were studied using Kawasaki mesophase fine carbon (KMFC) in different 1 M <TEX>$LiPF_6$</TEX>/PC-based electrolytes. Electrochemical experiments were completed using chronopotentiometry, cyclic voltammetry, impedance spectroscopy, X-ray diffraction, and scanning electron microscopy. From the observed results, we conclude that the MA and <TEX>$Li_2CO_3$</TEX> additive suppressed co-intercalation of the PC electrolyte into the graphite anode. The use of additives, for reducing the extent of solvent decomposition before exfoliation of the graphite anode, could therefore enhance the stability of a KMFC electrode.

Electrolytic Reduction of U(IV) Salts to U(III) inN,N-Dimethylformamide: Effects of Electrode Materials and Counter Anions

Experimental conditions of bulk electrolysis of U(IV) complexes to U(III) required for “all-uranium redox-flow battery” were examined in terms of effects of electrode materials (platinum and mercury) and of counter ions (perchlorate and triflate) in N , N -dimethylformamide. When U(IV) perchlorate was used as starting material, concentration of U(III) increased until time point when that of U(IV) decreased to about a half of its initial concentration. After that the concentration of U(III) turned to decrease, in correspondence to amalgamation in case of Hg or solvent decomposition in case of Pt. When U(IV) triflate was used as starting material, efficient generation was observed on Hg, whereas on Pt, it was not observed. Mercury electrode was preferred for efficient reduction of U(IV) to U(III) both in triflate and perchlorate system but suppression of the amalgamation process is necessary.

Low-temperature solvothermal synthesis of nanocrystalline indium nitride and Ga–In–N composites from the decomposition of metal azides

Nanocrystalline InN powders have been synthesized through metal azide decomposition in superheated toluene and refluxing hexadecane solvents near 280 °C. The metal azide intermediates were formed in situ through the metathesis reaction of InBr3 and NaN3. The InN products from toluene consist of ∼10 nm hexagonal (wurtzite) structured crystallites in aggregated arrangements. InN from hexadecane and lower temperature toluene reactions produced more poorly crystalline InN that appears to contain a cubic (zinc blende) component. Coordinating amine solvents led to decomposition of the nitride to indium metal. Several reactions were undertaken to produce mixed metal nitrides of the form Ga1−zInzN where z is 0.5 and 0.75. The mixed metal nitride products are analytically consistent with composite versus solid-solution formation, however some metal mixing is observed. Data from X-ray diffraction, electron microscopy, thermal analysis, elemental analysis, and several spectroscopic methods are combined to form a consistent picture of the bulk and surface structures for these nanocrystalline InN materials.

Deposition of calcium phosphate coatings with defined chemical properties using the electrostatic spray deposition technique

The electrostatic spray deposition (ESD) technique was used for biomedical purposes in order to deposit calcium phosphate (CaP) coatings onto titanium substrates. The relationship between various deposition parameters and the chemical properties of deposited coatings was investigated in order to be able to deposit CaP coatings with tailored chemical characteristics. The results showed that the chemical properties of the coatings were determined by both physical, apparatus-related factors and chemical, solution-related parameters. By varying the processing parameters of the technique, several crystal phases and phase mixtures were obtained, ranging from carbonate-free phases such as meta- and pyrophosphates, monetite and various tricalcium phosphates to carbonate-containing phases such as various carbonate apatites and calcite. On the basis of these results, a chemical mechanism of coating formation was proposed. Essentially, the deposition of the various crystal phases was the result of an acid–base reaction between basic CO 3 2− groups (originating from solvent decomposition reactions) and acidic HPO 4 2− groups from an intermediate monetite (CaHPO 4) phase of the CaP precipitate. The amount of carbonate incorporation (ranging from 0 to 15 wt%) determined the crystal and molecular structure of the deposited coatings.

Irreversible capacity of electrodeposited Sn thin film anode

Tin thin film anodes for lithium-ion cells were prepared by electroplating and morphology changes of the surface during alloying and de-alloying were investigated by in situ AFM to understand the origin of large irreversible capacity on Li–Sn alloy anodes. The results of cyclic voltammetry (CV) revealed that an irreversible reduction peak, which is assigned to solvent decomposition, was observed in the range 1.0–1.4 V not in the first cycle, but in the second cycle and later. AFM observation during CV revealed that surface roughening by alloying and de-alloying occurred significantly in the first and second cycles. This surface roughening destroyed existing surface film and brought about a large area of active surface, and therefore is the reason for the appearance of large irreversible capacities in the second and third cycles in constant current charge and discharge tests.