Non-conventional hexagonal structure for boric acid

Harabor, A.; Rotaru, P.; Scorei, Ion Romulus; Harabor, N. A.

doi:10.1007/s10973-014-4169-5

Cited by 29 publications

(29 citation statements)

References 21 publications

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“…The hexagonal prism structure of single crystals, as well as the strong anisotropy of the exotic HBA polycrystalline features, was observed by optical microscopy (OM), the crystal structure was confirmed by X-ray diffraction (XRD), and the lattice parameters were calculated (a = b=20.4869 Å and c = 12.1506 Å ), while the thermal behaviour was evidenced by a combination of thermogravimetric analysis (TG), differential scanning calorimetry (DSC) and differential thermal analysis (DTA) [28]. The dielectric properties and refractive index of the HBA ?…”

Section: Introductionmentioning

confidence: 95%

“…The hexagonal boric acid (HBA) was produced as result of a liquid mixture of TBA, D-glucose, calcium carbonate and calcium hydroxide at temperatures between 60 and 70°C, under controlled pH conditions [28]; the exact preparative conditions are the subject of a patent request by Scorei and co-workers.…”

Section: Experimental Tba and Hba Materialsmentioning

confidence: 99%

“…Recently, Harabor et al [28] reported on the modification of the crystallization system of the triclinic boric acid (TBA) to hexagonal boric acid (HBA), when a special obtaining procedure was applied. The hexagonal prism structure of single crystals, as well as the strong anisotropy of the exotic HBA polycrystalline features, was observed by optical microscopy (OM), the crystal structure was confirmed by X-ray diffraction (XRD), and the lattice parameters were calculated (a = b=20.4869 Å and c = 12.1506 Å ), while the thermal behaviour was evidenced by a combination of thermogravimetric analysis (TG), differential scanning calorimetry (DSC) and differential thermal analysis (DTA) [28].…”

Section: Introductionmentioning

confidence: 99%

“…The dielectric properties and refractive index of the HBA ? H 2 0 solutions (7 %) were studied also at various temperatures between 20 and 50°C, while the growth kinetics was investigated at room temperature (22°C) [28]. Currently, at the University of Craiova, Romania, Prof. R. Scorei and his co-workers are undertaking studies on the biologically active properties of HBA, up to now results revealing a higher activity than for TBA, thus advocating for promising improved antiseptic and antibacterial applications.…”

Section: Introductionmentioning

confidence: 99%

“…The kinetics of the thermally induced decomposition processes is performed by means of the most usual isoconversional integral kinetic method Kissinger-Akahira-Sunose (KAS) [29,30] and of the advanced isoconversional local differential kinetic method of Ortega [31]; the computations were done by using the versatile TKS-SP 2.0 software [32,33]. For both HBA and TBA, the thermal decomposition is a three-step process, with overlapping endothermic reactions [28], resulting in variable activation energy that make therefore impossible the evaluation of characteristic kinetic models. The different thermal and kinetic behaviour highlights the differences between the two types of materials and allows for understanding their temperature ranges of applications and why the triclinic symmetry enhances the formation actually of the pseudo-hexagonal crystals as crystal habit at the macroscopic scale.…”

Section: Introductionmentioning

confidence: 99%

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Thermal and kinetic study of hexagonal boric acid versus triclinic boric acid in air flow

Rotaru

2016

J Therm Anal Calorim

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Boric acid is a very important inorganic material with diverse uses in optoelectronics, petroleum industry, medicine, agriculture, etc. Recently, it was reported on the modification of the crystallization system of the triclinic boric acid (TBA) to hexagonal boric acid (HBA), when a special obtaining procedure is applied. In this paper, the thermokinetic stability of HBA novel material was comparatively studied with respect to the well-known TBA, in air flow atmosphere. Both HBA and TBA undergo a threestep overall thermal decomposition reaction (dehydration), following similar pathways; from the thermodynamic point of view HBA is more stable-decomposition temperatures and DH are higher in this case compared to those of TBA. The kinetic analysis was performed by means of the isoconversional methods, for each step of dehydration observing different thermokinetic regions. Higher thermal stability for HBA enables it to be employed at higher temperatures instead of TBA, explaining why the triclinic symmetry enhances the formation actually of the pseudohexagonal crystals as crystal habit at the macroscopic scale. Lower thermodynamic and kinetic stability of HBA makes it easier to be activated and thus more instable at the microstructural scale: this is an indirect proof of the TBA presence in the usual surrounding conditions and in the same time raises the probability for HBA molecules to slide onto their crystalline layers due to the lability of hydrogen bonds keeping them and thus increased potential to intercalate with other molecules. The present results open the possibility for promising applications of HBA as a better lubricant for various industries, while in the medical sector superior cleanser, antifungal and antibacterial properties may be foreseen.

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Section: Introductionmentioning

confidence: 95%

Section: Experimental Tba and Hba Materialsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermal and kinetic study of hexagonal boric acid versus triclinic boric acid in air flow

Rotaru

2016

J Therm Anal Calorim

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Oxygen‐Functionalized Boron Nitride for the Oxidative Dehydrogenation of Propane – The Case for Supported Liquid Phase Catalysis

et al. 2022

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Boron and boron containing materials have created a new class of catalysts for the highly selective conversion of light alkanes to building block olefins. Boron oxide species seem to play an essential role for the oxidative dehydrogenation of propane. For boron nitride they are created through an induction process under reaction conditions. It is still not obvious how different kinds of oxidative pre-activation influences the observed activity and selectivity. Here we compare two different oxygen activation strategies of boron nitride, a classical activation by calcination at different temperatures and ball-milling with varying rotation velocity. These treatments allow to control the amount of introduced boron oxide species from 0.2 to 17.5 wt.-%, as quantified by alkalimetric titration. The catalytic experimental data together with the pre, post as well as in situ characterization, give insights how the catalyst's surface changes under reaction conditions. On this backdrop it can be deduced that molten boron oxide predominantly acts as catalyst under reaction conditions, and boron nitride as catalyst support.

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The multistep decomposition of boric acid

Huber

Jahromy

Birkelbach

et al. 2020

Energy Science & Engineering

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Due to its high potential for thermal energy storage systems (Huber, Setoodeh Jahromy, Jordan, et al, Energies. 2019;12:17) the decomposition of boric acid is of particular interest in the field of applied research. The complexity of the reaction mechanism, with its multiple partial‐overlapping reaction steps, hitherto prevented a clear identification and analysis of each stoichiometric reaction step. So far, various research teams performed different kinetic analyses of boric acid, which led to various reaction mechanisms and stoichiometric reaction steps with yet inconclusive results for process modeling. Thus, a deeper examination of the process was desirable, to validate whether a proposed reaction is reasonable or not. For this purpose, experimental data were used for a deconvolution of the reaction sequence, using the Fraser‐Suzuki function, which clearly revealed the respective single reactions. The results of the deconvolution were compared with the proposed reaction steps in consideration of the stoichiometric ratio and thereby illustrated that the decomposition of polycrystalline boric acid more likely consists of three reaction steps. In contrary to the two‐step mechanism, the three‐step mechanism showed a very good correlation (r > 99%). Based on these outcomes, kinetic analyses were performed for each reaction step, by means of the nonparametric kinetics 2 (NPK2) method with subsequent determination of kinetic parameters. Additionally, for a deeper insight into the reaction, analyzing techniques like X‐ray diffraction (XRD), scanning electron microscopy (SEM) and simultaneous thermal analysis (STA) were applied.

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Non-conventional hexagonal structure for boric acid

Cited by 29 publications

References 21 publications

Thermal and kinetic study of hexagonal boric acid versus triclinic boric acid in air flow

Thermal and kinetic study of hexagonal boric acid versus triclinic boric acid in air flow

Oxygen‐Functionalized Boron Nitride for the Oxidative Dehydrogenation of Propane – The Case for Supported Liquid Phase Catalysis

The multistep decomposition of boric acid

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