Stabilization of borate by hot isostatic pressing after co-precipitation with hydroxyapatite using MAP.

Boric acid is one of the most mobile inorganic contaminant species in nature due to its pKa of 9.23. Co-precipitation of borate with hydroxyapatite (HAp: Ca5(PO4)3OH) facilitates the simultaneous removal of borate with co-existing oxoanions in natural waters. The cost of phosphate is an impediment to industrialize the co-precipitation of borate with HAp for treatment of geothermal waters. In the present work, an inexpensive industrial by-product of magnesium ammonium phosphate (MAP) derived from sewage sludge, was examined as a phosphate source. MAP includes 89% pure magnesium ammonium phosphate, resulting in better performance than the pure chemical form of NH4H2PO4, because Mg2+ and Al3+ (trace elements in MAP product) play roles in enhancing the removal rate of borate and lowering the equilibrium borate concentration. These ions have a good affinity with phosphate to nucleate crystal seeds independently of powdery Ca sources. To reduce the bulky volume of solid residues, hot isostatic pressing (HIP) was applied. There is structural water in HAp; therefore, the greatest volume reduction was achieved with 78.3 ± 2.0% (n = 3). Additionally, a synergic effect to suppress the released borate, greater than the sequential combination of calcination and cold isostatic pressing was accomplished in the toxicity contents leaching procedure (TCLP) test. This is not due to larger crystal sizes alone, but it is derived from boron stabilization in HAp at an atomic level by the synergic effect of heating and pressing simultaneously.

Evaluation of the Interaction between Borate Ions and Nickel-Aluminum Complex Hydroxide for Purification of Wastewater.

A new mixed metal hydroxide adsorbent (NA11, molar ratioNi-Al = 1 : 1) was prepared and its physicochemical properties (specific surface area, amount of hydroxyl group, scanning electron microscopy images, X-ray diffraction analysis, elemental distribution, and binding energy) were studied. In addition, the amount of borate ion adsorbed using several adsorbents, including NA11, was evaluated in this study. The specific surface area of and amount of hydroxyl group in NA11 was greater than those of the other studied adsorbents. The amount of borate ion adsorbed showed similar trends to those of the specific surface area and number of hyrdroxyl groups, which indicated that the adsorption mechanism of borate ion was related to the specific surface area and the amount of hydroxyl group. After adsorption, the binding energy of boron B(1s) peaked, and the sulfur peak intensity S(2s) and S(2p) reduced. These results suggest that ion exchange between borate and sulfate ions was one of the adsorption mechanisms. Equilibrium adsorption was reached within 6 h in the case of NA11. These data were fitted into a pseudo-second-order model (r = 0.813-0.998). The solution pH affected the capacity of NA11 for adsorbing borate ion from aqueous solution. It was found that adsorbance was greatest at pH 10. Adsorption isotherm data were fitted to both the Freundlich (r = 0.986-0.994) and Langmuir (r = 0.997-0.999) isotherm equations. Collectively, it is suggested that NA11 is prospectively useful for the adsorption of borate ion from aqueous solutions.

Recycling of typical supercapacitor materials.

A simple, facile and low-cost method for recycling of supercapacitor materials is proposed. This process aims to recover some fundamental components of a used supercapacitor, namely the electrolyte salt tetraethyl ammonium tetrafluoroborate (TEABF4) dissolved in an aprotic organic solvent such as acetonitrile (ACN), the carbonaceous material (activated charcoal, carbon nanotubes) purified, the current collector (aluminium foil) and the separator (paper) for further utilization. The method includes mechanical shredding of the supercapacitor in order to reduce its size, and separation of aluminium foil and paper from the carbonaceous resources containing TEABF4 by sieving. The extraction of TEABF4 from the carbonaceous material was based on its solubility in water and subsequent separation through filtering and distillation. A cyclic voltammetry curve of the recycled carbonaceous material revealed supercapacitor behaviour allowing a potential reutilization. Furthermore, as BF4(-) stemming from TEABF4 can be slowly hydrolysed in an aqueous environment, thus releasing F(-) anions, which are hazardous, we went on to their gradual trapping with calcium acetate and conversion to non-hazardous CaF2.

Assessment study for multi-barrier system used in radioactive borate waste isolation based on Monte Carlo simulations.

Radioactive waste generated from the nuclear applications should be properly isolated by a suitable containment system such as, multi-barrier container. The present study aims to evaluate the isolation capacity of a new multi-barrier container made from cement and clay and including borate waste materials. These wastes were spiked by (137)Cs and (60)Co radionuclides to simulate that waste generated from the primary cooling circuit of pressurized water reactors. Leaching of both radionuclides in ground water was followed and calculated during ten years. Monte Carlo (MCNP5) simulations computed the photon flux distribution of the multi-barrier container, including radioactive borate waste of specific activity 11.22KBq/g and 4.18KBq/g for (137)Cs and (60)Co, respectively, at different periods of 0, 15.1, 30.2 and 302 years. The average total flux for 100cm radius of spherical cell was 0.192photon/cm(2) at initial time and 2.73×10(-4)photon/cm(2) after 302 years. Maximum waste activity keeping the surface radiation dose within the permissible level was calculated and found to be 56KBq/g with attenuation factors of 0.73cm(-1) and 0.6cm(-1) for cement and clay, respectively. The average total flux was 1.37×10(-3)photon/cm(2) after 302 years. Monte Carlo simulations revealed that the proposed multi-barrier container is safe enough during transportation, evacuation or rearrangement in the disposal site for more than 300 years.

Synthesis of glucaminium-based ionic liquids and their application in the removal of boron from water.

A novel class of ionic liquids (ILs), exhibiting high selectivity towards boron species as well as the ability to phase separate from water, were synthesized from N-methyl-D-glucamine. The complexation of boric acid/borate with the ILs was confirmed using (11)B NMR.

Charge regulation enables anionic hydroxypropyl guar-borate adsorption onto anionic and cationic polystyrene latex.

Reported are adsorption isotherms for guar and hydroxypropyl guar (HPG), with and without the presence of borate ions, onto surfactant free anionic polystyrene latex. Guar and HPG formed adsorbed monolayers on the hydrophobic latex. The presence of borate ions converted the nonionic guar and HPG into an anionic polyelectrolyte. However, there was no measurable influence of bound borate ions on the adsorption of guar or HPG onto anionic, hydrophobic latex. To underscore the unusual behavior of HPG-borate, a sample of HPG was oxidized to introduce carboxyl groups, and the adsorption of the carboxylated HPG onto anionic polystyrene was measured. Unlike HPG-borate, oxidized HPG did not adsorb onto negative polystyrene latex at neutral pH because of electrostatic repulsion. To explain the adsorption of negative HPG-borate onto negative latex, we proposed that as HPG-borate segments approach the latex surface, the negative electrostatic potential near the latex surface induces the detachment of the labile borate groups from HPG.

Effect of saw dust on borate removal from groundwater in bench-scale simulation of permeable reactive barriers including magnesium oxide.

Effective immobilization of boron in groundwater is a major challenge. Permeable reactive barrier (PRB) column tests for removal of borate have been investigated using MgO agglomerates as the primary reactive material over 40 weeks. Additionally, saw dust was also blended with MgO agglomerates to facilitate for borate removal in this system. Boron accumulation was more than 1.6 times greater in the presence of saw dust, although MgO alone performed well. Increased boron accumulation in the presence of saw dust was primarily due to higher porosity of the PRB column, decreasing the impact of secondary Mg(OH)(2) passivating layers and leaving more reactive sites on MgO agglomerates. In addition, Mg(2+) ions released from MgO agglomerates are complexed with carboxylic acids leached from saw dusts. This sequestration prevents the formation of bulky Mg(OH)(2) which is an ineffective sorbent for borate and covers the surfaces and passivating reactive sites on the MgO agglomerates. The morphologies of Mg(OH)(2) precipitated in the PRB column were also significantly affected by the presence of saw dust, with crystallization of needle-like particles of Mg(OH)(2) was prevented by Mg(2+) ions-organic ligand complexation.

Micro-solvent cluster extraction using aqueous mixed solvents of ionic liquid.

Organic compounds (2-naphthol, phenol, 4-chlorophenol, 4-nitrophenol, and 1,3,5-naphthalenetrisulfonic acid) were sufficiently separated from mixtures during flow in a fused silica capillary tube (50 microm in i.d. and 45 cm in length) with an aqueous mixed solvent of an ionic liquid, 1-butyl-3-methylimidazolium chloride (BMIM(+)Cl(-)), without a specific separation column. The method is based on micro-solvent cluster formation in aqueous mixed solvents of ionic liquid and preferential solvation of solvent clusters to analytes. The measurement of large angle X-ray scattering (LAXS) of aqueous mixed solvents with an ionic liquid of tetrafluoroborate (BMIM(+)BF(4)(-)) indicated the formation of micro-solvent clusters of water and ionic liquid in the mixed solvent. A neutral polymer (polyvinylpyrrolidone, PVP) enhanced the separation. Polarized or ionic molecules eluted slowly. The theoretical plate numbers were 6320, 22907, 63645, and 37184 for 2-naphthol, phenol, 4-chlorophenol, and 4-nitrophenol, respectively, under the conditions of 1.0 M of BMIM(+)Cl(-) and 0.1 M of PVP; the flow rate was 1 microL min(-1). The separation mechanism is discussed from the viewpoint of the partition of analytes between micro-solvent clusters of water and organic solvent molecules.

Strategy for the resolution of a chiral dearomatization agent:[TpRe(CO)(1-methylimidazole)] coordination of alpha-pinene (Tp = hydridotris(pyrazolyl)borate).

A methodology for resolving TpRe(CO)(1-methylimidazole)(eta(2)-benzene) has been developed utilizing (R)-alpha-pinene. Each enantiomer of the [TpRe(CO)(MeIm)] system can be obtained with the enantiomer ratio (er) = 97:3 by taking advantage of differing rates of pinene substitution for the two diastereomers of TpRe(CO)(MeIm)(eta(2)-(R)-alpha-pinene).

Phase evolution, characterization, and impedance spectroscopic analysis of nanocrystalline SrBi2Nb2O9 in glassy Li2B4O7 matrix.

Transparent glass composites in the system (100 - x) Li2B4O7 - x SrBi2Nb2O9 (where x = 5, 10, 15, 20, 25, and 30, in molar ratio) were fabricated by conventional melt-quenching technique. The amorphous nature of the as-quenched glass composites was confirmed via X-ray powder diffraction (XRD) studies. Differential thermal analyses (DTA) established the glassy nature of the as-quenched samples. Glass nanocomposites (GNC's) with high-optical transparency were obtained by controlled heat-treatment of the glass composites at 750 K/6 h. Perovskite SrBi2Nb2O9 (SBN) phase formation through an intermediate fluorite phase was confirmed by XRD and transmission electron microscopy (TEM). The dielectric constant (epsilon r) in the frequency range from 100 Hz to 40 MHz at room temperature increases whereas dielectric loss (D) decreases with increase in SBN content in Li2B4O7 glass matrix. Impedance spectroscopy employed to rationalize the electrical behavior of the as-quenched glasses and glass nanocomposites suggests the coexistence of electronic and ionic conduction in these materials. The optical transmission and band-gap energy of these composites were found to be crystallite size dependent.

Oligosaccharides generated by partial hydrolysis of the borate-rhamnogalacturonan II complex from sugar beet.

The borate-rhamnogalacturonan II complex (B-RG-II), isolated from sugar beet (Beta vulgaris), was partially acid-hydrolyzed. The oligosaccharides generated were characterized by glycosyl-composition and glycosyl-linkage analyses, ES-mass, and NMR spectroscopy. Two disaccharides, alpha-L-Rhap-(1-->5)-D-Kdo and alpha-L-Araf-(1-->5)-Dha, an aceric acid-containing oligosaccharide, and a 2-O-Me-Xyl-containing oligosaccharide, in addition to partially methyl-esterified alpha-(1-->4)-oligogalacturonides were characterized. The data provide additional evidence that B-RG-II isolated from different plant species have identical structures.

Separation of disaccharides as their borate complexes by capillary electrophoresis with indirect detection in visible range.

Borate complexation was used to make possible the separation of disaccharides by capillary electrophoresis with indirect detection. A high borate concentration did not affect the indirect detection sensitivity in as negative a way as predicted previously. The concentration sensitivity for sucrose was determined to be 2 mM at the borate concentration of 200 mM in running electrolyte. The newly introduced background [corrected] chromophore, p-nitrophenol, allows the monitoring of the separation process in a visible range at 400 nm. This also enables the indirect detection of UV-absorbing compounds in complex mixtures in which they would be impossible to detect with a UV-absorbing background [corrected] chromophore.

[Isolation and use of stable borate-polyol pH gradients in the range of 1.9-12.0 for isoelectric focusing of proteins and low-molecular compounds]. / Poluchenie i ispol'zovanie stabil'nykh borat-poliol'nykh gradientov pH v diapazone 1,9-12,0 dlia izoélektricheskogo fokusirovaniia belkov i nizkomolekuliarnykh soedinenii.

Compositions of borate-polyol buffer solutions were developed, which enabled to produce pH gradients stable to the effect of electric potential in the limits of pH 1.9-4.5, pH 9.6-12.0 and pH 2.0-10.0. These buffers were used for isoelectrofocusing of proteins, low molecular peptides and amino acids.