Amount Of Ethylenediaminetetraacetic Acid Research Articles

Effects of EDTA and Boric Acid on the Morphology of CaCO3 Particles

Calcium carbonate (CaCO3) particles with different morphologies were prepared using calcium chloride (CaCl2) and sodium carbonate (Na2CO3) aqueous solutions containing various amounts of ethylenediamine tetraacetic acid (EDTA) or boric acid. The products were characterized by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). The sphere‐like CaCO3 particle was inclined to be formed in EDTA or boric acid solution at room temperature. The surface of CaCO3 is smooth in the presence of EDTA, and the crystal structure of CaCO3 is majorly vaterite. However, the CaCO3 has a rough surface in boric acid solution and pure calcite structure. The size of CaCO3 particle decreases with the increase in the amount of EDTA or boric acid.

Removal of EDTA from Aqueous Solutions Using Activated Carbon Prepared from Rubber Wood Sawdust: Kinetic and Equilibrium Modeling

AbstractAdsorptive removal of EDTA (ethylenediaminetetraacetic acid) from aqueous solution was studied using steam pyrolyzed activated carbon. Rubber wood sawdust, obtained from a local timber facility at Kodangavila, Trivandrum, Kerala, India was used as the precursor for the production of the activated carbon. Batch adsorption experiments were employed to monitor and optimize the removal process. The experimental parameters, i. e., solution pH, agitation time, initial EDTA concentration and adsorbent dosage, affecting the adsorption of EDTA onto sawdust activated carbon (SDAC) were optimized. The inner core mechanism for the interaction between EDTA and SDAC, which resulted in the adsorption process, was also discussed. The change in amount of EDTA adsorbed onto SDAC and CAC (commercial activated carbon) was compared over a wide range of pH (2.0–8.0). The maximum removal of EDTA took place in the pH range of 4.0–6.0 for SDAC and 5.0–5.5 for CAC, which demonstrates the effectiveness of the former adsorbent. Kinetic as well as equilibrium studies were performed to determine the rate constant and adsorption capacity, respectively. The adsorption kinetic data was fitted with pseudo‐first‐order kinetics and the equilibrium data was shown to follow the Langmuir isotherm model. These observations explain the formation of a monolayer of EDTA on the surface of SDAC as confirmed by the slow approach to equilibrium after 4 h of contact time. The adsorption capacity of SDAC for the removal of EDTA was 0.526 mmol/g and is seen to be greater than that of CAC and other reported adsorbents (0.193–0.439 mmol/g). Finally, it is clear that the production of steam pyrolyzed activated carbon in the presence of K2CO3 greatly enhanced EDTA removal and resulted in a product with possible commercial value for wastewater treatment strategies.

Self-Assembled Three-Dimensional Architectures of Y2(WO4)3:Eu: Controlled Synthesis, Growth Mechanism, and Shape-Dependent Luminescence Properties

Monoclinic Y2(WO4)3:Eu with three-dimensional hierarchical architectures were successfully synthesized by a hydrothermal method in ligand-free and chelating ligand-mediated processes, respectively. Microflowers assembled from two-dimensional nanoflakes were obtained in a surfactant- and template-free process, whereas microspheres with dandelion-like appearance assembled from one-dimensional nanoplates were observed upon the introduction of the appropriate amount of ethylenediamine tetraacetic acid (EDTA) to the precursor. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), energy-dispersive spectra (EDS), and photoluminescence (PL) spectroscopy were employed to characterize the as-obtained products. It was found that the amount of ligand agent, reaction temperature and time, and type of organic additive have crucial influences on the morphology of the resulting microstructures. The possible formation mechanisms for different microstructures were put forward. The addition of EDTA significantly changed the reaction pathway due to the excellent chelating and capping ability of EDTA. A detailed investigation on the photoluminescence of Y2(WO4)3:Eu samples with flower-like, dandelion-like, and spindle microstructures indicates that the optical properties of these phosphors are strongly dependent on the morphology and size. The dandelion-like structure exhibits the strongest red emission with high color purity.

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.

Redistribution of fractions of zinc, cadmium and lead in calcareous soils treated with EDTA

The effect of EDTA (ethylene diamine tetra acetic acid) on the fractionation of Zn, Pb, and Cd in six calcareous soils was investigated. A total of 400 mg kg−1 Zn, 200 mg kg−1 Pb, and 8 mg kg−1 Cd was added to soils as chlorides. Both natural and metal-amended soils were treated with Na2EDTA solution at amounts of 0, 1.0, and 2.0 g kg−1. Metals in the incubated soils were fractionated after 5 months by sequential extraction procedure, in which the metal fractions were defined as exchangeable (EXC), carbonate (CARB), Mn oxide (MNO), Fe oxide (FEO), organic matter (OM) and residual (RES) fractions. Increasing the amounts of EDTA significantly raised Zn concentrations in the EXC and CARB fractions in metal-amended soils. EDTA also increased Cd concentrations in the EXC fraction of the metal-amended soils. Increasing the amount of EDTA raised significantly Pb concentrations in the CARB and MNO fractions in metal-amended soils. In the metal-amended soils, EDTA removed some Pb from RES and OM fractions and redistributed them into CARB and MNO fractions. Based on relative percent in the EXC fraction, the order of solubility was Cd > Zn > Pb for metal-amended soils, before and after adding of EDTA.

Determination of Inorganic Arsenic(III) and Arsenic(V) in Water Samples by Ion Chromatography/Inductively Coupled Plasma-Mass Spectrometry

A method was validated for the direct determination of As(III) and As(V) in water samples by ion chromatography/inductively coupled plasma-mass spectrometry. Sample preservation required only dilution with a mobile phase containing a sufficient amount of ethylenediaminetetraacetic acid and acetic acid. Analyses of 6 certified reference materials (CRMs) of various water matrixes, including seawater, demonstrated good method accuracy. The matrixes included 2 natural water samples [National Institute of Standards and Technology Standard Reference Material (NIST SRM) 1643e and NIST SRM 1640], 1 fortified standard solution (TMDA-64), 1 fortified water sample (TM-DWS), and 2 seawater samples (CASS-4 and NASS-5). The sum of As(III) and As(V) in each CRM agreed with the respective certified value for the total amount of As within its stated uncertainty. Quantitative recoveries (96.7-102.1%) were obtained. Satisfactory results were achieved for intraday repeatability [relative standard deviation (RSD = 0.3-5.1%] and interday precision (RSD = 0.7-4.1%). In the study of fortified blanks and fortified CRMs, quantitative recoveries of As(III) and As(V) (92.5-102.6%) were obtained. Interconversion of As(III) and As(V) was not observed under the conditions of sample preservation. International comparability of analytical results was demonstrated by the analysis of 2 interlaboratory proficiency test samples, NY7011 and NY8511, from the New York State Department of Health.

Synthesis of Nanocrystalline La(Ca)CrO3 Through a Novel Gel Combustion Process and its Characterization

La(Ca)CrO3 (LCC) powders have been prepared through a novel gel combustion route using metal nitrates as oxidizers and ethylene diamine tetraacetic acid (EDTA) as a fuel. The process involves the combustion of a viscous gel obtained through mixed metal nitrate-EDTA solution. The effect of amount of EDTA used in the process on the nature of combustion reaction, phase formation, and densification has been studied. It was found that use of the fuel-rich precursor facile in controlling the reaction, which in turn helps in the scale up of the batch size. The calcination of the fuel-rich gel precursor at 650 degrees C resulted in the well-crystalline LCC along with a small amount of calcium chromate as a secondary phase. The HRSEM studies on the powder showed agglomerated nanoparticles. The average agglomerate size was found to be 0.54 microm. The cold pressing and sintering of the calcined powder at 1250 degrees C resulted in the mono-phasic La0.70Ca0.30CrO3 with 94% of its theoretical density. The sintered sample exhibited conductivity of 51 S/cm at 1000 degrees C. The average linear thermal expansion coefficient was found to be 10.3 x 10(-6) degrees C(-1).

Studies on radiation synthesis of PVA/EDTA hydrogels

Aqueous solutions of polyvinyl alcohol (PVA) containing different amounts of ethylenediaminetetraacetic acid (EDTA) were gamma irradiated from a Co-60 source to form PVA–EDTA hydrogels. The effect of irradiation dose and EDTA content on the specific viscosity (in feed), gel percentage and equilibrium degree of swelling (EDS) was investigated. The amount of EDTA in the hydrogel matrix was found to be considerably lower than in the feed composition. Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) technique was used to determine the amount of Pb(II), Cd(II) and Hg(II) absorbed by the hydrogel. The incorporation of EDTA moieties onto PVA network results in a hydrogel which has absorption affinity for Pb(II) and Cd(II). The maximum chelating capacities of the hydrogel were observed to be 8.5 mg/g for Pb(II) and 4.2 mg/g for Cd(II). No affinity for absorption of Hg(II) by the hydrogel was observed. The thermal stabilities of the prepared hydrogels were characterized by TGA. The efficiency of EDTA in the hydrogel matrix for chelation was observed to be approximately 10% of that of pure EDTA in solution.

Elution of copper from vermiculite with environmentally benign reagents

For the purpose of remediation of soils polluted by heavy metals, the use of some strong synthetic chelating agents such as ethylenediaminetetraacetic acid (EDTA) has been proposed. However, EDTA would not be considered as the preferential choice for the remediation of soil polluted with heavy metals like copper because of its nonbiodegradability and permanent residence in the natural environment. In the present work, some novel environmentally benign chelating agents, glucosamine hydrochloride, chito-oligosaccharide and l-asparaginic- N, N-diacetic acid (ASDA) were screened to find alternatives to EDTA by investigating the elution of copper from vermiculite with these reagents and comparing their effectiveness with EDTA. The effects of suspension contact time, reagent concentration and equilibrium pH of the solution on the removal of copper were examined. A stoichiometric amount of EDTA can quantitatively remove copper in both acidic and neutral conditions. Chito-oligosaccharide was a slightly less-effective reagent under acidic conditions compared to EDTA, and an amount well in excess of stoichiometry is required to achieve the maximum removal of copper from vermiculite. Glucosamine hydrochloride shows a relatively weak ability for the liberation of copper. The elution behavior of ASDA was equivalent to EDTA in acidic and neutral media. It was concluded that ASDA is the best substitute for EDTA because of its similar high complexing ability and superior biodegradability.

Factors affecting EDTA extraction of lead from lead-contaminated soils

The effects of solution:soil ratio, major cations present in soils, and the ethylenediaminetetraacetic acid (EDTA):lead stoichiometric ratio on the extraction of lead using EDTA were studied for three different Superfund site soils, one rifle range soil, and one artificially lead-contaminated soil. Extraction of lead from the lead-contaminated soils was not affected by a solution:soil ratio as low as 3:1 but instead was dependent on the quantity of EDTA present. Results of the experiments showed that the extraction efficiencies were different for each soil. If sufficiently large amount of EDTA was applied (EDTA–Pb stoichiometric ratio greater than 10), most of the lead were extracted for all soils tested except for a Superfund site soil from a lead mining area. The differences in extraction efficiencies may be due to the major cations present in soils which may compete with lead for active sites on EDTA. For example, iron ions most probably competed strongly with lead for EDTA ligand sites for pH less than 6. In addition, copper and zinc may potentially compete with lead for EDTA ligand sites. Experimental results showed that addition of EDTA to the soil resulted in a very large increase in metals solubility. The total molar concentrations of major cations extracted were as much as 20 times the added molar concentration of EDTA. For some of the soils tested, lead may have been occluded in the iron oxides present in the soil which may affect lead extraction. While major cations present in the soil may be one of the factors affecting lead extraction efficiency, the type of lead species present also play a role.

Kinetic Studies of Copper(II) Extraction from EDTA-Bearing Solutions by Aliquat 336 Using a Membrane Cell

The kinetics of extraction of copper(II) from aqueous solutions containing an equimolar amount of EDTA (ethylenediaminetetraacetic acid) with Aliquat 336 (a quaternary amine) in kerosene were studied using a microporous membrane-based stirred cell. This device could give the intrinsic reaction rate for the formation of the amine complex occurring at or near the organic–aqueous interface by eliminating the diffusion resistances. Experiments were performed as a function of aqueous pH 3-11, copper(II) concentration (0.79–3.14 mol·m−3), Aliquat 336 concentration (50–500 mol·m−3), and temperature (288–318 K). The experimental results showed that Aliquat 336 would adsorb at the interface and react with the Cu-EDTA chelated anions.

Effects of Amorphous Iron on Extraction of Lead-Contaminated Soil with EDTA

Ethylenediaminetetraacetic acid (EDTA) is one of the more common chelating agents used in the extraction of heavy metals from soil. For soil extraction processes to be economically competitive with other remedial technology, the amount of EDTA applied for extraction should be optimized; that is, extraction of metals should be maximized with a minimum amount of EDTA used. Generally, the molar amount of EDTA used is several times higher than the molar amount of the target metal present in the soil. This is to ensure there will be sufficient EDTA to extract the target heavy metals from the soil, since a host of non-target metals such as iron and calcium may compete for EDTA ligand sites. Bench-scale experiments using artificially prepared lead-contaminated soils were conducted to investigate the effects of amorphous iron and the different types of lead species on lead extraction. Three different lead species—lead sulfate, lead carbonate, and lead phosphate—were used. The extraction efficiency of lead was found to be a function of EDTA:Pb molar ratio, pH, lead species, and amorphous iron concentration. Experimental results showed that for a pH less than 6.0, amorphous iron in soil was found to strongly compete with lead for EDTA ligand sites. The extent of competition was dependent not only on the solution pH but also on the lead species present and the EDTA:Pb molar ratio. Amorphous iron was found to affect lead sulfate-contaminated soil the most, while lead carbonate-contaminated soil was the least affected. For EDTA:Pb molar ratios of less than 2, a solution pH between 6.5 and 8.5 must be maintained to optimize extraction of lead from lead sulfate- and lead phosphate-contaminated soil, if amorphous iron is present. The degree of difficulty of extraction of various lead species using EDTA:Pb molar ratios of less than 2 and in the presence of amorphous iron was lead sulfate>lead phosphate>lead carbonate.

Recycling of lead-contaminated EDTA wastewater

Ethylene diaminetetraacetic acid (EDTA) is one of the chelating agents used in the soil washing process for the decontamination of lead-contaminated soil. Lead–EDTA complexes in the wastewater from the soil washing process must be removed before the wastewater can be safely discharged. This study outlines a method to recycle Pb–EDTA wastewater by substituting the Pb complexed with EDTA with Fe(III) ions at low pH, followed by precipitation of Pb ions with phosphate or sulfate ions. Fe(III) ions complexed with EDTA were then precipitated at high pH using sodium hydroxide. The resulting solution (Fe-precipitated solution) was tested on three lead-contaminated soils. The Fe-precipitated EDTA solution was found to have similar extraction capabilities as fresh EDTA solution. Experimental results showed that the recycled EDTA solution may be recycled several times without losing its extractive power. Recycled EDTA wastewater with phosphate precipitation was found to be slightly more effective than recycled EDTA solution using sulfate precipitation. The recycling procedure may be applied to wastewater generated during soil washing of lead-contaminated soil, resulting in a reduction in wastewater generated and savings in the amount of EDTA used.

Behaviour of Ion Exchange Resins and Corrosion Inhibitors in Dilute Chemical Decontamination

Ethylene diamine tetra acetic acid (EDTA) is a versatile complexing agent and is being employed in decontamination formulations. The dilute chemical decontamination (DCD) process employs ion exchange resins for regeneration of complexants, collection of metal ions/active isotopes and for removal of the decontaminating chemicals. In this work the interactions of EDTA on cation and anion exchange resins have been studied. The pickup of EDTA on cation exchange resin is by ion exchange mechanism and not possibly by precipitation at the low pH existing in ion exchange resin matrix. A mathematical relationship has been worked out to calculate the amount of EDTA adsorbed per unit volume of the cation exchange resin at a given pH. In addition, the behaviour of DTPA, HEEDTA and NTA on cation exchange resin has been evaluated. The chromatographic behaviour of OH- form of strong base anion exchange resin for a formulation containing EDTA, oxalic acid and citric acid has been reported and its relevance to the decontamination process has been discussed. Even though the corrosion rate of DCD is very low on most of the materials of construction, influence of time, temperature and the composition of the formulation on carbon steel is studied. Different classes of inhibitors were evaluated for reducing carbon steel corrosion.

Behaviour of Ion Exchange Resins and Corrosion Inhibitors in Dilute Chemical Decontamination.

Ethylene diamine tetra acetic acid (EDTA) is a versatile complexing agent and is being employed in decontamination formulations. The dilute chemical decontamination (DCD) process employs ion exchange resins for regeneration of complexants, collection of metal ions/active isotopes and for removal of the decontaminating chemicals. In this work the interactions of EDTA on cation and anion exchange resins have been studied. The pickup of EDTA on cation exchange resin is by ion exchange mechanism and not possibly by precipitation at the low pH existing in ion exchange resin matrix. A mathematical relationship has been worked out to calculate the amount of EDTA adsorbed per unit volume of the cation exchange resin at a given pH. In addition, the behaviour of DTPA, HEEDTA and NTA on cation exchange resin has been evaluated. The chromatographic behaviour of OH- form of strong base anion exchange resin for a formulation containing EDTA, oxalic acid and citric acid has been reported and its relevance to the deconta...

Effect of Ethylene Diamine Tetra Acetic Acid (EDTA) on the Surface Reaction Behavior and the Hydrogen Evolution Efficiency of Ni-30at.%Cu Electrode in Alkaline Medium

The surface reaction characteristics, hydrogen evolution efficiency and hydrogen evolution reaction kinetics of Ni-30at.%Cu electrode have been investigated in 30wt.%KOH electrolyte in presence and absence of ethylene diamine tetra acetic acid (EDTA) at room temperature by cyclic voltammetric technique. Cyclic voltammogram of the electrode showed three couples of oxidation-reduction peaks in between the potential range - 1.1 to + 0.4 V. The peak couples were originated from the electrochemical transformations of Ni(0) ←→ Ni(OH)2, Cu(0) ←→ Cu(I) and Cu(I) ←→ Cu(OH)2. An interference of the adsorped hydrogen over Cu(0) surface on the transformation of Ni(OH) 2 → Ni(0) was found. It was realized that added EDTA forms Cu-EDTA complex over the electrode surface. With increasing the amount of EDTA, the thickness of Cu(OH) 2 layer gradually decreased. Addition of 0.04g, 0.08g and 0.12g EDTAincreased the hydrogen evolution efficiency of the electrode more than 6%, 12% and 17%. Tafel plots for both the systems showed two well-defined Tafel regions. 0.12g EDTA increased the exchange current density (i0) values 1.3 times for both the Tafel regions. The observed i0 value for the high overpotential (η) region is 1.8 and 2.9 times higher than those of Ni and Cu electrodes. The Tafel slope (b) values for both the low and high η regions are smaller than those observed for without EDTA system and also for the Ni electrode. From the achieved information, it can be concluded that addition of EDTA remarkably increased the hydrogen evolution efficiency of the Ni-30at.%Cu electrode. It seems that hydrogen evolution reactions (HER) followed like mechanisms in absence and presence of EDTA. Key words: Ni-30at.%Cu electrode, EDTA, Electrochemical transformation, Surface reactions, Hydrogen evolution, Hydrogen evolution reactions (HER)DOI: 10.3329/bjsir.v43i2.955 Bangladesh J. Sci. Ind. Res. 43(2), 145-158, 2008