High Aspect Ratio Ion Exchange Resin Bed – Hydraulic Results for Spherical Resin Beads

Abstract

A principal role of the DOE Savannah River Site is to safely dispose of a large volume of liquid nuclear waste held in many storage tanks. An in-tank ion exchange unit is being considered for cesium removal to accelerate waste processing. This unit is planned to have a relatively high bed height to diameter ratio (10:1). Complicating the design is the need to cool the ion exchange media; therefore, the ion exchange column will have a central cooling core making the flow path annular. To separate cesium from waste the media being considered is made of resorcinol formaldehyde resin deposited on spherical plastic beads and is a substitute for a previously tested resin made of crystalline silicotitanate. This spherical media not only has an advantage of being mechanically robust, but, unlike its predecessor, it is also reusable, that is, loaded cesium can be removed through elution and regeneration. Resin regeneration leads to more efficient operation and less spent resin waste, but its hydraulic performance in the planned ion exchange column was unknown. Moreover, the recycling process of this spherical resorcinol formaldehyde causes its volume to significantly shrink and swell. To determine the spherical media's hydraulic demand a linearly scaled column was designed and tested. The waste simulant used was prototypic of the wastes' viscosity and density. This paper discusses the hydraulic performance of the media that will be used to assist in the design of a full-scale unit.     

High Throughput Determination and QSER Modeling of Displacer DC‐50 Values for Ion Exchange Systems

Abstract

In this paper, the displacer concentration required to displace 50% of proteins bound in batch adsorption systems, DC‐50, was employed as a means of ranking high‐affinity, low molecular weight displacers for ion‐exchange systems. A relatively large data set of cationic displacers with varying chemistries were evaluated with two proteins on two strong cation exchange resins in parallel batch screening experiments. Using this methodology, a significant number of high affinity displacers were identified that could displace both proteins at relatively low concentrations. In addition, the DC‐50 data was used in concert with molecular structural information of the displacers to produce predictive quantitative structure‐efficacy relationship (QSER) models based on a support vector machine (SVM) regression approach. The resulting models were well correlated and the predictive power of these models was demonstrated. Examination of the features selected in these models provided insight into the factors influencing displacer efficacy in cation exchange systems. These results demonstrate the utility of a combined DC‐50/QSER approach to identify and design high‐affinity displacers for ion‐exchange displacement chromatography.     

Ion‐Exchange Separation of Pu from Macro Concentration of Th in HNO3 Medium

Abstract

Sorption behavior of Th and Pu from anion‐ as well as cation‐exchange resin was investigated from nitric acid medium by both batch and column methods. The anion‐exchange studies involved anionic nitrate complexes of Pu⁴⁺ and Th⁴⁺ sorbed onto DOWEX 1x4 resin (50–100 mesh), and the cation‐exchange studies involved the sorption of Pu³⁺ and Th⁴⁺ onto BIORAD AG 50Wx8 (50–100 mesh) or DOWEX 50Wx4 (50–100 mesh) resin. The batch data gave a separation factor (K _d,Pu/K _d,Th) of 22 for the anion‐exchange method and 0.017 for the cation‐exchange method at 3 and 2 M HNO₃, respectively. A two‐stage ion‐exchange separation method was developed for the quantitative separation of Pu (8 g/L) from a macro amount of Th (200 g/L) in nitric acid medium. The first step involved the quantitative sorption of plutonium from the mixture while about 90% of Th could be washed in 6 column volumes. The plutonium, eluted (as Pu³⁺) using 0.5 M HNO₃ + 0.2 M hydrazinium nitrate (HN) + 0.2 M hydroxyl ammonium nitrate (HAN), and the residual (～10%) Th were subsequently loaded onto a cation‐exchange column in the second step. Greater than 99% Pu was recovered with 2 M HNO₃ (in ～8 column volumes) containing 0.2 M HN + 0.2 M HAN. The final elution of thorium from the cation‐exchange column was achieved in about 6 column volumes of 1 M α‐hydroxy isobutyric acid. A (Pu, Th)O₂ fuel scrap sample was dissolved in 16 M HNO₃ containing 0.005 M HF and was used subsequently as the feed for the anion‐exchange column. The eluted Pu was subsequently loaded onto a cation‐exchange column for final purification. The recovery of plutonium and thorium was found to be >99% and >98%, respectively, while the respective decontamination factors were estimated to be 215 and 292.     

Evaluation of Amberlite IRC‐718 Chelating Ion Exchange Resin in Loading‐Elution‐Regeneration Cycles for the Separation and Recovery of Strontium from Alkaline Radioactive Waste

The separation and recovery of radiostrontium from simulated alkaline reprocessing waste solution has been studied using Amberlite IRC‐718, a chelating resin containing iminodiacetic acid groups. The breakthrough behavior of strontium has been determined by conducting an extended column run. The column loading performance has been correlated with batch equilibration results. Efficient elution of loaded strontium has been achieved using dilute nitric acid. Satisfactory column performance has been demonstrated in repeated loading‐elution‐regeneration cycles. Finally, the characteristics of used resin have been determined to ascertain its efficacy for further use.     

Investigation of Selectivity and Kinetic Behavior of Strong‐Base Ion Exchange Resin Purolite A 520E for Nitrate Removal from Aqueous Solution

Abstract

The aim of this work is to present experimental results on the removal of nitrate by nitrate selective ion exchange resin, Purolite A 520E. The resin particle size, nitrate concentration, temperature, and stirring speed were investigated as experimental parameters and the optimum conditions for nitrate removal were determined. Nitrate removal by strong base anion exchange resin Purolite A 520E was carried out with the batch method in the presence of chloride and sulfate ions. The existence of a high concentration of competing ions in a solution resulted in a reduction of nitrate removal. Nitrate removal ratios decreased from 98% to 85% and 88%, respectively, in the presence of chloride and sulfate ions when the chloride and sulfate ratios were increased in solution. The process kinetics were predicted by using Homogenous Diffusion Models. It was seen that about 98% of nitrate in the aqueous solution could be removed using optimum conditions.     

Transport Properties of Ion‐Exchange Membranes During Pervaporation of Water‐Alcohol Mixtures

Abstract

Pervaporation properties of PESS ion‐exchange membranes in contact with water‐aliphatic alcohol mixtures were obtained. PESS ion‐exchange membranes were prepared by chemical modification of the interpenetrating polymer network system polyethylene‐poly(styrene‐co‐divinylbenzene). PESS membranes were loaded with different alkali metal ions as counterions. The obtained data showed that properties of PESS membranes depended strongly on the kind of counterions, degree of crosslinking, and difference in the polarities between water and organic component of the binary mixture. Results obtained for PESS membranes were compared with data obtained for Nafion 117 ion‐exchange membrane.     

Removal of Metal Contaminants by Ion‐Exchange Resin Columns,Thala Valley Tip,Casey Station,Antarctica

Abstract

Salinity and low temperature effects on adsorption of contaminant metals from water using an iminodiacetic acid (IDA) ion‐exchange resin, were investigated under dynamic flow conditions. The order of selectivity of the resin (20°C and 0% seawater) was: Cu²⁺> Pb²⁺> Cr³⁺> Ni²⁺>Cd²⁺>Zn²⁺. Low temperature (4°C) had no significant effect on the selectivity of the contaminant metals and salinity only affected selectivity for Cr³⁺ and Cu²⁺. Copper had highest selectivity in all column experiments, except where extensive deprotonation occured. Buffering affected retention of Cr³⁺; possibly due to precipitation or complexation as a result of increase in pH.     

Adsorptive Separation of o‐/p‐Aminoacetophenones using Acidic Ion Exchange Resins

Abstract

Separation of o‐/p‐aminoacetophenones (o‐/p‐AAPs) is investigated by a two‐step process: selective solubilization in an organic solvent followed by reactive adsorption on functionalized polymers. Since, p‐AAP and o‐AAP show inter‐ and intra‐molecular hydrogen bonding, respectively, the former is solubilized to a much lesser extent than the latter in an organic solvent. For example, o‐AAP dissolves completely while p‐AAP shows only 1.8% saturation solubility in toluene. Selective solubilization of o‐AAP in toluene, therefore, gives pure p‐AAP as residual solid in high yields. In the subsequent adsorption step, a strongly acidic ion exchange resin removes selectively the trace amounts of p‐AAP from the toluene phase giving pure o‐AAP.     

Removal of Trace Concentrations of Heavy Metals Using Complexing Ion‐Exchange Resins

Abstract

Oak Ridge National Laboratory is examining potential new technologies for treating radiologically‐contaminated process wastewater. The current treatment facility is aging and is optimized to remove ⁹⁰Sr, but future wastewaters are likely to contain mostly activated metals, such as ⁵¹Cr and ⁶⁴Cu. Other low‐volume wastewaters may contain trace concentrations of Hg and U. Complexing ion‐exchange resins and other specialized sorbents were tested for removing trace concentrations of heavy metals. Short‐term column tests and batch loading tests were conducted using a surrogate wastewater and various sorbents. These tests showed that metal uptake was very rapid, and that good removal and relatively high loadings could be achieved from a very dilute wastewater surrogate. Forager M‐TU (Dynaphore, Inc.) showed the best overall results, removing 91.9% of the Cr, 99.3% of the Cu, >99.7% of the Hg, and >99.9% of the U with a contact time of 120 seconds in a short‐term column test.     

Multiple Ion Exchange Column Tests for Cesium (CS+) Removal from Hanford Site Tank 241‐AW‐101 with SuperLig® 644 Resin

Abstract

Six cycles of loading, elution, and regeneration were performed to remove cesium (Cs⁺) from a Hanford Site tank waste sample using SuperLig^® 644 resin. The sample, which was retrieved from Tank 241‐AW‐101, was diluted to 5.09 M Na⁺ and processed through dual ion exchange columns to remove ¹³⁷Cs. Each column had an inside diameter of 1.45 cm and a height of 30 cm; and contained 15 mL of wet resin in the sodium form. The columns, designated as primary (lead) and polishing (lag), were connected in series during loading, but they were separated during elution and regeneration. The cesium loading on the primary column during the six cycles ranged from 160 to 225 bed volumes (BV) at <50% breakthrough. A gradual decline of the resin loading performances was observed as a function of number of loading cycles. For all cycles, the percent removal of cesium (¹³⁷Cs) was greater than 99.99% and the decontamination factors (DFs) achieved were higher than 1.0 × 10⁴. Elution of the resin with 0.5 M nitric acid at 25 ± 2°C was effective. Approximately 99% of the ¹³⁷Cs bound on the resin was eluted with less than 15 BV of the eluent (0.5 M nitric acid). The cumulative dose absorbed by the resin in the primary column was 1.99 × 10⁷ rad with a 20% loss of ion exchange capacity was at 50% breakthrough after completing six loading cycles.     

Recovery of 1,4‐Dimethyl Piperazine from Aqueous Solutions Using Polymeric Adsorbent and Ion‐Exchange Resins

Abstract

Strong and weakly acidic ion exchange resins and polymeric adsorbents are used for recovery of 1,4‐dimethyl piperazine (DMP) from aqueous solutions. Sorption of the amine in undissociated form is the primary mechanism of uptake of DMP on the ion‐exchange resins. Equilibrium adsorption data for DMP on the resins, at various temperatures, are fitted in Langmuir adsorption isotherm. Kinetic studies show that intraparticle diffusional resistance controls the sorption of DMP into the resin matrix. A mathematical model based on intraparticle diffusion and external mass transfer is used for simulating breakthrough profiles and compared with the experimental results for a fixed bed of weakly acidic Indion‐652 resin. The DMP loaded bed of the resin was effectively regenerated with methanol.     

Efficient Separation of Cytosine‐Substituted Mildiomycin Analogue (MIL‐C) from the Fermentation Broth by Ion Exchange

Abstract

Cytosine‐substituted mildiomycin analogue (MIL‐C) was synthesized by supplementing cytosine into the culture medium of Streptoverticillium rimofaciens (one mildiomycin producer) and had a specific and strong inhibitory activity against powdery mildews. In order to facilitate the separation of MIL‐C from this fermentation broth, the cultivation conditions were optimized to increase MIL‐C productivity, and more than 0.9 g/l cytosine was added to the medium to inhibit the biosynthesis of mildiomycin (MIL). According to the ion‐exchange equilibrium and dynamics characteristic of MIL‐C, one weakly cationic resin (DK110) was screened out to separate MIL‐C from fermentation broth with one effective ion‐exchange method. When 2% ammonia aqueous solution was applied as eluent with 2 BVs/h, high recovery yield (97.6%) and purity (70.0%) of MIL‐C were achieved. This novel strategy of combining up‐stream biosynthetic controls and down‐stream purification is very promising for efficient production of this novel nucleoside antibiotic (MIL‐C).     

Selective Adsorption of Palladium(II) Complexes onto the Chelating Ion Exchange Resin Dowex M 4195 – Kinetic Studies

The chelating ion exchange resin – Dowex M 4195 was used in palladium(II) complexes adsorption from the acidic solutions. This study discusses the sorption kinetics, and more specifically the interparticle diffusion behavior of palladium(II) onto Dowex M 4195. The adsorption studies were used to determine the amount of palladium(II) complexes uptake (resin loading), the distribution coefficients, and the recovery efficiency of Pd(II) complexes. The influence of the agitation speed, the beads size (mean radius of swollen particles), the palladium concentrations, as well as acid concentrations (ionic strength of solutions), the macrocomponent addition (sodium chloride), and the phases contact time was also discussed. Moreover, the effect of temperature was taken into account during the determination of the isotherms. The experimental data obtained at 100 µg/cm³ Pd(II) initial concentration were applied to the kinetic models, and the sorption parameters as well as the normal standard deviation were calculated. Moreover, the Langmuir, Freundlich, and Tempkin‐Pyzhev isotherm models were applied and the isotherms parameters were calculated.     

Kinetic Studies on the Exchange of Bivalent Metal Ions on Amberlite IRC‐718—An Iminodiacetate Resin

Abstract

The rate of uptake of alkaline earth metals, copper, and lead have been investigated by a chelating ion exchange resin containing iminodiacetic acid as ligand attached to the copolymer of styrene and divinyl benzene of macroporous matrix structure. It binds alkaline earth metals, Cu, and Pb by the formation of chelate complexes with the carboxylate group of this resin. The experiments discussed in this work have allowed to establish the paramount importance of the presence of this chelating group in obtaining practically useful rates of metal ion uptake. The kinetic parameters like diffusion coefficient (D _o), activation energies (ΔE _a) and entropy of activation have been evaluated under the conditions favoring a particle diffusion control mechanism and the study followed the three models i.e., Nernst Planck, B _t technique and Ash model. K _d values in demineralised water (DMW) were found in the order Cu²⁺ > Pb²⁺ > Mg²⁺ > Sr²⁺ > Ba²⁺ > Ca²⁺.     

Ion Exchange of the Organometallic Aqua‐Ion fac‐[99mTc(CO)3(H2O)3]+ from Aqueous Solutions

Dynamic (column) studies on the ion exchange of triaquatricarbonyltechnetium(I) cation, fac‐[^99mTc(CO)₃(H₂O)₃]⁺ (1), in the system: amphoteric ion exchange resin (Purolite S‐950) ‐ aqueous HNO₃ solutions (0.05–2 M) corroborate the +1 charge of 1. Stability constants of fac‐[^99mTc(CO)₃(H₂O)_3?nCl_n]^1?n complexes, determined from the distribution coefficients in the system anion exchanger (Dowex 1X4) ‐ aqueous HCl solutions (0.1–12 M) differ from the literature values determined at a constant ionic strength. This difference, resulting from the decrease in the activity of water with increasing HCl concentration, may be a measure of the effect of non‐constant ionic strength on ion‐exchange equilibria. Weak acidic properties of 1 in aqueous solution at n.c.a. (no carrier added) level (pK_a ?9) have been demonstrated by paper electrophoresis.     

Novel Alkyl Ether Sulfonates for High Salinity Reservoir: Effect of Concentration on Transient Ultralow Interfacial Tension at the Oil–Water Interface

The effect of surfactant concentration on the occurrence and detection of transient ultralow interfacial tension (IFT) between crude oil and formation water at 75 °C has been investigated using a series of novel sodium alkyl ether sulfonates having various increasing molecular weights and degrees of ethoxylation. All surfactant systems displayed dynamic interfacial tension (DIT). Transient ultralow DIT (DIT_min) were detected only within an intermediate surfactant concentration. This behavior was attributed to an implicit concentration-related length scale required for the added surfactant to diffuse from the bulk phase to the freshly prepared oil–water interface. In the high surfactant concentration range, this length scale is relatively short and results in an instantaneous (and undetectable) occurrence of DIT_mim in a relatively very short time scale, well beyond the detection limit of the spinning drop tensiometer (~2–3 min). Interestingly, DIT_min were detected only in systems above the surfactant’s critical micelle concentration, suggesting that DIT_min occurs as a result of the diffusion (subsequent to the adsorption) of the oil acidic species from the interface to the bulk phase to form mixed micelles with the added surfactant. Measurements of DITs in the presence of decane showed no evidence for DIT_min, confirming the general belief that DIT_min is indeed due to the interaction of the added surfactant with the oil acidic components. Finally, the effect of surfactant concentration on the equilibrium IFT (γ_eq) showed evidence for relatively low values (~10⁻² mNm⁻¹) for some surfactant systems.     

Sol‐Gel Materials for High Capacity,Rapid Removal of Metal Contaminants

Abstract

An environmental waste remediation method is presented where porous cylindrical monoliths are interposed as septa between a solution contaminated with metal ions and a solution of a precipitant. Precipitant and contaminant diffuse and generate precipitate nano‐ and micro‐particles inside the monoliths. Two types of silica sol‐gel monoliths were tested. One class of materials was prepared following a conventional base‐catalyzed route which yielded fragile silica monoliths with pore diameters on the order of 7–10 nm. A second class of materials material consisted of templated silica macroporous monoliths that were cross‐linked with diisocyanate. These materials had pore diameters on the order of microns and were mechanically extremely strong, having a Young modulus in excess of 400 MPa. Both types of silica gel monoliths proved very versatile, and allowed to precipitate a wide variety of metal ions, including toxic metals such as Cd²⁺, and fission by‐products such as lanthanides and Sr²⁺. The capacity of the gel monoliths was also very high, at least 20 times higher than the capacity of conventional derivatized gels. Most importantly, precipitation inside the macroporous gels was a factor 7–8 more rapid than in microporous gels. The results indicate that macroporous cross‐linked sol‐gel monoliths are a promising material for the development of efficient, mechanically strong filter elements for environmental remediation.     

Quality of a High‐Enthalpy Flow upon Electric‐Arc Heating of Air in a Facility for Investigating Supersonic Combustion

The quality of a highenthalpy air flow is considered in terms of simulating fullscale flow parameters in studying supersonic combustion. It is shown that the plasmatron with gasvortex stabilization of the arc, which was used in experiments, can provide, in a wide range of pressures and temperatures, a level of specific erosion of electrodes equal to 10^-7–10^-9 kg/C and a concentration of nitric oxide lower than 0.06 %, which has almost no effect on the flow structure and basic characteristics of ignition and combustion processes.     

High Performance Liquid Chromatography–Size Exclusion Chromatography for Rapid Analysis of Total Polar Compounds in Used Frying Oils

Analysis of used frying oil samples by high performance liquid chromatography–size exclusion chromatography (HPLC–SEC or HPSEC) was compared to AOCS Official Method Cd 20-91 (silica gel column chromatography) for the purpose of developing a rapid analysis of total polar compounds (TPC). In a direct comparison of the two analytical methods using four different sets of used frying oils (21 total oil samples) ranging from fresh to discard quality (4.3 to 35.4% TPC by column chromatography), the weight percent total polar compounds (%TPC) determined by HPLC–SEC averaged 0.71% higher than the values by silica gel column chromatography. Reproducibility of the HPLC–SEC method of s _r = 0.30 and RSD_r% = 1.22 compares to the variability of s _r = 0.29 and RSD_r = 1.3 for samples of approximately the same %TPC, reported in AOCS Method Cd 20-91. Because the rapid method does not separate pure (non-polar) triacylglycerol (TAG) and polar, oxidized TAG (OX-TAG), a high concentration of OX-TAG will quantitatively affect the results. This places practical limits on the types of studies to which the method may be applied if a separate analysis for the OX-TAG is not performed. Advantages of the HPLC–SEC method include the following. It uses about 75% less solvent than standard column chromatography methods for determination of %TPC. This HPLC–SEC method is very similar to AOCS Official Method Cd 22-91, and thus, also separates and quantifies polymerized triacylglycerols. The HPLC–SEC method determines both TAG polymer concentration and %TPC of used frying oils in about 1 h.     

Kinetics of Ion Exchange of Zr/Sn(IV) Phosphonate–Phosphate Hybrid Materials for Separation of Lanthanides from Oxidized Actinides

ABSTRACT

The kinetics of ion exchange of Zr/Sn(IV) phosphonate–phosphate hybrid ion exchange materials have been studied with several types of ions of specific interest to nuclear fuel recycling including Nd³⁺ at 4.5 and 43 mM and NpO₂⁺ at 2.9 mM spanning multiple HNO₃ concentrations. In most cases, the equilibrium was reached in less than 12 h. The ion exchange behavior followed that of pseudo first-order adsorption with rates ranging from 0.430–4.10 h^?1 to 0.290–0.435 h^?1 for Nd³⁺ and NpO₂⁺, respectively. A separation with both Nd³⁺ and NpO₂⁺ present was performed, resulting in separation factors of 1.9–12, 1.7–6.6, and 2.0–5.7 at 1 × 10^?1, 1 × 10^?2, and 1 × 10^?3 M HNO₃, respectively.