Presence Of H3BO3 Research Articles

2D-network of boron-functionalized N-doped graphene quantum dots for electrochemical sensing of dopamine

A glassy carbon electrode (GCE) modified by boron-functionalized N-doped graphene quantum dots (B-GQDs) was employed for the electrochemical determination of dopamine (DA), a neurotransmitter. The B-GQDs were obtained by hydrothermal etching of GO with H2O2 and NH3 in the presence of H3BO3. By using various techniques, including transmission electron microscopy, atomic force microscopy, molecular absorption spectrometry, fluorescence, ICP-MS, and zeta potential analysis, it was demonstrated that B-GQDs are self-organized in 2D-network, being N-doped GQDs nanoparticles crosslinked by H3BO3. The GCE modification was carried out using the drop-casting method with B-GQDs in Nafion®, previously dispersed through ultrasonication. For the first time, the synthesized nanomaterial was tested in the electroanalysis of neurotransmitters. The B-GQDs/Nafion®/GCE modification led to a significant increase in peak currents in the presence of DA. The electrochemical and interfacial characteristics of the sensors were evaluated by cyclic voltammetry (CV). Under optimized square wave voltammetry and supporting electrolyte conditions, a linear dependence between the anodic peak current and DA concentration was observed in the range of 0.7 to 188 μmol L−1 (R2 = 0.9991). The limit of detection (LOD) was estimated at 0.05 μmol L−1. Selectivity was confirmed in the presence of potential interferents found in urine, with interference response below 12 %. The sensor exhibited excellent intra-day and inter-day repeatability, with a relative standard deviation of 4.12 % and 4.66 %, respectively. Electrochemical determination of DA was conducted in artificial urine samples (Surine®), with recovery values of 90–101 %. The new analytical platform B-GQDs/Nafion®/GCE demonstrated promising characteristics for application in biological and/or pharmaceutical analysis.

Effect of B2O3 on the Structure, Properties and Antibacterial Abilities of Sol-Gel-Derived TiO2/TeO2/B2O3 Powders.

This paper studies the influence of B2O3 on the structure, properties and antibacterial abilities of sol-gel-derived TiO2/TeO2/B2O3 powders. Titanium(IV) butoxide, telluric(VI) acid and boric acid were used as precursors. Differences were observed in the degree of decomposition of Ti butoxide in the presence of H3BO3 and H6TeO6 acids. The phase transformations of the obtained gels in the temperature range of 200-700 °C were investigated by XRD. Composite materials containing an amorphous phase and different crystalline phases (metallic Te, α-TeO2, anatase, rutile and TiTe3O8) were prepared. Heating at 400 °C indicated a crystalline-to-amorphous-phase ratio of approximately 3:1. The scanning electron microscopy (SEM) analysis showed the preparation of plate-like TiO2 nanoparticles. The IR results showed that the short-range order of the amorphous phases that are part of the composite materials consists of TiO6, BO3, BO4 and TeO4 structural units. Free B2O3 was not detected in the investigated compositions which could be related to the better connectivity between the building units as compared to binary TiO2/B2O3 compositions. The UV-Vis spectra of the investigated gels exhibited a red shift of the cut-off due to the presence of boron and tellurium units. The binary sample achieved the maximum photodegradation efficiency (94%) toward Malachite green dye under UV irradiation, whereas the ternary sample photoactivity was very low. The compositions exhibited promising antibacterial activity against E. coli NBIMCC K12 407.

Boric acid recovery in dilute during the desalination process in BMED system

Bipolar membrane electrodialysis (BMED) system allows the simultaneous desalination and acid and base production. Boric acid (H3BO3) and sodium chloride (NaCl) forms during dissolution of sodium tetraborate-decahydrate (Na2B4O7.10H2O) in hydrochloric acid (HCl). The study presents that BMED process provides H3BO3 purification in dilute during the desalination process. In this study, desalination ratio, H3BO3 purification efficiency, acid and base production, specific energy consumption, and current efficiency were defined as performance indicators. The effects of initial H3BO3 concentration and flow rates of solutions on performance indicators were investigated under acidic condition. Additionally, two acidic conditions were evaluated with respect to desalination ratio and H3BO3 concentration in dilute. The results of the experiments indicated that the presence of H3BO3 does not affect the desalination process. The more H3BO3 concentration allows the more decrease in purification efficiency and current efficiency based on proton ions. The varying feed flow rate was found not effective on desalination, while purification efficiency increased with increasing flow rate. Initial H3BO3 concentration was determined as less effective on acid and base conversion than that of flow rate. In addition to simultaneous salt removal, acid and base recovery, the most important output of BMED will be H3BO3 recovery in high purity.

Valorization of industrial waste lignin via pyrolysis in the presence of additives: Formation, characterization, and application of fuel valued bio-oil and activated char

The annual production of over 50 million tonnes of industrial waste kraft lignin and scant utilization invites environmental concern. To explore the potential of simultaneously produced bio-oil and modified char (Activated char), lignin from industrial effluents was subjected to pyrolytic degradation at 380 °C using various additives, viz., H3BO3, ZnCl2, and KOH yielding encouraging quantities of bio-oils besides substantial quantities of char. Quantitative and qualitative analyses of gaseous products (by GC-TCD) indicated a mixture of CO, CO2, H2, and methane, with some variation in volumetric composition suggesting potential for gaseous fuel/syngas. Gaseous products obtained in the presence of H3BO3 have the highest methane percentage. The bio-oils obtained in the presence of H3BO3, ZnCl2, KOH, and only pure lignin under otherwise similar conditions were respectively 37%, 21%, 27%, and 11 wt%. In all cases, mainly bio-oils contain phenols, cyclic esters, and carboxylic acids, as indicated by GC-MS analysis. Elemental (C, H, O) Analyses of bio-oils obtained in the presence of (H3BO3, ZnCl2, and KOH) indicated decreasing oxygen content compared to original lignin, suggesting their prima facie potential to lead to fuel additives/supplements. Similarly, the Char obtained in the presence of H3BO3, ZnCl2, KOH, and only pure lignin were respectively, 40%, 53%, 48%, and 33 wt% with a high calorific value. Char obtained from KOH application demonstrated good uptake of Carbofuran (pesticide) from the aqueous solution. Less modified, cost-effective activated char was characterized using FTIR, TG-DTA, XRD, SEM, and BET-BJH, indicating 188.798 m2/g; this explores the role of KOH to form a microporous structure. Pseudo-second-order kinetics explain chemisorption to be dominant in the adsorption process. Thus, pyrolysis at selected temperatures/additives/and further treatments provides a much better way to utilize industrial waste lignin.

Extraction of lithium from salt lake brine containing boron using multistage centrifuge extractors

Lithium extraction process from salt lake brine containing H3BO3 was investigated in this paper. The extraction, scrubbing, stripping and regeneration processes were studied respectively, using N, N-bi-(2-ethylhexyl) acetamide (N523) and tri-butyl phosphate (TBP) as the extractant, kerosene as diluent and FeCl3 as co-extractant. H3BO3 present in the brine could be extracted by TBP in the extraction stage. The presence of H3BO3 had no significant effect on lithium extraction efficiency and separation effect between lithium and magnesium. The main portion of the extracted H3BO3 could be scrubbed in the scrubbing stage, magnesium could be nearly scrubbed completely. The whole extraction process experiment and magnified experiment were conducted on separating funnels and centrifugal extractors, respectively, and no third phase appeared. The lithium extraction rate reached 96%. The Mg/Li mass ratio changed from 48 in salt lake brine to 0.0015 in the stripping liquor, meanwhile, H3BO3/Li mass ratio changed from 5.6 to 0.018. The stripping liquors contained 28 g/L Li+ with small amounts of H3BO3, and other impurity ions. This study indicated that the presence of H3BO3 in salt lake brine had no significant influence on lithium extraction and quality of stripping liquors. Furthermore, it was shown that centrifugal extractors were effective in the lithium extraction process.

Room temperature synthesis of crystalline anatase TiO2 on bamboo timber surface and their short-term antifungal capability under natural weather conditions

A facile room temperature route was developed for growing crystalline anatase TiO2 on the bamboo timber surface by a unique hydrolysis of titanium complexes in the presence of H3BO3. The effect of aging time on TiO2 crystallinity on the bamboo timber surface was studied. The crystal phase, microstructure, and chemical composition of the anatase TiO2 formed on the bamboo timber surfaces were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). XRD characterization on the samples showed that, for crystallization occurred at room temperature, the longer the aging time, the greater the crystallinity. The TiO2-coated bamboo samples look identical to the pristine samples as there is no essential effect on the optical properties of the bamboo timber surface. Moreover, the antifungal activity of TiO2 photo-catalytic reaction against mould fungi was investigated for bamboo timber under natural weather conditions during periods of 16 weeks. Results show that compared with the pristine bamboo timber, the anatase TiO2-coated bamboo timber presented more superior antifungal capability under natural weather conditions in Hangzhou, China.

A simple solution-phase route for room-temperature synthesis of mesoporous and nanocrystalline anatase TiO2

ABSTRACTA simple solution-phase route to synthesize mesoporous anatase TiO2 nanocrystallites at room temperature was presented. TiO2 nanocrystallites were prepared via a unique hydrolysis of titanium complexes in the presence of H3BO3. The mean size of the as-obtained TiO2 nanocrystallite was in about 10 nm. They possess large surface area of 48.6 m2 g−1 and the dominant pore size of 4.3 nm. The effect of aging time on crystallinity was studied. For crystallization occurred at room temperature, the longer the aging time is, the greater the crystallinity is.

One-Step Fabrication of Fluorescent Carbon Dots for Selective and Sensitive Detection of Cr (VI) in Living Cells

A one-step facile method of synthesizing fluorescent carbon dots (CDs) has been demonstrated, whereby fluorescent CDs are produced through hydrothermal treatment of glucose in the presence of H3BO3 with a fluorescence quantum yield of 14.5%. It is found that spherical CDs have an average size of 3.7[Formula: see text]nm as well as good monodispersion in aqueous solution. The added Cr (VI) selectively leads to the inner filter effect (IFE)-based fluorescence quenching of the CDs. Such fluorescence responses can be used for well quantifying Cr (VI) in the range of 0.05–200[Formula: see text][Formula: see text]M. Significantly, the CDs possess negligible cytotoxicity, excellent biocompatibility and high selectivity. All these features are favorable for label-free monitoring of Cr (VI) in complex biological samples. It was then successfully applied for the fluorescence imaging of intracellular Cr (VI). As an efficient chemosensor, the CDs hold great promise in broadening their applications in biological systems.

Properties of blue emitting CaAl2O4:Eu2+, Nd3+ phosphor by optimizing the amount of flux and fuel

Long afterglow CaAl2O4:0.03Eu2+, 0.03Nd3+ phosphor was prepared by solution-combustion synthesis. The active role of boric acid (H3BO3) as a flux in enhancing the Eu2+ photoluminescence and the effect of a varied amount of urea (CO (NH2)2) as a fuel on the morphological, structural and photoluminescent (PL) properties of the CaAl2O4:0.03Eu2+, 0.03Nd3+ systems were investigated. The results of X-ray diffraction, scanning electron microscopy, and PL spectra revealed the influence of the dosage of urea and hence the heated process on the crystallinity, morphology, and luminescence of the phosphor. The addition of H3BO3 favoured the formation of a monoclinic CaAl2O4 phase while the variation of the amount of CO (NH2)2 showed mixed phases although still predominantly monoclinic. Both H3BO3 and CO(NH2)2 to some extent influence the luminescence intensity of the obtained phosphor but unlike the case of CO(NH2)2, the presence of H3BO3 did not evidently shift the emission peak due to no obvious change in the energy level difference of the 4f–5d levels. The broad blue emissions consisting mainly of symmetrical bands having maxima between 440 and 445nm originate from the energy transitions between the ground state (4f7) and the excited state (4f65d1) of the Eu2+ ions while the narrow emissions in the red region (600–630nm) arise from the 5D0→7F2 transitions of the remnant unreduced Eu3+ions. Higher concentrations of H3BO3 (0.228mol and 0.285mol) reduce both intensity and lifetime of the phosphor. The optimized content of H3BO3 was 0.171mol for the obtained phosphor with the best optical properties.

Enhanced nucleation of Ni nanoparticles on TiN through H3BO3-mediated growth inhibition

In this paper, we have studied the effect of boric acid (H3BO3) on the nucleation of nickel (Ni) nanoparticles on titanium nitride (TiN). We linked the potential transients during galvanostatic deposition to the different regimes of Ni deposition. The two most important regimes, i.e. nucleation and growth regime, were found to depend on the H3BO3 concentration. Indeed, by lowering the amount of H3BO3 the particle density increased (nucleation), while it also resulted in an earlier growth termination. Based on these findings, we propose a growth-inhibited nucleation model to explain the impact of H3BO3 on the formation of Ni nanoparticles. During Ni nucleation the surface pH increases due to local H+ reduction, leading to the formation and adsorption of Ni(OH)2 on the Ni particles. As a result, the growth of the particles is inhibited and new nucleation is promoted. The formation of this inhibiting hydroxide is counteracted by the presence of H3BO3 as it buffers the surface pH. Therefore, a higher particle density is obtained at low H3BO3 concentrations. However, when the concentration of H3BO3 is too low, Ni(OH)2 is already formed in the diffusion layer during the nucleation regime as the onset of H2O reduction occurs sooner. This results in the termination of Ni deposition before the nucleation of Ni is complete yielding almost no deposited Ni at the surface at low H3BO3 concentrations. Therefore, an optimum H3BO3 concentration is needed where the degree of growth-inhibition is high while Ni is still deposited for a sufficient amount of time.

Preparation of grass-like TiO2 nanostructure thin films: Effect of growth temperature

TiO2 nanoparticles with various morphologies have been synthesized under various temperature conditions, namely 25, 50, 60 and 90°C via a liquid phase deposition technique. The liquid phase deposition technique is an electroless deposition of TiO2 onto the substrate surface via a unique hydrolysis of titanium complexes in the presence of H3BO3. FESEM characterization on the samples showed that, under the temperature treatment, the nanostructures morphology transformed from grass-like to agglomerated spherical-like shape with the increased of the temperature. The XRD analysis performed on these samples show that all of the samples were anatase and unmodified with the change in the morphology. The optical absorption window of the TiO2 nanostructures films was also found to enlarge with the increasing of the growth temperature, resulting from the structure modification. Owing to its simplicity, the present technique may produce TiO2 nanoparticles with a variety of morphologies for use in photocatalyst and solar cell applications.

Preparation of iridium nano- and submicroparticles on solid substrates by direct surface growth and drop-drying assembly

Iridium nanoparticles (IrNPs) and submicroparticles (IrSMPs) with different shapes were synthesized and assembled on indium thin oxide (ITO) and Si substrates using two different methods: direct surface growth and drop-drying assembly. The obtained IrNPs and IrSMPs were characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The IrSMPs (or IrNPs) with disc-like shape and irregular shapes were obtained on ITO substrate by direct surface growth method using polyvinylpyrrolidone (PVP) and sodium citrate as different stabilizers, respectively. The reaction time and the injection temperature of reducing agent are found to have great effect on the size and morphology of the surface-grown Ir particles. The disc-like, ellipsoidal, and spherical IrSMPs (or IrNPs) were also synthesized in homogeneous solution in the presence of H3BO3 and Na2B4O7 as assistant-stabilizer. These IrNPs and IrSMPs were used as building blocks to construct nanoparticle assemblies by using a simple drop-drying method. Uniform IrNP and IrSMP assemblies were successfully prepared on Si and ITO substrates, indicating that the drop-drying method is efficient for the preparation of not only nanoparticle assemblies but also submicroparticle assemblies.

Boron Uptake Behavior During Ettringite Synthesis in the Presence of H3BO3 and in a Suspension of Ettringite in H3BO3

Exchange between the SO42− ions in ettringite and borate is believed to occur during borate removal from wastewater by the Ca(OH)2–Al2(SO4)3 addition method. To investigate borate uptake by ettringite, we synthesized ettringite in the presence of H3BO3 and prepared suspensions of ettringite in H3BO3 solution. At the theoretical Ca(OH)2 / Al2(SO4)3 ratio for ettringite, with an increase in the H3BO3 / Al2(SO4)3 ratio, the ettringite concentration decreased but the concentration of amorphous compounds increased; further, the amount of borate uptake by the precipitate formed also increased. Upon alkalization of the H3BO3–Al2(SO4)3 solution to pH = 10 with NaOH solution, borate-containing amorphous Al(OH)3 was precipitated. It was proposed that the borate coprecipitated along with amorphous Al(OH)3 (which showed boron uptake) and did not undergo exchange with SO42− ions in ettringite; this was strongly supported by the results of IR and TG analyses performed on the boron-containing precipitates. At a high H3BO3 / Al2(SO4)3 ratio, ettringite decomposed to afford amorphous Al(OH)3, and borate coprecipitation was promoted. Upon suspension in H3BO3 solution, the ettringite precipitate showed low boron uptake, which was presumably due to the substitution of SO42− in ettringite with B(OH)4−.

Liquid phase deposition of titania onto nanostructured poly-p-xylylene thin films

We describe a simple, solution-based, two-step process for the fabrication of titania–parylene composite films as a prerequisite for their evaluation as materials for bioimplant applications. In the first step, a ligand capable of binding titania, such as phenylphosphonic acid, is physisorbed onto a nanostructured poly-p-xylylene thin film previously prepared via surface-promoted oblique angle polymerization of radicals formed during vapor-phase pyrolysis of [2.2]-p-cyclophanes. The adsorbed ligand templates conformal growth of titania on the polymer surface in the second step via a liquid phase deposition process involving the controlled hydrolysis of (NH4)2TiF6 in the presence of H3BO3 in pH 2.88 aqueous solution at ∼50 °C. SEM and AFM analyses support a deposition mechanism that includes direct growth of titania on the ligand-impregnated parylene surface, as well as incorporation of titania nanoparticles nucleated in solution into the growing film. XPS and XRD results show that the as-deposited titania contains both amorphous and nanocrystalline anatase phases, with the latter readily consolidated by annealing at ∼200 °C without destruction of the underlying parylene polymer. Titania adhesion can be tuned by proper choice of the ligand, with ligands such as phenylphosphonic acid that strongly bind to titanium dioxide leading to deposition of titania films that pass the Scotch® tape adhesion test.

Reactions of 2-hydroxy-5-(1-adamantyl)benzene-1,3-dicarbaldehyde with ethane-1,2-diamine, trans-cyclohexane-1,2-diamine, and N-(2-aminoethyl)ethane-1,2-diamine

Reactions of 2-hydroxy-5-(1-admantyl)benzene-1,3-dicarbaldehyde with ethane-1,2-diamine, transcyclohexane-1,2-diamine, and N-(2-aminoethyl)ethane-1,2-diamine were studied in strongly dilute solution and under conditions of template synthesis in the presence of H3BO3. The effects of reaction conditions and initial diamine structure on the cyclocondensation process were determined. Selective [3 + 3]-cyclocondensation of 2-hydroxy-5-(1-admantyl)benzene-1,3-dicarbaldehyde with trans-cyclohexane-1,2-diamine and [2 + 2]-cyclization with N-(2-aminoethyl)ethane-1,2-diamine were performed in chloroform in the presence of H3BO3. The first representative of adamantylcalixsalens was synthesized.

Synthesis, Structure, and Magnetic Properties of Hydroxo‐Bridged Vanadium Oxalate V2O2(OH)2(C2O4)(H2O)2

AbstractThe reaction of V2O5 with H2C2O4·2H2O in the presence of H3BO3 under hydrothermal conditions has afforded V2O2(OH)2(C2O4)(H2O)2 (1), which crystallizes in the triclinic system, space group P$\bar {1}$ with a = 5.2405(10) Å, b = 5.7340(11) Å, c = 7.1778(14) Å, α = 76.44(3)°, β = 69.37(3)°, γ = 75.37(3)°. The vanadium atoms in 1 form dimers by sharing edges consisting of μ‐OH groups, and these dimers are connected further by oxalate ligands to form chains. The magnetic susceptibility data of 1 fit excellently with the Heisenberg dimer model in the temperature interval 2–300 K. Compound 1 is antiferromagnetic with a J value of –29.6 cm–1. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

An open-framework three-dimensional indium oxalate: [In(OH)(C2O4)(H2O)]3·H2O

By hydrothermal reaction of In2O3 with H2C2O4·2H2O in the presence of H3BO3 at 155°C, an open-framework three-dimensional indium oxalate of formula [In(OH)(C2O4)(H2O)]3·H2O (1) has been obtained. The compound crystallizes in the trigonal system, space group R3c with a=18.668(3)Å, c=7.953(2)Å, V=2400.3(7)Å3, Z=6, R1=0.0352 at 298K. The small pores in 1 are filled with water molecules. It loses its filled water at about 180°C without the change of structure, then the bounded water at 260°C, and completely decompounds at 324°C. The residue is confirmed to be In2O3.

Reaction of Acetone Cyanohydrin with Thiosemicarbazide

We have established that when acetone cyanohydrin is heated with thiosemicarbazide in aqueous medium, 3-mercapto-6,6-dimethyl-1,2,4-triazin-5-one and 2-methyl-2-thiosemicarbazidopropanoic acid are formed. Cyclization of the latter in dioxane in the presence of H3BO3 leads to 2-amino-5,5-dimethyl-1,3,4-thiadiazin-6-one.

Borate buffer equilibria in nickel refining electrolytes

Buffer capacity studies, carried out using pH titrations, demonstrated that electrolytes containing NiSO4 + H3BO3 + Na2SO4 buffer more effectively than in the presence of H3BO3 + Na2SO4. The increased buffer capacity is dependent on the concentration of both Ni2+ and H3BO3. Thermodynamic analysis of the pH titration data suggested the formation of a weak complex, Ni(H2BO3)2, (logK ∼ 3.8 to 4.9) between Ni2+ and H3BO3 in mixed chloride-sulphate electrolytes at 55° C.

Pyrolytic reactions of carbohydrates. Part I. Mutarotation of molten D-glucose

The mutarotation of α- and β-D-glucose near their melting points has been studied in the neat materials as well as in the presence of water, and at low temperature in the presence of H3BO3 and NaHCO3. The process of mutarotation was found to become very fast as soon as the bulk of the material melted.