Optimal conditions for recovering boron from seawater using boron selective resins

We determined the optimal conditions for efficient recovery of boron from seawater using boron selective resins (BSRs). A commercialized BSR named CRB05 was adopted and prepared in two particle sizes: A fine-particulate BSR (effective particle size of 105 μm) and a coarse-particulate BSR (effective particle size of 445 μm). The performance of the two BSRs was compared in terms of boron adsorption, boron desorption, and BSR regeneration and reusability. During boron adsorption, for fine BSR, optimal reaction time, stirring speed and the amount of BSR needed for the adsorption of boron were 30 min, 150 rpm and 1 g-BSR/L respectively, whereas for coarse BSR, values of the above parameters were 300 min, 150 rpm and 3 g-BSR/L. It indicates that the fine BSR can adsorb boron about threetimes more than the coarse BSR. It also shows that the reaction rate of the fine BSR is almost ten-times higher than that of the coarse BSR. During the boron desorption, no significant difference was found between the efficiencies exhibited by the fine and the coarse BSRs. The best desorption performance can be attained with 11.9 mL/mg-B of 0.05 M H₂SO₄ and 15.9mL/mg-B of 0.25M HCl, regardless of the particle size of the BSR. Finally, the boron adsorption efficiency can be maintained at a stable level even after reusing the BSRs over ten times. The present study shows a possibility to recover boron with better efficiency from seawater in short time using the fine BSR, rather than the coarse BSR.     

Removal of boron from seawater by selective ion exchange resins

Reverse osmosis (RO) desalination process is an efficient and reliable membrane technology for the production of drinking water from seawater. However, some serious limitations had recently been discovered during the field practice. Boron problem is one of them. According to the WHO regulations, the boron concentration should be lower than 0.5 mg/L in drinking water. It is still difficult to reduce boron level to 0.5 mg/L or lower with the conventional reverse osmosis desalination plants equipped with commercially available RO membranes. Therefore, more efficient separation technologies are needed for boron removal.In this study, the performance of the boron-selective ion exchange resins containing N-methyl glucamine groups, as Diaion CRB 02 and Dowex XUS 43594.00, have been tested for boron removal from model seawater. The kinetic performances of these resins were compared. The kinetic data obtained were evaluated using Lagergren pseudo-first-order and second-order models. Also, the process kinetics were predicted by using diffusion models. In addition, column-mode tests have been carried out for boron removal from model seawater.     

Comparison of several polymeric sorbents for selective boron removal from reverse osmosis permeate

Fibrous sorbents based on polypropylene and viscose fibers grafted with styrene or glycidyl methacrylate and functionalized with N-methylglucamine were compared with classical polystyrene/DVB bead sorbent with N-methylglucamine functional group. Tests were carried out in dynamic column mode. Model solution of reverse osmosis permeate containing 1.5 mg/L of boron was pumped through 5 mL of sorbent packed in glass column. Fibrous sorbents showed much faster sorption kinetics than bead sorbent, tolerating high specific flow-rates. Compared to bead sorbent, boron regeneration profiles of fibrous sorbents were narrower and they could be successfully regenerated with more diluted hydrochloric acid.     

Polymer-based chelating adsorbents for the selective removal of boron from water and wastewater: A review

Boron removal from water is a highly interesting research area that has been addressed in various investigations in the recent years. This is due to the expansion of harmful effects of boron traces in water streams on the environment and human health with the rise in boron global demand in various industries that coincided with the implantation of more stringent water quality standards. Various technologies have been applied for the removal of boron from water solutions, including ion exchange technology, which has a great potential in treating varieties of boron-containing streams up to levels in parts per million using boron-selective adsorbents. This article comprehensively reviews the latest progress in the development of polymer-based boron-selective (chelating) materials and their applications for the removal of boron from water solutions, including commercial boron-selective resins (BSRs) and their researched counterparts. The emerging trends in the development of alternative adsorbents with different substrates, morphologies, and functional groups are also elucidated. The future directions to overcome the limitations of the present generation of resins are also discussed.     

Donnan dialysis of borate anions through anion exchange membranes: A new method for regeneration of boron selective resins

The studies on sorbent regeneration by Donnan dialysis have been presented. Two kinds of anion exchange membranes were evaluated: microheterogenous, based on interpenetrating polymer network and homogenous prepared from modified homopolymer. The studies revealed that sodium chloride is the salt that forced borate transport more effectively than sodium sulfate does. Both membranes showed similar efficiency in borate transport. It was shown that the particle diffusion within resin particles was the limiting process parameter for regeneration of boron selective resins.     

添加晶种的KNO_3水溶液间歇结晶动力学模型

针对添加晶种的二次成核结晶过程的特点,并基于Beer Lambert定律、ΔL定律和粒数衡算理论,建立了包含透光率变量的间歇结晶动力学模型。运用该模型对KNO3水溶液冷却结晶实验的溶液质量分数、相对过饱和度以及透光率数据进行关联,一次性获得了结晶体系的二次成核和生长动力学参数,其值与文献值吻合较好。尝试以光学法关联动力学模型的研究,将有助于结晶机理的深入认识,为动力学模型的进一步发展提供思路。     

Non-equilibrium sorption modeling for boron removal from geothermal water using sorption-microfiltration hybrid method

In this study, the boron removal performance of a hybrid system composed of ground ion exchange resin particles coupled with a microfiltration separation unit was investigated. A non-equilibrium sorption modeling approach was introduced so as to understand the contributions of mass transfer resistances on the effluent stream concentration profiles, as well as on the resin loading scheme of this sorption-microfiltration hybrid system. This modeling approach allowed us to suggest new system operations and/or scale-up processes of sorption-microfiltration hybrid systems. In this study, the highly porous crosslinked boron selective chelating resins Diaion CRB02 and Dowex XUS 43594.00 containing N-methyl-glucamine group were used. Geothermal water that has high levels of boron was fed into the stirred cell element of the microfiltration system. Kinetic behaviour of boron selective resins for boron removal from geothermal water by the microfiltration system was evaluated to investigate the effects of resin particle size, resin concentration, and permeate flow rate.     

Evaluation of boron removal by electrocoagulation using iron and aluminum electrodes

Boron compounds are used in the variety of products manufacturing and are introduced to the environment in the form of waste. Here the feasibility of the boron removal from wastewater by electrocoagulation (EC) is studied. Aluminum and iron were simultaneously used in the reactor as materials for cathode and anode. The results show that the EC process for boron removal strongly depends on the current density, initial concentrations, and time. The process is examined under varying indices in order to determine optimal operating conditions. It is important to note the EC application needs no chemical reagents and makes the boron-containing wastewater treatment easy for regulation and automation.     

Palladium carboxylate/boron trifluoride etherate catalyst system for the selective dimerization of styrene

The selective dimerization of styrene to 1,3-diphenyl-1-butene with Pd(carboxylate)₂ + BF₃OEt₂ catalyst system in both “phosphine-free” and “phosphine-modified” fashions has been investigated. For the Pd(OAc)₂ + 2PR₃ + 7BF₃OEt₂ catalyst system, a TON of 145 000 and 90% selectivity to dimers have been achieved at 80 °C for 5 h. This TON is twice as large as compared to that achieved with the Pd(β-diketonate)₂-based systems. Styrene dimers up to 95% consist of trans-1,3-diphenyl-1-butene. The simplicity of this catalyst system composition might be of industrial importance.     

Fuzzy modeling and hybrid genetic algorithm optimization of virus removal from water using microfiltration membrane

Membranes are finding increasing applications in disinfection processes including virus removal from water for municipal effluent reuse. The capability of virus removal from water by microfiltration membranes has previously been demonstrated. In this study, the capability of fuzzy logic for modeling and simulation of dead-end microfiltration process for removal of IBR and FMD viruses from water was elucidated. The main parameters indicating membrane performance i.e. flux and rejection were experimentally obtained under different conditions and compared with theoretically calculated flux and rejection using fuzzy inference system. The genetic algorithm which is an efficient and systematic method was employed in the design of fuzzy model for optimization of the poorly understood, irregular and complex membership function with improved performance. Hybrid genetic algorithm was used for optimizing the parameters that are located at the Gaussian membership functions in the premise and consequent of each rule.The results indicated that fuzzy inference system predicts the key parameters i.e. flux and rejection for different operating conditions with an acceptable error. In other words FIS is able to apply for modeling the microfiltration membrane which is mathematically difficult or in many cases an unpredictable process.     

Chloride/sulfate exchange on anion resins. Kinetic investigations. Chemical control in selective exchanges

Rate determinations for the Cl^-/SO⁼₄ exchange on anion resins in very diluted systems (1 ÷ 6 × 10^-3N), where resin selectivities for the divalent ion are drastically raised by the electroselectivity effect, show convincing evidence that the chemical reaction rate on fixed charges controls the overall process kinetics. Activation energies, in particular, (up to 16.83 kcal/eq) are definitely out of the range for usual diffusion-controlled kinetics.A spherically-symmetrical diffusion model with a billiard-ball-like mechanism of site-to-site jumping of ions inside the resin is suggested.     

Carboxyethylated polyaminostyrene for selective copper removal

In order to prepare copper selective chelating resin, β-alanine functionality was introduced into polystyrene matrix by the aza-Michael addition of poly(4-aminostyrene) to acrylic acid. The resin was characterized by elemental analysis and pH potentiometric titration in terms of the degree of carboxyethylation (DS = 1.3) and protonation constant of the amine group (log K _H = 7.48). The optimum pH for Cu²⁺ adsorption was found to be 7–8 (0.1 M ammonium acetate buffer) and the contact time required to achieve the equilibrium was about 1 h. The adsorption kinetics follows a pseudo-second order reaction rate, where the initial stage is governed by intraparticle diffusion. The adsorption isotherm data are in good agreement with the Langmuir model. The resin shows high adsorption capacity (1.26 mmol/g) and exhibits high selectivity toward Cu²⁺ ions with no affinity to Zn²⁺, Co²⁺, Cd²⁺ ions and only weak affinity to Ni²⁺ ions.     

The dielectric behaviour of shellac-urea-formaldehyde resins

The Cole-Cole method has been employed for an analysis of the dielectric relaxation data, obtained by Bhattacharya, of a shellac-urea-formaldehyde resin (SUF) in the temperature range 30–100°C. Three relaxation processes were observed for temperatures 30 to 50°C. At 60°C, two relaxation processes were noticed. The relaxations at 70°C and above represented typical Cole-Cole type. The static dielectric constant, relaxation time and distribution parameter of SUF were found to be greater than those of the unmodified shellac. Marked changes in the above mentioned parameters were observed during a rise of temperature from 70 to 100°C. The results of the present study indicate that some rearrangement in the tertiary disposition of the resin molecules takes place during the rise of temperature from 30 to 100°C.     

Solvent impregnated resins for MTBE removal from aqueous environments

MTBE removal from groundwater is difficult. State-of-the-art processes such as air stripping or adsorption can have significant drawbacks, like high energy consumption, low capacity and low selectivity. This is why the alternative technology of solvent impregnated resins is investigated. The extractant used is 3-iodophenol diluted with propylbenzene. From solids screening and impregnation experiments macroporous polypropylene (MPP) particles appear as a suitable solid support. The MTBE capacity of impregnated MPP is lower than that of a carbonaceous resin, but the selectivity of the SIR between MTBE and humic acid is significantly higher. Solvent impregnated resin (SIR) regeneration can be easily achieved with hot gas.     

悬浮液体系错流微滤过程研究

对悬浮液体系的错流微滤（ＣＦＭＦ）过程进行理论分析和实验研究，探讨了料液类别、浓度、循环流速及操作时间、压力等参数对ＣＦＭＦ性能的影响。建立了稳态ＣＦＭＦ过程的简化组合模型，对过程的计算具有现实意义。     

The removal of bisphenol A by hollow fiber microfiltration membrane

The removal of bisphenol A (BPA) from drinking water by hollow fiber microfiltration (MF) membrane using dead-end model was investigated. The experiment was focused on the effect of various factors including BPA initial concentration, pH, ionic strength and organic matter on removal efficiency. Adsorption plays a significant role in BPA removal in MF filtration. The results showed that MF could remove BPA effectively. A higher removal was obtained at the beginning of the filtration, and the removal efficiency decreased to around 20% when the membrane became saturated due to adsorption of BPA onto the MF membrane. As pH of solution approached to pKa (9.6-11.3) of BPA, BPA removal efficiency dropped significantly. The effect of ionic strength on BPA removal was negligible. The presence of natural organic matter (NOM) demonstrated no observable impact on BPA removal. After filtration, the backwash could recover removal efficiency effectively.     

The removal of perchlorate using amine-functionalized mesoporous anion-exchange resins with different number of ligands

Perchlorate anion (ClO ₄ ^t- ) in water has become an environmental issue because it can impair proper functioning of the thyroid gland. For the removal of perchlorate anions from water, adsorption using anion-exchange resins has been generally used as the most suitable method. We have prepared mesoporous anion-exchange resins via simple functionalization of amine ligands with different numbers of functional groups, and used them for the removal of perchlorate anions from aqueous solutions. The physical and chemical properties of the prepared samples were measured using nitrogen adsorption-desorption measurement, elemental analyses, X-ray diffraction, and Fourier transform infrared spectroscopy. We also investigated equilibrium isotherms for the measurement of adsorption capacities and kinetic performances of the prepared samples. The prepared materials showed fast adsorption kinetic performances, and M-3N among the prepared materials exhibited high perchlorate adsorption capacity of 175.4mg/g compared with the results of the previous reports.     

大孔吸附树脂脱除天然碱中有机质的实验

研究了弱极性或非极性大孔吸附树脂脱除天然碱中可溶有机质的方法。结果表明,D4020型大孔吸附树脂对天然碱碱液有机质的脱除率可达50%以上,优于活性炭;吸附有机质后的D4020型树脂可用氢氧化钠与丙酮联合处理再生,再生树脂平均吸附容量可恢复至80%以上。     

B_4C-C复合材料抗氧化行为研究

用混合磨碎法制备了B4C－C复合材料，考查了不同B4C含量、温度、湿度以及空气流量对复合材料抗氧化行为的影响，并讨论了其影响机制。     

Sorbitol-modified poly(N-glycidyl styrene sulfonamide) for removal of boron

A sorbitol-containing resinous polymer has been prepared starting from crosslinked polystyrene–10% divinylbenzene (DVB) resin beads (720–840 μm) by the following series of reactions: (1) chlorosulfonation, (2) sulfonamidation with N-propylamine, (3) condensation of sulfonamide with epichlorohydrin, and (4) modification with sorbitol. The resulting sorbitol-modified polymer has been demonstrated to be an efficient and regenerable specific sorbent for removal of boron in parts per million (ppm) levels. Kinetics of boron sorption and regeneration of the polymer were investigated. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 2113–2119, 1998