Initial Boron Concentration Research Articles

Boron removal by means of chemical precipitation with calcium hydroxide and calcium borate formation

Boron removal was investigated by chemical precipitation from aqueous solutions containing boron using calcium hydroxide. pH, initial boron concentration, amount of Ca(OH)2, stirring speed and solution temperature were selected as operational parameters in a batch system. The highest boron removal efficiency was reached at pH 1.0. Increasing initial boron concentration and amount of calcium hydroxide raised to boron removal efficiency. Boron removal efficiency was highest at a stirring speed of 150 rpm. The most important parameter affecting boron removal efficiency was solution temperature. Increasing solution temperature increased importantly boron removal. XRD analysis showed that CaB3O3(OH)5·4H2O, which is a borate mineral called inyoite, occurred between Ca(OH)2 and borate ions. As a result of the obtained experimental data, when the optimum operational conditions were selected, over 96% of boron removal efficiency was reached by this method.

The effect of process parameters on boric acid transport during the electrodialytic desalination of aqueous solutions containing selected salts

The separation of boric acid from salts by electrodialytic (ED) desalination has previously been presented. In this process, the boric acid species are retained in the diluate solution, whereas their accompanying salts are removed in the concentrate solution. By this approach, boron can be recovered in the subsequent steps, free from contaminating salts.In the present work, the effects of the ED process parameters on the boric acid transport rate from the diluate have been investigated. The effects of the boric acid concentration in the diluate, membrane type, ion type transferred across the membrane and electric current density were discussed. The boron flux across the membrane was observed to strongly depend on the initial diluate boron concentration as well as the electric current density. The cations migrating across the cation-exchange membranes were found to cause a statistically significant decrease in the boron flux across the membranes in the following order: K+>Na+>Ca2+>Mg2+. The anions transported across the anion-exchange membranes affected the boron flux in the following order: SO42−>NO3−≈Cl−. Tentative explanations for the observed boron fluxes were given.

Adsorption of boron from aqueous solutions by activated carbon impregnated with salicylic acid: equilibrium, kinetic and thermodynamic studies

Abstract The adsorption of boron from aqueous solution containing boron by activated carbon impregnated with salicylic acid (ACISA) was studied in a batch system. In order to investigate the effect of initial boron concentration and temperature on boron adsorption capacity of ACISA; the equilibrium, kinetic and thermodynamic parameters were calculated. The adsorption capacity data were obtained by using Langmuir and Freundlich isotherm models and both models fitted well. The pseudo-first-order, pseudo-second-order and the intraparticle diffusion models were used to describe the kinetic parameters and the rate constants were evaluated. The experimental data fitted very well the pseudo-second-order kinetic model. The activation energy (Ea ) calculated using the Arhenius equation was found to be 58.25 kJ mol−1. Various thermodynamic parameters such as Gibbs free energy (ΔG o), enthalpy (ΔH o) and entropy (ΔS o) changes were computed and the results showed that the adsorption of boron onto ACISA was spontaneo...

Surface glycosylation of polysulfone membrane towards a novel complexing membrane for boron removal

In this study, a novel complexing membrane was synthesized for boron removal from aqueous solution. A glycopolymer, poly(2-gluconamidoethyl methacrylate) (PGAMA), was grafted onto the chloromethylated polysulfone (CMPSF) microporous membrane via surface-initiated ATRP (SIATRP). The glycosylated PSF (GlyPSF) membrane was characterized by attenuated total refection-Flourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (FESEM). It was demonstrated that PGAMA was successfully anchored onto the membrane surface and the grafting yield can be tuned in a wide range up to 5.9mg/cm2 by varying the polymerization time. The complexing membrane can adsorb boron rapidly with the equilibrium reached within 2h and has a remarkable high boron adsorption capacity higher than 2.0mmol/g at optimized conditions. Freundlich, Langmuir, and Dubinin–Radushkevich adsorption isotherms were applied, and the data were best described by Langmuir model. Kinetic data were analyzed, and the data fitted very well to the pseudo-second-order rate expression. The optimal pH for boron uptake is in a wide range of 6–9, and the optimal initial boron concentration is over 300mg/L. Studies of ionic strength effects indicated the formation of inner-sphere surface complexes. The complexed boron can be leached quantitatively under acid condition.

Using pretreated waste oyster and clam shells and microwave hydrothermal treatment to recover boron from concentrated wastewater

Boron is an essential nutrient for animals and plants, but it can be harmful in excessive levels. In this study, three types of crushed shells (oyster, hard clam and freshwater clam) were pretreated and then reused as mineralizers to remove and recover the boron from concentrated wastewater by using the microwave hydrothermal method. Chemical and physical properties of raw and pretreated crushed shells were determined and compared using SEM, XRD, BET and WD-XRF. Effects of pretreatment method (heated or pyrolysis), particle sizes, initial boron concentrations, reaction times and shells dosages on boron recovery were investigated. The oyster shells pretreated by heat performed better than heated hard clam and freshwater clam shells, and the boron recovery efficiency reached around 95% within 10min of reaction time. The experimental results indicate that the pretreated oyster shell is an effective mineralizer for removal and recovery of boron from concentrated wastewater.

Synthesis of chitosan beads as boron sorbents

AbstractParameters, such as pH, temperature, initial boron concentration, adsorbent dosage, and ionic strength, affecting boron adsorption onto chitosan beads were examined in this study. The following values were obtained as the optimum conditions in our studied ranges: pH 8.0, temperature = 308 K, amount of chitosan beads = 0.15 g, initial boron concentration = 4 mg L−1, and ionic strength = 0.1 M NaCl]. The adsorption kinetics were also examined in terms of three kinetic models: the pseudo‐first‐order, pseudo‐second‐order, and intraparticle diffusion models. The pseudo‐second‐order kinetic model showed very good agreement with the experimental data. Intraparticle plots seemed to have two steps and indicated multilinearity. Equilibrium data were evaluated with nonlinear and linear forms of the Langmuir and Freundlich equations. The experimental data conformed to the Freundlich equation on the basis of the formation of multilayer adsorption. To characterize the synthesized chitosan beads, we used Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analyses. As shown by FTIR analysis, the boron species may have interacted with the NH2 groups on chitosan. Microparticles of about 5 μm appeared in the SEM micrographs of the chitosan beads. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Adsorption of boron from aqueous solutions using activated carbon prepared from olive bagasse

In this study, activated carbon was prepared from olive bagasse by physical activation. The pore properties including the BET surface area, pore volume, pore size distribution and average pore diameter were characterized. BET surface area of the activated carbon was determined as 803 m2g–1. In this study, boron removal from aqueous solutions by adsorption was investigated. In the batch mode adsorption studies, the effects of initial pH of solution, contact time, temperature and initial boron concentration of solution were examined. A comparison of kinetic models applied to the adsorption of boron onto activated carbon was evaluated for the pseudo-first order, pseudo-second order, intraparticle diffusion, Elovich and Bangham’s kinetic models. The experimental data fitted the pseudo-first order and intraparticle diffusion kinetic model. The thermodynamic parameters were also calculated. In the isotherm studies, the Langmuir, Freundlich and Dubinin –Radushkevich (DR) isotherm models were applied. The results...

Local Density Diffusivity (LDD-) Model for Boron Out-Diffusion of <i>In Situ</i> Boron-Doped Si<sub>0.75</sub>Ge<sub>0.25</sub> Epitaxial Films Post Advanced Rapid Thermal Anneals with Carbon Co-Implant

Boron in silicon has presented challenges for decades because of clustering and so-called transient enhanced diffusion [1-2]. An understanding of boron diffusion post rapid thermal annealing in general, and out of in situ doped epitaxially grown silicon-germanium films in particular, is essential to hetero junction engineering in microelectronic device technology today. In order to model boron diffusion, post-implantation, the local density diffusion (LDD) model has been applied in the past [3]. Via mathematical convolution of the diffusion model slope and the initial boron concentration profile, these former results were transferred to this work. In this way, non-diffusing boron was predicted to exist in the center of the presented in situ boron-doped films. In addition, boron diffusion control by co-implanted carbon was demonstrated and the applied LDD model was completed and confirmed by adapting A. Einstein’s proof [4] for this purpose.

Boron adsorption by clinoptilolite using factorial design

AbstractIn this article, boron removal from aqueous solutions by batch adsorption was investigated and 23 full factorial design was applied. Three parameters affected the performance and two levels of these parameters were investigated. The chosen parameters were temperature (25°C and 45°C), pH (3 and 7), and mass of adsorbent (0.1 g and 1 g). The significance of the effects was checked by analysis of variance (MINITAB‐Version 15). The model‐function equation for boron adsorption on clinoptilolite was obtained. The results showed that temperature, pH, and mass of adsorbent affected boron removal by adsorption. Boron removal increased with increasing pH and adsorbent dosage, but decreased with increasing temperature. The optimum conditions were found as pH = 7, adsorbent dosage = 1 g/25 mL solution, and temperature = 25°C by using factorial design. In addition, the effects of pH, temperature, adsorbent dosage, and initial boron concentration on boron removal were investigated. The adsorption isotherm studies were also performed. Maximum adsorbent capacity (qo) was calculated as 3.64 mg/g. © 2010 American Institute of Chemical Engineers Environ Prog, 2010

Boron removal from aqueous solution by using plasma-modified and unmodified anion-exchange membranes

The removal of boron from aqueous solution through plasma-modified and unmodified AFX anion-exchange membrane was investigated by the Donnan dialysis (DD) method. The surface of anion-exchange membrane was treated by electron cyclotron resonance plasma (ECR) to enhance the performance. The effects of plasma-modified anion-exchange membrane and initial boron concentration on the boron removal were investigated at 25 °C. The optimum pH was chosen as 9.5 from the literature data. The flux values ( J) and recovery factor (RF) of boron were obtained before and after the plasma modification. Under Donnan dialysis conditions, flux values and recovery factors of boron were calculated and the highest values were obtained for plasma-modified AFX membrane as compared with the unmodified one. This situation can be explained by change of morphology of pores in the plasma-modified membrane. In addition, the different valence anions also influence the flux of boron and the order of flux was found as Cl − > SO 4 2−.

Fractional Scaling Analysis for IRIS pressurizer reduced scale experiments

About twenty organizations joined in a consortium led by Westinghouse to develop an integral, modular and medium size pressurized water reactor (PWR), known as international reactor innovative and secure (IRIS), which is characterized by having most of its components inside the pressure vessel, eliminating or minimizing the probability of severe accidents. The pressurizer is responsible for pressure control in PWRs. A small continuous flow is maintained by the spray system in conventional pressurizers. This mini-flow allows a mixing between the reactor coolant and the pressurizer water, warranting acceptable limits for occasional differences in boron concentrations. There are neither surge lines nor spray in IRIS pressurizer, but surge and recirculation orifices that promote a circulation flow between primary system and pressurizer, avoiding power transients whether outsurges occur. The construction of models is a routine practice in engineering, being supported by similarity rules. A new method of scaling systems, Fractional Scaling Analysis, has been successfully used to analyze pressure variations, considering the most relevant agents of change. The aim of this analysis is to obtain the initial boron concentration ratio and the volumetric flows that ensure similar behavior for boron dispersion in a prototype and its model.

Recovery of boron from borax sludge of boron industry

A two-step process for boron recovery from borax sludge is proposed in the present work. The borax sludge was leached with sulphuric acid solution. Then, for the removal of alkaline species from the leachate, calcium and magnesium were precipitated by adjusting the pH of leachate using 1.5 M NaOH and 1.5 M HCl solutions. The effects of pH, temperature, concentration and time on the precipitation process were investigated. It was determined that the calcium and magnesium concentrations in the leachate were reduced from 121 mg/L to 2.6 mg/L and from 145 mg/L to 4.0 mg/L, respectively, at a pH value of 12, a temperature of 70 °C, an initial boron concentration of 500 mg/L and a precipitation time of 3 h. Under these optimum conditions, it was observed that the boron concentration in the solution decreased very slightly. In this process, the alkaline species were successfully separated from the boron. Finally, borax pentahydrate (Na 2B 4O 7·5H 2O) was produced by the evaporation of the final solution obtained after precipitation process.

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.

Equilibrium and Kinetic Studies of Adsorption of Boron on Activated Alumina

Boron is widely distributed in the environment, mainly in the form of boric acid or borate salts, and its contamination of waters is a concern around the world. This study focuses on boron removal by means of adsorption onto activated alumina. Optimum adsorption was achieved in the pH range 8.0 to 8.5. Approximately 60% (by mass) boron removal was achieved using an adsorbent dose of 5 g at an initial boron concentration of 50 mg/L. Adsorption isotherms at 10, 20, and 30 degrees C were investigated. The results fitted with the Langmuir and Freundlich equations showed a monolayer adsorption onto a surface, with a finite number of identical sites. To study the rate-limiting step, the adsorption kinetic data of boron were analyzed using first-order (Lagergren) and second-order kinetic models. The experimental results obtained showed that the adsorption process followed a second-order kinetic model.

Boron adsorption mechanism of a hybrid gel derived from tetraethoxysilane and bis(trimethoxysilylpropyl)amine

An organic/inorganic hybrid gel was prepared with tetraethoxysilane (TEOS) and bis(trimethoxysilylpropyl)amine (TSPA) as precursors. The adsorption of boron on the hybrid gel in aqueous solutions was investigated comprehensively by varying the initial boron concentration, pH, ionic strength, and temperature. The equilibrium adsorption amount of boron increases with the increase in initial boron concentration and ionic strength, but decreases with the increase in temperature. The adsorption amount exhibits a maximum at initial pH of 4–10. Boron appears to be adsorbed in both H 3BO 3 and B(OH) 4 − forms through the hydrogen bonding, electrostatic and hydrophobic attractions.

Boron adsorption using a new boron-selective hybrid gel and the commercial resin D564

A new hybrid gel with boron-selective functional groups is prepared with tetraethoxysilane (TEOS), (3-glycidoxypropyl)trimethoxysilane (GPTMS), and a new precursor ( W) synthesized from GPTMS and N-methylglucamine (MG). We investigate the boron adsorption onto the hybrid gel and the commercial resin D564 in aqueous solution by varying the initial boron concentration, pH, ionic strength, and temperature. Adsorption of both the hybrid gel and the D564 can be described by the second-order kinetics and the hybrid gel shows the lower second-order rate constant and the initial adsorption rate than the commercial resin. A maximum boron adsorption occurs at pH 4–9, which can be explained by the adsorption suppression by H + ions at low pH and the weakened complexation by electrostatic repulsion at high pH. Ionic strength of the solution affects both the adsorption kinetics and thermodynamics, and it has a more pronounced effect on the kinetics of the hybrid gel than the D564. For both the hybrid gel and the D564, adsorption was found to be a chemisorption, which may be more advantageous in removal of boron from water than physisorption due to a higher adsorption capacity and better selectivity. Compared with other boron-selective adsorbents, the boron-selective hybrid gel in this study is easy to prepare, and has a good mechanical strength and an adsorption capacity (1.15 mmol g −1).

Boron removal by membrane contactors: the water that purifies water

The potential of membrane contactors for treating boron containing waters were investigated. In particular, experimental tests at lab scale on flat membrane modules with 40 cm2 of membrane area were carried out, to identify the effect of different parameters, such as temperature, flow rate, boron concentration, etc. on the efficiency of the process. Water was chosen as the extractant in order to avoid the pollution of the feed stream and two symmetric microporous hydrophilic flat membranes with different pore size and porosity were used. From these tests, it results that the boron removal increases with the extractant temperature and with the operating flow rates. However, it is independent on the initial boron concentration in the feed water. Moreover, higher removals are obtained with the membrane with larger pore size and higher porosity. Based on the experimental results, an integrated reverse osmosis-membrane contactor system, where the membrane contactor works on the reverse osmosis permeate, was proposed and designed for a 100 m3/h fresh water production (with a boron content ≤0.4 ppm). In particular, membranes with higher porosity and lower thickness than those used in the experimental tests were considered for the calculations, in order to work at 25°C (so, there is no need of heating the extractant stream) with reasonable membrane areas. The comparison of the proposed plant to that actually used, has shown that the proposed one appears to be more effective in terms of size, energy and chemical consumption, flexibility and modularity.

Sorption of boron by invasive marine seaweed: Caulerpa racemosa var. cylindracea

The sorption of boron from aqueous solution onto Caulerpa racemosa var. cylindracea (CRC), collected from Seferihisar/Izmir region in Turkey, was investigated as a function of pH, temperature, initial boron concentration, adsorbent dosage, contact time and ionic strength. Optimum conditions for the sorption of boron were obtained at pH 7.5, 318 K, 8 mg L −1 initial boron concentration, 0.2 g of CRC, 2.5 h contact time and greater ionic strength (10 −1 M NaCl). As the temperature was increased the boron removal took place with higher percentages. In experiments conducted at optimum conditions, maximum boron sorption was determined to be about 63%. The experimental data were analyzed by Freundlich, Langmuir and Dubinin–Radusckevich (DR) equations. Freundlich and DR models provide best conformity with the experimental data. In order to describe kinetics of boron sorption onto CRC, first-order Lagergren equation, pseudo-second-order kinetic model and intraparticle diffusion model were used. It was seen that the first order Lagergren equation was better described than the pseudo-second-order kinetic model. Thermodynamic parameters of sorption process were also calculated. It was obtained that sorption process was not spontaneous. The characterization of CRC was carried out by Fourier transform infrared spectroscopy (FTIR) analysis.

An empirical model for kinetics of boron removal from boroncontaining wastewaters by the electrocoagulation method in a batch reactor

Boron removal from boron containing wastewaters prepared synthetically via the electrocoagulation method was studied. The experiments in which aluminum plate electrode was used were carried out in a batch reactor. The solution pH, initial boron concentration, current density, type of supporting electrolyte, temperature of solution and stirring speed were selected as experimental parameters. The obtained experimental results showed that efficiency of boron removal increased with increasing current density and decreased with increasing boron concentration in the solution. Supporting electrolyte had not significant effects on the percent of total boron removal. pH was very important parameter effecting boron removal and optimum pH was determined to be 8.0. This pH value reached an agreement with activity-pH diagrams for Al +3 species in equilibrium with Al(OH) 3 and boron species in aqueous media. As a result of increasing interaction between boron ions and dissolved aluminum ions in solution, the increasing solution temperature increased boron removal efficiency. Increasing stirring speed decreased boron removal efficiency where the increasing stirring speed decreased the capability of floc formation of aluminum ions. As a result, it was seen that about 99% of boron in the wastewater could be removed at optimum conditions. In addition, the process kinetics was predicted by using heterogeneous fluid–solid reaction models. It was seen statistically that the kinetics of this process agreed with the pseudo-second-order model as follows: X B /(l− X B ) = 18,241 ⁎[OH] ⁎[C] −3.45⁎[CD] 7.79⁎[t] 1.41⁎[S] −3.65⁎exp[−30,668/ R ⁎T ].

Removal of boron from aqueous solutions by batch adsorption on calcined alunite using experimental design

In the present paper, boron removal from aqueous solutions by batch adsorption was investigated and 2 3 full factorial design was applied. Calcined alunite was used as adsorbent. In the study, three parameters affected the performance and two levels of these parameters were investigated. The chosen parameters were temperature (25 and 45 °C, respectively), pH (3 and 10) and mass of adsorbent (0.5 g adsorbent per 25 mL solution and 1 g adsorbent per 25 mL solution). The significance of the effects was checked by analysis of variance (statistical software, MINITAB-Version 15). The model-function equation for boron adsorption on calcined alunite was obtained. The results showed that temperature, pH and mass of adsorbent affected boron removal by adsorption. Boron removal increased with increasing pH and adsorbent dosage, but decreased with increasing temperature. The optimum conditions were found as pH 10, adsorbent dosage = 1 g of calcined alunite per 25 mL solution and temperature = 25 °C by using factorial design. In addition, the effects of parameters such as calcination temperature, pH, temperature, adsorbent dosage and initial boron concentration on boron removal were investigated. The adsorption isotherm studies were also performed. Maximum adsorbent capacity ( q 0) was calculated as 3.39 mg/g. Thermodynamic parameters such as change in free energy (Δ G°), enthalpy (Δ H°) and entropy (Δ S°) were also determined.