Dowex 1X8 Research Articles

An Investigation of Lanthanum Recovery from an Aqueous Solution by Adsorption (Ion Exchange)

Lanthanum (La(III)) is one of the high-demand rare earth elements with applications in various products. However, La(III) in mining waste streams and electronic waste also poses environmental and health concerns. Therefore, the recovery of La(III) in the waste is needed. In the present study, the adsorption of La(III) with Dowex 50W-X8, Amberchrom50WX4, Amberlyst 15, and Amberchrom 50WX2 was evaluated using a shaker water bath. Dowex 50W-X8 was found to be the best adsorbent and was used to investigate the effect of the shaker speed (RPM = 50–150), adsorbent dosage (1.0–4.0 g), pH (2.0–7.0), and temperature (20–40 °C) on adsorption. La(III) adsorption was found to increase with the shaker speed, as expected. On the other hand, the adsorption capacity decreased with the adsorbent amount. Also, the highest La(III) adsorption was observed at pH = 6.0. La(III) percentage removal did not vary significantly with a temperature from 20 °C to 40 °C. However, the first-order kinetic rate constant decreased moderately with increases in temperature. The adsorption of La(III) by Dowex 50-X8 followed the Freundlich isotherm model better than the Langmuir model. In addition, the adsorption kinetics were represented well by the pseudo-first-order kinetic model. Moreover, enthalpy and Gibbs free energy changes were found to be negative, indicating an exothermic and thermodynamically favorable adsorption process.

2-Keto-gluconate production and purification by thermotolerant acetic acid bacterium Nguyenibacter vanlangensis KKS-R1

2-Keto-gluconic acid (2-KGA) is a pivotal intermediate in the production process of ascorbic acid, commonly known as vitamin C. The bacterium Nguyenibacter vanlangensis KKS-R1 is an acetic acid bacterium (AAB) that has been selectively screened for its ability to produce 2-KGA among twenty-five bacterial isolates at high temperatures up to 40°C. This thermotolerant property makes it advantageous for various industries. Therefore, it has garnered interest for its potential application in the production of 2-KGA and purification of the 2-KGA product. This study evaluated the production of 2-KGA by N. vanlangensis KKS-R1 using 1% gluconate as the substrate. The 2-KGA was determined by thin-layer chromatography, Lanning and Cohen’s method, and high-performance liquid chromatography. After fermentation in a minimal liquid medium for 24 hours, the bacterium showcased its prowess by producing 2-KGA concentrations of 7.5 g/L. However, the purity of the 2-KGA production is paramount for industrial applications. In addressing this, a rigorous chromatographic purification regimen was employed. This involved two sequential stages of ion exchange chromatography, DEAE-Sephacel and DOWEX 1X4, followed by SuperdexTM S-200 column chromatography. The collective efficacy of these methodologies yielded a product with an impressive purity index of 71.02%. The 2-KGA product was then subjected to a decolorization process using activated carbon and freeze-dried. This results in the compound being a pure white powder. This investigation indicates that N. vanlangensis KKS-R1 shows good potential as a 2-KGA producer at high temperatures. Under proper purification techniques. These findings contribute to developing purified processes and producing 2-KGA for industrial efficiency.

Chromatographic Separation of Rare Earth Elements as MGDA Complexes on Anion Exchange Resins

Chromatographic separation of rare earth elements (REE) as anionic complexes with chelating aminopolycarboxylate ligand methylglycine N,N-diacetate (MGDA) was studied experimentally. A synthetic mixture of La, Nd, and Eu were used to model a REE mixture obtained from processed secondary sources such as phosphogypsum (PG). In the REE extraction from PG, the REEs can be recovered with MGDA to obtain the REE–MGDA mixture. Three strong base anion exchange resins (Dowex 1X8, IRA-402, and IRA-410) were used as the separation materials. Successful separation of the REEs by elution with dilute HNO3 and HCl was attributed to differences in the stabilities of the REE–MGDA complexes. The pKa values of the complexes were determined by titration to be 3.81, 3.25, and 2.96 for La, Nd, and Eu, respectively. Fractionation of the ternary La-Nd-Eu mixture (with a 1:1:1 mole ratio) were studied. La was recovered at approximately 80% purity and 80% yield, but strong trade-offs between the yield and the purity of Nd and Eu must be made. Chromatographic separation was found to be an efficient process option, considering its simplicity and the recovery of several product fractions. The initial process design offers a promising starting point for investigating more advanced process configurations for the efficient recovery of pure REE from phosphogypsum.

Ion exchange behavior of astatine and bismuth

Astatine sorption by ion exchange resins from nitric acid media.

The removal of toxic metals from liquid effluents by ion exchange resins. Part XVII: Arsenic(V)/H+/Dowex 1x8

The performance of anionic exchange resin Dowex 1x8 in the removal of arsenic(V) from aqueous solutions was investigated. Batch experimentation was carried out under different variables, including, the stirring speed applied on the system, the pH of the aqueous solution, resin dosage and temperature. Due to the characteristic speciation of arsenic(V) in aqueous phases, the removal of this element from the solution is negligible at highly acidic or alkaline pH values, but it is possible at the aqueous pH range of 4-9, thus, both HAsO42- and H2AsO4- species are loaded onto the resin. At the above pH range, arsenic(V) uptake is exothermic. Different models are fitted to the experimental values in order to gain knowledge about this ion exchange system: rate law, kinetics and solute loading onto the resin. This loading is compared against the yielded using non-functionalized multiwalled carbon nanotubes. The elution step is investigated using acidic solutions (HCl medium) as eluent, from the eluted solutions, arsenic(V) can be efficiently stabilized as ferric or calcium arsenates.

Study of new routes for purification of fission 99Mo

99mTc is the most applied medical radioisotope in the world, especially for cancer diagnosis procedures. It is provided by 99Mo radioactive decay, which is one of the fission products from the uranium irradiation in nuclear reactors. At the main production plants, the 99Mo chemical processing may be lined up in several steps to separate it from other fission products according to the features of the used targets or the local requirements as well. In this work, two routes of 99Mo purification, MR1, and MR2, were purposed as an alternative to be set up in the Brazilian Multipurpose Reactor project (BMR). The MR1 route was performed by three chromatographic columns packed with Dowex 1x8 resin, Chelex resin, and alumina, respectively. The route MR2 was carried out also by chromatography applying two columns filled with Dowex 1x8 and alumina respectively, but including a sublimation process performed in a tubular oven under programmed conditions. The final yield for the MR1 route was 84.4 % and the overall time process was about 7 hours, whereas the MR2 route reached 75.3 % in 9 hours.

Comparative evaluation of dithiocarbamate-modified cellulose and commercial resins for recovery of precious metals from aqueous matrices

Economic and ecological issues motivate the recovery of precious metals (PMs: Ag, Au, Pd, and Pt) from secondary sources. From the viewpoint of eco-friendliness and cost-effectiveness, biomass-based resins are superior to synthetic polymer-based resins for PM recovery. Herein, a detailed comparative study of bio-sorbent dithiocarbamate-modified cellulose (DMC) and synthetic polymer-based commercial resins (Q–10R, Lewatit MonoPlus TP 214, Diaion WA30, and Dowex 1X8) for PM recovery from waste resources was conducted. The performances and applicability of the selected resins were investigated in terms of sorption selectivity, effect of competing anions, sorption isotherms, impact of temperature, and PM extractability from industrial wastes. Although the sorption selectivity toward PMs in acidic solutions by DMC and other resins was comparable, the sorption efficiency of commercial resins was adversely affected by competing anions. The sorption of PMs fitted the Langmuir model for all the studied resins, except Q–10R, which followed the Freundlich model. The maximum sorption capacity of DMC was 2.2–42 times higher than those of the resins. Furthermore, the PM extraction performance of DMC from industrial wastes exceeded that of the commercial resins, with a sorption efficiency ≥99% and a DMC dosage of 5–40 times lower.

Selective separation of uranium using modified Dowex 1X8 /TOA from carbonate leaching of Dolostone ore, Allouga area, Sinai

AbstractLeaching of uranium from a technological sample (680 mg/Kg U) in SW Sinai of Um Bogma Formation is carried out using a mix of sodium carbonte/sodium bicarbonate in presence of an oxidant (MnO2 or H2O2). The relevant factors e.g. (grain size=−200 mesh, alkali concentration= 100 g/l (3 : 1) mixed Na2CO3/NaHCO3, time=2 h, solid/liquid ratio=1/3, T=50 °C and H2O2=60 ml) of alkaline leaching of uranium have been optimized. This is followed by uranium recovery using an anion exchange resin, modified Dowex 1X8/TOA. Therefore, highly 92 % pure product of uranium has been obtained as sodium di‐urinate Na2U2O7.

Removal of sulfate ions from process water by ion exchange resins

High concentrations of sulfate and thiosulfate ions in the process water may cause significant problems in the flotation of sulfide ores through changing the pulp chemistry, surface chemistry of sulfide minerals and froth stability. In addition to that formation of colloidal gypsum and scaling problems in process plants are observed when lime is used for pH regulation. Therefore, reducing sulfate and thiosulfate ion concentration in the process water is required for minimizing gypsum formation and stabilizing pulp chemistry. In this study, strong base ion exchange resins; Amberlite IRA-400 and Dowex 1X2 were used to reduce the amount of sulfate and thiosulfate in the process water.Adsorption and regeneration behavior of resins were determined by bench scale laboratory experiments using synthetic water simulating the process water of a zinc flotation plant from an Iberian Mine (Portugal). In the second phase of the study, the resins were tested using the process water in the mine site. Batch scale flotation tests were conducted by using the process water treated with Amberlite IRA-400 to determine the effects of water treatment on flotation efficiency of the Zinc ore.Amberlite IRA-400 has higher degree of cross-linkage in its structure and higher adsorption capacity. More than 90% of the sulfate could be removed from the water in the first 5 min of the adsorption test. The resin has high adsorption kinetics and can remove majority of the anions by adjusting the required quantity of resin according to the concentration of dissolved ions in the process water. The resins were regenerated effectively by using 4% w/v NaOH solution as a regenerant and used multiple times for adsorption. The same regeneration solution could be used with stage addition of NaOH to achieve the balance between hydroxide ions and adsorbed ions.Effects of resin treated water on flotation efficiency and water chemistry profile in the grinding and flotation stages were investigated using an ore sample taken from the Zn flotation plant. The results show that concentration of all ions increased significantly after the grinding stage due to dissolution of the minerals. Water treatment by resins removed majority of sulfate and thiosulfate ions from the flotation water. Water treatment by ion exchange resins increased the pulp pH up to 12, due to the ion exchange reaction between the hydroxide ions and anions. However, high pH did not significantly affect Zn flotation efficiency.

Sorption of Metal Ions on an Anion-Exchange Resin in an Ammonium Acetate Solution

The distribution coefficients for 60 elements on the anion-exchange resin Dowex 1x8 in ammonium acetate medium (0.1–5.0 M) are determined. The values of Kd are presented as a periodic table of the elements. A range of possibilities for separating the elements of this system is proposed.

Application of MnO2Resin and Dowex 1X8 manganese dioxide impregnated resin for the separation of chromium from biological samples

MnO2Resin and Dowex 1X8 manganese dioxide impregnated resin was used for chromium separation from biological samples. We examined sorption of chromium from acid solutions: hydrochloric, nitric and sulphuric in concentration range from 0.01 to 2 mol/dm3. The sorption process was evaluated by batch and column experiments. We also examined sorption of other elements in the developed systems, to check the selectivity of the process. Determination of chromium by radiochemical neutron activation analysis after separation with MnO2Resin was described.

A comparative study using different resins to determine thorium isotopes

Thorium is a naturally occurring radioactive element that is widely distributed in the crust of the Earth. This element is very common in mineral formations in regions with high levels of natural radioactivity, therefore, its determination in environmental samples is important. Thorium isotopes (228Th, 230Th, and 232Th) were determined in a reference material, the IAEA Soil 327 sample, to validate the two methods, these isotopes were also analyzed in two groups of food samples, employing these different resins. The initial preparation with acid dissolution is the same to both, in the first is used anion exchange resin (DOWEX 1x2) and electrodeposition in silver planchets. And in the second method is used a specific chromatographic resin (TEVA) and cerium fluoride microprecipitation. At the end both analysis are quantified by alpha spectrometry. The two methods the results obtained were satisfactory for the reference material used, with relative error of less than 4% for 228Th, 230Th, and 232Th. The analysis of variance for samples foods analyzed seen to be no significant difference between the methods used for thorium isotopes determination. The main differences found between methods were spectrums resolutions, time and cost of analysis.

Optimization and modeling of simultaneous adsorption of Cr(VI) and phenol onto Dowex 1X8 ion exchange resin: kinetic and thermodynamic studies

Optimization and modeling of simultaneous adsorption of Cr(VI) and phenol onto Dowex 1X8 ion exchange resin: kinetic and thermodynamic studies

Изучение эффективности сильноосновных ионообменных смол при извлечении урана из продуктивных растворов подземного скважинного выщелачивания

The process of uranium sorption is one of the important stages in the production of uranium. This stage affects uranium extraction effectiveness from productive solutions. The sorption and desorption characteristic of anion exchange resins in dynamic condition were investigated in order to study the effectiveness of resins, which were used for extraction of uranium from sulfuric acid productive solution. The sorption and desorption of uranium from the productive solution on anion exchange resins AB-17 and DOWEX 1X8 200 was carried out in laboratory conditions. The sorption characteristics were investigated. The determined sorption capacities of the resins were 1.47 and 14.4 mg/mL, respectively. The most efficient anion exchanger is DOWEX 1X8 200 that has a high sorption capacity as well as good desorption characteristics, which make it possible to obtain solutions having 23 times higher uranium concentrations than in productive solutions.

Antifouling Ion-Exchange Resins.

Large quantities of organic ion-exchange resins are used worldwide for water decontamination and polishing. Fouling by microorganisms and decomposition products of natural organic matter severely limits the lifetime of these resins. Much research has thus been invested in polymer-based antifouling coatings. In the present study, poly(4-styrenesulfonate) (PSS) and a co-polymer of PSS and a zwitterionic group were used to spontaneously coat commercial Dowex 1X8 anion-exchange resin. UV-visible spectroscopy provided a precise measure of the kinetics and amount of PSS sorbed onto or into resin beads. When challenged with Chlamydomonas reinhardtii algae, uncoated resin was rapidly fouled by algae. Coating the resin with either the homopolymer of PSS or the co-polymer with zwitterion eliminated fouling. Using narrow- and wide-molecular-weight distribution PSS, a cutoff molecular weight of about 240 repeat units was found, above which PSS was unable to diffuse into the resin. Thus, only one monolayer of added PSS was sufficient to confer a highly desirable antifouling property on this resin while consuming less than 0.1% of the exchanger capacity. Radioactive sulfate ions were used to probe the kinetics of (self)exchange, which were virtually unaffected by the PSS coating. This resin treatment is a fast, ultra-low-cost step for potentially enhancing the lifetime of ion exchangers.

Adsorption of rare earth elements by strong acid cation exchange resin thermodynamics, characteristics and kinetics

The equilibrium and kinetic characteristics of rare earths adsorption process using the strong acid macro reticular resin Dowex 50X8 from El-Erediya chloride liqueurs have been determined. The adsorption parameters including pH, contact time, temperature, resin to aqueous ratio and rare earths initial concentration in aqueous have been optimized. The practical adsorption capacity of rare earths upon the resin under the optimum conditions has been found to attain 80 mg/g which matches with Langmuir theoretical capacity. The physical parameters including the adsorption kinetics, the isotherm models and the thermodynamic data have also been determined. The adsorption process has been found to agree with both the pseudo second order reaction, the Langmuir isotherm and confirms with the concept of the matrix diffusion controls. A successful preconcentration process for the rare earths content was done with a preconcentration factor of about 42.33. Considerable rare earths cake was precipitated from the chloride eluate solutions using oxalic acid.

La eliminación de metales tóxicos presentes en efluentes líquidos mediante resinas de cambio iónico. Parte VIII: Arsénico(III))/OH-/Dowex 1x8

En el presente trabajo se utiliza la resina de intercambio aniónico para la eliminación de arsénico(III) de medios acuosos. Esta eliminación se ha investigado teniendo en cuenta diversas variables experimentales como son: la velocidad de agitación del sistema, la temperatura, el pH de la disolución y la dosificación de resina al sistema. El equilibrio de intercambio aniónico tiene un carácter endotérmico y no espontaneo, en el rango de temperaturas comprendido entre 20 °C y 60 °C, la cinética del proceso responde al modelo de pseudo-segundo orden, sin embargo, el mecanismo de carga del arsénico en la resina cambia en el rango de temperaturas comprendido entre 20 °C y 40 °C. La isoterma de carga del metal en la resina responde al modelo linearizado de Freundlich. Se comparan los resultados de carga de arsénico en la resina Dowex 1x8 con los obtenidos con otras resinas y con nanotubos de carbono de pared multiple. La elución del arsénico se puede realizar con disoluciones acidas, por ejemplo 1 M HCl.

Ion exchange of alkali metal cations with an inorganic resin

ABSTRACTA comparison of the ion exchange properties of the inorganic resin Isolute SCX-2 with alkali metal cations, including francium, to the organic Dowex 50X8 resin is presented. The purpose of this study was to investigate the ion exchange properties of the alkali metal cations with a resin containing a less hydrophobic backbone structure. It was found that the less hydrophobic Isolute SCX-2 resin had a smaller range of values for the distribution coefficients when exchanged with the alkali metals than Dowex 50X8.

Adsorbent-Based Downstream-Processing of the Decarboxylase-Based Synthesis of 2,6-Dihydroxy-4-methylbenzoic Acid

In this case study the regioselective enzymatic carboxylation of 3,5-dihydroxytoluene (orcinol) using the nonoxidative 2,3-dihydroxybenzoic acid decarboxylase from Aspergillus oryzae (2,3-DHBD_Ao), followed by an adsorbent-based downstream approach, has been investigated. The product 2,6-dihydroxy-4-methylbenzoic acid (DHMBA) was herein purified by an adsorption–desorption cycle and subsequently obtained with purities >99% without a full elimination of the excess bicarbonate from its reaction solution. Ten adsorbent resins were studied in respect of their ability to recover the product from the reaction solution, whereas the strong anion exchange resin Dowex 1x2 in its chloride form showed affinities >99%, even at bicarbonate concentrations of >3 mol·L–1. Desorption from loaded resin was carried out by a 2 mol·L–1 HCl/acetone mixture, followed by product crystallization during acetone evaporation. This presented concept does not require a final column preparation step and improves the overall atom efficie...

Determination of Cadmium in Brown Rice Samples by Fluorescence Spectroscopy Using a Fluoroionophore after Purification of Cadmium by Anion Exchange Resin.

Simple analytical methods are needed for determining the cadmium (Cd) content of brown rice samples. In the present study, we developed a new analytical procedure consisting of the digestion of rice using HCl, Cd purification using anion exchange resin, and then determining the Cd content using fluorescence spectroscopy. Digestion with 0.1 M HCl for 10 min at room temperature was sufficient to extract Cd from the ground rice samples. The Cd in the extract was successfully purified in preference to other metals using Dowex 1X8 chloride form resin. Low concentrations of Cd in the eluate could be determined using fluorescence spectroscopy with a fluoroionophore. Overall, the actual limit of quantification value for the Cd content in rice was about 0.1 mg-Cd/kg-rice, which was sufficiently low compared with the regulatory value (0.4 mg-Cd/kg-rice) given by the Codex Alimentarius Commission. We analyzed authentic brown rice samples using our new analytical procedure and the results agreed well with those determined using inductively coupled plasma optical emission spectrometry (ICP-OES). Since the fluoroionophore recognized Zn2+ and Hg2+ as well as Cd2+, a sample containing high concentration of Zn2+ or Hg2+ might cause a false positive result.