Indirect Determination of Trace Tetraborate by Differential Pulse Polarography Using Its Copper Complex and Application to Waste and Drinking Water

A new differential pulse polarographic (DPP) method has been developed for the trace determination of boron. Its most stable copper complex is used in 0.5 M KNO₃ electrolyte since boron is not electroactive. By continuous addition of tetraborate to copper solution, the copper peak decreased first but then the peak became very small and nearly constant. This point was used for the boron determination. It was found that one mole of copper used two moles of tetraborate. Using this relationship, 1×10^?5 M tetraborate could be determined. The quantification limit was 2.5×10^?6 M and detection limit was 8×10^?7 M. In the presence of complex forming ions such as Pb, Zn, and Cd, the borate found in sample was somewhat smaller because of their reaction with borate. But since their complexes were not as strong as copper, only a few percent of borate were used. No interference was observed in the presence of calcium, chloride and sulfate. This method is applied for the determination of B in borax ore, waste water of borax industries and tap water of Ankara city.     

A modified method for determination of boron with curcumin and a simplified water elimination procedure

The formation of boric acid ester with curcumin is usually performed in highly acidic solution in the absence of water. Small water contents are permissible, but the efficiency is lowered. The water content of a sample can be eliminated by a reaction with propionic anhydride catalyzed by oxalyl chloride, thus avoiding methyl borate distillation or evaporation processes. An advantage is that the reaction between boron and curcumin takes place in a completely homogeneous liquid medium. The excess of protonated curcumin is best destroyed with an ammonium acetate buffer. For trace amounts of boron, extraction of the coloured complex with a mixture of methyl isobutyl ketone, chloroform and phenol is recommended. Standard procedures for aqueous solutions with boron contents between 0.0033–40.0 μg B/l are described.     

Targeted borate complex formation as followed with electrospray ionization Fourier transform ion cyclotron mass spectrometry: monomolecular model system and polyborate formation

Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) was applied to identify boric acid(B degrees)/borate(B-) complexes in a monomolecular model system, composed of aqueous caffeic acid and boric acid/borate solutions in various concentration ratios at pH 9.2. Using negative mode electrospray ionization as a 'soft' ionization technique, clusters of polyborate were detected beside the well-known BL degrees , BL- and BL2- complexes. An algorithm for the detection of boron complexes, based on their accurate mass and isotope patterns, is proposed which enabled the assignment of elemental compositions/structural formulae of boron/ligand complexes. We present experimental evidence of self-oligomerization of up to six borate units with caffeic acid, resulting in stable covalently bound polyborate-polyol complexes.     

镧－硼复合润滑添加剂的协合润滑机理

实验室和工业试验表明，含镧的润滑添加剂二烷基二硫代磷酸镧（ＬａＤＤＰ）和一种有机硼酸酯（ＯＢ）具有显著的协合润滑作用，将两种化合物复合加至润滑油中，可显著改善油品的抗磨减摩性能。采用俄歇电子能谱（ＡＥＳ）和Ｘ射线光电子能谱（ＸＰＳ）研究其协合润滑机理。结果表明，ＬａＤＤＰ和ＯＢ具有协合润滑作用的主要原因，除了在摩擦表面生成硫酸盐、磷酸盐、氧化镧和单质硼等表面膜起润滑作用外，更重要的是镧的存在对硼的摩擦扩散起到了“摩擦催渗”作用，使摩擦亚表面硼的含量增加，并形成Ｌａ－Ｂ摩擦共渗层，进一步提高材料表面硬度，从而改善耐磨性能     

Rapid technique for distillation of methyl borate for ICP atomic-emission spectrometric determination of boron in steel

The analysis time for determination of boron in steel can be remarkably shortened by simultaneous distillation of methyl borate and evaporation of the distillate for analysis by ICP atomic-emission spectrometry. Methyl borate, distilled with a large quantity of methanol, is collected in 4% sodium hydroxide solution heated in a water-bath at 90 degrees. As the boiling point of the mixture of absorption solution and methanol is lower than 90 degrees, the solvent mixture is easily evaporated. The limit of detection corresponds to 35 ng of boron in 0.5 g of steel.     

Volatilization of methyl borate in iron matrix. Determination of boron in steel by ICP atomic emission spectrometry

A rapid and reliable method for the determination of boron by ICP-AES in steels is described. The procedure is based on a discontinuous generation of methyl borate, in concentrated sulphuric acid and phosphoric acid medium, after injecting 45 microl of methanol in 20 microl of sample. The gaseous methyl borate and excess methanol are fed into the ICP torch via the intermediate tube by a flow of 430 ml/min Ar carrier gas, without disturbing the discharge. This work simplifies drastically the existing methodology of boron analysis in steels. Acid-soluble boron has been determined, but acid-insoluble boron can also be determined. The determination is carried out without iron interferences, with a reproducibility of 1.90% r.s.d. for a concentration of 20 microg/ml, and an absolute detection limit of 20 ng of total boron, working with a solution volume of 20 microl.     

298.15K下Li2B4O7-H2O体系水蒸汽分压及渗透系数的等压测定和离子相互作用模型

在已有研究含硼体系的文献中仅考虑了硼酸根B4O7^-2或B(OH)4^-和H3BO3的存在，而对Li2B4O7-H2O体系具有多种硼物种聚合平衡体系的热力学性质的研究尚未见报道．本文用等压法研究了Li2B4O7-H2O体系于298．15K下浓度由稀到过饱和溶液的平衡气相蒸汽压及渗透系数．考虑了水溶液中多种硼物种的存在，以Pitzer方程为基础，建立了可描述该含硼体系的离子相互作用模型。     

锆硼陶瓷材料中总硼分析方法研究

对锆硼陶瓷材料中总硼的分析方法进行了研究，采用硫酸和硫酸铵及重铬酸钾氧化两步溶解法分解样品，氮气载带硼酸三甲酯蒸馏分离硼与锆（氦气流速150mL/min水溶加热，NaOH溶液吸收），材料中成分为Zr粉＋B4C粉，Zr含量≥99％（ut），经阳离子交换法除去吸收液中Na后采用ICP-AES法测定硼。方法的相对标准偏差（n=6）小于2．0％；标准加入回收率为99％。     

ZrO<Subscript>2</Subscript>–Carbon nanotubes composite sorbent for treatment of aqueous solutions to remove boron

A composite adsorbent based on zirconium dioxide hydrosol and functionalized carbon nanotubes for removing soluble boron compounds from aqueous solutions was synthesized by the sol–gel method. Measurements of the borate adsorption on the synthesized adsorbent samples showed that introduction of carbon nanotubes into ZrO₂ sols used for preparing the adsorbents enhanced the adsorption ability of the adsorbents.     

Synthesis and Investigation of Energetic Boron Compounds for Pyrotechnics

The energetic boron esters tris(1‐ethyl‐5‐aminotetrazolyl) borate, tris(2‐ethyl‐5‐aminotetrazolyl) borate, tris(1‐ethyltetrazolyl) borate, tris(2‐ethyltetrazolyl) borate, and tris(2‐(3‐nitro‐1, 2,4‐triazolyl)ethyl) borate were synthesized and analyzed by NMR and IR spectroscopy, elemental analysis, and mass spectrometry. Two tetracoordinate borates potassium tetrakis(3‐nitro‐1, 2,4‐triazolyl)borate and potassium bis(4, 4′,5, 5′‐tetranitro‐2, 2′‐bisimidazolyl)borate were synthesized and fully characterized as well. Moreover, the energetic and thermal properties of the energetic boron esters and tetracoordinate borates were determined. The ¹¹B NMR chemical shifts of potassium tetrakis(3‐nitro‐1, 2,4‐triazolyl)borate and potassium bis(4, 4′,5, 5′‐tetranitro‐2, 2′‐bisimidazolyl)borate were calculated and compared to the experimental values. Tris(1‐ethyl‐5‐aminotetrazolyl) borate was tested as colorant in pyrotechnic formulations with respect to the combustion behavior and color properties as well as the energetic and thermal properties.     

Spectrophotometric determination of boron in complex matrices by isothermal distillation of borate ester into curcumin

In situ distillation of borate ester into the curcumin solution has been developed for the spectrophotometric determination of boron in a variety of complex matrixes. A polypropylene vessel containing the sample solution was placed inside a vessel (PP) containing 10 ml of curcumin solution and the distillation was carried out at room temperature/on a water bath. The borate ester collected in to the curcumin solution was evaporated to dryness on the water bath, taken in acetone and the absorbance was measured at 550 nm. In situ distillation of borate ester directly into the chromogenic reagent eliminates tedious sample treatment (before and/or after borate separation), use of methanol, complicated quartz set up, possible loss of boron and reduces the analysis time significantly. In situ dehydration of sample solution by ethanolic vapour in the absence of dehydrating acid prevents the formation of fluoborate and co-distillation of potential anionic interferents (nitrate and fluoride). This developed method has been applied for the determination of traces of boric acid in boron powder by the distillation of methyl borate at room temperature. For other matrixes (water, uranium oxide, uranyl nitrate, fluoride salt, etc.) distillation of ethyl borate was carried out on the water bath. LOD (3σ) was 5 ng g⁻¹ for water and 30 ng g⁻¹ for solid samples.     

硼特效树脂吸附硼的动力学研究

采用动边界模型对硼特效树脂XSC-800吸附模拟废水中硼酸根离子的动力学进行了描述.采用有限浴方法考察了体系温度、搅拌速度、树脂粒径及溶液中硼酸根离子浓度对交换过程的影响,并得到了交换动力学总方程.确定了硼酸根离子的交换过程属颗粒扩散控制,交换过程的表现活化能为20.38kJ/mol,表观反应级数为1.661.     

Note on the determination of boron in steel and ferro-boron

Generally 0.008% or even less of boron is added to steel for grain refining and increasing its hardenability. Difficulty arises for the determination of such a small amount of this element in presence of the prepondarent amount of iron by any of the existing methods. Two methods are known for the isolation and determination of boron in steel. Tschischewski ² separated iron with a mercury cathode and titrated with sodium hydroxide, first in the presence of methyl orange and then of phenolphthalein. Lundell et al. isolated boric acid from steel as methyl borate and titrated by use of colour indicators. Both the processes have limitations; cathodic separation of iron is not always complete and separation of boron as methyl borate is cumbersome.Alloy Steels Plant, Durgapur 8.     

Boron equilibria with high molecular weight guar: An NMR study

Equilibrium constants have been derived from ¹¹B-NMR spectra for water-soluble complexes between borate anion and high molecular weight guar (e.g., 2 × 10⁶ Da). The validity of constants was confirmed by their ability to predict the pH changes measured on mixing various combinations of sodium borate, guar, and caustic into aqueous salt solutions, by correlation of computed crosslink concentrations with the dynamic storage modulii measured on the same fluids, as well as published G′ data for borate/guar/HPG gels. A smooth correlation was also found between the computed crosslink concentrations and the viscosities of borate/guar gels (measured at constant shear). These equilibrium constants were also of the same order as those published for simple sugars forming six-member rings with borate anion. The stoichiometries of the complexes were obtained directly from the NMR peak areas rather than by analogy with simple, single-ring sugars, and at the low concentrations of chemicals used to produce moderately viscous fluids [e.g., 5700 CP at 1.5 mM boron, 10 g/L guar, and 4% salt]. The required analytical sensitivity was achieved with a 600 MHz NMR spectrometer. © 1996 John Wiley & Sons, Inc.     

高镁含硼盐卤体系反常现象解析

高镁含硼盐卤体系中存在"过饱和溶解度"、"稀释成盐"和同名离子"增溶"等反常现象。研究发现:氯化镁溶液在中低浓度时显中性,在高浓度时显酸性,饱和时pH值小于4.5。而各种镁硼酸盐基本都是pH值大于8.0的碱性矿物。水溶液中酸碱难共存,但镁硼酸盐与氯化镁却因具有相同离子而能够在高镁含硼盐卤体系中共存。结合氯化镁溶液特殊酸度变化规律与相关相化学数据可较圆满的解释高镁含硼盐卤体系中的反常现象。     

Structure and derivatization of the product from carbonylation of lithium triethylborohydride

Treatment of the reactive product from carbonylation of lithium triethylborohydride with the electrophilic reagent chlorotrimethylsilane does not produce the expected α-hydroxyborane derivative. Instead, a borinate arising through migration of a second ethyl group from boron to carbon is obtained. This result is rationalized in terms of the initial product being a borate having two possible constitutions. The borate nature of this initial product is confirmed by ¹¹B NMR.     

The chemistry of the azanonaborane cluster RNH2---B8H11NHR

The preparation and properties of the R¹R²NH---B₈H₁₁NHR cluster are described. The cluster is stable to aqueous solutions and can be made water-soluble by the introduction of a few hydrophilic groups. This makes the cluster a good candidate as the boron moiety in compounds for boron neutron capture therapy. The chemistry of the cluster preparation, the stability of the cluster, and conditions for reactions of the organic moieties are reviewed. Pyridine derivatives of the cluster show electronic interaction between the cluster and the pyridine.     

Multiple‐Site SO2‐Capture Ionic Liquids with Nearly Uniform Site Performance

We propose a series of azolium poly(azolyl)borate ionic liquids (ILs) for reversible SO₂ capture. Density functional calculations demonstrate that the designed borate anions can strongly bond to SO₂ at multiple sites with nearly uniform binding energies. Thus, as well as high overall uptakes, the ILs can achieve much higher effective uptakes (the uptake difference between absorption and desorption conditions) than existing SO₂‐capture reagents. The larger size of the borate anions, the evenly distributed negative charge among the azolyl rings, and the blocking of the conjugation by the tetrahedral boron concertedly reduce absorbate–absorbate repulsion, which leads to a large disparity among binding sites in other multiple‐site SO₂ sorbents.     

Low-level calibration study for a new ion chromatographic column to determine borate in deionized water

In the semiconductor industry, there is interest in determining borate at sub-ppb levels in ultrapure water, since borate is an early breakthrough ion from ion-exchange resin beds. Although dissolved silica is the most common species currently used to monitor the breakdown of the deionization systems, it is thought that borate probably breaks through earlier than silicate. To be of use as an early-warning indicator, borate must be determined at ppt levels. This paper discusses benchtop results with several new column products designed to deliver low-ppt detection limits for boron as borate. The system uses a prototype borate-specific concentrator column that is coupled to an ion-exclusion separator and suppressed-conductivity detection. The acidic eluent, containing mannitol, quantitatively elutes the borate from the concentrator. The analytical separation is performed using a specially designed ion-exclusion column. Data presented are from two multilevel calibration studies. Included is a discussion of detection-limit calculations and recommended formats for reporting results.     

盐卤硼酸盐化学——Ⅵ.扎仓茶卡盐湖卤水的蒸发和盐类的分离提取

扎仓茶卡盐湖是藏北地区具有经济开发远景的一个新类型硼酸盐盐湖。卤水在25℃蒸发浓缩过程中的析盐顺序符合"介稳相图"预示的结果。结合湖区地表卤水和晶间卤水化学组成,提出该盐湖卤水利用天然冷冻析出芒硝,利用夏季组成卤水日晒分离软钾镁矾,冬季析硝卤水日晒析出钾石盐的自然处理工艺,同时论述了加酸处理含硼浓缩卤水提取硼酸的原则流程。