Combination Of Ion Exchange Research Articles

Selective Recovery of Precious Metals from Acidic Leach Liquor of Circuit Boards of Spent Mobile Phones Using Chemically Modified Persimmon Tannin Gel

A tannin-based novel adsorbent, named “BTU-PT gel”, was prepared by immobilizing bisthiourea (BTU) ligand on persimmon tannin (PT) extract. The adsorption behaviors of precious metal ions along with other coexisting base metal ions onto BTU-PT gel were studied by batch and continuous column methods. The gel exhibited remarkable selectivity for precious metal ions such as Au(III), Pd(II), and Pt(IV) over base metal ions such as Cu(II), Fe(III), Ni(II), and Zn(II) in 1–5 mol dm–3 hydrochloric acid. The adsorption of precious metal ions on the present gel was found to obey the typical monolayer type of Langmuir model, and the maximum adsorption capacity of the adsorbent was evaluated as 5.18 mol kg–1 for Au(III), 1.80 mol kg–1 for Pd(II), and 0.67 mol kg–1 for Pt(IV). Combination of ion exchange, electrostatic interaction, and coordination through the thiocarbonyl group is the mechanism of adsorption of precious metals on BTU-PT gel. In the case of Au(III) adsorption, the adsorbed species was simultaneously ...

Purification and IgE-binding properties of soybean β-conglycinin subunits

The purpose of this study was to purify soybean β-conglycinin subunits and analyze their IgE-binding properties with IgE immunoblotting and their response in a basophil histamine release test. The method presented in this paper offers an effective procedure to purify β-conglycinin subunits with higher yield and purity compared with previous methods by using a combination of ion exchange and metal chelate affinity chromatography. Beginning with a column load of 600mg β-conglycinin, the new method yielded 100.4mg of protein containing 96.7% α subunit, 97.0mg of protein containing 91.6% α′ subunit and 89.4mg of protein containing 96.1% β subunit. All of the purified subunits of β-conglycinin reacted with IgE from sera of soybean-allergic patients and induced dose-dependent histamine release from basophils from these patients, suggesting that purified α, α′, and β subunits of β-conglycinin retained allergenic activity and could be used for in vitro and in vivo diagnosis of soybean-induced food allergy.

Electrochemical characterization of a supercapacitor flow cell for power production from salinity gradients

Salinity gradients could be a great source of energy in the future. Capacitive energy extraction based on Donnan Potential (CDP) is a new technique to directly convert this energy into electricity. CDP uses a supercapacitor-like device combining ion exchange membranes and capacitive materials to adsorb and desorb ions with the Donnan Potential of the membranes as only driving force. The resulting current can be extracted through an external load. In this study, traditional electrochemical techniques: galvanostatic charge–discharge and cyclic voltammetry were used to investigate intrinsic properties of this open system. This study demonstrates the feasibility to characterize the capacitive behavior of the cell in low concentration (0.5M). Presence of membranes, as well as the possibility of having the electrolyte flowing through the cell was investigated. In the studied cell, the presence of membranes showed a limitation by the anion exchange membrane at low current densities but no effect at high current densities. The flow rate did not influence the capacitance of the system either.

Characterization of anα-amylase from sorghum (Sorghum bicolor) obtained under optimized conditions

Sorghum malt α-amylase can compete with bacterial α-amylase in industrial applications, if sufficiently stable and produced in a large enough quantity. Conditions for maximal α-amylase production in sorghum malt and the physico-chemical properties of the α-amylase so produced are reported in this study. Sorghum grains were steeped in buffers with varying pH (4.0–8.0) for 24 h, at room temperature, and germinated for another 48 h to obtain the green malt. The buffer that induced the highest quantity of α-amylase was chosen as the optimal pH and served as the medium for further steeping experiments conducted at different temperatures (10, 20, 30, 40, 50 and 60°C). The α-amylase activity in the extract was determined in order to obtain the optimum temperature for α-amylase induction at this particular pH. For the purpose of comparison, the α-amylase produced at the optimum pH and temperature was purified to apparent homogeneity by a combination of ion-exchange and size-exclusion chromatography, and further characterized. Eight-fold higher α-amylase activity was induced in pH 6.5 buffer at 20°C compared with water, the traditional steeping medium. The Km and Vmax were estimated to be 1.092 ± 0.05 mg mL−1 and 3516 ± 1.981 units min−1, respectively. The activation energy of the purified amylase for starch hydrolysis was 6.2 kcal K−1 mol−1. Chlorides of calcium and manganese served as good activators, whereas CuSO4 inhibited the enzyme with a 42% loss in activity at 312 mm salt concentration. Copyright © 2012 The Institute of Brewing & Distilling

Purification and physicochemical characterization of a serine protease with fibrinolytic activity from latex of a medicinal herb Euphorbia hirta

A 34kDa serine protease, designated as hirtin, with fibrinolytic activity was purified to homogeneity from the latex of Euphorbia hirta by the combination of ion exchange and gel filtration chromatography. The N-terminal sequence of hirtin was found to be YAVYIGLILETAA/NNE. Hirtin exhibited esterase and amidase activities along with azocaseinolytic, gelatinolytic, fibrinogenolytic and fibrinolytic activities. It preferentially hydrolyzed Aα and α-chains, followed by Bβ and β, and γ and γ-γ chains of fibrinogen and fibrin clot respectively. The optimum pH and temperature for enzyme activity was found to be pH 7.2 and 50°C respectively. Enzymatic activity of hirtin was significantly inhibited by PMSF and AEBSF. It showed higher specificity for synthetic substrate p-tos-GPRNA for thrombin. The CD spectra of hirtin showed a high content of β-sheets as compared to α-helix. The results indicate that hirtin is a thrombin-like serine protease and may have potential industrial and therapeutic applications.

Transport of Indium, Gallium and Thallium Metal Ions Through Chromatographic Fiber Supported Solid Membrane in Acetylacetone Containing Mixed Solvents

The transport of metal ions of indium, gallium and thallium from source solution to receiving phase through the chromatographic fiber supported solid membrane in the acetylacetone (HAA) containing mixed solvent system has been explored. The fibers supported solid membranes were prepared with chemical synthesis from cellulose fibers and citric acid with the carboxylic acid ion exchange groups introduced. The experimental variables, such as concentration of metal ions (10 −2 to 10 −4 mol·L −1) in the source solution, mixed solvent composition [for example, acetylacetone, (2,4-pentanedione), (HAA) 20% (by volume), 1,4-dioxane 10% to 60% and HCl 0.25 to 2 mol·L −1] in the receiving phase and stirring speed (50–130 r·min −1) of the bulk source and receiving phase, were explored. The efficiency of mixed solvents for the transport of metal ions from the source to receiving phase through the fiber supported solid membrane was evaluated. The combined ion exchange solvent extraction (CIESE) was observed effective for the selective transport of thallium, indium and gallium metal ions through fiber supported solid membrane in mixed solvents. The oxonium salt formation in the receiving phase enhances thallium, indium and gallium metal ion transport through solid membrane phase. The selective transport of thallium metal ions from source phase was observed from indium and gallium metal ions in the presence of hydrochloric acid in organic solvents in receiving phase. The separation of thallium metal ions from the binary mixtures of Be(II), Ti(IV), Al(III), Ca(II), Mg(II), K (I), La(III) and Y(III) was carried out in the mixed solvent system using cellulose fiber supported solid membrane.

Isolation and characterization of BetaM protein encoded by ATP1B4 – a unique member of the Na,K-ATPase β-subunit gene family

ATP1B4 genes represent a rare instance of the orthologous gene co-option that radically changed functions of encoded BetaM proteins during vertebrate evolution. In lower vertebrates, this protein is a β-subunit of Na,K-ATPase located in the cell membrane. In placental mammals, BetaM completely lost its ancestral role and through acquisition of two extended Glu-rich clusters into the N-terminal domain gained entirely new properties as a muscle-specific protein of the inner nuclear membrane possessing the ability to regulate gene expression. Strict temporal regulation of BetaM expression, which is the highest in late fetal and early postnatal myocytes, indicates that it plays an essential role in perinatal development. Here we report the first structural characterization of the native eutherian BetaM protein. It should be noted that, in contrast to structurally related Na,K-ATPase β-subunits, the polypeptide chain of BetaM is highly sensitive to endogenous proteases that greatly complicated its isolation. Nevertheless, using a complex of protease inhibitors, a sample of authentic BetaM was isolated from pig neonatal skeletal muscle by a combination of ion-exchange and lectin-affinity chromatography followed by SDS–PAGE. Results of the analysis of the BetaM tryptic digest using MALDI-TOF and ESI-MS/MS mass spectrometry have demonstrated that native BetaM in neonatal skeletal muscle is a product of alternative splice mRNA variant B and comprised of 351 amino acid residues. Isolated BetaM protein was also characterized by SELDI-TOF mass spectrometry before and after deglycosylation. This allowed us to determine that the carbohydrate moiety of BetaM has molecular mass 5.9kDa and consists of short high-mannose type N-glycans. The results of direct analysis of the purified native eutherian BetaM protein provide first insights into structural properties underlying its entirely new evolutionarily acquired functions.

Recovery of americium from analytical solid waste containing large amounts of uranium, plutonium and silver

Trace metallic impurity analysis by spectroscopic techniques is one of the important steps of chemical quality control of nuclear fuel materials. Depending on the burn-up and the storage time of the fuel, there is an accumulation of 241Am in plutonium based fuel materials due to β decay of 241Pu. In this paper, attempts were made to develop a method for separation of 241Am from 1.2 kg of analytical solid waste containing 70% U, 23% Pu, 5% Ag and 1–2% C as major constituents along with other minor constituents generated during trace metal assay of plutonium based fuel samples by d. c. arc carrier distillation atomic emission spectrometry. A combination of ion exchange, solvent extraction and precipitation methods were carried out to separate ~45 mg of 241Am as Am(NO3)3 from 15 L of the analytical waste solution. Dowex 1×4 ion exchange chromatographic method was used for separation of Pu whereas 30% TBP–kerosene was utilized for separation of U. Am was separated from other impurities by fluoride precipitation followed by conversion to nitrate. The recovery of Pu from ion exchange chromatographic separation step was ~93% while the cumulative recovery of Am after separation process was found to be ~90%.

Strategy for purification of aggregation prone β-glucosidases from the cell wall of yeast: a preparative scale approach

Purification of biotechnologically important proteins is of vital interest to the biotech industry. β-Glucosidases, belonging to Family 1 and Family 3 of the glycosylhydrolases, have varied applications as carbohydrate hydrolyzing and synthesizing enzymes. Obtaining high quantities of these enzymes is important for exploring their biosynthetic potential, structural information and catalytic activities. Classical methods for their preparation fail to deliver high yields because of adoption of several/hydroxyapatite chromatography steps. We report here a preparative method for purification of large quantities of two closely related cell bound β-glucosidases (BGL I and BGL II) from Pichia etchellsii that belong to Family 3 glycosylhydrolases. A combination of ion-exchange and gel filtration chromatography was used to process milligram quantities of protein with recoveries of up to 53%. A simple affinity based separation resulted in resolution of BGL I and BGL II with high recovery and high specific activities of 74IU/mg and 32IU/mg protein respectively. Peptide sequences of BGL II indicated it to be a novel member of Family 3. Methods reported here present a successful strategy for obtaining large quantities of these enzymes.

Separation of Sr in combination of ion exchange and Sr resin with alcohol-nitric acid solution and rapid determination of 90Sr in wine and soil samples

This paper describes the procedures of isolating strontium from wine and soil samples which enable creating of procedure for rapid determination of 90Sr. The method of determination of 90Sr includes binding of Sr on the cationic exchanger IR-120 from the sample and simultaneous elution from the cation column and binding on the Sr column, separation of Sr on Sr resin with HNO3 even in presence of alcohols and subsequent Cherenkov counting. Sr can be efficiently bind on Sr resin and separated from the other elements with lower acid concentrations in the presence of a low portion of alcohol, or even from a wine sample without the loss of Sr resin capacity. The binding strength of Sr on Sr resin decreases with the rising of HNO3 concentration (1–5 M) in the presence of 13% of ethanol or methanol, and with the rising of the alcohol portion in constant concentration of HNO3. Application of cation exchanger for Sr binding in phase of sample preparation decreases Sr column loading and improve Sr recovery. The method allows the determination of 90Sr activities in wine and soil sample lower than 10 mBq in reasonable time.

ВЛИЯНИЕ ПРИРОДЫ И СВОЙСТВ РАСТВОРИТЕЛЯ НА СТЕПЕНЬ ИЗВЛЕЧЕНИЯ ЙОДА ИЗ РАЗЛИЧНЫХ МИНЕРАЛЬНЫХ ИСТОЧНИКОВ

The paper discusses the results of our studies on the effect of the nature and concentration of solvent on the extraction of iodine from various iodine-containing sources. Ion exchange in combination with liquid-phase emulsion membrane extraction is proposed as a technique for extraction of iodine ion. The obtained data allow us to make an informed choice of the system: extractant – solvent.

Ion-exchange–ultrafiltration system for surfactants removal from water solutions

Studies were performed to determine the effectiveness of hybrid system combining ion exchange and ultrafiltration for surfactant separation from water solutions. During the experiments the influnce of membrane cut-off, type of ion-exchange resin, resin dose and contact time was evaluated. The results obtained for the hybrid system were also compared with the effectiveness of the single processes, i.e. ultrafiltration and ion exchange. It was found that the combination of ion exchange and ultrafiltration was more effective in surfactant removal than ultrafiltration process alone. In the hybrid system because of the resin presence, the systematic increase in surfactant separation along with the filtration time was noticed. From among the ion-exchange resins tested the most effective was MIEX® one. For the smallest resin dose equal to 5 cm3/dm3 the reduction of anionic surfactants from model solution with concentration of 0.25 CMC reached almost 100% for the hybrid process with 30 kDa polyethersulfone membra...

Purification and characterization of the plasmodial phosphatase that hydrolyses the phosphorylated light chain ofPhysarummyosin II fromPhysarum polycephalum

A phosphatase was purified through a combination of ion-exchange and hydrophobic chromatography followed by native PAGE from Physarum plasmodia. Recently, we demonstrated that this phosphatase isoform has a hydrolytic activity towards the PMLC (phosphorylated light chain of Physarum myosin II) at pH 7.6. The apparent molecular mass of the purified enzyme was estimated at approximately 50 kDa by means of analytical gel filtration. The enzyme was purified 340-fold to a final phosphatase activity of 400 pkat/mg of protein. Among the phosphorylated compounds tested for hydrolytic activity at pH 7.6, the enzyme showed no activity towards nucleotides. At pH 7.6, hydrolytic activity of the enzyme against PMLC was detected; at pH 5.0, however, no hydrolytic activity towards PMLC was observed. The Km of the enzyme for PMLC was 10 microM, and the V(max) was 1.17 nkat/mg of protein. Ca(2+) (10 microM) inhibited the activity of the enzyme, and Mg(2+) (8.5 microM) activated the dephosphorylation of PMLC. Mn(2+) (1.6 microM) highly stimulated the enzyme's activity. Based on these results, we concluded that the enzyme is likely to be a phosphatase with hydrolytic activity towards PMLC.

A novel annexin A2 protein with platelet aggregation-inhibiting activity from amphibian Bombina maxima skin

Annexin A2 is a unique member of annexin family with multi-functions in membrane physiology, implicated in inflammation and cancer progression. mRNA of Annexin A2 is abundant in the skin of some amphibians. However, no annexin A2 protein has been isolated and characterized from amphibian skin. In this report, a novel annexin A2 protein with apparent molecular weight of 33 kDa and named Bm-ANXA2, was purified from frog Bombina maxima skin, which is highly toxic to mammals, by a combination of ion exchange and gel filtration chromatography. A full-length cDNA encoding the protein was obtained from the cDNA library constructed from the frog skin. Sequence analysis indicates that Bm-ANXA2 shares 89% and 80% amino acid sequence identities with those of Xenopus and human annexin A2, respectively. Different from other annexin A2 proteins, the N-terminal 26 amino acids of Bm-ANXA2 were truncated. Bm-ANXA2 dose-dependently inhibited human platelet aggregation stimulated by various agonists in a Ca 2+-dependent manner. It bound to activated platelets and significantly inhibited α IIbβ 3 activation and α-granular secretion. This is the first report that an annexin A2 protein possesses platelet aggregation-inhibiting activity, providing novel clues in the illustration of pathophysiological roles of annexin A2 proteins.

Extracellular expression and biochemical characterization of α-cyclodextrin glycosyltransferase from Paenibacillus macerans

The cgt gene encoding α-cyclodextrin glycosyltransferase (α-CGTase) from Paenibacillus macerans strain JFB05-01 was expressed in Escherichia coli as a C-terminal His-tagged protein. After 90 h of induction, the activity of α-CGTase in the culture medium reached 22.5 U/mL, which was approximately 42-fold higher than that from the parent strain. The recombinant α-CGTase was purified to homogeneity through either nickel affinity chromatography or a combination of ion-exchange and hydrophobic interaction chromatography. Then, the purified enzyme was characterized in detail with respect to its cyclization activity. It is a monomer in solution. Its optimum reaction temperature is 45 °C, and half-lives are approximately 8 h at 40 °C, 1.25 h at 45 °C and 0.5 h at 50 °C. The recombinant α-CGTase has an optimum pH of 5.5 with broad pH stability between pH 6 and 9.5. It is activated by Ca 2+, Ba 2+, and Zn 2+ in a concentration-dependent manner, while it is dramatically inhibited by Hg 2+. The kinetics of the α-CGTase-catalyzed cyclization reaction could be fairly well described by the Hill equation.

Combined ion exchange treatment for removal of dissolved organic matter and hardness

Dissolved organic matter (DOM) and hardness cations are two common constituents of natural waters that substantially impact water treatment processes. Anion exchange treatment, and in particular magnetic ion exchange (MIEX), has been shown to effectively remove DOM from natural waters. An important advantage of the MIEX process is that it is used as a slurry in a completely mixed flow reactor at the beginning of the treatment train. Hardness ions can be removed with cation exchange resins, although typically using a fixed bed reactor at the end of a treatment train. In this research, the feasibility of combining anion and cation exchange treatment in a single completely mixed reactor for treatment of raw water was investigated. The sequence of anion and cation exchange treatment, the number of regeneration cycles, and the chemistry of the regeneration solution were systematically explored. Simultaneous removal of DOM (70% as dissolved organic carbon) and hardness (>55% as total hardness) was achieved by combined ion exchange treatment. Combined ion exchange is expected to be useful as a pre-treatment for membrane systems because both DOM and divalent cations are major foulants of membranes.

Purification of an L-amino acid oxidase from Bungarus caeruleus (Indian krait) venom

Snake venoms are rich in enzymes such as phospholipase A2, proteolytic enzymes, hyaluronidases and phosphodiesterases, which are well characterized. However, L-amino acid oxidase (LAO EC.1.4.3.2) from snake venoms has not been extensively studied. A novel L-amino acid oxidase from Bungarus caeruleus venom was purified to homogeneity using a combination of ion-exchange by DEAE-cellulose chromatography and gel filtration on Sephadex® G-100 column. The purified monomer of LAO showed a molecular mass of 55 ±1 kDa estimated by SDS-PAGE. The specific activity of purified LAO was 6,230 ± 178 U/min/mg, versus 230 ± 3.0 U/min/mg for the whole desiccated venom, suggesting a 27-fold purification with a 25% yield. Optimal pH and temperature for maximum purified enzyme activity were 6.5 and 37ºC, respectively. Platelet aggregation studies show that purified LAO inhibited ADP-induced platelet aggregation dose-dependently at 0.01 to 0.1 µM with 50% inhibitory concentration (IC50) of 0.04 µM, whereas at a 0.08 µM concentration it did not induce appreciable aggregation on normal platelet-rich plasma (PRP). The purified protein catalyzed oxidative deamination of L-amino acids while the most specific substrate was L-leucine. The purified LAO oxidizes only L-forms, but not D-forms of amino acids, to produce H2O2. The enzyme is important for the purification and determination of certain amino acids and for the preparation of α-keto acids.

Rhamnogalacturonan I domains from ginseng pectin

Five rhamnogalacturonan I (RG-I) domains RG-I-1, RG-I-2, RG-I-3A, RG-I-3B and RG-I-4 were isolated from ginseng pectin by endo-polygalacturonase hydrolysis and a combination of ion-exchange and gel-permeation chromatography. The five domains all contain galacturonic acid, rhamnose, galactose and arabinose as main components and their rhamnose/galacturonic acid is from 0.26 to 0.64, among the range of RG-I. The molecular weights of RG-I-1 (5 kDa), RG-I-2 (4 kDa) and RG-I-3B (6 kDa) are smaller than those of RG-I-3A (45 kDa) and RG-I-4 (60 kDa). 13C NMR spectra of all domains showed RG-I features. RG-I-2 and RG-I-3B contained RG-I domains linked with highly methyl-esterified and acetylated homogalacturonan domains and the side chains probably belonging to type I and type II arabinogalactans, while RG-I-3A and RG-I-4 may have the side chains of type I arabinogalactans. 4-O-methyl-β- d-glucuronic acid residues were present at non-reducing terminals of RG-I-2.

Purification and characterization of β-agarase from agar-liquefying soil bacterium, Acinetobacter sp., AG LSL-1

The extracellular β-agarase LSL-1 produced by an agar-liquefying, soil bacterium Acinetobacter sp., AG LSL-1 was purified to homogeneity by combination of ion-exchange and size exclusion chromatography with final yield of 44%. The enzyme has a specific activity of 397 U mg −1 protein and with a molecular mass of 100 kDa. The agarase was active in the pH range of 5.0–9.0, optimally at pH 6.0 and temperature between 25 °C and 55 °C and optimal at 40 °C. The enzyme retained 63% of native activity at 50 °C suggesting it is a thermostable. The activity of the agarase was completely inhibited by metal ions, Hg 2+, Ag + and Cu 2+, whereas 25–40% of native activity was retained in the presence of Zn 2+, Sn 2+ and SDS. Neoagarobiose was the final product of hydrolysis of both agarose and neoagarohexaose by the purified agarase LSL-1. Based on the molecular mass and final products of agarose hydrolysis, the β-agarase LSL-1 may be further grouped under group III β-agarases and may be a member of GH-50 family. This is the first report on the purification and biochemical characterization of β-agarase from an agar-liquefying Acinetobacter species.

Acid groundwater in an anoxic aquifer: Reactive transport modelling of buffering processes

Abstract The acidification of groundwater, due to acid rain, was investigated in a Quaternary sandy aquifer in the Fuhrberger Feld, near Hannover, Germany. The groundwater, recharged through an area covered by a coniferous forest, had a pH in the range 4–5 down to a depth of 5 m. The evolution in groundwater chemistry along the flow path was investigated in a transect of multisamplers. A 2D groundwater flow model was established delineating the groundwater flow field and a groundwater flow velocity of around 80 m/a along the flow path was derived. Speciation calculations showed the groundwater to be close to equilibrium with the mineral jurbanite (AlOHSO4) over the pH range 4.0–6.5. This suggests an accumulation of acid rain derived SO 4 2 - in the aquifer sediment during the decades with high atmospheric S deposition. The groundwater has a pH of around 4.5 in the upstream part of the flow path increasing to near 6 further downstream. 1D reactive transport modelling, using PHREEQC, was used to analyze different combinations of buffering processes. The first model contains ion exchange in combination with jurbanite dissolution. At the ion exchange front Al3+ is adsorbed leading to the dissolution of jurbanite and an increase in pH. Comparison with field data showed that the simulated increases in pH and alkalinity are much lower than observed in the field. The second model includes organic matter degradation. In addition to ion exchange and jurbanite dissolution, the model included the reduction of SO 4 2 - and Fe-oxides as well as the precipitation of Fe sulfide. This model matches the field data well and illustrates the importance of redox processes for pH buffering in the Fuhrberg aquifer. The current progress of the acidification front is about 4 m/a. This corresponds to an average value of 150 a of acid input, which covers large historical variations. Remediation is expected to take the same time span because it requires desorption and neutralization of adsorbed Al3+ from the aquifer sediment.