Resin Bed Research Articles

Reversed-phase extraction chromatography–neutron activation analysis (RPEC–NAA) for copper in natural waters using Amberlite XAD-4 resin coated with 1-(2-thiazolylazo)-2-naphthol

A preconcentration neutron activation analysis method has been developed for the determination of trace levels of Cu in natural waters including seawater with an absolute detection limit of 0.106 μg. The method involves the preconcentration of Cu onto Amberlite XAD-4 resin coated with 1-(2-thiazolylazo)-2-naphthol using reversed-phase extraction chromatography (RPEC). Copper is assayed through its neutron activation product 66Cu (half-life = 5.10 min) by direct irradiation of the resin bed. Factors affecting the uptake of Cu onto the ligand-impregnated resin have been investigated; these include flow rate, pH, column height, presence of other trace elements, major elements, and interfering matrix. The RPEC–NAA method has been validated by analyzing NIST and NRC water reference materials.

COMPARISON OF RADIAL AND AXIAL FLOW CHROMATOGRAPHY FOR MONOCLONAL ANTIBODY DOWNSTREAM PROCESSING AT BENCH AND PILOT SCALES

Axial Flow Chromatography (AFC) is widely used for the purification of therapeutic Monoclonal Antibodies (MAbs). However, AFC columns can generate high pressure drops across the resin bed, preventing operation of the column at high flow rates especially at pilot or manufacturing-scales. Radial Flow Chromatography (RFC) was developed to provide lower pressure drops during chromatographic separations. In these studies, small and pilot-scale columns were used to evaluate purification of a MAb using both AFC and RFC technologies. A bench-scale, wedge RFC column (250 mL) was compared to a bench-scale AFC column at various linear velocities with resulting Residence Times (RT) using Protein A resin for the recovery of a monoclonal antibody. The bench RFC column was successfully operated at 4.5 min RT for equilibration and loading steps and 2 min RT for washing, elution and cleaning steps without compromising yield. The RFC column had approximately 50% lower pressure drop than the AFC column at similar flow rates. The process was then scaled-up to 5 L using a pilot-scale RFC column. The 5-L RFC column was operated at 4.5 min RT for equilibration and loading and 2 min. RT for washing, elution and cleaning with no loss of yield. However, pressure drop across the 5 L RFC column was higher than expected, but antibody recovery yields were similar for both column types. Subsequent investigations revealed a potential design issue with the RFC column. Overall, RFC has great potential to be used for pilot or manufacturing scale without high pressure drop concerns, which will certainly improve processing efficiency.

An evaluation of a hybrid ion exchange electrodialysis process in the recovery of heavy metals from simulated dilute industrial wastewater

Hybrid ion exchange electrodialysis, also called electrodeionization (IXED), is a technology in which a conventional ion exchange (IX) is combined with electrodialysis (ED) to intensify mass transfer and to increase the limiting current density and therefore to carry out the treatment process more effectively. It allows the purification of metal-containing waters, as well as the production of concentrated metal salt solutions, which could be recycled. The objective of this paper was to investigate the ability of the IXED technique for the treatment of acidified copper sulphate solutions simulating rinsing water of copper plating lines. A single-stage IXED process at lab-scale with a small bed of ion exchanger resin with a uniform composition was evaluated, and the treatment performance of the process was thoroughly investigated. The IXED stack was assembled as a bed layered with the ion exchanger resin (strong acid cation-exchange Dowex™) and inert materials. The stack configuration was designed to prevent a non-uniform distribution of the current in the bed and to allow faster establishment of steady-state in the cell for IXED operation. The influence of operating conditions (e.g. ion exchanger resin with a cross-linking degree from 2 to 8% DVB, and current density) on IXED performance was examined. A response surface methodology (RSM) was used to evaluate the effects of the processing parameters of IXED on (i) the abatement yield of the metal cation, which is a fundamental purification parameter and an excellent indicator of the extent of IXED, (ii) the current yield or the efficiency of copper transport induced by the electrical field and (iii) the energy consumption. The experimental results showed that the performance at steady-state of the IXED operation with a layered bed remained modest, because of the small dimension of the bed and notably the current efficiency varied from 25 to 47% depending on the conditions applied. The feasibility of using the IXED in operations for removal of heavy metals from moderately dilute rinsing waters was successfully demonstrated.

Electrostatics in gas–solid fluidized beds for different particle properties

Electrostatics in fluidized beds of glass beads and polyethylene resins of different physical and chemical properties were investigated in a fluidization column of 150mm inner diameter and 2.0m height. Eight collision ball probes at different levels and radial positions measured the degree of electrification. For Geldart group B particles, the degree of electrification increased slightly with decreasing particle size. Charging for group A particles was significantly greater than for group B particles. For binary mixtures, the degree of electrification increased as the proportion of small (65μm) particles increased. Bipolar charging was observed in all experiments where polyethylene resin particles constituted the bed materials, with large particles charging negatively, and fine particles positively. The effect of adding fine (<30μm) glass beads on electrostatics in a fluidized bed of relatively large (574μm) glass beads was also studied. As the proportion of fines increased from 0.0 to 2.0wt%, the degree of electrification decreased, charge fluctuations decreased and the bed exhibited smoother fluidization. Particles entrained in the freeboard were charged oppositely to those in the bed. The degree of electrification decreased as the proportion of Larostat 519 increased from 0.0 to 0.5wt%, but increased when the wt% of Larostat reached 1.5%, probably due to the tendency of Larostat particles to adsorb water and agglomerate. Entrained Larostat particles carried the same charge polarity as the large particles in the bed.

The Sr–Nd isolation procedure for subsequent isotopic analysis using multi-collector ICP-mass spectrometry in the context of provenance studies on archaeological glass

Sr and Nd isotopic analysis of glass can be relied upon to unravel the provenance of the flux component and the sand used in the manufacturing of archaeological glasses, respectively. For a reliable isotopic analysis of the target elements using multi-collector ICP-mass spectrometry, the target elements need to be isolated from the matrix to permit adequate correction for instrumental mass discrimination. In this paper, a simple, fast and reliable analytical method for the isolation of Sr and Nd from complex sample matrixes such as archaeological glasses is proposed. Special attention is focused on the Nd isolation protocol, with the definition of TRU-Spec and Ln-Spec resin bed volumes and of an appropriate HCl concentration to optimize Nd elution from the column.

Fast and interference free determination of calcium and magnesium in honeys by solid phase extraction followed by flame atomic absorption spectrometry

A sample preparation procedure based on the solid phase extraction and the two-step elution was developed for the determination of the total concentrations of Ca and Mg in bee honeys. The honey samples were treated as follows: the 5.0% (m/v) sample solutions (50 mL) were passed at the flow rate of 20 mL min-1 through the resin beds of Dowex 50W×8-400 to retain the Ca(II) and Mg(II) ions and separate them from the matrix of glucose and fructose in addition to the anionic minerals. Afterwards, 20 mL of a 0.5 mol L-1 HNO3 solution was used to remove the K and Na ions. Finally, Ca and Mg were eluted prior to the measurements of their concentrations by flame atomic absorption spectrometry (FAAS) using 5 mL of a 2.0 mol L-1 HCl solution. The proposed sample preparation procedure was fast (30 min) and enabled to measure the concentrations of Ca and Mg in honey with the precision of 1-5% and the accuracy of 1-3%. The limits of detection of 24 ng g-1 of Ca and 4.4 ng g-1 of Mg were obtained for FAAS with this procedure.

Solid phase extraction and sequential elution for pre-concentration of traces of Mn and Zn in analysis of honey by flame atomic absorption spectrometry

A pre-concentration procedure based on solid phase extraction and two-step elution was developed for the determination of the total concentrations of traces of food safety relevant elements (Mn and Zn) in ripened honeys. Accordingly, 10% (m/v) solutions of analyzed honeys (100 ml) were passed at 20 ml min−1 through resin beds of Dowex 50W × 8–400 to retain Mn and Zn ions and separate them from the glucose and fructose matrix. Afterwards, 20 ml of a 0.5 mol l−1HNO3 solution was used to elute K and Na, easily ionized interfering metals. Finally, Mn and Zn were recovered prior to measurements by flame atomic absorption spectrometry (FAAS) using 5 ml of a 2 mol l−1HCl solution. This procedure was applied in the analysis of six honeys and resulted in the determination of 0.2–13.6 μg g−1 of Mn and 0.2–1.2 μg g−1 of Zn with the precision (n = 3) within 3–10% and an accuracy better than 5%. Detection limits of Mn and Zn with this pre-concentration/separation procedure and the FAAS detection were 4 and 3 ng g−1, respectively.

Thermal Analysis and Immobilisation of Spent Ion Exchange Resin in Borosilicate Glass

The underground disposal of waste arising from the nuclear industry needs constant evaluation in order to improve upon it through minimizing the volume and cost by reducing the amount of glass used without compromising the safety of any leakage from the radioactive waste form. The immobilization of the spent resin (NRW-40) in borosilicate glass was investigated to meet the acceptance criteria for disposal of nuclear waste. The organic mixed bed resin in granular form was used as a waste target. The analysis of surrogate resin doped with radioactive and non-radioactive cesium (Cs) and cobalt (Co) was carried out to investigate their thermal and chemical properties and their compatibility with an alkaline borosilicate glass. The thermal analysis indicates that the structural damage caused by 1 mSv gamma radiation to the radioactive resin has altered its properties in comparison with the non-radioactive resin, same amount of cesium (8.88 wt%) and cobalt (1.88 wt%) were used in both resins. The immobilization of residue shows that the excess sulfur in the residue caused phase crystallization in the final glass matrix. It was found that the volatilization of Cs-137 and Co-60 from the successful radioactive resin-glass matrix (HG-3-IER-500) were more than that in the non-radioactive resin-glass matrix (HG-3-IEX-500). The study demonstrates comprehensive experimental and analytical works and shows that it is possible to minimise the volume of the waste while keeping the required safety levels, however further research needs to be carried out in this area.

A High-Throughput Microchromatography Platform for Quantitative Analytical Scale Protein Sample Preparation

Protein analysis (using either specific protein quantitation by methods such as HPLC and immunoassays or structural analysis by methods such as LC-MS) usually requires significant sample preparation, including quantitative purification of the target protein from complex sample matrices and potentially enzymatic treatment or labeling. We have developed platform for high-throughput microchromatography, capable of running 96 or more small volume samples in parallel, producing from 10 pg to 100 μg of purified protein from each sample. The platform is based on disposable cartridge devices with 5 μL packed bed of resin. The cartridges may be operated as spin columns or run on a modified 96-channel liquid handler with ultra-low dead volume syringes that directly connect to the cartridges, providing very precisely controlled positive-displacement flow control. A major application is quantitative purification of target proteins using affinity or physical chromatography. Using large diameter nonporous beads, standard microplate enzyme-linked immunosorbent assay reagents can be used to perform 30-min immunoassays. Enzymatic digestion methods have also been developed on the system for application in glycan profiling.

Surface-functionalized electrospun carbon nanofiber mats as an innovative type of protein adsorption/purification medium with high capacity and high throughput

Due to recent advances in the production of biotherapeutics, high capacity, high throughput adsorption media for efficient and economic separation of these medically important products are in great demand. One option that has been evaluated extensively is membrane/mat adsorption. While these media allow for rapid adsorption (due to the decreased internal diffusion) and high throughput processing (due to the open porous structure), they often suffer from low capacity and poor enrichment factors. Herein, we report the fabrication, characterization, and protein adsorption evaluation of an innovative type of membrane/mat adsorption media based on electrospun carbon nanofibers. By surface-functionalization of these nanofibers with a weak acid cation-exchange ligand, the capacity was doubled for binding a model protein (i.e., lysozyme) compared to commercial products; and the capacity value was over 200 mg lysozyme per gram of adsorption media. Meanwhile, the thin nanofibers (having diameters of ~300 nm) along with open pores among nanofibers in the mats (having sizes of ~10-15 μm) allowed for higher operating flow rates and lower pressure drops. Furthermore, the incorporation of higher ligand density and the addition of a non-ionic surfactant (i.e., Triton X-305) into the adsorption buffer eliminated the non-specific binding of a competing protein (bovine serum albumin). In combination, this study suggested that electrospun carbon nanofiber adsorption media would provide a promising alternative to packed resin beds for bioseparations.

Adsorption of Cu 2+ on new hyper-crosslinked polystyrene adsorbent: Batch and column studies

In this paper, a new hyper-crosslinked polystyrene adsorbent WJN-101 for removal of Cu 2+ from the water was prepared and its adsorption capacity was tested by using the commercial resins IRC-84 and D-110 as references. The higher uptake capacity of Cu 2+ by WJN-101 was achieved at higher pH values, and the lower uptake capacity was observed in an acidic medium. When the temperature was raised within the range of 278–308 K, the adsorption enthalpy changes of WJN-101were about from 22.24 to 28.89 kJ mol −1, and the free energy changes were about from −5.71 to −5.90 kJ mol −1. The batch kinetic study indicated that the adsorption of Cu 2+ could be well fitted by the pseudo-second-order equation, suggesting intra-particle diffusion process as the rate-limiting step of the adsorption process. By using the Elovich equation, the initial adsorption rates of Cu 2+ onto three investigated resins were calculated, which was 11.50, 2.46, and 9.88 mg (g min) −1 of WJN-101, IRC-84 and D-110, respectively. The column adsorption data of Cu 2+ on WJN-101 could be well fitted by the Thomas model, and it could be employed for the designing of adsorption columns over a range of feasible flow rates and resin bed height successfully. 2% HCl solution could be used as effective eluant to desorb the Cu 2+ adsorbed by WJN-101.

Dispersive mixing and intraparticle partitioning of protein in size-exclusion chromatographic refolding

Refolding enables bioprocesses predicated on proteins expressed as inclusion bodies in Escherichia coli. Optimization of size-exclusion chromatography (SEC) refolding is a significant challenge because a wide range of factors, including the choice of gel media, the column dimensions and configuration, affect the final yield in a protein-specific manner. In this study, we investigated these factors by relating them to dispersive mixing and partitioning of refolding molecules within the SEC pore structure. Lysozyme was refolded using SEC resins giving different column dispersion and chromatography resolution. Despite a low separation resolution, the desalting SEC resin Sephadex G-25 resulted in a refolding yield that was 12–30% higher than those obtained with Superdex 75 and Superdex 200. This finding supported the notion that SEC refolding was enhanced by dispersive mixing, which was increased by a wide particle size distribution of the Sephadex G-25 used. Column dispersion was further improved by strategically placing an inlet gap before the packed resin beds, leading to a 20% increase in refolding yield. Refolding yield in Superdex 75 was 20% higher than that in Superdex 200 under conditions giving similar dispersive mixing. This yield enhancement is expected to be protein-specific since Superdex 75 was chosen to specifically maximize partitioning of lysozyme molecules within the resin particles, reducing the likelihood of aggregation during refolding. The highest refolding yield (65%) was achieved using a Sephadex G-25 column with a 15 mm inlet gap, suggesting that desalting systems optimized for dispersive mixing might be an economical and generic alternative for preparative SEC protein refolding.

Role of MbtH-like Proteins in the Adenylation of Tyrosine during Aminocoumarin and Vancomycin Biosynthesis

MbtH-like proteins consist of ∼70 amino acids and are encoded in the biosynthetic gene clusters of non-ribosomally formed peptides and other secondary metabolites derived from amino acids. Recently, several MbtH-like proteins have been shown to be required for the adenylation of amino acid in non-ribosomal peptide synthesis. We now investigated the role of MbtH-like proteins in the biosynthesis of the aminocoumarin antibiotics novobiocin, clorobiocin, and simocyclinone D8 and of the glycopeptide antibiotic vancomycin. The tyrosine-adenylating enzymes CloH, SimH, and Pcza361.18, involved in the biosynthesis of clorobiocin, simocyclinone D8, and vancomycin, respectively, required the presence of MbtH-like proteins in a 1:1 molar ratio, forming heterotetrameric complexes. In contrast, NovH, involved in novobiocin biosynthesis, showed activity in the absence of MbtH-like proteins. Comparison of the active centers of CloH and NovH showed only one amino acid to be different, i.e. Leu-383 versus Met-383. Mutation of this amino acid in CloH (L383M) indeed led to MbtH-independent adenylating activity. All investigated tyrosine-adenylating enzymes exhibited remarkable promiscuity for MbtH-like proteins from different pathways and organisms. YbdZ, the MbtH-like protein from the expression host Escherichia coli, was found to bind to adenylating enzymes during expression and to influence their biochemical properties markedly. Therefore, the use of ybdZ-deficient expression hosts is important in biochemical studies of adenylating enzymes.

Analyses of fuel crud and coolant-borne corrosion products in normal water chemistry BWRs

The samples of crud removed from the surface of fuel rods and corrosion products sampled by filtration of condensate and feed water in three boiling water reactors (BWR) operating at normal water chemistry (NWC) were analyzed using 57Fe Mössbauer spectroscopy. The corrosion products concentration and phase composition was examined in filter membranes exposed to influent and effluent of condensate polishing resin beds, as well as to final feed water. The brushed and scraped portions of fuel crud extracted from fuel rods during refueling outage comprised mostly hematite, α-Fe 2O 3, and submicron-sized goethite particles, α-FeOOH, in weight ratio similar to that observed in feed water. The observed phases are consistent with the oxidizing water chemistry of NWC BWRs. The feasibility of identifying other iron oxides and oxyhydroxides, as well as copper and zinc bearing phases in corrosion products from BWRs is briefly discussed. The results of this work can be used to better understand and minimize iron transport and crud deposition on fuel rods in BWRs.

Removal of oil from oil-in-water emulsion using a packed bed of commercial resin

The present study reports the removal of oil from oil-in-water (o/w) emulsion using a commercial resin which is a co-polymer of styrene and di-vinyl benzene. The stability of the 0.05% (w/w) o/w emulsion was investigated for different surfactant concentrations (0.25–4%), mixing time (5–60 min) and stirring rate (500–2500 rpm). The emulsion stability was estimated by measuring the relative volume of emulsion after 24 h of the preparation of emulsion and the zeta potential. 1% of surfactant, 18 min of mixing time and 2000 rpm stirring were found to be the optimum conditions for the most stable emulsions. A series of experiments were performed to investigate the effect of such parameters as influent oil concentration (30–500 mg/dm 3), bed height (30–100 mm) and flow rate (10–20 dm 3/h) on the oil removal efficiency of the resin. More than 89% of emulsified oil was removed under optimal operating conditions: 10 dm 3/h flow velocity, 75 mm bed height, and 500 mg/dm 3 influent concentration of oil in the o/w emulsion. SEM and FTIR results indicate that the hydrogen bonding and hydrophilic interaction were the principal driving forces for the adhesion of oil onto the polymeric resin surfaces. The results indicated that the resin is very effective in removing oil from o/w emulsion.

Solid phase extraction with flame atomic absorption spectrometry for determination of traces of Ca, K, Mg and Na in quality control of white sugar

A fast and straightforward pre-concentration procedure based on solid phase extraction with a strongly acidic cation-exchanger Dowex 50 W × 8–400 was proposed to determine traces of Ca, K, Mg and Na in white sugar samples by means of flame atomic absorption spectrometry. For this purpose, 20% (m/v) white sugar solutions (100 ml) were driven through resin beds at 10 ml min −1 to retain Ca, K, Mg and Na ions and to separate sucrose that passed through unretained. Thereafter, columns were rinsed with water and elements of interest were recovered prior to measurements using 5 ml of a 2 mol l −1 HCl solution. Detection limits of 0.04, 0.05, 0.02 and 0.01 μg g −1 for Ca, K, Mg and Na, respectively, and precision of measurements within 1–3% were achieved. The proposed method enabled to determine Ca, K, Mg and Na in samples of white sugar within corresponding ranges: 0.66–0.99 μg g −1 (Ca), 2.9–12.2 μg g −1 (K), 0.53–1.57 μg g −1 (Mg) and 0.06–0.30 μg g −1 (Na). Accuracy of this sample pre-treatment procedure and analysis method was assessed by performing spikes and recovery experiments. Recoveries of added Ca, K, Mg and Na were found to be within 97–102%, demonstrating good reliability of results.

Numerical Modeling of Flow in the Condensate Polisher Vessel of a Nuclear Reactor, with Applications to PVNGS

The flow distribution in a condensate demineralizer vessel of a nuclear power plant is studied using the computational fluid dynamics (CFD) approach. The model simulates the flow through the packed resin bed installed in the vessel as well as the exit of flow through the porous resin retention assembly at the bottom of the vessel. The computational model is subsequently revised to assess the impact of a proposed modification to the retention assembly to enhance drainage of the vessel and minimize unwanted resin separation during resin bed regeneration. The subject model has been developed using the ANSYS ICEM CFD meshing tool and the FLUENT 6.3 CFD software as well as associated postprocessing tools. Comparisons of flow patterns in the vessel resin beds prior to and with the modification demonstrate a sharp increase in the flow rate at the end walls of the vessel, thus resulting in accelerated depletion of resin in high-velocity areas and nonuniform consumption of resin inventory. The computational results are also compared with a theoretical analysis of the basic process.

Ion and ionic current sinks for electrodeionization of simulated cadmium plating rinse waters

AbstractIn this study, electrostatic shielding zones made of electrode graphite powder were constructed and used as a new type of ionic and electronic current sinks. Because of the local elimination of the applied electric field, voltage, and current within these zones, ions are led inside them and accumulate there. The current sinks were implemented in electrodeionization of simulated cadmium plating rinse waters containing 50 mg/L of Cd2+ ions with simultaneous electrochemical regeneration of the ion exchange resin beds. Pure water was obtained with a Cd2+ ion concentration of less than 0.1 mg/L at a flow rate of 3.27 × 10−4 L/s diluate stream, a current density of 2 mA/cm2, and a current efficiency of 28% for Cd2+ ion removal. © 2010 American Institute of Chemical Engineers Environ Prog, 2011

Study on Performances and its Structural Designing of the High-Speed CNC Lathe Epoxy Resin Concrete Bed

The epoxy resin concrete is one of high performance composite materials used to the basic parts of machine tool and measuring instruments. Based on the study of related technologies at home and abroad, technical route and manufacturing process on the development of machine tool bed have been proposed. The epoxy resin concrete material self developed and results of its performances testing are introduced, and they are contrasted with cast iron material. The high-speed CNC lathe was taken as example which characteristic of the epoxy resin concrete bed structural design has been explained in this paper. The cast iron bed and epoxy resin concrete bed of the high-speed CNC lathe has respectively been analyzed and contrasted by finite element method. At last, the performances of epoxy resin concrete bed exceeding to cast iron bed have been educed.

Use of mixed ion exchange resin and the denitrifier method to determine isotopic values of nitrate in atmospheric deposition and canopy throughfall

Abstract The objective of this study was to test a technique that utilizes mixed bed resins and the denitrifier method to determine δ15N and δ18O of nitrate inputs under varying conditions found in the field. Temperature increases and greater loading of nitrogen led to significant increases in δ18O values and longer incubation times led to significant increases in δ15N values, but the changes were relatively small. Results of our study confirm that mixed ion exchange resin can be used to accurately measure natural abundance isotopic values of nitrate in samples of atmospheric deposition and throughfall. However, we also conclude that caution should be applied when using these mixed bed resins in the field if they will be exposed to high temperatures (e.g., >40 °C). This method can increase the feasibility of conducting high density sampling of stable isotopes in atmospheric deposition and canopy throughfall samples with the goal of identifying sources of nitrate, and thus represents an important methodological advance for ecosystem science.