Aqueous Boric Acid Research Articles

Field evaluations of biodegradable boric acid hydrogel baits for the control of Argentine ants: Promising results in vineyards and citrus orchards

Argentine ants are a major pest in California. In this study, a biodegradable calcium alginate hydrogel with an aqueous boric acid bait was tested against Argentine ant populations in a citrus orchard and a vineyard. A new continuous method was developed to produce large quantities of hydrogel bait for the field test. Foraging activity levels of ants were compared between baited and untreated zones. For both study sites, four to five monthly bait applications throughout summer provided a greater than 80% reduction in ant activity. Based on spatial analyses by distance indices, the baited areas were characterized by gaps (areas with lower ant counts) and the untreated control zones were characterized by patches (areas with higher ant counts). This indicated area-wide suppression of Argentine ants. For the citrus orchard, post-baiting panel trap monitoring showed reductions of both ants and Asian citrus psyllid in the baited zone compared to the control. For the vineyard, mid-season soil analyses indicated that the impact of boric acid baiting on soil boron concentration was negligible. In sum, the calcium alginate hydrogel bait with boric acid as an active ingredient may provide a promising solution for Argentine ant baiting.

Laser doping of n-type 4H-SiC with boron using solution precursor for mid-wave infrared optical properties

Laser doping of n-type 4H-silicon carbide (SiC) semiconductor substrates with boron (B) using a pulsed Nd:YAG laser (λ = 1064 nm) is reported. An aqueous boric acid solution was used as a boron precursor. A simple theoretical heat transfer model was employed to select the laser processing parameters, i.e., laser power and laser-substrate interaction time, and determine the appropriate temperature to dope 4H-SiC substrates. The selected processing parameters ensured that the temperature at the laser-substrate interaction zone was below the SiC peritectic temperature to prevent any crystalline phase transformations in SiC. Fourier-transform infrared spectrometry was conducted to determine the optical properties of both undoped and boron-doped 4H-SiC substrates within the mid-wave infrared (MWIR) wavelength range (3–5 μm). Boron atoms create an acceptor energy level at 0.29 eV above the valence band in the 4H-SiC bandgap, which corresponds to λ = 4.3 μm. Boron-doped 4H-SiC substrate exhibited reduced reflectance and increased absorptance for the MWIR range. An absorption peak at λ = 4.3 μm was detected for the doped substrate. This confirmed the creation of the acceptor energy level in the 4H-SiC bandgap and, thus, doping of 4H-SiC with boron. A notable decrease in the refractive index, i.e., from 2.87 to 2.52, after laser doping of n-type 4H-SiC with boron was achieved.

Speciation and Phase Equilibria of Aqueous Boric Acid and Alkali Metal Borates from Ambient to Hydrothermal Conditions: A Comprehensive Thermodynamic Model

Speciation and Phase Equilibria of Aqueous Boric Acid and Alkali Metal Borates from Ambient to Hydrothermal Conditions: A Comprehensive Thermodynamic Model

Validation of a high-performance thin-layer chromatography method for the quantitative determination of trehalulose

A novel, simple and reliable high-performance thin-layer chromatography (HPTLC) method was developed and validated for the quantification of trehalulose in stingless bee honey. The chromatographic separation was performed using silica gel 60 F254 HPTLC plates and 1-butanol‒2-propanol‒aqueous boric acid solution (5 mg/mL) (30:50:10, V/V) as the mobile phase. The retardation factor (RF) for trehalulose was found to be 0.045. The method showed linearity over the concentration range of 100–800 ng per band with a coefficient of correlation (R) of 0.9996. The limit of detection and limit of quantification for trehalulose were found to be 20.04 ng per band and 60.72 ng per band, respectively and the mean per cent recovery of trehalulose was 101.8%. The method has been validated for its specificity, linearity, sensitivity, precision, accuracy, repeatability and robustness following the International Council for Harmonisation Q2 (R1), and it has been successfully applied in the determination of trehalulose in stingless bee honey.

Boron Adsorption Kinetics of Microcrystalline Cellulose and Polymer Resin

Tailoring boron-polysaccharide interactions is an important strategy for developing functional soft materials such as hydrogels, fire retardants, and sorbents for environmental remediation, for example, using lignocellulosic biomass. For such applications to be realized, it is paramount to understand the adsorption kinetics of borate anions on cellulose and their local structures. Here, the kinetic aspects of boron adsorption by microcrystalline cellulose, lignin, and polymeric resin are investigated and compared. Borate anions interact with the vicinal diols in the glucopyranoside moieties of cellulose to yield chemisorbed boron chelate complexes. In contrast to cellulose, technical lignin contains fewer cis-vicinal diols, and it does not have a tendency to form such chelate complexes upon treatment with the aqueous boric acid solution. The formation kinetics and stability of these chelate complexes strongly depend on nanoscale structures, as well as reaction conditions such as pH and concentration of the sorbate and sorbent. Specifically, insights into the distinct boron adsorption sites were obtained by solid-state one-dimensional (1D) 11B magic-angle spinning NMR and the local structures and intermolecular interactions in the vicinities of boron chelate complexes are elucidated by analyzing two-dimensional (2D) 1H-13C and 11B-1H heteronuclear correlation NMR spectra. The total boron adsorption capacity of cellulose is estimated to be in the 1.3-3.0 mg range per gram of sorbent, which is lower than the boron adsorption capacity of a polystyrene-based resin, ∼17.2 mg of boron per gram of Amberlite IRA 743. Our study demonstrates that the local backbone and side chain flexibility as well as the structures of polyol groups play a significant role in determining the kinetic and thermodynamic stability of chelate complexes, yielding to different boron adsorption capabilities of lignocellulosic polymers.

Two-Level 3D Column-like Nanofilms with Hexagonally-Packed Tantalum Fabricated via Anodizing of Al/Nb and Al/Ta Layers-A Potential Nano-Optical Biosensor.

Reanodizing metal underlayers through porous anodic alumina has already been used extensively to fabricate ordered columns of different metal oxides. Here, we present similar 3D multilayered nanostructures with unprecedented complexity. Two-level 3D column-like nanofilms have been synthesized by anodizing an Al/Nb metal layer in aqueous oxalic acid for forming the first level, and an Al/Ta layer in aqueous tartaric acid for forming the second level of the structure. Both levels were then reanodized in aqueous boric acid. The Ta layer deposited on partially dissolved porous anodic alumina of the first level, with protruding tops of niobia columns, acquired a unique hexagonally-packed structure. The morphology of the first and second levels was determined using scanning electron microscopy. Prolonged etching for 24 h in a 50%wt aqueous phosphoric acid was used to remove the porous anodic alumina. The formation mechanism of aluminum phosphates on the second-level columns in the process of long-time cold etching is considered. The model for the growth of columns on a Ta hexagonally-packed structure of the second level is proposed and described. The described approach can be applied to create 3D two- or three-level column-like systems from various valve metals (Ta, Nb, W, Hf, V, Ti), their combinations and alloys, with adjustable column sizes and scaling. The results of optical simulation show a high sensitivity of two-level column-like 3D nanofilms to biomedical objects and liquids. Among potential applications of these two-level column-like 3D nanofilms are photonic crystals for full-color displays, chemical sensors and biosensor, solar cells and thermoresponsive shape memory polymers.

Resistance of the welded joint of austenitic steel NEUTRONIT A 976 SM in the corrosive environment of boric acid

Abstract The paper deals with the influence of the operating environment on the safe resistance of the welded joint of the construction material used in the nuclear power industry in the production of spent nuclear fuel containers. This material contains a higher percentage of alloying boron and is used as a shielding construction material for neutron and gamma radiation. It is used to produce baskets for spent nuclear fuel containers. When the containers are being filled, the welded joint of the basket structure are briefly exposed to an aqueous boric acid solution. The aim of this work was to determine the effects of exposure to the corrosive boric acid environment on the mechanical properties of the material. Tensile tests on the original weld and post weld exposure in H3BO3 and corrosion cracking tests on unexposed welds were performed. The evaluation of the results revealed that the exposure to the corrosive environment of boric acid did not significantly affect the strength characteristics of the tested material NEUTRONIT A 976 SM.

The pH dependence of the isotopic composition of boron adsorbed on amorphous silica

The use of the boron content and isotopic composition of secondary silicate minerals and siliceous organisms to trace weathering reactions and past ocean pH requires characterizing the fundamental reactions that govern the incorporation and subsequent isotope fractionation of this element in these materials. Toward this goal we have investigated boron adsorption on the surface of amorphous silica (SiO2·0.32H2O) and quantified its isotopic fractionation. Boron adsorption envelopes and corresponding isotope fractionation factors were measured in dilute aqueous solutions (0.01 M) of NaCl and CaCl2. B maximum adsorbed fraction was found to be about 2 times higher in CaCl2 solutions than in NaCl. The modelling of chemical and isotopic data in NaCl solutions allowed to identify the formation of two main B surface species at the SiO2(am)/water interface: a neutral trigonal (B3) inner-sphere complex, >SiOB(OH)20, characterized by a fractionation factor of ~−16‰ relative to aqueous boric acid, and a negatively charged tetrahedral (B4) inner-sphere complex, >SiOB(OH)3–, with fractionation factors of −5‰ with respect to aqueous borate. In CaCl2 solutions the data modelling indicates the presence of B4 inner-sphere complexes with a fractionation factor of −6.5‰ relative to aqueous borate, but excludes the presence of trigonal surface species and suggests instead the formation of a Ca-B(OH)4– complex that could partly account for the observed increase of boron adsorption in these solutions. These observations indicate that changes in the surface charge density and interfacial water structure due to different background electrolytes can induce changes in concentration and both chemical and isotopic composition of B adsorbed on silica surfaces.Although this study suggests that the B adsorption reaction on SiO2(am) plays a minor role in the B incorporation and isotopic signature of clay minerals and siliceous cements forming during weathering reactions, the acquired data should allow for an improved knowledge of the biomineralization reactions. The observed B isotopic fractionations between adsorbed and aqueous B species should help determining the relative contribution of various processes, such as cellular transport, biological mediation and silicification reactions, on the amount of B incorporated in siliceous microorganisms and its isotopic signatures. In addition, the presence in NaCl solutions of both trigonal and tetrahedral boron complexes at the silica surface could explain the observed weak pH dependence of the boron isotopic composition of marine diatoms.

Equilibria, kinetics, and boron isotope partitioning in the aqueous boric acid–hydrofluoric acid system

The aqueous boric, hydrofluoric, and fluoroboric acid systems are key to a variety of applications, including boron measurements in marine carbonates for CO2 system reconstructions, chemical analysis and synthesis, polymer science, sandstone acidizing, fluoroborate salt manufacturing, and more. Here we present a comprehensive study of chemical equilibria and boron isotope partitioning in the aqueous boric acid–hydrofluoric acid system. We work out the chemical speciation of the various dissolved compounds over a wide range of pH, total fluorine (FT), and total boron (BT) concentrations. We show that at low pH (0 ≤ pH ≤ 4) and FT ≫ BT, the dominant aqueous species is BF4−, a result relevant to recent advances in high precision measurements of boron concentration and isotopic composition. Using experimental data on kinetic rate constants, we provide estimates for the equilibration time of the slowest reaction in the system as a function of pH and [HF], assuming FT ≫ BT. Furthermore, we present the first quantum-chemical (QC) computations to determine boron isotope fractionation in the fluoroboric acid system. Our calculations suggest that the equilibrium boron isotope fractionation between BF3 and BF4− is slightly smaller than that calculated between B(OH)3 and B(OH)4−. Based on the QC methods X3LYP/6-311+G(d,p) (X3LYP+) and MP2/aug-cc-pVTZ (MP2TZ), α(BF3−BF4−) ≃ 1.030 and 1.025, respectively. However, BF4− is enriched in 11B relative to B(OH)4−, i.e., α(BF4−−B(OH)4−) ≃ 1.010 (X3LYP+) and 1.020 (MP2TZ), respectively. Selection of the QC method (level of theory and basis set) represents the largest uncertainty in the calculations. The effect of hydration on the calculated boron isotope fractionation turned out to be minor in most cases, except for BF4− and B(OH)3. Finally, we provide suggestions on best practice for boric acid–hydrofluoric acid applications in geochemical boron analyses.

Rate-based simulation study of boric acid promoted potassium carbonate capture system

This study presents parametric analysis and process modification on a post-combustion carbon dioxide (CO2) capture system using boric acid promoted potassium carbonate (K2CO3) solution. The model was simulated in Aspen Plus® V10 and ELECNRTL property package was employed. Un-promoted K2CO3 system was adopted as a base case study and its simulation was validated using literature data. The K2CO3 concentration in the lean solvent makeup was then varied from 25 wt% to 40 wt% to examine the effects of lean solvent concentration on key operating variables such as stripper reboiler duty, stripper condenser duty and CO2 capture rate. A 2 wt%, 4 wt% and 6 wt% aqueous boric acid solutions were then added as promoter to the hot K2CO3 solvent and the simulation results indicated that capture rate efficiency can be enhanced by 0.7%, 0.9% and 1.2% respectively. Energy saving process modification was also carried out to the stripper column. Compared to the conventional unmodified H3BO3/K2CO3 system, the modified promoted system is able to achieve 21.09% savings in reboiler duty.

Boron isotopic analysis using molecular emission from double-pulse laser-induced plasma in aqueous boric acid solution

The molecular emission of BO and BO2 radicals in laser-induced plasma has been investigated to analyze the boron isotopes in aqueous boric acid solution.

Triborate Formation Constants and Polyborate Speciation under Hydrothermal Conditions by Raman Spectroscopy using a Titanium/Sapphire Flow Cell

Solvent-corrected reduced isotropic Raman spectra of aqueous boric acid + sodium borate solutions have been obtained from perpendicular and parallel polarization measurements in a novel custom-made titanium flow cell with sapphire windows over the temperature range 25 to 300 °C at 20 MPa using the perchlorate anion, ClO4-, as an internal standard. The reduced isotropic spectra of solutions yielded the first reported quantitative speciation results for polyborate ions in equilibrium with boric acid and borate in high-temperature aqueous solutions above 200 °C. The spectra obtained from solutions at low sodium/boron ratios, 0 < mNaST/ mBST < 0.254, displayed well-defined bands at 880, 747, 615, and 532 cm-1, corresponding to the species B(OH)3 > [B(OH)4]- > [B3O3(OH)4]- ≫ [B5O6(OH)4]-, respectively. The triborate ion, [B3O3(OH)4]-, was found to be the major polyborate species in these boric acid-rich solutions in the range 25 to 300 °C. Thermodynamic formation constants for the triborate species, [B3O3(OH)4]-, calculated from the peak areas, are in agreement with the literature values reported by Mesmer et al at 50, 100, and 200 °C to within the combined experimental uncertainties. At 300 °C, the value for the formation constant, log K31, m b= 2.259 ± 0.060, is larger than the value extrapolated from the results of Mesmer et al. by a factor of ∼3.

Boric acid and borate incorporation in inorganic calcite inferred from B/Ca, boron isotopes and surface kinetic modeling

The boron concentration (B/Ca ratio) and isotopic composition (δ11B) of biogenic calcite are widely applied to reconstruct past changes in seawater carbonate chemistry. Knowledge of B incorporation pathways into calcite is critical for these applications and for improving the theoretical basis of B proxies. While the canonical interpretation of δ11B holds that B in calcite predominantly derives from dissolved borate anion in seawater, recent studies of the B content, coordination, and isotopic composition in calcite suggest more complex B incorporation pathways. To provide new insights into these pathways, here we present δ11B of inorganic calcite precipitated from saline solutions of varying pH, calcium and dissolved inorganic carbon (DIC) concentration for which B/Ca data were previously reported by Uchikawa et al. (2015). Results show that calcite δ11B significantly increases with increasing pH and decreases with increasing [Ca2+] and [DIC]. In combination, these experiments show that the difference in δ11B between solid calcite and aqueous borate linearly decreases with increasing calcite precipitation rate. To interpret these data, we present the first application of surface kinetic modeling (SKM) to boron incorporation. The SKM can simultaneously explain rate-dependent B/Ca and δ11B patterns observed in our and previously published inorganic calcite precipitation experiments when both aqueous borate and boric acid contribute to boron in inorganic calcite. If the B incorporation mechanism shown here for inorganic calcite is applicable to biogenic calcite, precipitation rate variations could modify δ11B patterns by changing the contributions of aqueous boric acid and borate to boron in calcite. However, better knowledge of biogenic calcite precipitation mechanisms and rates is needed to assess the importance of this effect for applications of B proxies in biogenic carbonates.

Theoretical investigation of carbon dioxide capture by aqueous boric acid solution: A termolecular reaction mechanism

Hitherto, boric is suggested and used as a promoter or catalyst for carbon dioxide capture in various chemical absorption reactions, such as, absorption by aqueous potassium carbonate solution to increase mass transfer rate. But in this study, a single step termolecular reaction mechanism is suggested for the chemical absorption of carbon dioxide directly by boric acid and water. The reaction thermochemistry and reaction kinetics for termolecular mechanism are investigated by using density functional theory calculations at the B3LYP/6-31G(d) level of theory by taking into account of the implicit solvent effects of water through the polarizable continuum model and dispersion corrections. The findings obtained from theoretical calculations indicate that it is possible to capture carbon dioxide with boric acid in the form of B(OH) 2 OCOOH.

Raman Spectroscopic and ab Initio Investigation of Aqueous Boric Acid, Borate, and Polyborate Speciation from 25 to 80 °C

Temperature-dependent Raman studies of the aqueous speciation of boric acid and sodium borate have been carried out at 25 and 80 °C. Normalized solvent-corrected reduced isotropic Raman spectra were obtained from perpendicular and parallel polarization measurements using perchlorate anion, [ClO4]−, as an internal standard. The intensity variations of these bands with concentration and temperature provided strong evidence that these arise from boric acid B(OH)3, borate [B(OH)4]−, and the polyborate species [B3O3(OH)4]−, [B4O5(OH)4]2–, and [B5O6(OH)4]−. A very weak high frequency shoulder on the borate band may indicate the presence of the diborate species [B2O(OH)5]−. Temperature- and concentration-independent quantitative Raman molar scattering coefficients (S) for the symmetric vibrational bands of boron-containing species were calculated, consistent with the mixed solvent electrolyte model reported by Wang et al. (Pure Appl. Chem. 2013, 85, 2117–2144) up to approximately 100 °C. The band assignments and...

Theoretical isotopic fractionation between structural boron in carbonates and aqueous boric acid and borate ion

The 11B/10B ratio in calcite and aragonite is an important proxy of oceanic water pH. However, the physico-chemical mechanisms underpinning this approach are still poorly known. In the present study, we theoretically determine the equilibrium isotopic fractionation properties of structural boron species in calcium carbonates, BO33−, BO2(OH)2− and B(OH)4− anions substituted for carbonate groups, as well as those of B(OH)4− and B(OH)3 species in vacuum. Significant variability of equilibrium isotopic fractionation properties is observed among these structural species which is related to their contrasted coordination state, BO bond lengths and atomic-scale environment. The isotopic composition of structural boron does not only depend on its coordination number but also on its medium range environment, i.e. farther than its first coordination shell. The isotopic fractionation between aqueous species and their counterparts in vacuum are assessed using previous investigations based on similar quantum-mechanical modeling approaches. At 300 K, the equilibrium isotope composition of structural trigonal species is 7–15‰ lighter than that of aqueous boric acid molecules, whereas substituted tetrahedral borate ions are heavier than their aqueous counterparts by 10–13‰. Although significant uncertainties are known to affect the theoretical prediction of fractionation factors between solids and solutions, the usually assumed lack of isotopic fractionation during borate incorporation in carbonates is challenged by these theoretical results. The present theoretical equilibrium fractionation factors between structural boron and aqueous species differ from those inferred from experiments which may indicate that isotopic equilibrium, unlike chemical equilibrium, was not reached in most experiments. Further research into the isotopic fractionation processes at the interface between calcium carbonates and aqueous solution as well as long duration experiments aimed at investigating the kinetics of equilibration of boron environment and isotopic composition are therefore required to refine our understanding of boron coprecipitation in carbonates and thus the theory behind the use of boron isotopes as an ocean pH proxy.

Effects of borate polyester mixed with water on anodizing behavior and electrical properties of ZrO2-coated Al foil

ZrO2-Al2O3 composite oxide film is a promising dielectric material for future application in aluminum electrolytic capacitors. Herein, ZrO2-Al2O3 composite oxide films are prepared on etched Al foils via ZrO2 sol-gel coating and anodization. Generally, Al foil anodization is performed in an aqueous boric acid electrolyte. However, if the Al foils are anodized above approximately 700V, a boric acid solution is unsuitable for use as an electrolyte, because it facilitates O2 evolution. Therefore, in this study, we use a borate polyester solution as an electrolyte for anodization at a relatively high voltage, and discuss the effects of the borate polyester concentration on the anodization behavior and electrical properties of the ZrO2-coated Al foils. The results suggest that a borate polyester electrolyte with high resistivity is suitable for use in high-voltage anodization, as it effectively increases the sample withstanding voltage. Further, the specific capacitances of the samples decrease as the borate polyester to water ratio increases; the most suitable ratio is found to be 0.4. Relative to those of samples anodized in boric acid solution, the specific capacitances of the samples anodized in the borate polyester electrolyte with a 0.4 mixing ratio are increased by 12.7%, 8.9%, and 43.3% for 700, 800, and 900V, respectively.

Synthesis of mono- and di-α-l-fucosylated 2-acetamido-2-deoxy-N-glycyl-β-d-glucopyranosylamines, spacered fragments of glycans of N-glycoproteins

α-l-Fucp-(1→3)-d-GlcNAc, α-l-Fucp-(1→6)-[α-l-Fucp-(1→3)]-d-GlcNAc, and β-d-Galp-(1→3)-[α-l-Fucp-(1→4)]-d-GlcNAc were converted into corresponding β-glycopyranosylamines by action of ammonium carbamate in aqueous boric acid, or in aqueous methanol in case of α-l-Fucp-(1→6)-d-GlcNAc. N-Acylation of these fucooligosaccharides with N-Z-glycine N-hydroxysuccinimide ester (Z is benzyloxycarbonyl) followed by hydrogenolytic removal of Z-group afforded corresponding N-glycyl-β-glycopyranosylamines of these fucooligosaccharides; three of them model carbohydrate-peptide region of N-glycoproteins, and the forth is an amino-spacered Lea-antigen.

Boron isotopic fractionation in aqueous boric acid solutions over synthetic minerals: Effect of layer and surface charge on fractionation factor

Boron isotopic fractionation in boric acid solutions during adsorption on synthetic manganese oxides (birnessite “B” and cryptomelane “C”) and Mg–Al-layered double hydroxide “LDH” was investigated. The materials were characterized by elemental analyses, powder X-ray diffraction, FTIR spectra, BET surface area and zeta potential measurements. Batch experiments were conducted without changing the solution pH to correlate the boron sorption properties of the adsorbents with isotopic fractionation in the associated boric acid solutions. The results showed that boron isotopic composition of the contact solution is heavily dependent on the selective adsorption of B(OH)3 or B(OH)4− species due to the charge properties of the minerals. With B and C, possessing negatively charged surfaces, 10B(OH)4− was preferentially fractionated in the solution due to the transfer of the Lewis acidic 11B(OH)3 species while with LDH selective adsoption of 10B(OH)4− by positive layers was favorable resulting in the enrichment of the heavier isotope in the solution.

A new optical boron detection method

A new optical sensor detects aqueous boric acid and phenylboronic acid in the ppb range by a simple experimental procedure.