Supercritical water oxidation (SCWO): a process for the treatment of industrial waste effluents

Abstract

SuperCtical Water Oxidation (SCWO) process is investigated at the Institut of Technical Chemistry, ITC-CPV. The objectives were to determine destruction efficiencies of model compounds and industrial waste effluents and to study the feasability of the SCWO process.

Two continuous SCWO bench scale plants are operated a pipe reactor and a transpiring wall reactor system (design data: T= 630°C, P = 32MPa, feed rate waste water =10 and 50kg/h, air feed rate = 20kglh, transpiring and quench water feed rate = 50 kg/h). Suspensions containing up to 5%wt solid material can be fed to the reactor using a membrane pump.

With the pipe reactor, efficiencies of up to 99.99% were achieved for the oxidation of model compounds (ethanol, toluene, phenol) as well as real waste effluents (paper, chemical, pharmaceutical industry, sewage works). The use of the pipe reactor is limited to feeds without salt to avoid plugging.

Salty feeds are processed using the transpiring wall reactor, which is consisting of a pressure bearing tube outside and a porous tube as reactor inside. Water is steadily running through the porous reactor preventing the formation of deposits on the wall.

SCWO has a high potential at least for the destruction of halogented organic compounds using the transpiring wall reactor system and is seen to be competitive to other processes for waste destruction.     

Analysis of hydrogen bonding and weak interactions in the crystal structure of (E)-N-(4-ethylphenyl)-2-(4-hydroxybenzylidene)thiosemicarbazone: experimental and theoretical studies

Hydrogen-bonding interactions play an important role in the rational design of crystal systems with desirable architectures. The novel thiosemicarbazone derivative described herein, namely (E)-N-(4-ethylphenyl)-2-(4-hydroxybenzylidene)thiosemicarbazone, C₁₆H₁₇N₃OS, (I), was prepared and characterised by ¹H NMR, IR and single-crystal X-ray crystallography techniques. The compound is arranged in the lattice by O–H···S and N–H···S bonded polymeric ribbons that extend along the crystal b-axis, and the intermolecular N–H···S hydrogen bonds formed R2 2(8) ring motifs. More importantly, C–H···π interaction stabilises the supramolecular structure of (I). Hirshfeld surface and their associated two-dimensional fingerprint plot analyses are presented to illustrate the supramolecular connectivity in the solid state. The result shows that the short H···H contacts is dominated in the total Hirshfeld surface. As well as we report on n→π* interactions in thiosemicarbazone derivatives by using the reduced density gradient function and natural bond orbital analyses. Besides, molecular electrostatic potential (MEP) and frontier molecular orbital (FMO) analysis of the title compound are also investigated by theoretical calculations.     

Self-burial of radioactive waste

The problem of the “self-burial” of radioactive waste into melting rock is solved for a spherical container of finite thickness. The mathematical model constructed, unlike the existing ones, takes into account the thermal losses to the solid rock and to the melt behind the container, as well as the reverse evolution of heat upon solidification of the melt. A calculation for the particular case of self-burial in granite shows that consideration of these factors significantly increases the maximum permissible radius at which the container will remain in the solid state and slows the burial rate. Zh. Tekh. Fiz. 69, 123–127 (November 1999)     

Complexation of Molecular Iodine by Linear Poly (Ethylene Glycol)

Abstract

Linear poly (ethylene glycol) (PEG) is able to complex with neutral molecular Iodine in the solution state and in solid state, to produce I^? ₃ ions detectable by conventional spectroscopy and by photoacoustic spectroscopy (PAS). This behavior of PEG is another instance of its ability to mimic the complexation features of the macrocyclic polyether 18-crown-6.     

Metallization of fluid hydrogen at 140 GPa (1.4Mbar) by shock compression

Abstract

The minimum electrical conductivity of a metal was produced in dense hydrogen using shock compression. Metallization occurs at 140 GPa (1.4 Mbar), 0.6 g/cm³ (ninefold compression of initial liquid-H₂ density), and 3000 K. The relatively modest temperature generated by a reverberating shock wave produced the metallic state in a warm quantum fluid at a lower pressure than expected previously for the crystallographically ordered solid at low temperatures. Future research directions are discussed. Possible scientific and technological uses of metastable solid metallic hydrogen are speculated upon in the unlikely event that the metallic fluid can be quenched to this state at ambient pressure and temperature.     

D abstraction by H at a D-saturated Ru(0 0 1) surface

D abstraction (ABS) by H at Ru(0 0 1) surfaces initially saturated with D adatoms has been investigated using in situ mass spectrometry. HD and D₂ desorption rates are measured at various surface temperatures T as a function of H exposure time. Yield of D₂ desorption increases with T, while that of HD is little affected. Analyzing the measured rate curves, HD and D₂ desorption orders are evaluated to be 1.7 ± 0.1 and 2.5 ± 0.1, respectively, with respect to D coverage θ_D. To pursue the origin of the derived non-integral reaction orders the rate curves are further analyzed with the rate equations constructed to involve several ABS channels. Consequently, we find that the HD desorption is mainly governed by a second-order rate law in θ_D rather than the conventional hot atom-mediated ABS reaction even when it is corrected to include an isotope effect on ABS. We argue that such second-order ABS kinetics becomes important when the H atoms in excited state of chemisorption have energetically relaxed to some extent, and thereby tend to reside at, e.g. hexagonal closed packed hollow sites, interacting with nearby adatoms. On the other hand, the D₂ rate curves can be fit with third-order kinetics, consistent with the Langmuir-Hinshelwood mechanism in a super-saturation state. The isotope effect plays an essential role in the ABS reaction of D abstraction by H which competes with H abstraction by H as D adatoms are replaced by H atoms.     

High pressure treatment of pharmaceutical drug delivery and related systems

Abstract

Solids like layer silicates (kaolinite and montmorillonite) as well as ZnO are in use in pharmacy. They are pressure treated and subsequently analyzed by means of ESR spectroscopy. The structural changes indicated by Fe³⁺ ions and paramagnetic defects are reponsible for the enhanced chemical activity of the pressurized systems.

Especially active Fe-O-species are formed which can react with intercacalated organic molecules. The most probable first step of such reactions will be a solid state single electron transfer. Spin probes and spin traps were used to prove this statements. The activation of the drug delivery systems by mechanical treatments is of importance for the stability of the drugs incorporated.     

STUDY OF HEAVY ION MODIFIED CR-39 (DIETHYLENEGLYCOL BISALLYL CARBONATE)

The commercially available solid state nuclear track detector CR-39 was bombarded with 100 MeV Si⁸⁺ ions. The Fourier transfonned infrared (FTIR) spectroscopic technique was employed for studying the changes in chemical properties whereas differential scanning calorimetry was used for studying the changes in thermal properties. It was observed that there were substantial chemical modifications in the sample, such as the breaking of C-0 single bonds and the formation of phenolic 0-H bonds. lt was further observed that CR-39 is amorphous and rigid and shows no glass transition temperature.     

Poly[lithium methacrylate-co-oligo(oxyethylene)methacrylate] as a solid electrolyte with high ionic conductivity

Poly[lithium methacrylate-co-oligo(oxyethylene)methacrylate] film was prepared as a polymeric solid electrolyte which showed lithium ionic conductivity of 2×10^?7(S/cm). This film contained no organic plasticizer nor low molecular weight lithium salts and shown to be a single-ion conductor in solid state. Li⁺ ionic conductivity was deeply influenced by the glass transition temperature and lithium methacrylate content of this film. A rechargeable battery composed of metallic lithium/this film/graphite showed better characteristics than any previously reported systems using polymeric solid electrolytes.     

Morphology and dynamic mechanical properties of poly(acrylonitrile-butadiene-styrene)/polycarbonate/clay nanocomposites prepared by melt mixing

The morphology and dynamic mechanical properties of poly(acrylonitrile-butadienestyrene) (ABS)/polycarbonate (PC)/clay nanocomposites were investigated. From the studies of the transmission electron microscopy (TEM) analysis of the ABS/PC (70/30 wt%) nanocomposites with clay, it was observed that most of the clay existed in the ABS phase and the interface of the ABS and PC. From the studies of the scanning electron microscopy (SEM), droplet size of the PC in the ABS/PC/clay nanocomposites did not change significantly with the clay and has been found to be from 1.0 to 1.5 μm when the clay was added up to 5 phr. The small difference of the droplet size of the PC was maybe due to the similar values of the viscosities of the dispersed phase (PC) and continuous phase (ABS). From the dynamic mechanical properties of the ABS/PC/clay nanocomposites, the storage modulus was increased by the addition of the clay at the rubbery state between 120 and 150°C. From the studies of the tan δ of the ABS/PC/clay nanocomposites, it was shown that double tan δ peaks were observed. The height of the lower temperature tan δpeak was decreased from 4.5 to 3.3 when the clay was increased up to 5 phr. The decrease of the height of the lower tan δ peak in the ABS/PC/clay nanocomposites suggested that the ABS chain motion was restricted by the clay in the ABS phase.     

Structural and spectroscopic investigations of non‐planar tris(dialkylamino)cyclopropenium cations

The mixed triaminocyclopropenium cation bis(diisopropylamino)dimethylaminocyclopropenium was prepared from bis(diisopropylamino)chlorocyclopropenium by reaction with dimethylamine. It was isolated as the perchlorate salt and found to have a distorted structure in the solid state. Tris(diisopropylamino)cyclopropenium was prepared by reaction of pentachlorocyclopropane with diisopropylamine in a refluxing dichloroethane solution for 2 days. The solid state structure was found by X‐ray crystallography to have two planar amino groups and one pyramidal amino group, however, the ¹H‐NMR and infrared solution spectra show equivalent isopropyl groups in solution. The compounds were also characterised by Raman and infrared spectroscopy. Additionally, a new polymorph of [C₃(NMe₂)₃]ClO₄ is described as well as the X‐ray structure of bis(diisopropylamino)cyclopropenone. Copyright © 2007 John Wiley & Sons, Ltd.     

Morphology and Mechanical Properties of Polyamide 6/Acrylonitrile-Butadiene-Styrene Blends Containing Carbon Nanotubes

The blends of polyamide 6/acrylonitrile-butadiene-styrene (PA6/ABS), with added styrene-maleic acid copolymer (SMA) compatibilizer, were prepared through melt mixing in an internal mixer. The effects of blend composition and various process conditions, as well as the addition of multi-wall carbon nanotubes (MWCNTs) to the blends, on the morphology and mechanical properties were investigated. The morphology of the blends and blend nanocomposites were observed by scanning electron microscopy (SEM) and analyzed using an image analysis technique. The mechanical behavior of the blends was investigated by tensile and also impact testing. The results showed that the blend composition as well as the processing conditions significantly affected the morphology and mechanical properties of the PA6/ABS blends. Among the various compositions, the blend with 36?wt.% of ABS and 4?wt.% of SMA compatibilizer exhibited the best mechanical properties. Comparing various speeds and times of mixing, it was found that less mixing speed and longer mixing times resulted in the favorable morphology and conditions for achievement of the desired toughness for the polyamide 6. By adding different amounts of MWCNTs to the blends, it was found that the presence of the carbon nanotubes changed the viscosity of the resulting nanocomposite and thus changed the morphology. These nanocomposites also showed an improvement in mechanical properties. The MWCNTs acted as a second compatibilizer, resulting in a synergistic effect on the mechanical properties of the PA6/ABS blend nanocomposites.     

Backscattering of low-energy (0–8 eV) electrons by a silicon surface

An experimental apparatus and method for investigating elastic and inelastic backscattering (180°) of low-energy (0–8 eV) monoenergetic electrons by a solid surface are described and the first results are presented for the reflection of electrons by samples of pure single-crystalline silicon with a polished surface (Si), doped p-type single-crystalline silicon with a porous surface (Si-p) as well as H₂O and H₂O₂ passivated porous samples, Si-p + H₂O and Si-p + H₂O₂. A structure due to the excitation of surface plasmons has been observed for the first time in the loss spectra. Features corresponding to a resonance excited state of molecular nitrogen adsorbed on the surface of porous silicon have been observed in the constant residual energy spectra. Zh. Tekh. Fiz. 67, 103–108 (May 1997)     

Morphological,Thermal and Mechanical Properties of Compatibilized Nylon 6/ABS Blends

Super‐tough nylon 6/ABS blends were prepared by using styrene/acrylonitrile/maleic anhydride co‐polymer (SAM) as a compatibilizer. The variations in morphology, mechanical behavior, and crystallinity associated with the reaction of the SAM with the nylon were characterized. The results showed that the addition of SAM to nylon 6/ABS blends enhanced the interfacial adhesion between nylon 6 and ABS, and this led to the decrease of ABS domain size and the improvement of mechanical properties of their blends. Moreover, it could be found that the crystallinity and phase morphology changed with the variation of SAM.     

Interplay of structural, magnetic and transport properties in thelayered Co-based perovskite LnBaCo 2 O 5 (Ln = Tb, Dy, Ho)

The oxygen deficient cobaltites LnBaCo₂O₅ (Ln = Tb, Dy, Ho) exhibit two successive crystallographic transitions at T _N ∼340 K and at T _CO ∼210 K. Whereas the first transition (P4/mmm to Pmmm) is related to the long-range antiferromagnetic ordering of the Co ions (spin ordering), the second transition (Pmmm to Pmmb) corresponds to the long-range ordering of the Co²⁺ and Co³⁺ species (charge ordering) occurring in 1:1 ratio in the structure. The charge ordered (CO) state was directly evidenced by the observation of additional superstructure peaks using neutron and electron diffraction techniques. The CO state was also confirmed indirectly from refinement of high resolution neutron diffraction data as well as from resistivity and DSC measurements. From the refined saturated magnetic moment values only, ∼3.7 and ∼2.7 , the electronic configuration of the Co ions in LnBaCo₂O₅ remains conjectural. Two pictures, with Co³⁺ ions either in intermediate spin state ( t ⁵ _2g e ¹ _g ) or in high spin state ( t ⁴ _2g e ² _g ), describe equally well our experimental data. In both cases, the observed magnetic structure can be explained using the qualitative Goodenough-Kanamori rules for superexchange. Finally, in contrast to the parent Ln = Y compound [Vogt et al. , Phys. Rev. Lett. 84, 2969 (2000)], we do not report any spin transition in LnBaCo₂O₅ (Ln = Tb, Dy, Ho). Received 13 December 2000     

Vibrational Spectra of Benzylidene Aniline,O-Hydroxybenzylidene O-Hydroxyaniline and its Complexes with Cu(II) and NI(II) Metal Ions

Abstract

The FTIR and FT Raman spectra of benzylidene aniline, and o-hydroxybenzylidene o-hydroxyaniline compounds in the solid state in the wavenumber (1800-200 cm^?1) are recorded. An assignment for nearly all fundamentals are proposed. Comparison of the spectra of trans stilbene and benzylidene aniline reveals that v N-Ph stretch for the latter compound is situated at 1368 cm^?1 in the IR spectra with medium intensity. for o-hydroxybenzylidene o-hydroxyaniline, the stretching modes v N-Ph, and v C-Ph are observed at 1356 and 1226 cm^?1 respectively. the two v O-Ph are observed as intense bands in the IR spectra at 1245 and 1278 cm^?1, respectively. the FTIR spectra of the o-hydroxybenzylidene o-hydroxyaniline complexes with Cu(II) and Ni(II) metal ions are also recorded and assigned.     

Synthesis, Characterization and DNA-binding Properties of Ln(III) Complexes with 6-Ethoxy Chromone-3-Carbaldehyde Benzoyl Hydrazone

A novel 6-ethoxy chromone-3-carbaldehyde benzoyl hydrazone (L) and its Ln(III) complexes, [Ln = Sm (1), Eu (2), Gd (3), Tb (4)], have been synthesized and characterized. The fluorescence properties of the Eu(III) and Sm(III) complexes in solid state and Eu(III) complex in different solutions (DMF, DMSO, methanol and acetonitrile) were investigated. At the same time, the DNA-binding properties of the two complexes are investigated using UV-Vis absorption spectroscopy, fluorescence spectroscopy, viscosity measurement. All the experimental evidences indicate that the two complexes can bind to CT-DNA via an intercalation mechanism. Furthermore, antioxidant activity tests in vitro showed that the complexes have significant antioxidative activity against hydroxyl free radicals from the Fenton reaction.     

IR-Spectral Study of Solid State Complexes of Lanthanum with Mono-and bis-(2-Ethylhexyl) Phosphoric Acids

IR-spectra of the solid state lanthanum complexes with mono-and bis-(2-ethylhexyl) phosphoric acids (H₂B, resp. HA) are studied. It is confirmed that La coordinates HA as LaO₆-octahedra, connected through -La-O-P-O-La-bridging bonds. The so fixed polynucleous chains form the crystal structure of the complex. The obtained IR-spectral data as well as the results of the X-ray powder diffraction analysis show that La forms shorter polymeric chains than the other rare earth complexes of the same type.

Certain methods for the synthesis of the solid state complexes of La with H₂B (studied for the first time) are considered. It is shown that the structure of La-HB-complexes is consituted also by LaO₆-octahedra, resp.-La-O-P-O-La-polymeric chains. However they are binded through crosswise PO—H., O(H)-P hydrogen bonds, owing to the non-deprotonized hydroxo-group presented in the complex. The so formed supramolecular structure has to be more disordered than the one in the case of the complexes with HA. This determines the amorphous (nanocrystalline) state of the H₂B-complexes and, probably, their abiliity to coordinate water as well.     

Infrared Spectra of Morfolonium (mpH)2Mo2Cl6(H20)2(I),(mpH)2Mo2ClxBr6-x(H2O)2(II)/ (mpH)2Mo2Br6(H2O)2(III) and the Pyridinium (PyH)2Mo2I6(H2O)2(IV)Hexahalo-di(aquo): dimolybdate(II) Complexes,Containing Quadruple Metal-Metal Bounds

Abstract

The electronic (800–400 nm), infrared (4000–200,400–20 cm^?1), ordinary Raman (400–200 cm^?1) spectra of morpholinium and the pyridium hexahalo-di(aquo) dimolybdate(II) complexes, containing quadruple metal-metal bonds were investigated. The electronic spectra of the solid compounds at various temperatures (25,100 and 300K) demonstrate intense and structured bands in the visible region (510–582 nm) attributed to the expected δ→δ? transitions.

From the infrared and Raman spectra, the skeletal stretching modes in these complexes have been localized, and the charectenstic bands of these ions were observed in the expected regions.

Finally, the ionic interections were relatively weak, but the existance of phenomena was perceptible and the result was obtained in agreement with X-ray data.     

Infrared and Raman Spectra of bis-Thiourea Lead(II) Chloride

Abstract

PbCl₂.2[(SC(NH₂)₂] is an important complex for environmental chemistry. Single crystals were studied using infrared absorption, and Raman spectroscopy in low temperature conditions (10 K). Assignments of the lead complex bands were made by searching correlations and group frequencies with separate PbCl₂ and thiourea spectra in the solid state. Lattice modes separation was achieved down to 20 cm^?1 in Raman and down to 50 cm^?1 with far infrared spectroscopy. Spectral signatures of the unusual seven-coordinated lead in the complex were tentatively determined and are in accordance with structural data.