Separation Of Boron Research Articles

A high‐throughput system for boron microsublimation and isotope analysis by total evaporation thermal ionization mass spectrometry

Research on the ocean carbon cycle is vitally important due to the projected impacts of atmospheric CO2 on global temperatures and climate change, but also on ocean chemistry. The direct influence of this CO2 rise on the seawater pH can be evaluated from the boron isotopic composition in biogenic carbonates; however, conscientious laboratory techniques and data treatment are vital in obtaining accurate and precise results. A rapid-throughput boron purification and Total Evaporation Thermal Ionization Mass Spectrometry method was developed for high accuracy and precision boron isotopic analysis for small (ng) sample sizes. An improved microsublimation method, in which up to 20 samples can be processed simultaneously under identical temperature conditions, was developed. Several tests have confirmed the viability of this technique. First, seawater and Porites coral samples were processed with H2 O2 and the results compared with those obtained using microsublimation; second, the impact of various sublimation times was evaluated; and third, quantitative recovery was assessed using standard addition. Microsublimation provides a valid method for the quantitative recovery and separation of boron from both major elements and organic matter under low-blank conditions. The close agreement of our results with published values validates the accuracy of the measurements. The isotopic ratio for SRM 951a boric acid isotopic standard was 4.0328 ± 0.0054 (2 STD, n = 25). The reproducibility of boron isotopic composition for standards including AE121, IAEA B-1 and an in-house coral standard UM-CP1 was ±0.68‰ (2 STD, n = 15), ±1.12‰ (2 STD, n = 24), and ±1.17‰ (2 STD, n = 14), respectively. The sample sizes were <1 ng for each measurement. The developed method for preparing and measuring boron isotopic values in a variety of carbonate materials should facilitate the reconstruction of past ocean pH conditions with decadal-scale resolution.

Basic features of boron isotope separation by SILARC method in the two-step iterative static model

In this paper we develop a new static model for boron isotope separation by the laser assisted retardation of condensation method (SILARC) on the basis of model proposed by Jeff Eerkens. Our model is thought to be adequate to so-called two-step iterative scheme for isotope separation. This rather simple model helps to understand combined action on boron separation by SILARC method of all important parameters and relations between them. These parameters include carrier gas, molar fraction of BCl3 molecules in carrier gas, laser pulse intensity, gas pulse duration, gas pressure and temperature in reservoir and irradiation cells, optimal irradiation cell and skimmer chamber volumes, and optimal nozzle throughput. A method for finding optimal values of these parameters based on some objective function global minimum search was suggested. It turns out that minimum of this objective function is directly related to the minimum of total energy consumed, and total setup volume. Relations between nozzle throat area, IC volume, laser intensity, number of nozzles, number of vacuum pumps, and required isotope production rate were derived. Two types of industrial scale irradiation cells are compared. The first one has one large throughput slit nozzle, while the second one has numerous small nozzles arranged in parallel arrays for better overlap with laser beam. It is shown that the last one outperforms the former one significantly. It is argued that NO2 is the best carrier gas for boron isotope separation from the point of view of energy efficiency and Ar from the point of view of setup compactness.

Coupling ion exchange with ultrafiltration for boron removal from geothermal water-investigation of process parameters and recycle tests

A hybrid process was established in a stirred vessel coupling ion exchange with ultrafiltration (UF). Boron selective chelating ion-exchange resins Dowex XUS-43594.00 with an average particle diameter of 20μm were used for boron separation from geothermal water and a submerged hollow fiber type UF membrane module (ZW-1, GE) was used for the filtration of the resin suspension and collecting permeate. Process variables such as the concentration of ion exchange resin in the suspension, replacement rates of fresh and saturated resins in the stirred vessel, and flow rate of permeate were evaluated in order to determine the efficiency of the hybrid process for boron removal from geothermal water. The recycle performance of the hybrid system was monitored following ten sorption–washing–elution–washing–regeneration–washing cycles.

Conversion of covalent to ionic behavior of Fe2O3–CeO2–PbO–B2O3 glasses for ionic and photonic application

Iron oxide doped cerium lead borate glasses have been prepared and characterized to investigate the structural, physical and optical studies using XRD, FTIR, density and UV–Visible spectroscopy. IR spectroscopic studies have been employed to explore the role of iron oxide in the structure of the studied glasses. Results obtained from FTIR spectra indicate that Fe2O3 acts as a network modifier by converting three coordinated boron atoms [BO3] to four coordinated boron atoms [BO4]. The effect of transition metal content on the optical properties of the present glass system has been studied from the optical absorption spectra. The optical absorption spectra shows the shifting of band edge towards the higher wavelength and corresponding decrease in the band gap is due to the conversion of Ce3+ ions to Ce4+ ions. The physical properties such as density and molar volume help to evaluate the compact structure of prepared glass samples due to presence of [BO4] groups. This is also confirmed by average boron–boron separation result. The addition of iron oxide increases the ionicity value and corresponding decrease in covalent behavior.

Use of methyltrioctyl/decylammonium bis 2,4,4-(trimethylpentyl)phosphinate ionic liquid (ALiCY IL) on the boron extraction in chloride media

Recent restriction of boron concentration in drinking water has produced some problems in the seawater desalinization plants because the rejection of boron in most of the plants is inadequate. Three ionic liquids derived from Cyanex 272 as an anion with different cations (from Aliquat 336, Cyphos IL 101 and Cyphos IL 167) were prepared to be used as boron extractants. Liquid–liquid extraction experiments were carried out to evaluate the viability of boron separation from high chloride media. The effect of ILs and boron concentration and pH were determined. Successive extractions, maintaining the organic phase, provided satisfactory results in order to implement these ILs on supported liquid membrane technologies. The use of the ionic liquid as a carrier can overcome the inconvenience associated with the membrane stability. In this sense, the ionic liquids ALiCY and the mixture of Cyphos IL 101 and Cyphos IL 167 with Cyanex 272 have been tested as liquid carrier for boron separation by using a flat sheet supported liquid membrane. The results obtained allow us to think about the application of this kind of ILs on the process intensification to remove boron from chloride solutions.

Carbothermal formation and microstrutural evolution of α′-Sialon–AlN–BN powders from boron-rich blast furnace slag

Boron-rich blast furnace slag of low activity is one of the major products created during the separation of iron and boron from ludwigite in a blast furnace process, and the high-efficiency utilisation of its is of great importance to the Chinese boron industry. This paper proposes one new application process to synthesize α′-Sialon–AlN–BN powders by a carbothermal reduction–nitridation method using boron-rich blast furnace slag as the staring material and describes a series of experimental studies that were performed to elucidate the mechanism of phase formation and microstructure evolution during CRN. The experimental results revealed that the phase compositions and microstructures of the synthesized products were greatly affected by the initial compositions ((Ca,Mg)xSi12–3xAl3xOxN16–x), x=0.3–1.8), temperature and holding time. With the compositions shifting from values of x of 0.3–1.8, the relative amount of α′-Sialon, AlN and BN increased gradually, and the amount of α′-Sialon reached a maximum at a value of x of 1.4. The optimal condition for powder synthesis was a temperature of 1480°C with a holding time of 8h, under which the crystalline phases included α′-Sialon, AlN, BN and less SiC. More elongated α′-Sialon grains were observed at higher x values and temperatures. During the CRN process, MgAl2O4, Mg2SiO4, Ca2Al2SiO7, MgSiN2, β′-Sialon and 27R appeared sequentially as intermediate products. The volatilisation of SiO gas and magnesium vapour resulted in additional weight loss of the samples, which was aggravated with increases in the synthesis temperature and holding time.

Fundamental Study on Application of Gas-Based Shaft Furnace Direct Reduction Process to High Efficiency and Clean Utilization of Paigeite

The paigeite resources are abundant in China, but most of them are difficult to be utilized efficiently because of the current technical problems on industrial practice. It is necessary to perfected and innovated for comprehensive utilization of paigeite. The new process of gas-based shaft furnace direct reduction-electric furnace smelting separation provides a new way to efficient and clean comprehensive utilization of paigeite resources. In this paper, the pellets are prepared from boron-bearing iron concentrate. The mechanisms of roasting, the rules of reduction, and the properties of reduction swelling are also investigated. And then the pellets after reduction are smelted and separated in electric furnace to study the properties of products and analyze the feasibility and superiority of new technique. The results showed that boron-bearing iron concentrate is a kind of good raw material for pelletizing process. The properties of boron-bearing pellets after roasting for 20 min at 1200°C could meet to the requirements of gas-based shaft furnace direct reduction process, which exhibited fast reaction rate, good reduction swelling properties and high compressive strength both before and after reduction. With the new process, the efficient separation of boron and iron can be realized. The high boron grade and high activity of boron-rich slag obtained from new process can be used directly in boric acid manufacture. The new process shows excellent tech-economy feasibility to achieve efficiency and clean comprehensive utilization of paigeite resources.

Positive Thermal Ionization Mass Spectrometric Analysis of Boron Isotope on River/Rain Water with Low Content and Rich Organic Matter

A method for separation and isotopic determination of boron with low content and rich organic matter in the river/rain water samples was developed. Samples were concentrated by ion exchange Amberlite IRA-743 resin. The concentrated solution was subsequently micro-sublimated for 12 h to eliminate the organic matters. Then the boron isotope ratio was determined by measuring positive Cs(2)BO(2)(+) thermal ions. The average recovery was between 97. 5% and 101. 2%. The results that were determined by positive thermal ionization mass spectrometry were closed to those by MC-ICP-MS. The precision of isotopic measurement for boron in river/rain water was better than 0. 05 parts per thousand. The results demonstrated that this method was extremely effective for elimination organic matter interference during boron isotopic analysis with low sample size, high precision and accuracy.

Influence of thermally induced structural transformations on hardness in Fe 89.8Ni 1.5Si 5.2B 3C 0.5 amorphous alloy

Effect of heat treatment on mechanical behavior of Fe 89.8Ni 1.5Si 5.2B 3C 0.5 amorphous alloy was investigated by measuring microhardness. It was shown that the as-prepared amorphous alloy has an unexpectedly high microhardness. This can be attributed not only to boron dispersed in the alloy, but also to the structure which exhibits aspects of a nanocomposite of nanoparticles dispersed in an amorphous matrix. As the alloy crystallizes at temperatures above 540 °C, microhardness decreases continuously as a function of heating temperature. This is attributed to separation of boron out of the amorphous matrix into nanocrystals of Fe 2B phase. Further decrease in microhardness is attributed to crystallite growth with the accompanying change in the dominant nature of the interfaces from amorphous/crystal to crystal/crystal, and creation of a porous structure. When the crystallization is complete, the alloy exhibits microhardness close to that of a hypothetical mixture of α-Fe and Fe 2B phases of the same composition.

Effective elimination of organic matter interference in boron isotopic analysis by thermal ionization mass spectrometry of coral/foraminifera: micro‐sublimation technology combined with ion exchange

In order to better estimate the effectiveness of micro-sublimation technology on the elimination of organic matter interference during boron isotopic analysis, a series of improved experiments was carried out using simple apparatus. Recovery rates after micro-sublimation were measured for boric acid solutions with different B contents or different B/organic matter ratios. The improved micro-sublimation procedure combined with ion-exchange technology was then used to test natural samples (coral and foraminifera) for the separation of boron. Our results show that the time taken for 100% recovery of different amounts of B differed and that the proportions of B/organic matter within the natural organic matter have little effect on the relationship between the recovery rates of B and the micro-sublimation times. The experiments further confirm that the organic matter does indeed have an effect on boron isotope analyses by positive thermal ionization mass spectrometry and that the use of micro-sublimation can effectively remove interferences from the organic matter during boron isotopic analysis.

Direct separation of boron from Na- and Ca-rich matrices by sublimation for stable isotope measurement by MC-ICP-MS

An improved technique for precise and accurate determination of boron isotopic composition in Na-rich natural waters (groundwater, seawater) and marine biogenic carbonates was developed. This study used a ‘micro-sublimation’ technique to separate B from natural sample matrices in place of the conventional ion-exchange extraction. By adjusting analyte to appropriate pH, quantitative recovery of boron can be achieved (>98%) and the B procedural blank is limited to <8 pg. An additional mass bias effect in MC-ICP-MS was observed which could not be improved via the standard-sample-standard bracketing or the ‘pseudo internal’ normalization by Li. Therefore a standard other than NBS SRM 951 was used to monitor plasma condition in order to maintain analytical accuracy. An isotope cross-calibration with results from TIMS shows that the space-charge mass bias on MC-ICP-MS can be successfully corrected using off-line mathematical manipulation. Several reference materials, including the seawater IAPSO and two groundwater standards IAEA-B-2 and IAEA-B-3, were used to validate this approach. We found that the δ 11B of the reference coral JCp-1 was 24.22 ± 0.28‰, corresponding to seawater pH based on the coral δ 11B-pH function.

Separation and Preconcentration of Boron with a Glucamine Modified Novel Magnetic Sorbent

AbstractA novel, simple method based on magnetic separation was developed for analytical purposes. In this method, N‐methyl‐D‐glucamine (NMDG) modified magnetic microparticles that were synthesized by using the sol‐gel method were used for the selective extraction and preconcentration of boron from aqueous solutions. This method combines the simplicity and selectivity of solvent extraction with the easy separation of magnetic microparticles from a solution with a magnet without any preliminary filtration step. The structure of the prepared γ‐Fe2O3‐SiO2‐NMDG (magnetic sorbent) composites were characterized by using X‐ray diffraction (XRD), Transmission Electron Microscopy (TEM), and Fourier Transform Infrared Spectroscopy (FTIR). The influence of different parameters on the sorbent capacity, such as the sorption/desorption of boron, magnetic sorbent dosage, pH, equilibrium time, type, and amount of stripping solution, were evaluated by using the magnetic sorbent. Any equilibrium pH greater than 6 can be used for sorption. Desorption from the sorbent was carried out by using 1.0 M HCl. The sorption and desorption efficiency of the γ‐Fe2O3‐SiO2‐NMDG was found as 92.5 ± 0.5% and 99.8 ± 6%, respectively.

Separation of Boron from Geothermal Water Using a Boron Selective Macroporous Weak Base Anion Exchange Resin

In this study, batch and column mode tests were performed to evaluate the efficiency of boron removal from geothermal water containing 10-11 mg B/L using Lewatit MK 51 which is a macroporous weak base anion exchange resin with polyhydroxyl groups showing a very high selectivity and capacity for boron. The optimum resin amount for boron removal from geothermal water was determined as 4.0 g resin/L-geothermal water. It was found that the sorption kinetics was influenced by particle size of the resin and temperature. The stirring rate had almost no effect on kinetic performance of the resin. According to the results of column-mode study performed, breakthrough and total capacities of the resin were obtained as 2.75 and 4.98 mg/mL-resin, respectively.

Boron recovery from clay waste using Diaion CRB‐02 resin

A two‐step process for boron recovery from clay waste is proposed in the present work. The leachate obtained after the clay waste was leached with sulphuric acid solution was treated with Diaion CRB‐02 – a boron‐specific resin for the separation of boron from the alkaline species in the leachate. The batch studies showed that a maximum boron recovery of about 95% was obtained at a pH value of 8.0, an initial boron concentration of 50 mg L−1, a contact time of 24 h and a temperature of 25 °C. Equilibrium sorption data fitted the Langmuir isotherm. Column studies were carried out using different inlet boron concentrations and flow rates at a pH value of 8.0 and a temperature of 25 °C. The Yoon–Nelson and Thomas models were used to describe the dynamic behaviour of the column and to determine the column kinetic parameters. By these models and graphical integration, the column capacity values were found to be 7.3–8.5 mg g−1 and 7.1–8.5 mg g−1, respectively, and the 50% breakthrough time values were found to be 21–155 min and 19–149 min, respectively, depending on the inlet concentration and flow rate. It was observed that about 76% of the boron in the leachate solution could be recovered at an inlet boron concentration of 250 mg L−1, a flow rate of 2.5 mL min−1, a pH value of 8.0 and a temperature of 25 °C.

Bond character, optical properties and ionic conductivity of Li 2O/B 2O 3/SiO 2/Al 2O 3 glass: Effect of structural substitution of Li 2O for LiCl

A glass of composition (20 − x)Li 2O– xLiCl–65B 2O 3–10SiO 2–5Al 2O 3 where 0 ⩽ x ⩽ 12.5 wt% is prepared using the normal melt-quenching technique. The optical constants and electrical conductivity and their correlation are investigated, furnished and discussed with the substitution of Li 2O for LiCl. The mechanism of the optical absorption and the calculated Urbach energy follow the rule of phonon-assisted transitions. The ionic conduction mechanism is determined by activation energy process. Substitution up to 10 wt% LiCl provides high ionic conductivity (1.9 × 10 −2 Ω −1 m −1) due to the high average electronegativity of LiCl which increases the polarizability of lithium ions. The small cation–anion distance approach confirmed the enhancement in ionic conductivity of LiCl containing glass compared to that of Li 2O. Due to the large size of Cl − ions, there is an expansion of the lattice which in turn broadens the available path windows. For 12.5 wt% LiCl, anomalous density behavior is observed and a reduction in conductivity is occurred, σ = 5.4 × 10 −3 Ω −1 m −1. Owing to the model of bond fluctuation, the reduction is attributed to the increase in the alkali halide concentration which creates bottlenecks that hinder the motion of Li + ions. The ionic conductivity character is strongly supported by the behavior of the glass ionicity factor, density, molar volume, refractive index, average boron–boron separation, molar refraction, metallization criterion and non-bridging oxygen concentration of the studied glass.

Simultaneous determination of trace amounts of borate, chloride and fluoride in nuclear fuels employing ion chromatography (IC) after their extraction by pyrohydrolysis

An accurate and sensitive method based on the combination of pyrohydrolysis-ion chromatography (PH-IC) is proposed for the simultaneous separation and determination of boron as borate, chloride and fluoride in nuclear fuels such as U 3O 8, (Pu,U)C and Pu-alloys. The determination is based on the initial pyrohydrolytic extraction of B, Cl and F from the samples as boric acid, HCl and HF, respectively, which are subsequently separated by ion chromatography (IC). The proposed method significantly improves the existing analytical methodology as it combines the determination of boron, a critical trace constituent in nuclear materials, along with F − and Cl − for chemical quality control measurements. Various experimental parameters were optimized to achieve maximum recoveries of the analytes during the pyrohydrolysis and to get better ion chromatographic (IC) separation of borate, F − and Cl − along with other anions such as CH 3COO −, NO 2 −, NO 3 −, Br −, PO 4 3− and SO 4 2−. Recoveries of more than 93% could be obtained for all the analytes in the sample (0.5–1.5 g) at 1200 ± 25 K and distilled with pre-heated steam at the flow rate of 0.3 mL/min. An isocratic elution with a mobile phase of 0.56 M d-mannitol in 6.5 mM NaHCO 3 was used for the IC separation. The detection limits for B (as borate), F − and Cl − were 24, 13 and 25 μg L −1, respectively. Precision of about 5% was achieved for determination of boron, Cl − and F − in the samples containing 1–5 ppm w of boron, and 10–25 ppm w of Cl and F. The method was validated with reference materials and successfully applied to the nuclear fuels. The methodology is easy to adapt on routine basis.

Removal of boron from water by electrodialysis: effect of feed characteristics and interfering ions

Boron removal from aqueous solution by electrodialysis was studied as a function of solution pH, applied voltage, flow rate and initial boron concentration. TS-l-l0 electrodialysis equipment (Tokuyama) modified with rotameters was employed for experimental studies. It was obtained that the highest boron transport was achieved at pH 10.5 due to the increase in dissociation of boric acid in the solution. When initial boron concentration in the solution is high, percent removal of boron increased. The existence of chloride affected the efficiency of boron removal. The effect of sulphate ions was not so apparent for boron removal although the process time for boron separation became longer in the presence of sulphate ions. It was obtained that the specific power consumption increased when the boron concentration in the solution and pH of solution was increased. SPC values increased as the number of ionic species in the solution increased.

Boron recovery from borax sludge using solid–liquid extraction followed by sorption with a boron selective resin in column

AbstractThe recovery of boron from borax sludge was studied. Initially, the solid–liquid extraction was applied to borax sludge in a batch reactor. Subsequently, the extraction solution was treated with the Amberlite IRA‐743—boron specific resin for the separation of boron from the calcium and magnesium components in the extraction solution. In the batch studies, the effect of pH on the boron recovery was studied by adjusting the pH of extraction solution using HCl and NaOH solution. Optimum boron recovery of 44% was obtained at pH 8. The column studies were carried out using different inlet boron concentrations and flow rates at pH 8 and 25°C. Thomas and the Yoon–Nelson Models were found suitable to describe the dynamic behavior of the column and to determine the column kinetic parameters for process design. Almost all the boron, which was sorbed by the resin was eluted using a 0.5 M H2SO4 solution. It was seen that the concentrations of other species in the elution solution were insignificant so that it could not to be detected. In this process, boron was successfully separated from the calcium and magnesium species. It was determined that approximately 70% of the boron in the extraction solution could be recovered at an inlet boron concentration of 250 mg/L, a flow rate of 2.5 mL/min, a pH value of 8 and a temperature of 25°C. © 2007 American Institute of Chemical Engineers Environ Prog, 2007

Removal of boron from refined brine by using selective ion exchange resins

Boron removal by ion exchange resin from refined brine which was used to produce low-boron lithium salts was studied. A new boron-specific resin, XSC-800 was used in the experiments for the separation of boron. The column-mode and batch-mode sorption studies were both performed so as to obtain the optimum conditions for boron removal from refined brine. Parameters such as flow rate of brine, boron concentration, temperature, pH, height/diameter ( H/ D) ratio of the column, anion concentration, stirring speed and diameter of the resin were investigated. The results showed that the removal effect of boron by XSC-800 improved with increasing temperature, pH, H/ D ratio, and with decreasing the flow rate of brine, boron concentration, chloride anion concentration and diameter of the resin. While the stirring speed and the recycles of the resin had no significant effects on boron removal. As a result, boron can be removed from refined brine much completely by the resin at the optimum conditions. On the other hand, kinetics of the exchange process was studied by using the moving boundary model. In order to describe the kinetics more accurately, the model was modified by introducing a time correction factor. The results showed that the rate-determining step of this process under the conditions studied was controlled by particle diffusion. In addition, the apparent activation energy E a of the process was found to be 20.38 kJ/mol.

Recovery of boron from borax sludge using solid–liquid extraction followed by ion exchange with amberlite resin

AbstractTo recover boron from borax sludge, initially solid–liquid extraction with dilute sulfuric acid was utilized in a batch reactor. The optimum working conditions for boron extraction were determined. A maximum extraction yield of 85.0% for boron was obtained. In the process, 9.14% of the calcium and 16.8% of the magnesium contained in the solid waste passed to the extraction solution. Subsequently, batch ion‐exchange studies were performed using Amberlite IRA‐743‐boron specific resin for the separation of boron from the calcium and magnesium components in the extraction solution. The effects of contact time and resin dosage on the ion‐exchange process were investigated. A second order kinetic model seemed to be appropriate for the boron ion‐exchange. The boron, which was sorbed on the resin, was eluted completely using a 0.5 M sulfuric acid solution. It was seen that the calcium and magnesium components were not present in the elution solution. In this process, boron was successfully separated from the calcium and magnesium species. It was determined that approximately 98.70% of the boron in the extraction solution could be recovered at a pH value of 8, a contact time of 24 h, an initial boron concentration of 500 mg/L, a resin dosage of 2.5 g of resin/50 mL of extraction solution, and a temperature of 25°C. © 2007 American Institute of Chemical Engineers Environ Prog, 2007