Natural Borate Research Articles

Thermoluminescence and optically stimulated luminescence properties of ulexite mineral

Although naturally occurring luminescence materials such as quartz and feldspars are generally used for radiation dosimetry and dating, natural borates may also stand as a promising material for dosimetry and dating. We report thermoluminescence (TL) and optically stimulated luminescence (OSL) of one of the most abundant boron minerals in Turkey namely, ulexite (NaCaB5O6(OH)6·5H2O). An X-ray diffraction (XRD) analysis confirmed that the sample has triclinic crystal structure and contains 40.55% of B, 5.92% of Na2O, 12.3% of CaO. A thermogravimetric analysis indicates two stages of dehydration within 60–160 °C, 160–250 °C and dehydroxylation within 260–580 °C. Analysis of TL glow curves using fractional glow and deconvolution reveal that there are four glow peaks at 154, 211, 273 and 327 °C in the glow curve of ulexite. All the glow peaks follow a non-first order kinetics. The activation energies of the traps are estimated from the fractional glow curves as 0.72, 0.93, 1.16 and 1.28 eV and that evaluated from the deconvolution analysis as 0.76, 0.83, 0.96 and 1.27 eV. The lifetimes of these traps are estimated within 1.55 days–3.6 × 104 years. The radiation dose responses of the TL peaks are supra-linear between 8 Gy and 1024 Gy. OSL decay curve of ulexite consists a fast, a medium and a slow component with recombination lifetimes of (0.63 ± 0.08), (7.51 ± 0.71), (93.49 ± 3.62) s respectively. The fast OSL component obeyed first order, whereas medium and slow components obeyed general order of kinetics. The dose response of the medium and slow OSL components showed a sub-linearity from 64 Gy to 4096 Gy whereas the fast component showed linear response between 8 and 4096 Gy.

Thermal stability and high-temperature behavior of the natural borate colemanite: An aggregate in radiation-shielding concretes

Colemanite is a natural borate that can be used as an aggregate in neutron-radiation shielding concretes. In this study, we report its thermal behavior, up to 500 °C, by describing: 1) its dehydration mechanisms and 2) its thermo-elastic parameters. The thermal expansion of colemanite is significantly anisotropic. The refined volume thermal expansion coefficient at ambient conditions is: αV0 = 4.50(10)·10−5 K−1. The loss of structural H2O occurs at least from ∼240 °C, and at T > 325 °C an irreversible amorphization occurs, followed by a complete dehydration. The potential implications on the use of colemanite as concrete-aggregate are discussed.

Spectroscopic Evaluation of DNA-Borate Interactions.

We describe the binding characteristics of two natural borates (colemanite and ulexite) to calf thymus DNA by UV-vis absorbance spectroscopy, circular dichroism (CD) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and a competitive DNA binding assay. Our results suggest that colemanite and ulexite interact with calf thymus DNA under a non-intercalative mode of binding and do not alter the secondary structure of the DNA helix. The FT-IR spectroscopy results indicate that the two borates might interact with DNA through sugar-phosphate backbone binding.

Flexible-structured systems made of ceramic fibers containing Pt-NaY zeolite used as CO oxidation catalysts

Catalytic ceramic papers were developed by incorporating Pt-NaY zeolite to ceramic papers. The necessary mechanical strength was enhanced by the addition of natural borate compounds, which confer elasticity and resistance similar to those obtained using colloidal suspensions, which are the most commonly used binders. Pt-NaY zeolite was incorporated into ceramic papers either during the papermaking process or by spraying a zeolitic suspension on ceramic papers. The partial encapsulation of the faujasite by the sintering of the borate compound during the calcination step made catalytic ceramic papers less active toward the CO oxidation reaction than the corresponding traditional systems (Pt-NaY zeolite coated onto cordierite monoliths or the powder Pt-NaY faujasite). Light-off curves indicated that the activity of Pt-NaY zeolite was preserved when incorporating the zeolitic component by spray, in which case the CO oxidation reaction ran away at ca. 130 °C, and the total CO conversion was achieved at 150 °C, maintaining 100 % CO conversion for more than 90 h.

ChemInform Abstract: Interaction of Natural Borates with Potassium Hydroxide Solution.

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Chemical, mineralogical and thermal characterisation of natural and synthetic borates

The present study establishes a methodology for characterising natural and synthetic borates used as raw materials in the ceramic industry, since detailed information on this subject is unavailable in the literature. Four natural borates, three colemanites of different richness and one ulexite, were analysed in addition to two synthetic borates, a boric acid and a borax pentahydrate. The following analytical techniques were used for the characterisation: X-ray fluorescence (XRF) spectrometry, inductively coupled plasma-atomic emission spectrometry (ICP-OES), potentiometry, X-ray diffraction (XRD), thermogravimetry (TG), and differential thermal analysis (DTA). In the chemical characterisation, the elements Si, Al, Fe, Ca, Mg, Na, K, Ti, Sr, As and S were analysed by XRF, B by ICP-AES and potentiometry and F by potentiometry ISE and XRF. In the mineralogical characterisation, the boron minerals and the accessory minerals were determined and their concentration was estimated by rational analysis. The boron minerals found were colemanite, ulexite, boric acid and borax pentahydrate and the accessory minerals were calcite, dolomite, quartz, celestine and orpiment. In the thermal characterisation, the samples were subjected to a controlled heating cycle and the thermal weight losses and characteristic transformations of the samples were studied.

The isotopic composition of anthropogenic boron and its potential impact on the environment.

The present study investigates the isotopic composition of anthropogenic boron (B) and its potential affects on the environment. The isotopic ratios of B in synthetic products from the main ores in the world have been measured by negative thermal ionization mass spectrometry. The data show that the isotopic compositions of Na-borate products and washing powders overlap with those of natural Na-borate minerals. In contrast, the 11B/10B ratios of synthetic Ca-borate and Na/Ca borate products are significantly lower (by 15 permil) and overlap with those of the natural Ca-borate minerals. Consequently, the original isotopic signature of natural borate minerals is not modified during the manufacturing process of synthetic products. The B isotopic composition of domestic wastewater from Israel and Riverside, California suggests that B in sewage is derived from Na-borate components used in detergents. Since B, like other inorganic ions, is not removed during conventional sewage treatment, it accumulates in domestic wastewater. Although the B concentration in pristine groundwaters is generally low (<0.05 mg/L), contaminant sources (e.g., wastewater) are relatively enriched in B (0.5-1 mg/L). The isotopically distinguished signature of borate compounds is used to trace groundwater contamination.

Scientific Serials

American Journal of Science, October.—The relations between wind velocity and pressure, by H. Allen Hazen. A comparative study is made of the experiments carried out by Borda, Hagen, Piobert, Didion, Morin, and more recently at Washington, showing the great necessity there is for further research before absolutely trustworthy results can be obtained. Experiments are much needed, especially with larger plates than 2 feet square, with bodies of other forms than those hitherto employed and with high velocities by a straight-line motion.—Is there a Huronian Group? (continued), by R D. Irving. After establishing the existence of a true Huronian Group, the author proceeds to define its character, showing that many formations even in the Lakes Superior and Huron regions, have been wrongly referred to this type. The presence is clearly demonstrated of two entirely distinct and mutually discordant series in the Marquette, Penokee, and Menominee districts. In all these regions there are great discordances between a lower set of gneisses and other crystalline schists, intruded by granite, and an upper set of detrital rocks carrying iron. The so-called Animike series is then considered, and referred with the older Penokee formations to the Huronian system.—Oxygen in the sun; contributions from the Physical Laboratory of Harvard University, by John Trowbridge and C. C. Hutchins. The experiments here described have been carried out in order to test the soundness of the conclusion generally drawn from Dr. Henry Draper's discovery of bright spaces in the solar spectrum apparently coincident with the bright lines of the spectrum of oxygen. This conclusion is shown to be at least premature, and in the numerous photographs taken of the solar spectrum by them the authors have failed to discover any line that could with certainty be pronounced brighter than its neighbours. The bright bands of Dr. H. Draper's spectrum are found to be occupied by numerous dark lines of various degrees of intensity; but the hypothesis of Prof. J. C. Draper that these are the true representatives of the oxygen lines is rendered untenable by the lack of any systematic connection between the two.—Bismutosphærite from Willimantic and Portland, Connecticut, by H. L. Wells. An analysis of two specimens of basic bismuth carbonate shows them to be apparently identical with Weis-bach's bismutosphærite, the composition of which had been considered somewhat doubtful.—Note on some remarkable crystals of pyroxene from Orange County, New York, by George H. Williams. The lower back part of some of these specimens is exactly like the lower front quarter, but in a reversed position, so that the lower half is a twin as represented by Von Rath, while the upper half is apparently simple and of the usual habit.—The flow of solids, or liquefaction by pressure, by William Hallock. The experiments here described point at the conclusion that pressure alone cannot truly liquefy a solid—that is, diminish its rigidity; consequently neither can chemical or mineralogical changes be produced by pressure alone without a rise of temperature.—Analysis of some natural borates and borosilicates, by J. Edward Whitfield. The series of analyses here described have been undertaken to verify, if possible, the given formulæ, and correct errors caused by-defective analytical methods of estimating the boric acid of natural borates. The percentages of boric acid as here determined by direct analysis do not differ greatly from the results of Stromeyer's and Marignac's methods.—The Texas section of the American Cretaceous, by Robert T. Hill. In this paper the author studies the true character of the deep marine Cretaceous strata already determined by him in Texas, at the same time explaining some new features of it, which throw much light on the various American chalk systems.—Notice of new fossil mammals, by O. C. Marsh. Descriptions are given of some new species of Bison alticornis, Aceratherium acutum, Brontops robuslus, Menops varians, Titanops elatus, and Allops serotinus, recently received at the Yale Museum from the West.

Analyses of some natural borates and borosilicates

Analyses of some natural borates and borosilicates