Chelating Resin Research Articles

Mining value from waste: Scandium and rare earth elements selective recovery from coal fly ash leach solutions

Global demand for rare earth elements (REEs) has been on the rise due to recent rapid technological advancements. Even though most REEs are mainly recovered from rich ores and mineral deposits, recovery of REEs from secondary sources has attracted attention. However, low metal concentration, complex matrices and high levels of other impurities in mine wastes and tailings have remained the toughest challenges to overcome. The presence of low amount of valuable metals such as Sc requires utilization of very selective separation techniques such as ion exchange. A series of ion exchange resins (chelating, solvent impregnated and strongly acidic) were studied in the recovery of Sc from synthetic and actual pregnant leach solutions obtained from acid-leaching of coal fly ash. To the best of our knowledge, this paper exhibits the first attempt in selective recovery (from other REEs as well as major Fe and Al contaminations) of Sc in coal fly ash using ion exchange separation technique. With maximum capacity of ∼24 mg Sc/g resin, Sc was adsorbed quickly on phosphorus containing Lewatit® VP OC 1026 and TP 272 resins even in the presence of high levels of potentially interfering Fe3+ and Al3+ ions. Full elution of the adsorbed REEs from VP OC 1026 was achieved with 5 M H2SO4, with only minor Sc removal. While elution of Sc from these chelating resins has been reported to be challenging, Sc could be eluted almost completely with 2 M NH4F. Recovery of REEs with 5 M H2SO4 from TP 272 resulted in co-elution of only 7% of the adsorbed Sc while the rest could be eluted efficiently with 6 M HNO3.

Field-deployable method for iron analysis using a simple preconcentration procedure and a 3D portable spectrophotometric system

In this paper, a field-deployable method for the spectrophotometric determination of iron after a simple preconcentration procedure in column is proposed. A 3D-printed portable system, housing a small spectrophotometer with a CCD detector and a LED as homemade light source is used for spectrophotometric detection. The entire system is powered through two USB outputs of a notebook. The Fe (III) preconcentration is based on a solid phase extraction with a column packed of Chelex-100 chelating resin. The Fe (III) eluted in the cuvette was reduced to Fe (II) and the iron concentration was determined using the o-phenanthroline method. Preconcentration factors between 9.7 and 98 were obtained. Under optimized conditions, linear calibration curves without and with preconcentration were constructed (R2 > 0.9992). Low LD (5 µg L−1) and LQ (10 µg L−1) were achieved, and good values for intra-day and inter-day precision were obtained (RSD ≤ 2.9% and RSD ≤ 9.6%, respectively). Recoveries of spiked iron in local tap water, sea water, well water, leachate and supernatant of anaerobic digester were ranged from 93 to 106%. The validation of method was also carried out by successfully analyzing a river water reference material SLRS-4.

Sensitive extraction-free SARS-CoV-2 RNA virus detection using a chelating resin

SummaryCurrent conventional detection of SARS-CoV-2 involves collection of a patient’s sample with a nasopharyngeal swab, storage of the swab during transport in a viral transport medium, extraction of RNA, and quantitative reverse transcription PCR (RT-qPCR). We developed a simplified preparation method using a chelating resin, Chelex, which obviates RNA extraction during viral testing. Direct detection RT-qPCR and digital droplet PCR were compared to the current conventional method with RNA extraction for simulated samples and patient specimens. The heat treatment in the presence of Chelex markedly improved detection sensitivity as compared to heat alone, and lack of RNA extraction shortens the overall diagnostic workflow. Furthermore, the initial sample heating step inactivates SARS-CoV-2 infectivity, thus improving workflow safety. This fast RNA preparation and detection method is versatile for a variety of samples, safe for testing personnel, and suitable for standard clinical collection and testing on high-throughput platforms.

Comparative studies on the adsorption of various radioactive nuclides from waste aqueous solutions on graphene oxide, inorganic and organic ion exchangers

Abstract Adsorption of the radionuclides 141Ce, 140La, 140Ba, 137+134Cs, 131I, 125Sb, 103Ru, 95Nb and 95Zr are studied on graphene oxide from waste aqueous solution samples and their adsorption behaviors are compared to that on the inorganic ion exchanger Ceric tungstate as well as on the strong acidic cation exchanger Dowex-50X8 H+ form, the chelating resin Chelex-100 Na+ form and the strong basic anion exchanger AG-1X8 Cl− form. The waste samples are dilute aqueous solutions resulting from previous work. These solutions contained neither oxidizing nor reducing agents, consequently, it is expected that these radionuclides are existing in their most stable oxidation states, i.e. Ce(III), La(III), Ba(II), Cs(I), Ru(III) & (IV), Sb(III) & (V), Nb(V) and Zr(IV). The adsorption is studied under static conditions for all these radioactive nuclides in the presence of each other. Gamma radiometric analysis is carried out for these radionuclides. Effect of some factors on the adsorption is studied such as pH, graphene oxide particle sizes, contact time, temperature and other parameters. Complete removal of some radionuclides is achieved from these waste solutions by adsorption on graphene oxide. Some separation alternatives for some of these radionuclides are also achieved.

Amberlite IRC-718 ion chelating resin extraction of hazardous metal Cr (VI) from aqueous solutions: equilibrium and theoretical modeling.

Under varied conditions, the IRC 718 ion-exchange resin is used to extract chromium (VI) ions from aqueous solutions. On chromium (VI) removal effectiveness, the effects of adsorption dosage, contact time, beginning metal concentration, and pH were examined. The batch ion exchange process reached equilibrium after around 90 minutes of interaction. With an initial chromium (VI) concentration of 0.5 mg/dm3, the pH-dependent ion-exchange mechanism revealed maximal removal in the pH 2.0-10 range. The adsorption mechanism occurs between Cr (VI) determined as the electron acceptor, and IRC 718 determined as the electron donor. The equilibrium ion-exchange potential and ion transfer quantities for Amberlite IRC 718 were calculated using the Langmuir adsorption isotherm model. The overall ion exchange capacity of the resin was determined to be 187.72 mg of chromium (VI)/g of resin at an ideal pH of 6.0.

Mechanisms of arsenic removal from simulated surface water based on As(III) retention on thiol chelating resins

A novel system for arsenic speciation in the aqueous environment has been developed based on the high affinity of As(III) for the sulfhydryl groups present in thiol resins (R-S). The performance of tailor-made cartridges filled with the thiol resin was then compared with a commercial silica-based anion exchange cartridge with a quaternary ammonium group (R-N) typically used for As(V) speciation. Both were able to separate arsenic species efficiently, As(V) and As(III), within a broad pH range using flow rates of up to 5 ml min−1. The R-S resin was shown to be suitable for the inorganic arsenic speciation in aqueous systems containing calcium, magnesium, ferrous and ferric ions. The R-S selectivity for As(III) was affected only at sulfate or phosphate/As mass ratio > 500, in a behavior similar to R-N for As(V). The thiol resin's selectivity for As(III) and its immobilization mechanism were investigated through X-ray Absorption Spectroscopy. At pH 5, each arsenic atom bounds to three sulfur atoms, with an As-S inter-atomic distance of 2.26 ± 0.01 Å, and a coordination number (CN) of 2.8 ± 0.3. The separation of the neutral As(III) species by a thiol resin presents itself as an alternative to the available anion exchange methods. The sorption of As(III) on the thiol resin followed a pseudo-second-order kinetic model and can be described by the Langmuir isotherm.

Performance of Pd/Sn catalysts supported by chelating resin prestoring reductant for nitrate reduction in actual water

Catalytic hydrogen reduction has appeared as a promising strategy for chemical denitrification with advantages of high activity and simple operation. However, the risk and low utilization of H2 is the disadvantage of catalytic hydrogen reduction. In recent years, catalytic reduction reactions in the presence of sodium borohydride (NaBH4) have been extensively studied. NaBH4 can be used as an electron source to generate electrons on the surface of the catalyst and can catalyze the reduction of pollutants. But it makes commercialization costly and causes significant environmental pollution if widely use NaBH4. In this study, we prepared supported Pd/Sn bimetallic nanoparticles which could adsorb NaBH4 during the preparation of the Pd/Sn bimetallic catalyst as the prestoring reductant. No additional reducing agent is required during nitrate reduction process. The performance and mechanism for nitrate reduction by using Pd/Sn bimetallic nanoparticles were discussed. Moreover, the catalyst D-Pd1/Sn1 reached a complete nitrate removal in the municipal wastewater treatment plant effluent water within 3 h. The results provide a prospect for denitrification in biological wastewater treatment plants.

Cyclotron production of 225Ac from an electroplated 226Ra target

PurposeWe demonstrate cyclotron production of high-quality 225Ac using an electroplated 226Ra target.Methods226Ra was extracted from legacy Ra sources using a chelating resin. Subsequent ion-exchange purification gave pure 226Ra with a certain amount of carrier Ba. The radium target was prepared by electroplating. We successfully deposited about 37 MBq of 226Ra on a target box. Maximum activation was achieved using 15.6 MeV protons on the target at 20 µA for 5 h. Two functional resins with various concentrations of nitric acid purified 225Ac and recovered 226Ra. Cooling the intermediate 225Ac for 2–3 weeks decayed the major byproduct of 226Ac and increased the radionuclidic purity of 225Ac. Repeating the same separation protocol provided high-quality 225Ac.ResultsWe obtained 225Ac at a yield of about 2.4 MBq at the end of bombardment (EOB), and the subsequent initial purification gave 1.7 MBq of 225Ac with 226Ac/225Ac ratio of < 3% at 4 days from EOB. Additional cooling time coupled with the separation procedure (secondary purification) effectively increased the 225Ac (4n + 1 series) radionuclidic purity up to 99 + %. The recovered 225Ac had a similar identification to commercially available 225Ac originating from a 229Th/225Ac generator.ConclusionThis procedure, which involves the 226Ra(p,2n)225Ac reaction and the appropriate purification, has the potential to be a major alternative pathway for 225Ac production because it can be performed in any facility with a compact cyclotron to address the increasing demand for 225Ac.

A one‐pot biosynthesis of an aerogel composite based on attapulgite clay/bacterial cellulose to remove Pb 2+ ion

A one‐pot biosynthesis of an aerogel composite based on attapulgite clay/bacterial cellulose to remove Pb ²⁺ ion

Performance and mechanism of chelating resin (TP-207) supported Pd/Cu bimetallic nanoparticles in selective reduction of nitrate by using ZVI (zero valent iron) as reductant

• Novel Pd/Cu-resin catalyst was applied for denitrification by using ZVI as reducing agent. • High N 2 selectivity (>90%) in final products of nitrate reduction were obtained under neutral condition. • High N 2 selectivity may be brought by the slow rate of nitrate reduction. • ZVI, Pd/Cu-resin, and the neutral conditions with high N/H ratio resulted in low ammonia production and high N 2 selectivity. In the present study, a Pd/Cu bimetallic catalyst supported on a chelating resin (TP207) was prepared in order to selectively reduce nitrate to N 2 with ZVI (zero valent iron) as a reductant. The effects of Pd/Cu mass ratio, temperature, and initial solution pH on the removal of nitrate and TN were then examined. The highest nitrate (63.2%) removal was obtained under neutral conditions at a ratio of Pd/Cu 2:1, in which 57.8% of TN was removed and N 2 accounted for more than 90% of the final products. Additional ammonia (30–40%) were formed when the reaction was conducted at a higher temperature (313 K) compared to when performed at 303 K. The mechanism study for nitrate reduction indicated that this catalyst could broaden the suitable pH range and improve the selectivity of N 2 without the generation of other intermediate compounds or by-products in comparison to ZVI and its combination with a non-supported Pd/Cu catalyst. The slow rate of ZVI corrosion, high Fe(Ⅱ) proportion in corrosion products and high N/H ratio at neutral pH conditions may serve as reasons for the high N 2 selectivity. The chelating resin also played a key role via its load capacity and dispersion ability to Pd/Cu particles in enhancing N 2 selectivity. Accordingly, the proposed method may have great potential application for nitrate reduction to N 2 , which warrants further study.

Evaluation of V2 18S rDNA barcode marker and assessment of sample collection and DNA extraction methods for metabarcoding of autotrophic euglenids.

SummaryEven though the interest in metabarcoding in environmental studies is growing, euglenids are still underrepresented in both sea and freshwater bodies researches. The reason for this situation could be the unsuitability of universal eukaryotic DNA barcodes and primers as well as the lack of a verified protocol, suitable to assess euglenid diversity. In this study, using specific primers for the V2 hypervariable region of 18S rDNA for metabarcoding resulted in obtaining a high fraction (85%) of euglenid reads and species‐level identification of almost 90% of them. Fifty species were detected by the metabarcoding method, including almost all species observed using a light microscope. We investigated three biomass harvesting methods (filtering, centrifugation and scraping the side of a collection vessel) and determined that centrifugation and filtration outperformed scrapes, but the choice between them is not crucial for the reliability of the analysis. In addition, eight DNA extraction methods were evaluated. We compared five commercially available DNA isolation kits, two CTAB‐based protocols and a chelating resin. For this purpose, the efficiency of extraction, quality of obtained DNA, preparation time and generated costs were taken into consideration. After examination of the aforementioned criteria, we chose the GeneMATRIX Soil DNA Purification Kit as the most suitable for DNA isolation.

Recovery of Zinc from Municipal Solid Waste Incineration Fly Ash

In recent years, over one million tons of Municipal Solid Waste (MSW) incineration fly ash has been generated annually Taiwan. Only a small percentage of the ash was used as raw material for other utilities besides landfill. Fly ash contains many harmful heavy metals, such as Cd and Cr, among others; however, fly ash also contains many valuable metals, including as Zn, Pb, and Ga.To recover Zn from fly ash, in this work, an experiment was first designed to determine the physical and chemical properties of the fly ash. Then, treatment processes, including water leaching, acid leaching, and ion exchange were conducted.Test samples were subjected to scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence spectrometer (XRF), and atomic absorption spectroscopy (AAS) to determine their physical and chemical properties. Then, water leaching was conducted under optimal experimental conditions. Thereafter, acid leaching was performed using two different acids (hydrochloric and sulfuric) to extract the target metal ions, and finally the ion exchange process was deployed to concentrate and recover the target metal ions.Ultimately, an optimal process to recover zinc from MSW incineration fly ash was developed in this work. An aqueous solution containing approximately 1 wt% zinc was obtained by leaching with sulfuric acid. Zn was then concentrated using a chelating resin IRC-747 in column mode.

Automated separation and measurement of 226Ra and trace metals in freshwater, seawater and fracking water by online ion exchange chromatography coupled with ICP-MS

An online solid-phase extraction method combined with ICP-MS was developed to separate and quantify low levels of 226Ra and other metals in drinking water, lake, river and sea water, and fracking fluids. A dual-column lab-on-valve and multi-syringe flow injection analysis (LOV-MSFIA) system was developed to provide precise measurement of 226Ra in samples with total dissolved solids (TDS) less than 2%. For samples with higher levels of TDS (up to 20%), a triple-column LOV-MSFIA system was developed, which used AG 50 W-X8 cation exchange, Sr spec andNobias Chelate resins. Compared to earlier automated systems for Ra analysis, the dual and triple column systems described here were optimized to accommodate smaller sample volumes, more precise flow control and lower limits of detection (LOD). The LOV-MSFIA system coupled with ICP-MS is a significant improvement over traditional methods for low level 226Ra measurements, which require extended sample holding and/or analysis time. External calibration and standard addition were used to quantify the concentration of Ra for the LOV-MSFIA system. After method optimization, LODs for 226Ra as low as 4.3 mBq L−1 (1.75 fg L−1) were obtained in different sample matrices. The concentrations of selected metals were also measured on the triple-column system, together with Ra, with a total online processing time of 28.5 min per sample. Thus, the online LOV-MSFIA system is shown to be a powerful tool for the rapid analysis of low levels of 226Ra, as well as other metals, in various types of aqueous samples.

Determination of Nd isotopic composition in seawater using newly developed solid phase extraction and MC-ICP-MS

Determination of neodymium (Nd) isotopic composition in seawater is useful for tracing water masses and geochemical cycles for lithogenic elements in the ocean. A new separation procedure for determination of the Nd isotopic composition of in seawater samples was developed that offers enhanced sample throughput and improved measurement reliability. The procedure consists of conventional Fe hydroxide coprecipitation, solid phase extraction using DGA chelating resin column chromatography, and Ln Resin column chromatography to preconcentrate samples. High selectivity in HNO3 medium and elution by low concentration HCl medium for Nd are characteristics of extraction using DGA Resin®, and they allowed an evaporation step to be omitted between the chromatographic steps. These chromatographic steps, using DGA Resin to separate REEs and Ln Resin® to remove Sm, were refined from a previous study. The procedural blank value of Nd was obtained as 2 pg (n = 6) from 3 L of water samples. Chemical yield of Nd from 3 L of seawater ranged within 90–95%. The developed procedure was combined with multiple collector-ICP-MS and applied to analysis of vertical seawater samples obtained from the western subarctic gyre of the North Pacific Ocean, where εNd ranged from −1.29 ± 0.42 at the surface to −3.80 ± 0.41 at 4000 m depth. These results were validated by comparing them with results obtained by the conventional method verified in the GEOTRACES inter-calibration program.

Removal of iron, aluminium, manganese and copper from leach solutions of lithium-ion battery waste using ion exchange

The shift to electric mobility necessitates recycling the metals from lithium ion battery waste. Ion exchange was studied for use in the removal of impurities from synthetic lithium ion battery waste leachate in laboratory-scale batch and column experiments. Aminomethylphosphonic acid functional chelating resin (Lewatit TP260) was capable of removing Fe, Al, Mn, and Cu from the leachate, while leaving valuable Co, Ni, and Li as a pure mixture in the raffinate. Increasing the pH up to 3 and the temperature to 60 °C improved the purity and productivity. Iron and aluminium could not be eluted efficiently by mineral acids, but an oxalate solution was found feasible. A two-step elution procedure, in which Cu and Mn are first removed with sulfuric acid, followed by Fe and Al removal with potassium oxalate, was successfully demonstrated. The suggested process produced a > 99.6% pure Li + Co + Ni solution (battery grade), along with a Mn and Cu rich sulfuric acid solution with Co as an impurity and an oxalate solution of Fe + Al as by-products. The productivities for these solutions were 0.39, 0.16, and 0.38 BV/h, respectively. The Co loss was very low (1.1%) as compared to previously suggested impurity removal processes using precipitation and solvent extraction. Moreover, Co can be easily recycled back to the ion exchange column feed after Mn and Cu are recovered as pure by-products.

Distribution of platinum (Pt), palladium (Pd), and rhodium (Rh) in urban tributaries of the Scheldt River assessed by diffusive gradients in thin films technique (DGT)

The performance of the newly developed DGT technique for the platinum group elements (PGEs) rhodium (Rh), platinum (Pt) and palladium (Pd) was evaluated in two tributaries of the Scheldt River, the Marque River close to the city of Lille (France), and the Zenne River which flows through the city of Brussels (Belgium). In the Marque River, an interlaboratory comparison was performed between the two laboratories where the DGT techniques dedicated to PGEs were developed (AMGC, VUB & LASIRE, U-Lille). PGEs were also analysed in an effluent of a Brussels hospital and monthly grab sampling was performed at the wastewater treatments plants (WWTPs) of Brussels. The concentrations of the 3 elements are higher in the Zenne River than in the Marque River and much higher Pt concentrations are found in the hospital effluent. Good agreement for Pt was observed between the three selected chelating resins and a relatively good agreement was observed between the two laboratories using the same chelating resin, whereas lower results were observed with the anion-exchange resin. Larger discrepancies between the two laboratories were observed for Pd and no comparison could be made for Rh due to the low natural concentrations. The results show that in small urban rivers with high impact of urbanization, WWTPs are an important source of Pt, resulting from the use of anticancer drugs in hospitals and households. The limited retention of PGEs in WWTPs results in increased concentrations in urban rivers downstream.For Pd and Rh, similar trends were found with other traffic related elements such as Cu, Zn and Pb, showing the highest concentrations in waters collecting runoff from a highway. The data show that these elements, together with Gd, can be useful to trace specific pollution sources and their dispersion.

A developing method for preconcentration and determination of Pb, Cd, Al and As in different herbal pharmaceutical dosage forms using chelex-100

A simple, rapid and efficient method of preconcentration and determination of selected toxic heavy metals from herbal phytopharmaceutical product matrices using inductively coupled plasma and flame atomic absorption spectrometry after preconcentration with chelating resin (chelex-100) was developed. In this study, 24 samples representing phytopharmaceutical remedies in different dosage forms such as tablet, capsule, suppository, syrup and tea bag that are available in Pharmaceutical Jordanian companies were investigated for the presence of Pb, Cd, Al and As to establish their normal concentrations range and consider their levels according to some worldwide permissible limit guidelines. The %relative standard deviation was < 5%. Pb, Cd, and Al concentrations were ranged (0.01–30.84 μg/g), (0.001–0.85 µgg−1) and (1.81–215.19 µgg−1), respectively, whereas As level was below the detection limit. The percent contribution of raw material heavy metal content for tablet dosage forms was in the average of 88.39%, 79.85% and 83.13% for Pb, Cd and Al, respectively.

Laser-induced breakdown spectroscopy analysis of copper and nickel in chelating resins for metal recovery in wastewater

Recovery of heavy metals from industrial waste streams is becoming an important challenge due to increasing wastewater production. Chelating resins provide an effective treatment for selective adsorption of metals. Several analytical techniques can be used to assess the adsorption performance, but LIBS offers the unique advantage of in-process continuous monitoring. In this work, LIBS measurements of copper and nickel spectra were performed on single and bi-component resin samples. Single component calibration curves for copper and nickel were obtained with high correlation (R2 = 0.99 and R2 = 0.98 respectively). Bi-component resin measurements reveal good prediction accuracy for nickel and copper concentrations, the mean relative error in concentration prediction being 4.69% and 7.98% respectively. From the calibration curves, the prediction of concentration shows a high correlation with the real values (R2 = 0.99 for copper and 0.98 for nickel).

Iron limitation by transferrin promotes simultaneous cheating of pyoverdine and exoprotease in Pseudomonas aeruginosa.

Pseudomonas aeruginosa is a primary bacterial model to study cooperative behaviors because it yields exoproducts such as siderophores and exoproteases that act as public goods and can be exploited by selfish nonproducers behaving as social cheaters. Iron-limited growth medium, mainly casamino acids medium supplemented with transferrin, is typically used to isolate and study nonproducer mutants of the siderophore pyoverdine. However, using a protein as the iron chelator could inadvertently select mutants unable to produce exoproteases, since these enzymes can degrade the transferrin to facilitate iron release. Here we investigated the evolutionary dynamics of pyoverdine and exoprotease production in media in which iron was limited by using either transferrin or a cation chelating resin. We show that concomitant loss of pyoverdine and exoprotease production readily develops in media containing transferrin, whereas only pyoverdine loss emerges in medium treated with the resin. Characterization of exoprotease- and pyoverdine-less mutants revealed loss in motility, different mutations, and large genome deletions (13-33 kb) including Quorum Sensing (lasR, rsal, and lasI) and flagellar genes. Our work shows that using transferrin as an iron chelator imposes simultaneous selective pressure for the loss of pyoverdine and exoprotease production. The unintended effect of transferrin uncovered by our experiments can help to inform the design of similar studies.

Synchronous reduction-fixation of reducible heavy metals from aqueous solutions: Application of novel mesoporous MFT/SBA-15 composite materials

The usual treatment for Cr(VI)-contaminated wastewater primarily included reduction, adsorption, and the subsequent separation of the Cr-laden adsorbent. Among these factors, the adsorbent is the most critical factor in determining Cr removal efficiency. In this study, a novel melamine-formaldehyde-thiourea (MFT) chelating resin/mesoporous silica composite material (MFT/SBA-15) was synthesized via a co-condensation method and used for the reduction and fixation of Cr(VI)-contaminated water. Cr(VI) adsorption onto MFT/SBA-15 obeyed the pseudo-second-order model, and the chemical adsorption was the rate-limiting step in the adsorption process. Also it followed the Langmuir adsorption model, with single molecular layer adsorption characteristics. The organic components within MFT/SBA-15 were the core functional groups for Cr(VI) adsorption, and the formation of a coordination bond (CS→Cr) between the lone electron pairs of the S atom and Cr during the adsorption process led to the synchronous reduction-fixation processes of Cr(VI). These synchronous effects were further demonstrated for other reducible heavy metals, including As(V) and Cu(II), but negligibly observed in chemically stable elements, such as Zn(II), Ni(II), Pb(II), Cd(II), and As(III). The novel mesoporous MFT/SBA-15 materials combine the advantages of the chelating resin and mesoporous silica and have excellent potential for the wastewater treatment of reducible heavy metals through synchronous reduction-fixation.