Use Of Anion Exchange Resin Research Articles

Improvement of Inventory and Leaching Rate Measurements of C-14 in Hull Waste, and Separation of Organic Compounds for Chemical Species Identification

ABSTRACTIn order to analyze the C-14 inventory and leaching rate for safety evaluation of transuranic waste disposal, it is necessary to establish an analytical method that can measure C-14 with sufficient precision [1]. Oxidative decomposition of organic compounds containing C-14 is carried out to absorb carbon dioxide (CO2) in an alkaline solution, which is mixed with a liquid scintillation cocktail, and the amount C-14 is quantified by measuring a beta ray spectrum with a liquid scintillation counter. It has been difficult to completely decompose carbon compounds in a sample, even to CO2, by using conventional oxidizing agents. In the work described here, we improved the method of oxidative decomposition used to completely decompose carbon compounds using peroxydisulfuric acid (K2S2O8). When C-14 in the form of CO2 was absorbed in a sodium hydroxide (NaOH) aqueous solution, only 80% of the actually used quantity was detected. Total organic carbon measurements showed that the entire quantity of CO2 was absorbed by NaOH. When NaOH aqueous solution was used, it was found that only the analytical value was 80%. The entire quantity of the actually used carbon could be measured by absorbing the CO2 in Carbo-Sorb®. An anion form and a neutral molecule exist in the organic compound released from activated metals. In order to identify organic compounds efficiently, fractionation into an anion and a neutral molecule and separation by high performance liquid chromatography (HPLC) are necessary. Here, we propose the combined use of an ion exchange resin and HPLC as an improved technique for identification of the chemical species.

One-Pot Synthesis of Enantiopure 3,4-Dihydroisocoumarins through Dynamic Reductive Kinetic Resolution Processes

A straightforward chemoenzymatic synthesis of enantiopure 4-alkyl-3-methyl-3,4-dihydroisocoumarins through a ketoreductase-catalyzed one-pot dynamic reductive kinetic resolution is reported. E. coli/ADH-A cells have shown outstanding diastereo- and enantioselectivity toward the bioreduction of a series of racemic ketones, with the use of anion exchange resins or triethylamine being compatible in the same aqueous reaction medium. The so-obtained enantiopure alcohols were subsequently cyclized in acid media affording the corresponding lactones in good to excellent conversions (72-96%) and excellent selectivities (dr ≥99:1 and ee >99%).

Anion Exchange Resins as a Source of Nitrosamines and Nitrosamine Precursors

Anion exchange resins are important tools for the removal of harmful anionic contaminants from drinking water, but their use has been linked to the presence of carcinogenic nitrosamines in treated drinking water. In bench-scale batch and column experiments, anion exchange resins from a large, representative group were investigated as sources of the nitrosamines N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosodi-n-propylamine (NDPA), and N-nitrosodi-n-butylamine (NDBA) and their precursors. Several resins were found to release high levels (up to >2000 ng/L, orders of magnitude above drinking water regulatory levels) of nitrosamines upon initial rinsing with lab-grade water, with levels subsiding within 50-100 bed volumes of rinsing. Resins released similarly high levels of nitrosamine precursors, with spikes in precursor release triggered by regeneration of resins with sodium chloride or by interruptions in flow resulting in prolonged contact times. Free chlorine or preformed monochloramine in feedwater led to the production of nitrosamines. Resins released different nitrosamines and precursors depending on their functional groups, with some resins releasing as many as three different nitrosamines and their precursors. These findings have significant implications for the pretreatment and appropriate use of anion exchange resins by drinking water utilities and for the production of anion exchange resins by manufacturers.

Evaluation of a high surface area fractional precipitation process for the purification of paclitaxel from Taxus chinensis

In this study, we evaluated a high surface area fractional precipitation process to achieve the effective purification of paclitaxel, an anticancer agent, from plant cell cultures. Fractional precipitation experiments were performed by increasing the surface area per working volume (S/V) to 0.428/mm using a variety of ion exchange resins. When the cation exchange resin Amberlite IR 120 H was used, the highest purity (>85%) and yield (>80%) of paclitaxel could be obtained in the shortest fractional precipitation time (within 6 h). Use of an ion exchange resin resulted in the production of smaller paclitaxel precipitates since it inhibited the growth of particles. When Amberlite IR 120 H in particular was used, paclitaxel particles were 2 ∼ 3 times smaller (less than 30 μm radius) than those obtained in the absence of ion exchange resin. Paclitaxel particle size was inversely correlated with the zeta potential of the fractional precipitation solution after the addition of ion exchange resin.

Effect of ion exchange resin on increased surface area crystallization process for purification of vancomycin

We investigated the effects of ion exchange resins on the efficiency of crystallization with an increased surface area for the purification of vancomycin. As surface area-increasing materials, diverse types of ion exchange resin were used to increase the surface area per working volume (S/V). When the S/V was increased, in cation exchange resin Amberlite 200, Amberlite IR 120 (Na), and Amberlite IRC 50 and in anion exchange resin Amberlite IRA 400 (Cl) and Amberlite IRA 910 (Cl), vancomycin crystals were successfully generated. The yield of vancomycin increased (>97%), and the time necessary for crystallization was reduced dramatically (reduced from 24 hr to 12 hr). On the other hand, the purity of the vancomycin was approximately 95% and was not affected by increasing S/V. Use of an ion exchange resin also resulted in the production of smaller vancomycin crystals than in the absence of ion exchange resin.

Use of Anion Exchange Resins for One-Step Processing of Algae from Harvest to Biofuel

Some microalgae are particularly attractive as a renewable feedstock for biodiesel production due to their rapid growth, high content of triacylglycerols, and ability to be grown on non-arable land. Unfortunately, obtaining oil from algae is currently cost prohibitive in part due to the need to pump and process large volumes of dilute algal suspensions. In an effort to circumvent this problem, we have explored the use of anion exchange resins for simplifying the processing of algae to biofuel. Anion exchange resins can bind and accumulate the algal cells out of suspension to form a dewatered concentrate. Treatment of the resin-bound algae with sulfuric acid/methanol elutes the algae and regenerates the resin while converting algal lipids to biodiesel. Hydrophobic polymers can remove biodiesel from the sulfuric acid/methanol, allowing the transesterification reagent to be reused. We show that in situ transesterification of algal lipids can efficiently convert algal lipids to fatty acid methyl esters while allowing the resin and transesterification reagent to be recycled numerous times without loss of effectiveness.

Development of an Integrative Process for the Production of Bioactive Peptides from Whey by Proteolytic Commercial Mixtures

The aim of this work is to develop an integrative process based on the use of an ion exchange resin for the enzymatic hydrolysis of β-lactoglobulin to produce peptides with angiotensin converting enzyme (ACE) inhibitory activity using whey as a feed stock. Unlike the conventional methods, the main advantage of this approach is that by integrating the selective separation of β-lactoglobulin from whey and its hydrolysis less complex mixtures of peptides are produced. Furthermore, peptides of similar charge as β-lactoglobulin remain adsorbed achieving further purification. In this work, the enzyme protease N Amano at an enzyme to substrate ratio of 1/100 (wt/wt) was added directly to the adsorbed proteins in a thermostatically controlled membrane reactor operated in batch mode. Separation of the smaller peptides from the enzyme and larger peptides was achieved with a 1 kDa molecular weight cut-off ultrafiltration membrane. Also, this step enables the recycling of non-hydrolyzed substrates, large peptides, and enzyme. The adsorbed protein was re-solubilised in a 10 mM potassium phosphate buffer (pH 7 and 45°C). The different fractions were assayed for their bioactivity in terms of angiotensin converting enzyme inhibition percentage (ACEi%) and IC50 which is the concentration of peptides that can inhibit the ACE activity by 50%. Results show that permeates of 2 and 6 hrs hydrolysis have the highest bioactivity with IC50 = 67 and 98 µg/ml respectively.

Characterization of Acidic Species in Athabasca Bitumen and Bitumen Heavy Vacuum Gas Oil by Negative-Ion ESI FT−ICR MS with and without Acid−Ion Exchange Resin Prefractionation

Because acids in petroleum materials are known to corrode processing equipment, highly acidic oils are sold at a discount [on the basis of their total acid number (TAN)]. Here, we identify the acidic species in raw Canadian bitumen (Athabasca oil sands) and its distilled heavy vacuum gas oil (HVGO) as well as acid-only and acid-free fractions isolated by use of an ion-exchange resin (acid−IER) and negative-ion electrospray ionization Fourier transform ion cyclotron resonance (ESI FT−ICR MS) mass spectrometry. The ultrahigh mass resolving power ( m/Δ m 50% > 400 000) and high mass accuracy (better than 500 ppb) of FT−ICR MS, along with Kendrick mass sorting, enable the assignment of a unique elemental composition to each peak in the mass spectrum. Acidic species are characterized by class (N n O o S s heteroatom content), type [number of rings plus double bonds to carbon or double-bond equivalent (DBE)], and carbon number distribution. We conclude that the analytical capability of FT−ICR MS and the selecti...

Cyanide Recovery from Gold Extraction Process Waste Effluents by Ion Exchange I. Equilibrium and Kinetics

The use of an ion exchange resin in the recovery of copper cyanide complexes from wastewater and the recycling of the cyanide used in cyanidation to the gold cyanidation step is an economically interesting process. The equilibrium and kinetics in the loading stage using a strong base resin, Bayer Lewatit MP500, have been studied in this work. Two theoretical models were applied to the interpretation of these data. Experimental data on copper concentration were fitted to well known models. The constant separation factor isotherm was used to fit the equilibrium results, high values of the equilibrium constants being obtained at different pH. Two theoretical models were applied. Both the film mass transfer and the pore diffusion models give good fitting of the experimental results providing Kf and Dp for different pH. The Helfferich criteria allowed to establish control of the process in the liquid film surrounding the resin particles.

Accurate measurement of uranium isotope ratios in soil samples using thermal ionization mass spectrometry equipped with a warp energy filter

A chemical and mass-spectrometric procedure for uranium isotopic analysis using a thermal ionisation mass spectrometer equipped with a Wide Aperture Retardation Potential energy filter has been developed and applied to uranium isotopic measurements for various soil samples. Soil samples were digested using a microwave digestor. Uranium was isolated from soil samples by the chemical separation procedure based on the use of anion-exchange resin and UTEVA extraction chromatography column. The isotope ratios were measured for two certified reference materials by using a VG Sector 54-30 thermal ionisation mass spectrometer in dynamic mode with Faraday cup and Daly ion counting system. Replicates of standard reference materials showed excellent analytical agreement with established values supporting the reliability and accuracy of the method. Precision of the 235U/238U ratio was achieved by a correction factor of 0.22% amu as a function of ion-beam intensity with sample loads of around 250 ng of U. The resulting reproducibility for standards and soil samples was better than 0.2% at two standard deviations (SD). Uranium isotopic compositions have been determined in several reference soil samples such as Buffalo river sediment, NIST 2704, river sediment SRM 4350b and ocean sediment NIST-4357 and a Chernobyl soil sample. There was a significant deviation from the natural uranium in comparison with Chernobyl soil samples.

Effects of pH and competing anions on the speciation of arsenic in fixed ionic strength solutions by solid phase extraction cartridges

Anion exchange resins (AERs) separate As(V) and As(III) in solution by retaining As(V) and allowing As(III) to pass through. Anion exchange resins offer several advantages including cost, portability, and ease of use. The use of AERs for the instantaneous speciation of As minimizes the effects of preservatives on As species analysis. The aims of this study were to: (1) Examine the effects of pH and competing anions on the efficacy of solid phase extraction cartridges (SPECs) for speciation of As in a 0.01 mol L −1 NaNO 3 background electrolyte. (2) Identify optimal conditions (e.g. flow rates) for As speciation. (3) Calculate method detection limits (MDLs) from spiked background electrolyte and percent recoveries of As species from spiked extracts of mine wastes. The most effective SPEC retained As(V) through a range of environmentally relevant pH values (4–8). The mass loading capacity for As(V) was reduced in the background electrolyte (0.006 mg) compared with As(V) in deionized H 2O (0.75 mg). Some retention (10–20%) of As(III) occurred on pre-wetted cartridges. Approximately 98% of spiked As(III) passed through dry cartridges. The recommended flow rate (0.5 mL min −1) was increased to 5 mL min −1 without significant effect on As(V) retention. The presence of anions decreased the retention of As(V) with sulfate and phosphate having the greatest impact. MDLs were 0.004 mg L −1 for both inorganic species. Spike recoveries in 0.01 M NaNO 3 mine waste extracts averaged 94% for As(III) and 107% for As(V).

Isotope ratios determination of uranium in soil samples affected due to Chernobyl accident using thermal ionisation mass spectrometer

A rapid and highly precise method was developed for the separation of uranium from soil samples for thermal ionisation mass spectrometry. The chemical separation procedure is based on the use of anion exchange resin and UTEVA extraction chromatography column. The isotope ratios of uranium, 234 U/ 238 U, 235 U/ 238 U and 236 U/ 238 U were measured by using a VG Sector 54 TIMS equipped with a Wide Aperture Retardation Potential (WARP) energy filter with a precision of better than 0.2% at two standard deviations (sd). The use of a WARP energy filter improves abundance sensitivity by an order of magnitude over a conventional VG Sector TIMS. Replicates of standard reference materials showed excellent analytical agreement with established values, supporting the reliability and accuracy of the method. Uranium isotopic compositions have been determined in soil samples in the exclusion zone of Chernobyl nuclear power plant. The isotopic composition of Chernobyl soil samples showed significant deviation from the natural uranium and the 236 U/ 238 U ratio varied from 105 to 10 4.

Purification of glutathione s-transferase fusion proteins from yeast

Publisher Summary This chapter discusses the purification of glutathione s-transferase fusion proteins from yeast. The purification of affinity-tagged recombinant proteins from prokaryotic hosts is an efficient method to obtain milligram quantities of protein for binding and activity studies. Yeast provides an opportunity to express large amounts of recombinant protein in a eukaryotic host using microbiological media. However, difficulties with the expression level of recombinant protein, toxicity of the recombinant protein, proteases, and yield from the affinity purification step have prevented researchers from taking advantage of yeast as an expression host. The choice of an appropriate host strain, induction media, and expression plasmid can overcome the expression level and protease problems, and the use of an ion-exchange resin before the affinity purification step increases recombinant protein yield, presumably by removing an inhibitor of binding to the affinity resin. The yield from these preparations is approximately 10 percent of the expressed protein; most of the loss is at the affinity purification step.

Methods for separation of trace amounts of platinum and investigation of the influence of interfering elements during platinum determination in copper ores and copper concentrates by graphite furnace atomic absorption spectrometry

A THGA graphite furnace with Zeeman background correction has been used to determine platinum content in copper ore and copper concentrate at the part per billion (ppb) concentration level. Two different procedures for the separation of trace platinum have been applied: (i) use of an ion exchange resin; and (ii) a two-stage method based on platinum separation on inorganic carriers. The influence of interfering elements in the matrix (Cu, Pb, Fe, Ti, V, Au, Pd, Ir, Rh and Al) has been examined using a graphite furnace. It was found that the presence of Cu (12.5–100 mg l−1), Pb (100–500 mg l−1), Fe (100–2000 mg l−1), Ti (25–100 mg l−1), V (25–100 mg l−1), Au (25–300 mg l−1), Pd (20–250 mg l−1), Ir (0.5–3.5 mg l−1) and Rh (0.025–1 mg l−1) in the samples analyzed has no effect on the platinum absorption signal when using a recommended temperature program (Tpyr=1300°C, Tat=2450°C). Spectral interference was observed, which was due to aluminum, as a result of the close neighborhood of the Pt 265.945-nm and Al 266.039-nm lines. This interference could not be eliminated by the Zeeman background correction.

Availability of phosphorus in a Brazilian Oxisol cultivated with eucalyptus after nine years as influenced by phosphorus‐fertilizer source, rate, and placement

This work evaluated the effect of different placement and rates of two phosphorus (P) fertilizers on P‐availability by three methods of extraction, nine years after application to a Brazilian Oxisol cultivated with Eucalyptus camaldulensis. The treatments were applied to 24x18 m plots and 96 seedlings of E. camaldulensis were planted (3.0x1.5 m) in each plot. Single superphosphate (SSP) and rock phosphate (RP) were tested in three rates (100, 200, and 400 kg ha‐1 of P2O5). Each fertilizer was either (1) surface‐applied in bands (0.6 m either side of the rows of trees) and incorporated before planting or (2) incorporated into furrows (0.2 m deep in the tree rows) before planting. As additional treatments, the combination of RP (96 kg ha‐1 of P2O5 applied in broadcast, or bands, or in furrows) + SSP (54 kg ha‐1 of P2O5 localized in the planting hole before planting) were tested. Twelve soil subsamples from two layers (0–15 and 25–40 cm) were taken from each plot (from the planting rows or between the planting rows) and were analyzed for pH in water (1:2.5), available P by Mehlich‐1, Bray‐1 and anionic resin, exchangeable Ca, and Al by 1 mol L‐1 Kcl. For both methods of fertilizers placement, the highest values of available P were observed in the surface soil and in the planting row, and were strongly related to fertilizer rate. Samples taken between the planting rows did not exhibit treatment effects on available P. The higher values of available P obtained with Mehlich‐1 and the lower eucalyptus plant uptake efficiency of fertilizer‐P from banded RP confirms the fact that this extractant can overestimate the availability of P in soils receiving RP. The use of anion exchange resin in this situation to estimate available P is supported. The results obtained with the localized application of RP indicate root system activity (P and Ca uptake and acidification of rhizosphere) as a factor in increasing fertilizer dissolution rates.

Silicalite-1 containing microspheres prepared using shape-directing macro-templates

Silicalite-1 microspheres were prepared by a novel method based on the use of anion exchange resins as shape-directing macro-templates. In a first step, spherical beads of the ion exchange resin were hydrothermally treated in a silicalite-1 synthesis solution. This resulted in the crystallization of silicalite-1 in the pores of the resin and the formation of a silicalite-1/resin composite material. The organic ion exchange resin was then removed by calcination leaving self-bonded spherical particles of silicalite-1. The influence of the type of ion exchange resin, the treatment time as well as the weight ratio between synthesis solution and resin on the properties of the resultant materials were investigated. The silicalite-1 containing microspheres were characterized by XRD, Raman spectroscopy, SEM, nitrogen adsorption and microhardness measurements.

The effect of salinity on the capacity and selectivity of ion exchange resins for gold cyanide

Despite the success of several resin-in-pulp pilot plant operations in the Western World and large scale plants in the former Soviet Union the process of extracting gold from slurries using ion exchange resins is yet to gain recognition as a viable alternative to the carbon-in-pulp process. An experimental research program has investigated the potential use of anion exchange resins containing a variety of quaternary ammonium functional groups in highly saline process water such as that found in Western Australia. The effect of univalent and bivalent ions on gold adsorption has been studied. It was shown that the selectivity of the resin for gold cyanide was enhanced with increasing ionic strength. It has been proposed that the degree of hydration, polarisation and size of the adsorbing species are factors that contribute to the observed change in selectivity of the ion exchange resin at different salinity. It was observed that in highly saline solutions copper cyanide did not load significantly on any of the experimental resins studied. Furthermore, it has been shown that an existing commercial non-selective resin loads no significant amount of copper cyanide under saline conditions. It is proposed that the apparent change in selectivity of resins for gold cyanide is caused by anions that have a stronger affinity for the resin in these highly non-ideal solutions as well as a possible change in the distribution of copper cyanide complexes in solution. The results of this study demonstrate that the selectivity of ion exchange resins in highly saline water is significantly improved and as a consequence the resin-in-pulp process may be more efficient than carbon-in-pulp in process streams of high salinity.

The use of anion exchange resins for the synthesis of combinatorial libraries containing aryl and heteroaryl ethers

Quaternary ammonium exchange resins (Amberlite ® IRA-900) were prepared that contained each a mixture of ten aryloxides and heteroaryloxides. The feasibility of generating combinatorial libraries containing aryl and heteroaryl ethers was demonstrated by reacting the resin's with a single electrophile (n-butyl bromide) to afford mixtures of ether products. The advantages of using quaternary ammonium exchange resins over solution phase chemistry to prepare this library are discussed.

Comparison of DTPA and resin extractable soil Zn to plant Zn uptake

Abstract Extraction of soil zinc with routine chemical extractants does not always reflect differences in Zn availability as detected by plant uptake. This study was undertaken to explore and compare the use of an ion exchange resin and diethylenetriaminepentaacetic acid (DTPA) for extracting soil Zn as related to plant Zn uptake. Beans were grown in 1989 following differential cropping with corn and beans or fallow in 1988 on a Portneuf silt loam near Kimberly, Idaho. Two Zn fertilizer treatments were imposed across previous cropping treatments. A batch method for determining resin extractable soil Zn was established. Both plant Zn concentration and Zn uptake by beans in 1989 were significantly higher in Zn fertilized than unfertilized treatments regardless of previous crop; and higher in plots previously cropped with corn than beans or fallow, regardless of Zn treatment. DTPA and resin extractable soil Zn were significantly higher in Zn fertilized plots compared to unfertilized plots but did not differ between previous cropping treatments. Resin and DTPA extractable soil Zn concentrations were positively correlated. Resin extracted soil Zn correlated better with plant Zn concentration and Zn uptake throughout the growing season than DTPA extracted soil Zn, particularly in plots that had been fallowed or previously cropped with corn. Resin may be extracting labile soil Zn not extracted with DTPA and, therefore, be better simulating plant uptake. Both extraction methods correlated better with Zn uptake when evaluated within cropping treatments, emphasizing the need to consider previous crop when calibrating soil tests.

Gas chromatographic separation and determination of chloroacetic acids in water by a difluoroanilide derivatisation method

A simple method for the micro-determination of chloroacetic acids in water was developed. Chloroacetic acids in a water sample were converted into the difluoroanilide derivatives by reaction with difluoroaniline and dicyclohexylcarbodiimide. The derivatives were extracted into ethyl acetate, cleaned up and determined by gas chromatography with electron-capture detection. The detection limits for monochloroacetic, dichloroacetic and trichloroacetic acids were ca. 2, 1 and 0.6 µg l–1, respectively, in a 50-ml water sample. A pre-treatment method involving the use of an ion-exchange resin is also described, which allows determination at lower levels. The method was applied to the determination of chloroacetic acids in chlorinated water.