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Boric acid

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Abstract

pH ranges of existence of boric acid and its ionic species H2BO 3−, HBO 32−, BO 33−, and B(OH) 4− in aqueous solutions are calculated using Mathcad software package.

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... They were estimated using Eq. (14). The behavior of solubility at the other temperatures is similar. ...
... H 2 O during the dissociation of this acid in water. The presence of these species was verified experimentally by NMR shifts.Perelygin and Chistyakov[14] performed the speciation of boric acid solutions for the complete pH range. For a total concentration of 0.1 M, for pH less than 7, H 3 BO 3 is the prevalent specie, at pH 8, the predominant species are H 3 BO 3 , H 2 BO 3 ...
... Parameters and standard deviation of Eq.(14) for modeling boric acid solubility in salt aqueous solutions from 293.15 K to 313.15 K. a ...
... They were estimated using Eq. (14). The behavior of solubility at the other temperatures is similar. ...
... H 2 O during the dissociation of this acid in water. The presence of these species was verified experimentally by NMR shifts.Perelygin and Chistyakov[14] performed the speciation of boric acid solutions for the complete pH range. For a total concentration of 0.1 M, for pH less than 7, H 3 BO 3 is the prevalent specie, at pH 8, the predominant species are H 3 BO 3 , H 2 BO 3 ...
... Parameters and standard deviation of Eq.(14) for modeling boric acid solubility in salt aqueous solutions from 293.15 K to 313.15 K. a ...
... It has a water solubility of about 50 g l À1 (21°C). The pH value of a 0.1 M solution of boric acid is 5.1; thus, it is considered as a weak acid [10]. Boric acid is considered as a non-toxic material with a 5.14 g kg À1 oral median lethal dose (LD 50 ) in rats [11]. ...
... Boric acid does not liberate a proton in water, but rather bonds to the O atom of an H 2 O molecule, which then releases an H + ion to form the B(OH) 4À ion (with a pK a of 9.23) according to the following chemical equation [10,[12][13][14][15]: ...
... The pK a 's of boric acid are 9.24, 12.40 and 13.40, respectively [10]. According to the Henderson-Hasselbalch equation equation, in the acidic pH of the stomach (about 2.0), almost all boric acid molecules exist as B(OH) 3 [10] and at physiologic pH of the human body (7.4), about 1.8% of boric acid molecules exist as B(OH) 4À and 1.4% of those exist as H 2 BO À 3 . ...
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Aluminium phosphide (AlP) is a storage fumigant pesticide, which is used to protect stored grains especially from insects and rodents. It releases phosphine (PH3) gas, a highly toxic mitochondrial poison, in contact with moisture, particularly if acidic. Although the exact mechanism of action is unknown so far, the major mechanism of PH3 toxicity seems to be the inhibition of cytochrome-c oxidase and oxidative phosphorylation which eventually results in adenosine triphosphate (ATP) depletion and cell death. Death due to AlP poisoning seems to be as a result of myocardial damage. No efficient antidote has been found for AlP poisoning so far, and unfortunately, most of the poisoned human cases die. PH3, like ammonia (NH3), is a Lewis base with a lone-pair electron. However, boric acid (B(OH)3) is a Lewis acid with an empty p orbital. It is predicted that lone-pair electron from PH3 is shared with the empty p orbital from B(OH)3 and a compound forms in which boron attains its octet. In other words, PH3 is trapped and neutralised by B(OH)3. The resulting polar reaction product seems to be excretable by the body due to hydrogen bonding with water molecules. The present article proposes boric acid as a non-toxic and efficient trapping agent and an antidote for PH3 poisoning by investigating the chemical reaction between them.
... 5 So far, boric acid and boron oxide have already been used for a broad range of applications and products such as ceramics, detergents fertilizers, glass, mineral wool, sport equipment, insecticides, or medical treatments. [6][7][8][9] However, recently, the boric acid-boron oxide system received further attention as a promising candidate for storing thermal energy. 10 Its high-energy density of 2.2 GJ/m 3 could meaningfully contribute to the global sustainable energy supply. ...
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Abstract 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.
... Nearly 75% of the worldwide borate consumption concerns the production of ceramics, detergents, fertilizers, and (heat-resistant) glass [24]. In addition to this area of application, it is further used for mineral wool, sport equipment, insecticides, or medical treatments [26][27][28]. Furthermore, there were investigations regarding its usage as rocket propulsion or military use [29]. ...
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This paper aims to describe the capability of the system boric acid–boron oxide for thermochemical energy storage. As part of the systematic research and in-depth analysis of potential solid/gas reaction systems, performed during the last years, this reaction system appears to be highly promising for the future of worldwide sustainable energy supply. The analysis of the reaction heat, by means of thermogravimetric and macroscopic investigations, not only showed a significantly higher energy density of 2.2 GJ/m3, compared to sensible- and latent energy storages, but the reaction kinetic further demonstrated the reactions’ suitability to store energy from renewable energy and waste heat sources. This paper, therefore, shows a new approach regarding the application of the boric acid–boron oxide reaction system and elaborates on the advantages and challenges for its use as energy storage.
... In contrast, the PEC activity of ZnO NRs can be preserved when the borate buffer electrolyte is employed. This is probably due to the fact that the HBO 3 2− species existing at 12 < pH < 14 44 are mainly responsible for proton transport and reduce the concentration of hydroxyl ions at the ZnO/electrolyte interface. Another possible reason is the formation of the borate radical, • B(OH) 4 , (eqs 12−14), from the oxidation of B(OH) 4 − by photogenerated holes at pH > 11.5, which might oxidize water and suppress the decomposition of ZnO NRs. 45 ...
Article
This work demonstrates the improved stability of zinc oxide nanorods (ZnO NRs) for the photoanode of solar water splitting under voltage biases by the addition of borate or carbonate ions in the aqueous electrolyte with suitable pH ranges. The ZnO NRs prepared by the hydrothermal method are highly active and stable at pH 10.5 in both borate and carbonate buffer solutions, where a photocurrent higher than 99% of the initial value has been preserved after 1 h polarization at 1.5 V (vs reversible hydrogen electrode) under AM 1.5G. The optimal pH ranges with a minimum morphological change of ZnO NRs for photoelectrochemical (PEC) water splitting in borate and carbonate buffer solutions are 9–13 and 10–12, respectively. The working pH range for PEC water splitting on ZnO NR photoanodes can be extended to 8.5–12.5 by the combination of borate and carbonate anions. The lifetime of ZnO NR photoanodes can be synergistically prolonged for over an order of magnitude when the electrolyte is the binary electrolyte consisting of borate and carbonate in comparison with these two anions used individually. On the basis of the experimental results, a possible mechanism for the protective behavior of ZnO in borate and carbonate solutions is proposed. These findings can be used to improve the lifetime of other high-performance ZnO-based catalysts and to understand the photocorrosive and protective behaviors of ZnO NRs in the borate and carbonate solutions.
... There was no significant difference between the strength of chemotaxis at pH 6.0 and 7.0. As a Lewis acid, boric acid abstracts OH from water 25 : ...
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Chemotaxis enables bacteria to move toward more favorable environmental conditions. We observed chemotaxis toward boric acid by Ralstonia pseudosolanacearum Ps29. At higher concentrations, the chemotactic response of R. pseudosolanacearum toward boric acid was comparable to or higher than that toward L-malate, indicating that boric acid is a strong attractant for R. pseudosolanacearum. Chemotaxis assays under different pH conditions suggested that R. pseudosolanacearum recognizes B(OH)3 (or B(OH3) + B(OH)4⁻) but not B(OH)4⁻ alone. Our previous study revealed that R. pseudosolanacearum Ps29 harbors homologs of all 22R. pseudosolanacearum GMI1000 mcp genes. Screening of 22 mcp single-deletion mutants identified the RS_RS17100 homolog as the boric acid chemoreceptor, which was designated McpB. The McpB ligand-binding domain (LBD) was purified in order to characterize its binding to boric acid. Using isothermal titration calorimetry, we demonstrated that boric acid binds directly to the McpB LBD with a KD (dissociation constant) of 5.4 µM. Analytical ultracentrifugation studies revealed that the McpB LBD is present as a dimer that recognizes one boric acid molecule.
... Boron, in nature, is widely distributed in the form of borates. The borate, which is commonly used as boric acid (BA) and is a monobasic Lewis acid of boron having the chemical formula of H 3 BO 3 /B(OH) 3 , occurs in the form of white powder that is soluble in water [14]. Boron is mandatory to support biochemical routes by serving functional and structural roles [15]. ...
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Increased synthesis of heat shock protein 70 (Hsp70) occurs in prokaryotes and eukaryotes in response to physiological, environmental, and chemical exposures, thus allowing the cell survival from fatal conditions. Hsp70 cytoprotective properties may be clarified by its anti-apoptotic function. Boron has been reported to play an essential role in various organ developments and metabolisms. However, it is not known if boron is also able to modulate the Hsp70. In the present study, the actions of boron on ostrich spleen and expression level of Hsp70 were investigated. Thirty healthy ostrich chicks were randomly assigned to six groups: groups I, II, III, IV, V, and VI and fed the basal diet spiked with 0-, 40-, 80-, 160-, 320-, and 640-mg boric acid (BA)/L, respectively, in drinking water. The histomorphological examination in the spleen was done by hematoxylin and eosin (HE) staining. The expression level of Hsp70 was analyzed by immunohistochemistry (IHC) and western blotting, and mRNA expression of Hsp70 was investigated by quantitative real-time PCR (qPCR). In order to investigate apoptosis, TUNEL assay reaction in all treatment groups was analyzed. Our results showed that the histological structure of spleen up to 160 mg/L BA supplementation groups well developed. The Hsp70 expression level first induced at low-dose groups (up to group IV) and then inhibited dramatically in high-dose groups (V and VI) while comparing with the group I (0 mg BA). The TUNEL assay reaction revealed that the cell apoptosis amount was decreased in group IV, but in group V and especially in group VI, it was significantly increased (P < 0.01). Taken altogether, proper dietary boron treatment might stimulate ostrich chick spleen development by promoting the Hsp70 expression level and inhibiting apoptosis, while a high amount of boron supplementation would impair the ostrich spleen structure by inhibiting Hsp70 expression level and promoting cell apoptosis.
... On the other hand, boric acid is a weak acid that does not completely dissociate in water, resulting in negatively charged boron containing species [48] ...
Article
The effect of varying the boron and aluminium content of the starting electrolyte for extrinsically doped ZnO films grown on SnO2:F substrates by electrochemical deposition was investigated. The ZnO:B film surface was characterised by grains with mainly hexagonal faces exposed while the exposed faces of the ZnO:Al grains were rectangular. Whereas a B3 +/Zn2 + ratio of up to 10 at.% in the electrolyte had no significant effect on the crystalline structure of the ZnO films, an Al3 +/Zn2 + ratio above 0.25 at.% increased the disorder in the crystalline structure. All the boron doped films exhibit a strong E2-high Raman mode related to wurtzite ZnO structure but this peak was much weaker for ZnO:Al and diminished with increasing Al incorporation in the films. Exposing the films to ultra-violet light reduced their effective sheet resistance from values beyond measurement range to values between 40 and 5000 kΩ/sq for film thicknesses of 200-550 nm. Inspection of the optical spectra near the bandgap edge and the plasma edge in the mid infrared range, showed that the Al-doping resulted in a higher carrier concentration ~ 10 20 cm− 3 than B-doping. X-ray electron spectroscopy showed that the dopant efficiency was limited by the absence of dopant atoms near the surface of all the ZnO:B films and of the lightly doped ZnO:Al and, by the formation of aluminium oxide at the surface of the more highly doped ZnO:Al films.
... This equilibrium is possible only when the concentration of boric acid in solution less than or equal to 0.025M. 2,3,4,5,8 B(OH) 3 + H2O  B(OH) 4 -+ H + (pK= 9.0) [equation No 1] MATERIAL AND METHODS: Chemicals Required: Boric Acid (USP grade) was purchased from Bio Laboratories, New Delhi. Hydrochloric acid, Glacial Acetic acid and Methanol was purchased from Rankem, India. ...
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Boric acid is one of the widely used inorganic compound in pharmaceutical industry. We find its utilization as an antiseptic, in eye wash preparations, as an insecticidal, as a buffering agent etc. In this present work, a comparative study of the UV-Vis spectras of the boric acid solution in different solvents have been done. A variety of solvents like water, ethanol, methanol, glacial acetic acid, hexane, Tetrahydrofuran and 0.2M HCl solution have been employed for spectral analysis. When water was taken as a solvent, aqueous boric acid solution gave negative absorbance in complete range of UV-Vis analysis i.e. 1100nm to 190 nm. In contrary to this, when methanolic solution of boric acid was taken, positive absorbance in the complete range of spectrum was noticed. Purely on the basis of spectras obtained for boric acid solution in different solvents, best solvent out of those have been regarded as the most suitable solvent for carrying out the UV-Vis analysis for boric acid.
Article
This review provides insight into the use of boric acid as a pharmaceutical, a buffer, and an adjuvant/excipient in pharmaceutical formulations. Boric acid is a Lewis acid with a pKa of 8.92-9.24 that is sensitive to temperature, ionic strength, and concentration. The pKa varies with concentration because of polymerization above 0.02 M. Boric acid reacts reversibly with alcohols, especially 1,2-diols including carbohydrates, with carboxylic acids, thiols, and amines. These esters/adducts, are also Lewis acids with lower pKa values. Boric acid can stabilize some materials while catalyzing the degradation of others. Boric acid is used in various dermal and women’s hygiene products because of its mild antibacterial and antifungal activity. In ophthalmic products, it is used as a buffer and in combination with other preservatives to broaden the prservative spectrum. Boric acid has been used reluctantly in parenteral products but appears to be quite safe at low doses. However, at high exposure, toxicity, including death, has been reported in humans, especially in children. Animal toxicities have also been noted, including reductions in male sperm counts. Boric acid is well absorbed on oral dosing. Its biological half-life is about 21 hours in humans and has an affinity for some tissues, especially bone.
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A great deal of progress has been made with regard to the morphology and growth mechanism of metal nanostructures, here we report a novel method to control the morphology of silver nanostructures by galvanic replacement reaction with the assistance of boric acid. Silver nanotubes and nanocombs were obtained by varying the concentration and pH value of boric acid. The growth status of silver nanostructure were captured during the process, meanwhile, a novel growth mechanism of silver nanocombs and nanoflowers was proposed. We hypothesized that the boric acid acts as a modified electrode and template molecule in the system. The possible molecular configuration of boric acid, the modification and adsorption of boric acid on the electrode during the galvanic replacement were also investigated. Finally, this paper has demonstrated the versatility of a simple, green and conceptually novel naturally occurring template approach for the controllable synthesis of metal nanostructures.
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The chemistry of post-synthetic modification of borosilicate zeolites, and their understanding and use in catalytic applications are reviewed. First, a survey is given on the practical application of solid state NMR to follow the structural properties of boron. Then, the hydrolytic chemistry of boron in zeolites is summarized with a focus on selective reactivities of trigonal boron created by counterions, and stepwise extraction of boron from the framework. The reinsertion of other heteroatoms (mainly Al is discussed here) can be carried out by three different methods with different selectivities. First, the extent of Al reinsertion can be tailored quantitatively by controlling boron removal and vacancy formation with appropriate counterions. Secondly, the substitution of Al for B can be kinetically retarded by using uncalcined as-made zeolites with organic structure directing agents still occluded in the pores. Although these zeolites are not porous, quantitative replacement of framework atoms (Al for B) is possible, most likely by a solid state diffusion mechanism. Finally, Al reinsertion can be efficiently achieved in aqueous Al(NO3)3 solution under acidic conditions and is pore selective. This is due to the finding that the hydrated aluminum cations are too bulky for medium-sized pores, so that preferably 12-membered ring pores can be aluminated, and 10-membered ring pores do not substitute Al for B. This substitution can be quantitatively followed by the pH change in the zeolite/Al(NO3)3 slurry. A variety of catalytic test reactions are used to characterize the catalytic properties of the aluminosilicate zeolites prepared via post-synthetic treatment of their borosilicate counterparts.
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When a special preparation procedure has been applied, the crystallization system of boric acid has been changed from triclinic to hexagonal: at temperatures between 60 and 70 �C, under controlled pH conditions, the boric acid belonging to triclinic system was mixed with Dglucose, calcium carbonate, and calcium hydroxide. Thermal analysis evidenced a final compound with quite similar thermal behavior as that of initial triclinic boric acid but having some differences in decomposition kinetics. X-ray diffraction analysis showed a new compound, named HBA, belonging to the hexagonal crystallization system with the following lattice parameters: a = b = 20.4869 A ° and c = 12.1506 A ° . This strong anisotropic structure was also confirmed by the hexagonal form of the crystallites, grown from HBA and water solutions, which have been observed with a light polarized optical microscope. Exotic polycrystalline conglomerates grown from water solution of HBA have nice colours that are changing when they are set different angles between polarizer and analyser. FTIR measurements revealed the IR absorbance bands belonging to O–H, O–B, and H–O–B bonds of the trigonal planar boric acid, for both crystallographic systems, but some small differences between wave-numbers and peak
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Weak polyelectrolyte brushes exhibit pH-responsive swelling behaviour, tuneable surface energy, and some promise as "smart" responsive coatings. In this paper, we demonstrate the growth of two weak polybase brushes by surface-initiated atom transfer radical polymerisation (SI-ATRP) using electrostatically adsorbed polyelectrolyte macro-initiators. Poly[2-(diethylamino)ethyl methacrylate] (PDEA) and poly[2-(diisopropylamino)ethyl methacrylate] (PDPA) brushes of 150 and 170 nm thickness respectively were grown within 22 h at 20 [degree]C. Using in situ ellipsometry an acid-induced swelling transition was observed at pH 7.4 for PDEA and pH 6.5 for PDPA, similar to the pKa values reported for the corresponding free polymer chains. The kinetics of brush swelling involves an initially fast regime followed by a subsequent slower regime. Reversible surface energy switching with pH modulation was also demonstrated by contact angle goniometry. Finally, it was demonstrated that PDPA brushes respond to the presence of acidic vapours. On exposure to humid HCl vapour, such brushes become hydrophilic, resulting in water uptake and swelling, producing a visible change in the thin film interference colour.
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