Study of various parameters influencing the fixation of metallic ions Cu2+, Zn2+, and Ni2+ at the catalytic Amberlyst-15 resin in the presence of alcohols

The ionic exchange behavior of Zn²⁺, Ni²⁺, and Cu²⁺ metallic ions on Amberlyst-15 commercial resin was studied as a function of resin solution contact time, initial concentration of metallic ions, nature of the solvent, and the amount of resin. The metallic ions were studied in ternary mixtures using both column and batch experiments. In addition, water, methanol, ethanol, and propan-2-ol were used as solvents for dissolving metallic ions. It was found that the resin behavior depends on the solvent nature and the metallic ion concentration. The analysis of solutions by atomic absorption spectrometry revealed that the affinity of the resin for the studied metallic ions followed the sequence Cu²⁺ > Ni²⁺ > Zn²⁺ in the case of an aqueous medium. Furthermore, uptake increased with increasing amount of resin. A better uptake was observed in the case of the 75:25 % water/methanol compositions when the column technique was used. For the batch technique, we noted a better uptake using 100 % water. The uptake rate decreased with an increase in the number of carbons for the 50 % water–50 % alcohol solvents. The acid–base properties of Amberlyst-15 commercial resin were studied by 2-propanol decomposition test. Propene and acetone are the main expected products and it is believed that they are formed through dehydration or dehydrogenation reaction on acid and base sites, respectively.     

Ultrasound assisted preparation of calcium alginate beads to improve absorption of Pb+2 from water

Calcium alginate (CaAlg) beads were prepared using ultrasound for use in the removal of lead from natural and wastewaters by ion exchange. Ultrasound was applied in a batch mode with an ultrasonic bath or in a flow mode using an ultrasonic clamp-on device. For comparison purposes the synthesis was performed in batch mode in the absence of the ultrasound. The beads prepared using ultrasound showed a greater ion exchange capability which could be ascribed to a larger specific surface area as a result of surface roughening induced by cavitation.Scanning Electron Microscopy (SEM) images revealed that the roughening was in the form of corrugation for the product with the best ion exchange capability obtained in the flow process where preformed CaAlg droplets were subjected to ultrasound during the setting process. These beads performed 11% better for lead removal than those synthesized in the absence of ultrasound.     

树脂分离-氢化物发生-原子荧光光谱法测定中草药中不同形态的砷

本文建立了应用离子交换树脂分离技术结合氢化物发生 原子荧光光谱法测定中草药方剂原生药、残渣、悬浮态及可溶态中的三价及五价砷的方法。研究了树脂静态分离和动态分离的最佳条件 ,利用两种方法成功地对黄连解毒汤中的三价及五价砷进行了分离。考察了仪器的工作条件、试剂浓度、增感剂的选择及共存离子的干扰及消除方法。方法检出限为 89 1ng·L- 1 ,RSD为 1 4 % ,样品加标回收率为 91 1%～10 9 3%。     

Determination of Cr(III) and Cr(VI) in water by wavelength‐dispersive X‐ray fluorescence spectrometry after preconcentration with an ion‐exchange resin disk

A rapid and simple method using an ion‐exchange resin disk combined with wavelength‐dispersive X‐ray fluorescence (WDXRF) spectrometry was developed for the determination of Cr(III) and Cr(VI) in water. A 100‐ml water sample was first adjusted to pH 3 with nitric acid and then passed through an anion‐exchange resin disk placed on top of a cation‐exchange resin disk at a flow rate of 1 ml min^?1 to separate Cr(III) and Cr(VI). Anionic Cr(VI) was preconcentrated on the upper anion‐exchange resin disk, whereas cationic Cr(III) was preconcentrated on the lower cation‐exchange resin disk. Each ion‐exchange resin disk was dried at 100 °C for 30 min in an electric oven and coated with a commercially available laminate film. The specimens were measured using a WDXRF spectrometer. The calibration curves of Cr(III) and Cr(VI) showed good linearity in the range 1–10 µg. The detection limits corresponding to three times the standard deviation (n = 5) of blank values were 0.17 µg for Cr(III) and 0.16 µg for Cr(VI). If a 1‐l water sample is used, these limits would be 0.17 and 0.16 µg l^?1, respectively. A spike test for 50 µg l^?1 Cr(III) and Cr(VI) in tap water and river water showed quantitative recoveries (94–114%), although this was not observed for mineral drinking water owing to the overlap of V Kβ with Cr Kα. The recovery after overlap correction was satisfactory (115%). Copyright © 2011 John Wiley & Sons, Ltd.     

Effect of ultrasound on the kinetics of cation exchange in NaX zeolite

In this study, we focused on the effect of ultrasound on ion exchange kinetics to obtain the Li-, Ca- and Ce-rich NaX zeolite. The results were compared to those obtained from the traditional batch exchange method under similar conditions. Contact time and initial cation concentration (fold equivalent excess) were studied. Ultrasound enhanced the replacement of Na⁺ ion with Li⁺, Ca²⁺ and Ce³⁺ ions in the extra-framework of zeolite up to 76%, 72% and 66%, respectively. The intraparticle diffusion is the rate limiting step in the ion exchange for both exchange methods. As compared to the traditional exchange method, the ultrasonic method applied in this study was found to be very effective on the exchange amount at equilibrium.     

Effect of ultrasound and mechanical agitation on adsorption of 4-(2-pyridylazo) resorcinol (PAR) by amberlite XAD-2

The work reported here is a continuation of earlier work¹ in which ultrasound is found to promote ion exchange but is less effective than mechanical agitation. Correspondingly, an effort has been made to study the effect of ultrasound on adsorption by a non-polar adsorbent, XAD-2 resin. The present work shows, as in the previous case of ion exchange resins, that the rate controlling step is also a diffusion process in the uptake by the non-polar XAD-2.     

Synthesis and characterization of an enhanced heterogeneous cation exchange membrane via nanoclay

Electrodialysis (ED) is a separation process based on the transport of ions through ion exchange membranes. Ion exchange membranes are the key factor of this system. In this research, PVC/HIPS/ABS blended heterogeneous cation exchange membranes were made by solution casting method using tetrahydrofuran as solvent and cation exchange resin. The blend of various ratios of these polymers was prepared, and the best ratio was selected as the polymeric matrix. Montmorillonite K10 nanoparticles (with cation exchange characteristics) were then added to the appropriate polymeric matrix to enhance the electrochemical properties of the membrane. All the electrochemical properties of the synthesized membranes (with and without additives) were investigated. Montmorillonite K10 particles enhanced the membrane properties due to their cation exchange capacity. The best results were obtained with PVC/ABS binder and 0.03 additive ratio, where the membrane electrical resistance was decreased 37% while the IEC and transport number were improved 75 and 6%, respectively.     

Ultrasound-assisted adsorption of copper(II) ions on hazelnut shell activated carbon

The present study was aimed to removal of Cu(II) ions from aqueous solution by ultrasound-assisted adsorption onto the granular activated carbon obtained from hazelnut shells. The attention was focused on modeling the equilibrium and kinetics of Cu(II) adsorption onto the granular activated carbon. The granular activated carbon was prepared from ground dried hazelnut shells by simultaneous carbonization and activation by water steam at 950 °C for 2 h. Adsorption isotherm data were better fitted by the Langmuir model than the Freundlich model in both the absence and the presence of ultrasound. The maximum adsorption capacity of the adsorbent for Cu(II), calculated from the Langmuir isotherms, in the presence of ultrasound (3.77 mmol/g) is greater than that in the absence of ultrasound (3.14 mmol/g). The adsorption process in the absence and the presence of ultrasound obeyed to the pseudo second-order kinetics. The removal of Cu(II) ions was higher in the presence of ultrasound than in its absence, but ultrasound reduced the rate constant. The intraparticular diffusion model indicated that adsorption of Cu(II) ions on the granular activated carbon was diffusion controlled as well as that ultrasound promoted intraparticular diffusion.     

Ion-Exchange selectivity coefficients in the exchange of calcium,strontium, cobalt,nickel, zinc,and cadmium ions with hydrogen ion in variously cross-linked polystyrene sulfonate cation exchangers at 25°C

The ion-exchange selectivity parameters for the exchange of trace calcium, strontium, cobalt, nickel, zinc, and cadmium ions with hydrogen ion in cross-linked polystyrene-sulfonic acid cation exchangers have been determined from equilibrium ionic distribution measurements at 25°C in dilute solutions of perchloric acid and polystyrene-sulfonic acid. The selectivity behavior in perchloric acid solutions shows that the divalent ion is always preferred by the resin phase. The selectivity coefficients are a smooth function of resin phase concentration, increasing with concentration for Sr²⁺ more than for Ca²⁺ and Cd²⁺ and being practically independent of resin phase concentration for Co²⁺, Ni²⁺, and Zn²⁺. The selectivity coefficients measured in salt-free solutions of polystyrene-sulfonic acid show a marked dependence on the polyelectrolyte concentration, the divalent ion being preferred by the aqueous phase. This preference diminishes with the concentration of polyelectrolyte. These results are interpreted by resort to the Gibbs-Duhem equation. This thermodynamic analysis has been facilitated by the availability of osmotic coefficient data for the pure polyelectrolyte ion forms over a large concentration range. Ion-exchange selectivity predictions by using this approach accurately reflect the observed ion-exchange selectivity behavior.     

Ion-exchange resin decomposition in supercritical water

Abstract

Using supercritical water oxidation, the cation exchange resin was decomposed fast and completely to water, carbon dioxide and sulfuric acid. While the resin decomposition yield increased with the reaction time and the amount of hydrogen peroxide added as oxidizing agent, it was constant in the resin concentration from 0.14 to 1.9 dry resin weight percent to water. More than 99% of the cation exchange resin was decomposed with hydrogen peroxide added in the amount of 7 times the stoichiometric value at 673 K and 30MPa for 30 minutes of the reaction time. The cation exchange resin is decomposed through two main reaction pathways. One has a rate controlling intermediate such as acetic acid whose decomposition rate was very slow, and the other does not have stable intermediates. The decomposition of the acetic acid is a significant factor for the complete decomposition of the resin, although it does not dominate the whole resin decomposition. A simple kinetic model that estimates the resin decomposition yield was developed.     

Effect of some physical and chemical parameters on fluoride removal by nanofiltration

In natural waters, fluoride ions are necessary and beneficial for the human being. At higher level of F⁻ in water, it is toxic and detrimental to human health, leading to serious problems such as dental and skeleton fluorosis. According to the World Health Organization, the acceptable concentrations of fluoride in potable water are in the range of 0.7–1.5 mg L⁻¹. Various treatment technologies for fluoride removal from water have been used such as ion exchange, adsorption and membrane processes. In the present study, removal of fluoride ions from aqueous solutions was investigated using a polyamide thin film composite nanofiltration membrane denoted as HL 2514 T from Osmonics Company. Through this membrane, the mechanism of transport was investigated. The Kedem–Katchelsky model was applied in order to determine phenomenological parameters σ and P _s, respectively, the reflection coefficient of the membrane and the solute permeability of ions. The convective and diffusive parts of the mass transfer were quantified. The retention of monovalent and bivalent salts by this membrane shows that it is negatively charged. In the second part, retention of fluoride anions was investigated. Results show that the retention of fluoride by HL membrane exceeds 80%. The influence of the chemical parameters (feed concentration and ionic strength) and the physical parameters (applied pressure and recovery) on the elimination of fluoride was studied.     

离子交换树脂相光度法测定钯的研究

根据钯（Ⅱ）与１－（５－溴－２－吡啶偶氮）－２－萘酚－６－磺酸（５－Ｂｒ－ＰＡＮ－Ｓ）形成稳定络合物这一物质,利用阴离子交换树脂为吸附载体,建立了离子交换树脂相光度法测定钯的新方法。以最大吸收波长６９０ｎｍ为测定波长,８００ｎｍ为参比波长,用双波长法进行测定,灵敏度高,选择性,重现性好,钯量在０￣２０μｇ范围内服从比尔定律。方法用于合成水样及催化剂中钯的测定,结果满意。     

Optical Properties of Gamma Irradiated Soda-Lime Silicate Glasses Exchanged with Copper

The effect of copper ion exchange upon the optical absorption and room temperature gamma colouration of soda lime silicate glasses has been investigated. After ion exchange performed at 720 K, copper ions substitute mainly the alkali ions and do modify the optical absorption spectra of the specimens. It has been shown that gamma irradiation does not induce the formation of colloidal copper. Moreover, the colouration process itself is independent of the presence of copper ions. The generated colour centres are rather related to the presence of sodium and potassium ions. The optical bleaching by the UV light occurs in two stages. First disappear centres related to the Na-type defects and next those related to the K-type defects.     

氢化物发生-原子荧光光谱法测定7种中草药中不同形态的水溶性砷

微波提取样品后,使用树脂分离不同形态的砷,以盐酸为测定介质,硫脲-抗坏血酸为预还原剂,硼氢化钾为还原剂,用氢化物发生-原子荧光法测定7种驱虫类中草药中的不同形态砷含量。砷含量在10—100ng/mL浓度范围内线性关系好,回收率在91.4%—106.4%之间。本方法简便、快速、灵敏、准确,可用于中草药中砷的形态测定。     

Curing properties of furfuryl alcohol condensate with carbonaceous fine particles under ultrasonication

Ultrasonic treatment (sonication) was carried out through the curing process of furan resin by using an ultrasonic homogenizer at the frequency of 20 kHz and the various intensities (0-90 W). Various carbonaceous fine particles were added to furan resin to investigate the change of polymerization degree. The curing rate of furan resin was accelerated by sonication, which increased the polymerization degree with an increase in ultrasound intensity. The increase of curing rate was also observed by small additions of carbonaceous fine particles. In this case, the curing rate was increased with an increase in the specific surface area on additives.     

离子交换树脂-固相萃取富集-电感耦合等离子体光谱法测定水中重金属元素

建立了离子交换树脂-固相萃取富集-电感耦合等离子体光谱(ICP-AES)联用测定水中的重金属元素Zn,Mn,Cu,Co,Ni,Cd,Pb的方法。实验采用Dowex50WX8强酸型阳离子交换树脂,通过优化富集分离条件和排除共存离子的干扰,最终确定最佳的样品pH,样品流速,洗脱液种类和浓度,样品体积分别为3.0~4.0,3.0 mL·min-1,3.0 mol·L-1 HNO₃,200 mL。方法中各元素的检出限和定量限范围分别为0.09~0.45和0.31~1.50 μg·L-1,加标回收率和相对标准偏差RSD(n=6)分别为95.3%～104.2%和1.25%～4.12%。采用该方法测定不同地区的样品,并与直接采用ICP-MS法进行对比,其测定结果基本吻合。实验表明该方法的检出限,定量限可以满足水中重金属元素Zn,Mn,Cu,Co,Ni,Cd,Pb的检测要求,准确性和精密度好,结果可靠,适用于测定水中Zn,Mn,Cu,Co,Ni,Cd,Pb。     

黄腐酸络合铜离子光谱学特征及机理构建

二价金属离子C u2+在很多工矿企业周围水源及土壤中存量超标,造成生态环境恶化,传统的药剂及生物处理容易产生二次污染.黄腐酸由性质相似分子团簇构成,具有水溶性好、络合作用强及化学活性高的特点,对环境中C u2+分布、迁移和生物利用度可以实现高效控制与环保处理,是近年科学研究热点.现代多光谱表征分析有助于揭示黄腐酸与金属...     

Fast Doping of Cu into ZnSe NCs by Hydrazine Promoted Cation Exchange in Aqueous Solution at Room Temperature

Controllable doping is an effective way of tuning the properties of semiconductor nanocrystals (NCs). In this work, a simple strategy of fast doping Cu ions into ZnSe NCs under ambient conditions was proposed. The principle of doping is based on hydrazine (N₂H₄) promoted cation exchange reaction. By direct addition of Cu ion stock solution into the preformed ZnSe NCs, Cu doped ZnSe NCs can be obtained. Furthermore, the emission of doped NCs can be tuned by changing the amount of impurity ion addition. The cation exchange reaction is facilitated by three factors: 1) N₂H₄ addition, 2) fast impurity ions, and 3) partial stabilizer removal. The proposed cation exchange reaction in aqueous solution could be an alternate route for NC doping as well as synthesis of ionic NCs.     

Ion beam modification of surface properties of CR-39

The effects of ion-beam bombardment on the physical and chemical properties of poly(allyl diglycol carbonate) (CR-39) polymer have been investigated. CR-39 samples were bombarded with 320 keV Ar and 130 keV He ions at fluences ranging from 1 × 10¹³ to 2 × 10¹⁶ ions/cm². The nature and extent of radiation damage induced were studied by UV–VIS spectrometry, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analysis, as well as Vickers' hardness measurements. In addition, the effect of ion fluence on the wetting properties of ion-beam bombarded CR-39 polymer was determined by measuring the contact angle for distilled water. UV–VIS spectra of bombarded samples reveal that the optical band gap decreases with increasing ion fluence for both Ar and He ions. In the FTIR spectra, changes in the intensity of the bands on irradiation relative to pristine samples occurred with the appearance of new bands. XRD analyses showed that the degree of ordering of the CR-39 polymer is dependent on the ion fluence. Changes of surface layer composition and an increase in the number of carbonaceous clusters produced important change in the energy gap and the surface wettability. The surface hardness increased from 10.54 MPa for pristine samples to 28.98 and 23.35 MPa for samples bombarded with Ar and He ions at the highest fluence, respectively.     

Investigation of radiation damage and hardness of H- and He-implanted SiC

In this study, an investigation was conducted in order to determine the effects of high-dose H and He ion implantation on the structure of 3C-SiC and 6H-SiC as well as the effects on material hardness in order to understand the role of H and He produced in SiC by neutron-induced transmutations as described by Heinisch et al. [J. Nucl. Mater. 2004, 327, 175–181.]. H and He ions were implanted into polycrystalline 3C-SiC on a Si substrate and single-crystal bulk 6H-SiC, respectively, at an ion energy of 100 keV, and the total dose that was used for both species was 10¹⁷ ions/cm² in the temperature range of 473–573 K. The specimens were annealed at 1000°C for 20 min in an inert Ar atmosphere. The damaged region in the He-implanted 6H-SiC had a high density of small bubbles, but no cracks were observed. Severe cracking was observed along the damaged region in the H-implanted 3C-SiC specimens as well as a high density of hydrogen platelets. Neither specimen displayed any amorphization. Nanoindentation hardness measurements showed a marked increase in the hardness of the annealed He-implanted 6H-SiC, which was ascribed to the creation of point defects inhibiting interplanar slip. There was also a large decrease in hardness corresponding to the depth of the ion damage.