Chelating Agent Ethylenediaminetetraacetic Acid Research Articles

The release and extraction of lanthanide ions from metal-encoded poly (styrene-co-methacrylic acid) microspheres

This article describes a systematic study of ion release, carried out on lanthanide-encoded polystyrene-co-methacrylic acid (P(S-MAA)) and polystyrene-co-acrylic acid (P(S-AA)) copolymer particles, which were synthesized by two-stage or three-stage dispersion polymerizations. These particles with different levels of lanthanide (Ln) ion content and containing several different types of Ln ions were dispersed in normal buffer media, namely 2-(N-morpholino)ethanesulfonic acid (MES), phosphate buffered saline solution (PBS), ammonium acetate (AmAc) and buffers containing strong chelating molecules like ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA). Traditional inductively coupled plasma mass spectrometry (ICP-MS) was employed to follow the loss of ions into the aqueous medium as a function of time. The release behavior of the Ln ions were compared. In MES and PBS buffers at neutral pH, and AmAc at pH 9.0, there was essentially no significant loss of Ln ions from the particles to the buffer. When the chelating agents EDTA or DTPA were present in the buffer, the loss of Ln ions was more prominent, but less than 15% after 8 weeks under stirring. The differences among the different samples were small. Considering the ability of EDTA and DTPA to remove Ln ions from the particles and the fact of minimal ion release in the presence of PBS buffer, we infer that the ion loss is a more active process involving the EDTA or DTPA molecules. The main conclusion is that in the absence of strong chelating agents, these particles are stable against ion leakage, even upon prolonged storage and stirring. This is of great importance for their application in bead-array biological assays based on mass cytometry detection.

Soil washing of chromium- and cadmium-contaminated sludge using acids and ethylenediaminetetra acetic acid chelating agent

In this research, the effect of soil washing in the removal of chromium- and cadmium-contaminated sludge samples collected from Pond 2 of the Tehran Oil Refinery was investigated. These metals are considered as hazardous substances for human health and the environment. The carcinogenicity of chromate dust has been established for a long time. Cadmium is also a potential environmental toxicant. This study was carried out by collecting sludge samples from different locations in Pond 2. Soil washing was conducted to treat the samples. Chemical agents, such as acetic acid, ethylenediaminetetra acetic acid (EDTA) and hydrochloric acid, were used as washing solutions to remove chromium and cadmium from sludge samples. The results of this study indicated that the highest removal efficiencies from the sludge samples were achieved using a 0.3 M HCl solution with 82.69% and 74.47% for chromium and cadmium, respectively. EDTA (0.1 M) in the best condition extracted 66.81% of cadmium and 72.52% of chromium from the sludges. The lowest efficiency values for the samples, however, were achieved using 3 M acetic acid with 41.7% and 46.96% removals for cadmium and chromium, respectively. The analysis of washed sludge indicated that the heavy metals removal decreased in the order of 3 M acetic acid < 0.1 M EDTA<0.3 M HCl, thus hydrochloric acid appears to offer a greater potential as a washing agent in remediating the sludge samples.

Accumulation mechanisms and subcellular distribution of Cu in maize grown on soil treated with [S, S]-ethylenediamine disuccinic acid

Aims Many studies have proved that EDTA (ethylenediaminetetraacetic acid), EDDS ([S, S’]-ethylenediamine disuccinic acid), and other chelating agents significantly enhance phyto-extraction of copper (Cu) from soil. However, some key factors, such as changes in membrane permeability of root cells and subcellular distribution of Cu and Cu-EDDS complex in leaves and roots, remain unresolved.

Influence of Ethylenediaminetetraacetic Acid (EDTA) on the Structural Stability of Endoglucanase from Aspergillus aculeatus

The effect of the chelating agent ethylenediaminetetraacetic acid (EDTA) on the structure and function of endoglucanase is studied. In the presence of 2 mM EDTA, endoglucanase showed an enhanced enzymatic activity of 1.5-fold compared to control. No further change in activity was observed with increase in the concentration of EDTA to 5 mM. The K(m) values for control and in the presence of EDTA are 0.060 and 0.044%, respectively, and K(cat) was 1.9 min(-1) in the presence of EDTA. The kinetic parameters indicated a decrease in the K(m) with an increase in the K(cat). Far-ultraviolet circular dichroism (far-UV-CD) results showed a 20% decrease in ellipticity values at 217 nm in the presence of EDTA compared to native enzyme. The apparent T(m) shifted from a control value of 57 ± 1 to 76 ± 1 °C in the presence of EDTA (5 mM). The above results suggested that the enhanced activity in the presence of EDTA is due to an increase in the K(cat) and flexible conformation of the enzyme. The stability of endoglucanase increased in the presence of EDTA.

Nanoparticles reduce nickel allergy by capturing metal ions

Approximately 10% of the population in the USA suffer from nickel allergy, and many are unable to wear jewellery or handle coins and other objects that contain nickel. Many agents have been developed to reduce the penetration of nickel through skin, but few formulations are safe and effective. Here, we show that applying a thin layer of glycerine emollient containing nanoparticles of either calcium carbonate or calcium phosphate on an isolated piece of pig skin (in vitro) and on the skin of mice (in vivo) prevents the penetration of nickel ions into the skin. The nanoparticles capture nickel ions by cation exchange, and remain on the surface of the skin, allowing them to be removed by simple washing with water. Approximately 11-fold fewer nanoparticles by mass are required to achieve the same efficacy as the chelating agent ethylenediamine tetraacetic acid. Using nanoparticles with diameters smaller than 500 nm in topical creams may be an effective way to limit the exposure to metal ions that can cause skin irritation.

Molecular characterization of a serine protease Pro1 from Plasmodiophora brassicae that stimulates resting spore germination

Clubroot, caused by Plasmodiophora brassicae, is one of the most serious diseases of cultivated cruciferous crops in the world. However, the basis for pathogenicity in P. brassicae is not well understood. In this study, a serine protease gene (PRO1) was cloned from P. brassicae and its molecular characteristics were investigated. Southern analysis and specific polymerase chain reaction (PCR) amplification indicated that PRO1 is a single-copy gene present in a broad range of P. brassicae pathotypes. Northern analysis revealed that the expression of PRO1 was induced during plant infection, and that the quantity of transcript fluctuated according to the stage of pathogenesis. Amino acid sequence analysis suggested that the encoded protein (Pro1) belongs to the S28 family of proteases, with a predicted signal peptide and a theoretical molecular mass of 49.4 kDa. The open reading frame (ORF) of PRO1 was transferred into Pichia pastoris and Pro1 was heterologously produced. Pro1 showed proteolytic activity on skimmed milk and N-succinyl-Ala-Ala-Phe-7-amido-4-methylcoumarin, and the activity could be inhibited by serine protease inhibitors and the chelating agent ethylenediaminetetraacetic acid. The optimal temperature of Pro1 was 25 degrees C, and it exhibited high activity at pH 6.0-6.4. These values coincide with the temperature and pH conditions favourable for P. brassicae resting spore germination in the field. When Pro1 was used to treat canola root exudates, it enhanced the stimulating effect of the root exudates on P. brassicae resting spore germination, indicating that Pro1 may play a role during clubroot pathogenesis by stimulating resting spore germination through its proteolytic activity.

Effect of Fe(III) and Ca on Extraction of Pb from Contaminated Soils with Chelating Agents

The effect of Fe(III) and Ca as coexistent elements on the extraction of Pb from contaminated soils with the biodegradable chelating agent [S,S]-ethylenediaminedisuccinic acid (EDDS) and the low biodegradable chelating agent ethylenediaminetetraacetic acid (EDTA) was investigated as a series of studies for their applicability for the removal of Pb from contaminated soils by soil washing and electrokinetic processing. The results obtained in this study are summarized as follows: The extraction of Pb with EDTA is suppressed by Ca as coexistent elements at the pH above 7 and by Fe(III) as coexistent elements at acidic region. Meanwhile, the extraction of Pb with EDDS has no effect of Ca at the wide pH range. However, the extraction of Pb with EDDS is significantly suppressed by Fe(III) at the wide pH.

Effect of EDTA on the Growth Kinetics and Structural and Optical Properties of KDP Crystal

The solubility of potassium dihydrogen phosphate (KDP) was determined for five different temperatures. Metastable zone width of aqueous solutions of KDP saturated at different temperatures was determined by nucleation method in pure form and adding a well-known chelating agent ethylenediaminetetraacetic acid (0.5 mol% EDTA). The induction period was measured, experiments were performed at selected degrees of supersaturation (), and the critical nucleation parameters like interfacial energy () were calculated, based on the classical theory of nucleation. The structural and optical properties of the grown crystals have been investigated. FTIR analysis has been carried out to characterize the grown crystals. Band gap has been calculated from transmission spectra.

Bioavailability of Lead and Cadmium in Soils Artificially Contaminated with Smelter Fly Ash

This study evaluated lead and cadmium uptake by maize grown on soils artificially spiked with smelter fly ash and possible changes in chemical fractionation of these metals in the soil. Maize grown on the less contaminated soil (1,466 mg Pb kg(-1); 19 mg Cd kg(-1)) did not exhibit any chlorosis/necrosis symptoms or lower biomass yields compared to the control. The addition of the chelating agent ethylenediaminetetraacetic acid increased lead uptake by maize, as expected. Neither maize cultivation nor the addition of the chelant influenced significantly the chemical fractionation of lead and cadmium in the soil during the experiment.

An on-line electrodialyzer-ICP-MS analytical system for direct determination of trace metal impurities in KOH

We have developed an on-line electrodialysis system equipped with a cation-permeable membrane that, when coupled to an ICP mass spectrometer, provides a simple and sensitive hyphenated method for the determination of trace metal impurities in concentrated KOH. Because our proposed on-line electrodialysis method allows the quantitative removal of K+ and OH− ions, which may seriously interfere with and potentially damage the ICP-MS system, the safety risks and the analytical errors arising from the presence of extremely high alkalinity KOH are both low. To prevent loss of the analyte cations during the electrodialysis process, a selective chelating agent—ethylenediaminetetraacetic acid (EDTA)—was added to form anionic metal–EDTA complexes. To achieve maximum signal intensities, we optimized the sample flow rate and the amount of EDTA in terms of their effects on the retention and removal efficiencies of the analyte species and K+ ions. Based on the optimized operating conditions, near 100% of trace metal ions in 11.25% KOH solutions—added with 10 mg EDTA L−1 in advance—could pass through electrodialyzer and be delivered to the ICP-MS at a flow rate of 0.1 mL min−1. Because over 99.99% of 11.25% KOH was removed prior to ICP-MS measurement and low blank levels were achieved, this hyphenated method is sufficiently robust for the determination, with detection limits ranging from μg L−1 to sub-μg L−1, of trace Cu, Mn, Zn, Co, Ni, Cd, and Pb impurities in high-alkalinity samples. Because no certified values for the analyte content in KOH were available, the overall analytical method was validated for accuracy and precision by analyzing KOH solutions spiked with known amounts of analytic ions. Based on the analytical data, the analytical accuracy, expressed as spike recovery was found to be at 100 ± 10% for all the elements tested. This method is superior to the reported voltammetric methods for the determination of trace impurities in terms of detection limits, ability of simultaneous multi-elements analysis and speed of analysis. The validated method was successfully applied to determine trace levels of metal impurities in concentrated KOH solutions.

Removal of Lead from Contaminated Soils with Chelating Agents

The biodegradable chelating agents [S,S]-ethylenediaminedisuccinic acid (EDDS), citric acid and the low biodegradable chelating agent ethylenediaminetetraacetic acid (EDTA) were investigated for their applicability for the removal of lead from soil by soil washing and electrokinetic processing. In the soil washing tests at 298 K, the removal efficiency of lead with EDDS and EDTA was high in the pH range from 7 to 10 and the ability of lead removal with EDDS in this pH region is comparable to that with EDTA. Meanwhile, the removal efficiency of lead with citric acid was approximately 50% at pH 4 and decreased with increasing pH. Therefore, citric acid was hardly useful. Acid contribution was predominant for the removal of lead with EDDS and citric acid at pH 4 and the complexation between these chelating agents and lead were negligible. In the electrokinetic tests at ambient temparature, EDTA was more effective than EDDS and citric acid for lead transport through the soil by electrokinetic processing.

Atomic Force Microscopy of Removal of Dentin Smear Layers

The regular periodontal practice of scaling and root planing produces a smear layer on the root surface that is detrimental to the readhesion of tissues during subsequent regeneration therapy. Although it has been demonstrated that gels containing the chelating agent ethylenediaminetetraacetic acid (EDTA) can assist in the removal of this contaminating layer, no quantitative method is yet available by which to evaluate the efficiency of the treatment. In this article, the power of atomic force microscopy (AFM) as a technique for monitoring and mapping the surfaces of dentinal roots is demonstrated. Roughness parameters of teeth that had been scaled and root planed were determined from AFM images acquired both before and after treatment with EDTA. The results confirmed that EDTA is an efficient cleaning agent and that dentinal samples free from a smear layer are significantly rougher than the same samples covered by a contaminating layer. AFM analysis is superior to alternative methods involving scanning electron microscopy because the same sample section can be analyzed many times, thus permitting it to be used as both the control and the treatment surface.

Screening for a new Streptomyces strain capable of efficient keratin degradation

Keratinous wastes could be degraded by some microorganisms in nature. Native human foot skin (NHFS) was used as sole nitrogen source to screen microorganisms with keratin-degrading capability. From approximately 200 strains, a strain of Streptomyces sp. strain No.16 was found to possess the strongest keratinolytic activity, and the total activity in the culture was 110 KU/ml with specific activity of 2870 KU/mg protein (KU: keratinase unit). Substrate specificity test indicated that the crude keratinase could degrade keratin azure, human hair, cock feathers and collagen. The optimal pH of the crude keratinase ranged from 7.5 to 10 and the temperature ranged from 40°C to 55°C. Metal chelating agent ethylenediamine tetraacetic acid obviously stimulated the keratinolytic activity but suppressed the proteolytic activity. To our knowledge, this is the first report on specific induction of keratinases by NHFS from an actinomycete. Moreover, excellent characteristics of its crude keratinase may lead to the potential application in waste treatment and recovery, poultry and leather industry, medicine, and cosmetic development.

Copper biosorption on immobilized seaweed biomass: Column breakthrough characteristics

Abstract The biosorption of copper by the brown seaweed Sargassum baccularia, immobilized onto polyvinyl alcohol (PVA) gel beads, was investigated with fixed-bed experiments. Laboratory-scale column tests were performed to determine breakthrough curves with varying flow rates and feed concentrations. A theoretical fixed-bed model, known as the Bohart-Adams equation, was evaluated in simulating the experimental breakthrough curves. The Bohart-Adams model qualitatively predicted the breakthrough trends. PVA-immobilized seaweed biomass beads were amenable to efficient regeneration with aqueous solution containing the chelating agent ethylenediaminetetraacetic acid (EDTA). The biosorbent retained most of its original uptake capacity over three cycles of use. The excellent reusability of the biosorbent could lead to the development of a viable metal remediation technology.

Effects of calcium on the thermal stability, stability in organic solvents and resistance to hydrogen peroxide of artichoke ( Cynara scolymus L.) peroxidase: A potential method of enzyme control

The effects of calcium ions (Ca 2+) on the stability of artichoke ( Cynara scolymus L.) peroxidase (AKPC) have been studied. The thermal stability of AKPC was improved by the addition of Ca 2+; the melting temperature increased by 20 °C and the deactivation energy by 26 kJ mol −1. AKPC was stable in a selection of organic solvents but was less active with 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) than under aqueous conditions. Ca 2+-free AKPC retained more activity in the presence of organic solvents due to its better maintenance of the rate of compound I formation with hydrogen peroxide (H 2O 2) compared to AKPC-Ca 2+. AKPC retained at least 75% activity over 24 h in the pH range 3.0–10.5 and about 50% over 1 month at pH 7.0 or 5.5, irrespective of the Ca 2+ content. AKPC-Ca 2+ was considerably more resistant to inactivation by H 2O 2 than Ca 2+-free AKPC suggesting that the presence of Ca 2+ boosts turnover under oxidizing conditions. AKPC has been applied as an alternative to horseradish peroxidase (HRP) in glucose concentration assays; the presence of Ca 2+ or of the Ca 2+ chelating agent ethylenediaminetetraacetic acid made no difference to the final result. The possibility is discussed that addition and removal of a labile Ca 2+ from AKPC could be used to control enzyme activity both in vivo and in vitro.

A kinetic study of chelant-assisted remediation of contaminated dredged sediment

A study on the remediation of a real heavy metal-contaminated sediment was conducted using the four chelating agents ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), citric acid and the S, S-isomer of the ethylenediaminedisuccinic acid ([ S, S]-EDDS). Different chelant washing experiments were carried out at a chelant/total metal content of 1 and 10 mol/mol for treatment durations from 0.5 to 48 h to study the extraction kinetics of trace metals and major cations. The objective was to evaluate the removal efficiency of conventional chelating agents as compared to innovative, biodegradable species. Among the target contaminants, Cd, Cu, Pb and Zn were found to be adequately removed by both EDTA and EDDS, while NTA and citric acid yielded unsatisfactory results in some cases. It was also found that As was a critical contaminant which would require an additional specific treatment step, since the residual concentrations after the washing treatment were still far above the regulatory limit values.

Influence of Chelating Agents on the Recovery of Al(III), Fe(III), Ti(IV) and Na(I) from Red Mud by Cation Exchange Membranes

The metal recovery from red mud solution containing chelating agents such as nitriloacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), citric acid, and phosphoric acid were studied by using the Neosepta CMX and CMB cation exchange membranes in Donnan dialysis process. The stripping solution was 1.0 M HCl solution and no external potential field is applied. The efficiency of chelating agents on the recovery of metal ions through membranes was correlated with the flux data. It was observed that the removal and fluxes of metals were enhanced with citrate, EDTA and NTA chelating agents in contrast were decreased with phosphate complexing agent.

Spermicidal activity of dermaseptins

Objective The present study was undertaken to elucidate the spermicidal efficacy of two synthetic antimicrobial peptides, dermaseptin (DS1 and DS4). Methods Twenty samples of fresh semen were obtained from patients aged between 23 and 35 years. The ability of DS to kill sperm was evaluated by the Sander–Cramer test under in vitro conditions. Results The data showed that sperm motility was inhibited with various concentrations of DS at different intervals ranging from 2 to 240 min. The effective 100% inhibitory concentration (EC 100) of DS4 in 2 min during the sperm immobilization assay was 100 μg/mL whereas the sperm immobilization of EC 100 of DS1 was 200 μg/mL. The presence of 0.1% chelating agent ethylenediaminetetraacetic acid (EDTA) reduced the EC 100 of DS4 to 10 μg/mL whereas less than a two-time enhancement in DS1 activity was observed upon combination with EDTA. The action of DSs on sperm motility was observed to be dose dependent. Supplementation with pentoxifylline and that with calcium are known to enhance the motility of sperm but they did not prevent the spermicidal action of DSs. Conclusion This present study indicates that DS is an effective agent to kill sperm. In view of this fact, it is suggested that DS4 has antibacterial, antiviral, antifungal and potentially spermicidal activities and could be a potent vaginal contraceptive.

Role of the EDTA Chelating Agent in Bioscouring of Cotton

Our previous work demonstrated that ethylenediamine-tetra-acetic acid (EDTA) markedly enhances the apparent activity of commercial xylanase and pectinase enzymes in cotton bioscouring, accelerating degradation and removal of impurities. In this study, we explore how EDTA can improve the efficiency of the enzyme process in cotton bioscouring. The effects of EDTA on the enzyme action and degradation of seed-coat fragments—the most resistant natural impurities of cotton to be degraded in bioscouring—are investigated. Results show that application of EDTA in different concentrations does not inhibit the main activities of the enzymes investigated. Thus, the pectinase activity of Viscozyme 120L and the xylanase activity of Pulpzyme HC remain almost unchanged. On the other hand, EDTA modifies the substrate structure by removing the calcium ions from the cross bridges that link the macromolecules in pectin to one another or pectin to other polysaccharides. While EDTA pretreatment significantly decreases the efficiency of enzymatic hydrolysis monitored by reducing sugar liberation, simultaneous application of EDTA and enzyme in one treatment bath largely accelerates the degree of hydrolysis, indicating a synergistic effect of enzyme and EDTA.

Effect of ferric chloride addition on the removal of Cu and Zn complexes with EDTA during municipal wastewater treatment

The presence of the synthetic chelating agent ethylenediaminetetraacetic acid (EDTA) in municipal wastewater has a significant impact on the efficacy of wastewater treatment plants because pollutant metal–EDTA complexes are difficult to remove. To understand the potential of FeCl 3 addition during primary treatment to improve metal removal, laboratory experiments and a full-scale study were conducted. Results of laboratory experiments designed to simulate primary and secondary wastewater treatment indicate that a portion of pollutant metal–EDTA species can be converted into FeEDTA − by addition of FeCl 3 during simulated primary treatment. Addition of FeCl 3 also resulted in improved metal removal by adsorption. The combination of these two processes improved removal of Cu and Zn by 20% during simulated primary treatment. During full-scale treatment, a slight increase in the concentration of FeEDTA − in secondary effluent was observed when FeCl 3 was added during primary treatment. However, FeCl 3 addition had no observable effect on metal concentrations in the wastewater effluent. The most noticeable change in EDTA speciation at full scale occurred during primary treatment, where most of the pollutant metal–EDTA complexes were converted into FeEDTA −, irrespective of whether or not FeCl 3 was added. The formation of FeEDTA − during primary treatment plays a potentially important role in metal removal and should be considered in future evaluations of wastewater treatment plant performance.