Diethylenetriaminepentaacetic Acid Solution Research Articles

Comprehensive analysis of the effect of reservoir key parameters on the efficacy of DTPA chelating agent in minimizing interfacial tension and enhanced oil recovery

Chelating agents reduce the salinity of seawater (SW) and mimic low salinity water (LSW) by binding metal ions in the solution and on the rock surface. This process decreases SW dilution costs and prevents scale formation while improving oil recovery without damaging the reservoir. This study investigates the impact of Diethylenetriaminepentaacetic acid (DTPA) chelating agent on the reduction of interfacial tension (IFT) between oil and SW, without the use of additional chemicals. For the first time, we comprehensively analyzed how reservoir key parameters (concentration, salinity, temperature, and pH) affect the performance of DTPA in reducing IFT. Additionally, rock wettability alteration and sand pack flooding experiments were conducted to evaluate the effect of DTPA on rock wettability and oil recovery. The results revealed that increasing the temperature to 75 °C and the concentration of DTPA to 5 wt% resulted in an IFT reduction to less than 1 mN/m, making the oil miscible in the DTPA solution. Salinity studies demonstrated that by increasing the solution salinity up to the optimal level, the IFT of oil/brine decreased. Furthermore, using 5 wt% DTPA solution altered the rock/oil contact angle from 143° (oil-wet) to 23° (strongly water-wet), highlighting the effect of DTPA on rock wettability alteration. Based on these findings, 5 wt% DTPA was selected as the optimal concentration, resulting in an increase in oil recovery up to 20.3% of original oil in place (OOIP) after SW injection. Elemental analysis of DTPA flooding effluent also confirmed the chelation of metal ions from rock and solution.

Effects of DTPA, HEDTA, and EDDS on the Growth of Watermelon and Chemical Properties of Plastic Film House Soil

A chelating agent helps crops to reuse as nutrients by mobilizing salts from the soil. This study was conducted to evaluate the effects of Diethylenetriamine pentaacetic acid (DTPA), N-(2-hydroxyethyl)-ethylene diaminetriacetic acid (HEDTA), and Ethylene diamine disuccininc acid (EDDS) for improving plant growth and reusing accumulated nutrients in soils of plastic film house. Two experiments were carried out of follows: i) For the incubation test, the availability of nutrients were examined for soils treated with distilled water, 1 mM of DTPA, HEDTA and EDDS solutions. ii) In the pot test, the impacts of watermelon growth response were examined by adding 0.5, 1, and 5 mM of chelating agent to soil. In incubation test, application of chelating agents increased the availability of soil nutrients in the following order : DTPA ≒ HEDTA > EDDS > distilled water. However, biomass of watermelon in pot test, tended to be highest in EDDS 1 mM. The absorption amount of N, P, and K of crop in EDDS 1 mM was similar to that of NPK treatment and K, Ca, Mg, and Fe tended to be high. Soil Electrical conductivity (EC) of 1 mM EDDS showed a 66% decrease compared to no treatment. These results showed that EDDS could be improved the watermelon growth. Further research is needed to evaluate the effects of EDDS for plant growth on field scale.Difference in watermelon biomass by chelating agents (DTPA, HEDTA, and EDDS) and their concentrations (0.5, 1, and 5 mM) treated in salt-accumulated soil under pot scale (†Duncan’s multiple range test (p < 0.05), ‡Relative biomass percent of other treatments compared to NPK).

Dissolution behavior of DTPA-promoted barium slag and synthesis of submicron BaSO4 particles

Barium slag (BS) is a kind of industrial solid waste generated in barium salt production. Barium in BS can be considered as a secondary source as the content of BaO is as high as 34.80%. The main existent forms of barium in BS are BaSO4, BaCO3 and BaSiO3. It is challenging to dissolve BaSO4 using conventional acids and alkalis due to the low solubility. In this study, diethylenetriaminepentaacetic acid (DTPA) was introduced to investigate the dissolution behavior of barium in BS, and the DTPA complex solution was acidified to release barium for submicron BaSO4 products preparation. Leaching tests were carried out at DTPA concentrations of 0.025–0.30 mol/L, liquid solid ratio of 10–100 mL/g, pH of 8.0–13.0, and reaction temperature of 20–80 °C. The leaching efficiency of barium was 78.64% under the conditions of using 0.10 mol/L DTPA solution (pH of 12.0) at 80 °C for 300 min with the liquid solid ratio of 50 mL/g. BaSO4 products were obtained by the addition of H2SO4 to acidify the leachate at pH ranges of 9.0–7.5. Characterization results from X-ray diffraction, scanning electron microscopy, transmission electron microscopy and dynamic light scattering indicated that the BaSO4 products were nearly sphere particles with the average diameter of 300–500 nm. This work demonstrates that DTPA can dissolve barium in BS and acidifying Ba-DTPA leachate can dissociate barium ions. Furthermore, barium source in BS can be recovered in the form of submicron BaSO4 products through DTPA complexation and decomplexation process.

Removal of barite from zircon using an aqueous solution of diethylenetriaminepentaacetic acid and potassium carbonate

Abstract In most geologic applications, if barite is present, it must be separated from zircon to enable analysis of the zircon. Current methods of barite removal include mechanical comminution in a ball mill or conversion to barium carbonate by boiling in an aqueous solution of sodium carbonate. Both procedures have potentially serious drawbacks. We optimized an alternative technique for barite removal to avoid these shortcomings. In repeated experiments, boiling in an aqueous solution of 0.1 M diethylenetriaminepentaacetic acid (DTPA) and 6 wt% potassium carbonate for one hour dissolved about 90% of sand-size barite grains. Examination of barite after boiling in DTPA solution revealed evidence for attacks on crystal surfaces in the form of microscopic scallops and pits. In contrast, zircon crystal surfaces were not detectably altered at the microscopic scale by a boiling solution of DTPA and potassium carbonate. The DTPA and potassium carbonate solution procedure may be superior to the other two barite removal methods in two ways. First, it might not introduce bias into the sample, in contrast to both of the other two methods. Second, it requires less time than the sodium carbonate solution technique. If future research shows that the DTPA and potassium carbonate solution technique does not affect isotopic systems in zircon, this method appears to be a favorable alternative to both milling and boiling in sodium carbonate solution.

Zinc desorption kinetics from some calcareous soils of orange (Citrus sinensis L.) orchards, southern Iran

ABSTRACT Zinc (Zn) desorption is an important process to determine Zn bioavailability in calcareous soils. An experiment was performed to assess the pattern of Zn release from 10 calcareous soils of orange orchards, southern Iran and the soil properties influencing it. For Zn desorption studies, soil samples were extracted with diethylene triamine penta-acetic acid solution at pH 7.3 for periods of 0.083–48 h. Suitability of seven kinetic models was also investigated to describe Zn release from soils. Generally, Zn desorption pattern was characterized by a rapid initial desorption up to 2 h of equilibration, followed by a slower release rate. The simple Elovich and two-constant rate kinetic models described Zn release the best, so it seems that Zn desorption is probably controlled by diffusion phenomena. The values of the rate constants for the superior models were significantly correlated with some soil properties such as soil organic matter (SOM) content, cation exchange capacity (CEC), and soil pH, whereas carbonate calcium equivalent and clay content had no significant influence on Zn desorption from soils. SOM had a positive effect on the magnitude of Zn release from soils, while soil pH showed a negative effect on Zn desorption. Furthermore, the initial release rate of soil Zn is probably controlled by CEC in the studied soils. Finally, it could be concluded that SOM, CEC, and soil pH are the most important factors controlling Zn desorption from calcareous soils of orange orchards, southern Iran. Abbreviations: Soil organic matter (SOM); Cation exchange capacity (CEC); Calcium carbonate equivalent (CCE); Zinc (Zn).

Interactions of DTPA chelating agent with sandstone rocks during EOR: Rock surface charge study

Enhanced oil recovery (EOR) using low salinity water has been proven experimentally and at the field scale. One of the mechanisms behind recovery enhancement due to low salinity water injection has been related to the change of rock surface charge which might lead to wettability alteration. Low salinity water EOR has its own disadvantages such as the high cost due to the need for enormous amounts of fresh water and it may cause scale precipitation and fines migration. Therefore, efficient and alternative low-cost EOR methods are needed. In this work, chelating agent diethylenetriaminepentaacetic acid (DTPA) for EOR application in sandstone rock was investigated. DTPA is an efficient metal ion control agent and can seize certain cations (especially Fe3+) from rock surfaces. DTPA chelating agent is very stable up to 400 °F at high pH values. The effect of DTPA injection on the surface charge of the sandstone rocks was investigated. Zeta potential measurements, ions analysis after interaction with the rock, and coreflooding experiments were performed. Three different types of sandstone rocks were used to investigate the changes in rock surface after conditioning with DTPA. Several scenarios were tested to compare low salinity water, deionized water, and seawater with DTPA chelating agent. The comparison was made by measuring the zeta potential of the rock powder. Coreflooding experiment was conducted along with effluent analysis for SO42−, Ca2+, Mg2+, Fe3+, and Al3+ ions to observe the effect of injecting DTPA with seawater on oil recovery and permeability. The results showed that the addition of DTPA resulted in Fe+3 ions absorption from the rock surface. Absorbing such trivalent cation resulted in a significant change in surface charge. Zeta potential dropped towards a more negative value for all sandstone rocks samples used in this study. Zeta potential results showed that mixing Berea sandstone with 5 wt% of DTPA in seawater led to similar surface charge value as if it was mixed with low salinity water for the same period. This means that DTPA combats the effect of the concentrated salts in seawater. DTPA chelated all multivalent cations in seawater and eliminated their effects on the surface charge. Also, DTPA increased the pH of the seawater from 7 to 11 and this will drag the surface charge to more negative. From coreflooding experiment, we observed that injecting 5 wt% DTPA solution in seawater after seawater injection enhanced the oil recovery from 56% to 75% in Berea sandstone cores at 100 °C. The additional oil recovery can be explained by more negative values of the zeta potential of the rock surface. We expect that chelating agent EOR using DTPA is a viable alternative to low salinity water flooding where huge fresh water is required to dilute the seawater.

Stimulation of high temperature carbonate gas reservoirs using seawater and chelating agents: Reaction kinetics

The use of hydrochloric acid (HCl) in gas well stimulation of high temperature reservoirs is currently facing different challenges. These challenges include rapid corrosion of the well tubulars, face dissolution, very high and uncontrolled reaction rate, and formation damage in high clay content and iron-rich reservoirs. In this study, water-soluble diethylene triamine penta acetic acid (DTPA) chelating agent is introduced as alternative to eliminate the risk associated with HCl at high temperatures. In addition, the potential of using seawater to replace fresh water in the stimulation process is explored to save the cost of fresh water transportation to deep offshore oil and gas wells. The effect of seawater on the reaction kinetics of DTPA with carbonate rocks under high pressure and high temperature conditions is investigated using the rotating disk apparatus. The reactions of DTPA solution diluted with fresh water (DTPA/DI) and seawater (DTPA/SW) with carbonate rocks were carried out at the same conditions. In the case of fresh water, the reaction is controlled by the surface reaction regime. Adding HCl to adjust DTPA pH did not turn the reaction into a mass transfer controlled reaction like the case of using HCl alone. The heavy matrix of seawater increased the resistance of ions diffusion, which resulted in a low reaction rate and transformed the reaction into a mass transfer limited regime. Corrosion tests were carried out on production and coiled tubing coupons obtained from the gas wells and the results of the new DTPA/SW formulation is compared to the standard HCl formulation. DTPA showed very low corrosion rate of 0.0034 g/cm2 without adding corrosion inhibitors compared to 0.205 g/cm2 of 15 wt% HCl with 3% corrosion inhibitors while the industry limit is 0.0244 g/cm2 in 6 h. The reaction regime of DTPA chelating agent with calcite is identified to be mass transfer limited in seawater and surface reaction limited in fresh water. The rate expression for the dissolution of Ca2+ in DTPA/SW solution is obtained. Coreflooding experiments were performed to determine the optimum injection rate using low permeability Indiana limestone core samples. The optimum injection rate required to stimulate a very deep carbonate gas well was found to be 1.4 bbl/min after scaling up the coreflooding results to field scale. The application of the new DTPA/SW formulation in treating deep gas wells is expected to save the cost of fresh water and eliminate the cost of corrosion inhibitors.

Geochemical assessment of lake sediments in protected areas in Poland – a search for reference condition

&lt;p&gt;This paper presents the results of an assessment of macro- and microelements in the sediments of lakes laying within protected areas in Poland – the Drawa National Park, the Wel Landscape Park and the Górzno-Lidzbark Landscape Park. In each lake two grab sediment sample were collected: one in the littoral zone and the other in the deepest part of the lake basin. Sediment samples analysed for their content of inorganic carbon (IC) and the loss on ignition (LOI at 550°C) and, according to these parameters classified into three sediment types. Micro elements were detected with SEM-EDX system and the bioavailability of Zn, Cu, and Fe was evaluated after an extraction with DTPA (diethylenetriaminepentaacetic acid) solution. The most diverse chemical composition of the sediments was observed in the lakes of the Wel Landscape Park Lacustrine sediments were characterized by the heterogeneous content of organic matter (from 11.70 to 52.89%), calcium carbonate (from 0.0 to 42.73%) and mineral fractions (from 38.24 to 79.46%). They consisted of three different types of gyttja (fine grain-size, clayey-calcareous, clayey). The highest content of trace elements was determined in fine grain-size gyttja, which results from their current sorption properties, as well as alimentation by river waters flowing into the lakes. &lt;br /&gt;The sediments contained relatively low concentrations of the analysed elements, which was reflected in the low values of the contamination factor (CF), the contamination degree (C&lt;sub&gt;deg&lt;/sub&gt;), the geo-accumulation index (I&lt;sub&gt;geo&lt;/sub&gt;) and the enrichment factor (EF). Values of the I&lt;sub&gt;geo&lt;/sub&gt; point out also that these lake sediments were not contaminated by heavy metals. The total content of zinc and copper in some analyzed sediments was higher than the content assumed as acceptable for protected areas. The contribution of bioavailable forms of Zn and Cu ranges from 2.3 to 29.1% for Zn, and from 4.6 to 18.4% for Cu. The type of sediment, and the surface area largely determined the lake sediment chemical composition, while land-use in the catchments had a minor effect. This applies to both lakes of different parks and lakes within each of the parks.&lt;/p&gt;

Structure and Optical Properties of Carbon Nanoparticles Generated by Laser Treatment of Graphite in Liquids.

In this paper, we report the one-step synthesis of luminescent carbon nanoparticles (NPs) via laser irradiation of a graphite target in a solvent [H2 O, ethanol, or a 0.008 m aqueous diethylenetriaminepentaacetic acid (DTPA) solution]. This is a simple approach for the fabrication of carbon dots with tunable photoluminescence (PL) that differs from other preparation methods, as no post-passivation step is required. The unfocused beam of the second harmonic (wavelength 532 nm) of the Nd:YAG laser was used in our experiments. The sizes of the prepared NPs were mainly distributed in the range of 1-8 nm with an average value of 3 nm. Carbon NPs of different inner structure were prepared: hexagonal diamond phase in aqueous DTPA solution, orthorhombic carbon phase in ethanol, and amorphous carbon in water. The synthesized carbon NPs have strong luminescence in the visible region, which makes them attractive for numerous biological applications. The photoluminescence of the synthesized NPs was investigated at different excitation wavelengths, from 260 to 450 nm. The highest intensities of the emission bands were detected for an excitation wavelength of 400 nm.

Purification of BaSO4 precipitate contaminated with organic matter for oxygen isotope measurements (δ18 O and Δ17 O).

Sulfate precipitates are often contaminated with nitrates and organic materials (OM), which reduce the precision and accuracy of measurements of δ18 O and Δ17 O values in the sulfate. Although nitrates can be effectively removed using diethylenetriaminepentaacetic acid solution, removing OM from the precipitates is often difficult. One effective approach is to heat powdered precipitates to high temperatures. In this study, the effect of this procedure on the δ18 O and Δ17 O values of BaSO4 precipitate was fully examined. OM-contaminated BaSO4 precipitates and 18 O- and 17 O-labeled purified BaSO4 precipitates were loaded into alumina and gold crucibles and heated at 450°C, 600°C and 800°C for 2h. The nitrogen and carbon contents in the initial and the final BaSO4 were measured using an elemental analyzer. The values of δ18 O and Δ17 O were measured using a temperature conversion/elemental analyzer coupled with an isotope ratio mass spectrometer, and a CO2 laser system coupled with an isotopic ratio mass spectrometer. OM was effectively (88±17%) removed from the BaSO4 precipitates by this treatment, and heating at 800°C had the highest removal efficiency (98%). The differences in δ18 O and Δ17 O values between the final and initial BaSO4 precipitates was -0.6‰ to 0.3‰ (average of -0.1‰) and -0.24‰ to 0.10‰ (average of -0.02‰), respectively. Significant positive relationships between the δ18 O and Δ17 O values of the initial BaSO4 precipitate and those of the high-T-treated aliquots were found, with slopes having mean values of 0.96±0.06 and 1.04±0.01, respectively. The result demonstrates high removal efficiency for OM in BaSO4 precipitates and no significant differences in the oxygen isotopic compositions between high-T treated BaSO4 and initial BaSO4 . This study indicates that the modified high-T treatment (800°C, 2h) is an effective method for purifying BaSO4 precipitated from geological and environmental samples with a high OM content for δ18 O and Δ17 O measurements. Copyright © 2016 John Wiley & Sons, Ltd.

Decomposition Studies of Aqueous Phase Ligands Used in Advanced Reprocessing Flowsheets

Two potential methods for decomposing organic ligands in nitric acid have been studied using acetic acid and diethylenetriaminepentaacetic acid (DTPA) as examples; these methods were oxidation by nitric acid at elevated temperatures (70-110°C) and electrochemical oxidation, both direct and mediated electrochemical oxidation. Based on total carbon measurements, acetic acid proved to be rather stable against nitric acid oxidation whereas 60-80% of DTPA was decomposed at 100-110°C. Electrochemical oxidation methods were generally more effective in decomposing acetic acid and DTPA with mediated electrochemical oxidation using Ag(II) ions the most effective method under the conditions tested, with ∼80 and >90% loss of carbon from acetic acid and DTPA solutions respectively, at ambient temperature in 6M HNO3.

Chromatographic Separation of Americium(III) from Europium(III) Using Alkyl Diglycolamic Acid

The alkyl derivatives of diglycolamic acid (DGAA) (alkyl = butyl to decyl) were synthesized and characterized by 1H and 13C nmr, and IR spectroscopy. The diglycolamic acids were impregnated in Tulsion ADS 400 for the chromatographic separation of hazardous Am(III) and Eu(III). The extraction behavior of Am(III) and Eu(III) in the impregnated resin was studied as a function of various parameters such as aqueous phase pH, concentration of DGAA, and diethylenetriaminepentaacetic acid (DTPA), etc. The distribution coefficient (Kd) of Am(III) and Eu(III) in the resin phase increased with increase in pH of aqueous phase and loading of DGAA in the resin. The concentration of DTPA needed for efficient separation of Am(III) from Eu(III) was optimized and the performance of the resin under dynamic extraction conditions was assessed by following the breakthrough curve in the column study using octyl derivative of DGAA. The conditions needed for the elution of Am(III) alone from the column was performed using 0.001 M DTPA solution at pH 2.5. The study confirmed the feasibility of separating Am(III) from Eu(III) using octyl-DGAA by extraction chromatography.

Comparison of Copper, Manganese, and Zinc Extraction with Mehlich 1, Mehlich 3, and DTPA Solutions for Soils of the Brazilian Coastal Tablelands

Deficiency of micronutrients is increasing in crop plants in recent years in Oxisols and Ultisols in the tropics. The predominant soils in the coastal tablelands of Brazil are Ultisols and Oxisols, with low cation exchange capacity and kaolinitic clay mineralogy. Soil copper (Cu), manganese (Mn), and zinc (Zn) extracted by the Mehlich 1 solution, currently used in the regional soil-testing laboratories, were compared with those extracted by the Mehlich 3 and diethylenetriaminepentaacetic acid (DTPA) solutions in a greenhouse experiment with 10 soil samples (0–20 cm deep) collected from representative Ultisols and Oxisols from various locations in the region. Corn was grown as a test crop, and its dry matter and micronutrient uptake was measured at 30 days of growth. Soil Cu, Mn, and Zn extracted with the three solutions were significantly correlated (0.65–0.95 range for r values), with the Mehlich 3 solution extracting greater quantities than the Mehlich 1 and DTPA solutions. Zinc and Cu taken up by corn plants were significantly related to their soil-extractable levels measured at harvest with all three of the solutions, except for Zn DTPA. However, similar relations between plant uptake and soil extractable Mn were poor, except for DTPA extracting solution.

Time-Dependent Zinc Desorption in Some Calcareous Soils of Iran

Desorption of zinc (Zn) from soil is an important factor governing Zn concentration in the soil solution and Zn availability to plants. Batch experiments were performed to study the kinetics of Zn desorption by diethylenetriaminepentaacetic acid (DTPA) from 15 calcareous soil samples taken from Golestan Province in northern Iran. Soils were equilibrated with 0.005 mol L−1 DTPA solutions for 0.25 to 192 h. The results showed that the extraction process consisted of rapid extraction in the first 2 h followed by much slower extraction for the remainder of the experiment. Desorption kinetic data was fitted to pseudo-first-order kinetic model. The experimental data were found to deviate from the straight line of the pseudo-first-order plots after 2 h. The model of two first-order reactions was fitted to the kinetic data and allowed to distinguish two pools for Zn: a labile fraction (Q1), quickly extracted with a rate constant k1, and a slowly labile fraction (Q2), more slowly extracted with a rate constant k2. The applicability of pseudo-second-order model in describing the kinetic data of Zn desorption was also evaluated.

Adsorption and desorption behavior of tetravalent zirconium onto a silica-based macroporous TODGA adsorbent in HNO3 solution

To understand the separation behavior of Zr(IV) in the partitioning process for high level liquid waste, a silica-based macroporous adsorbent (TODGA/SiO2-P) was prepared by impregnating N,N,N′,N′-tetraoctyl-3-oxapentane-1,5-diamide (TODGA) into a macroporous silica/polymer composite particles support (SiO2-P). Adsorption and desorption behavior of Zr(IV) from nitric acid solution onto silica-based TODGA/SiO2-P adsorbent were investigated by batch experiment. It was found that TODGA/SiO2-P showed strong adsorption affinity to Zr(IV) and this adsorption process reached equilibrium state around 6 h at 298 K. Meanwhile, HNO3 concentration had no significant effect on the adsorption of Zr(IV) above 1 M. From calculated thermodynamic parameters, this adsorption process could occur spontaneously at the given temperature and was confirmed to be an exothermic reaction. This adsorption process could be expressed by Langmuir monomolecular layer adsorption mode and the maximum adsorption capacity were determined to be 0.283 and 0.512 mmol/g for Zr(IV) at 298 and 323 K, respectively. In addition, more than 90 % of Zr(IV) adsorbed onto adsorbent could be desorbed with 0.01 M diethylenetriamine pentaacetic acid solution within 24 h at 298 K.

Effects of FeEDDS and EDDS on Peat-based Substrate pH and Cu, Fe, Mn, and Zn Solubility

Common chelating agents used in horticultural fertilizers like ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and ethylenediaminedi(o-hydroxyphenylacetic) acid (EDDHA) are not readily biodegradable and may persist in the environment, maintaining the capacity to solubilize heavy metals. For this reason, biodegradable chelating agents like ethylenediaminedisuccinic acid (EDDS) are being evaluated for use in horticultural crop production. Therefore, the objectives of the study were to determine the effects of FeEDDS and EDDS on substrate pH and copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) solubility in peat-based substrate compared with various Fe and chelate-ligand sources. Extractions were performed using the 1:2 by volume substrate analysis method with an incubation period of 24 hours. The control was distilled deionized water extractions. Iron-source (FS) extractants consisted of 1 mg·L−1 Fe solutions derived from FeEDDS, FeEDTA, FeDTPA, FeEDDHA, and FeSO4. Iron-source extractant solution pH ranged from 7.1 (FeEDDS) to 5.4 (FeSO4). The extract pH for all Fe-source treatments was similar at pH 6.7, demonstrating the buffering capacity of the peat-based substrate. Iron recovery rates for FS treatments were determined after subtracting Fe that was freely extracted with distilled-deionized water: FeSO4 (13%), FeEDDHA (68%), FeEDDS (73%), FeEDTA (102%), and FeDTPA (121%). Iron-source treatments were not different for Mn, averaging 0.03 mg·L−1, and Cu (0.04 mg·L−1) and Zn (0.24 mg·L−1) were greatest in the FeEDDS treatment. Chelate-ligand (CL) extractants consisted of 5 mm solutions of EDDS, EDTA, and DTPA. Chelate-ligand extractant solution pH ranged from 9.7 (EDDS) to 2.3 (DTPA), and extract solution pH ranged from 7.2 (EDDS) to 4.7 (DTPA). Extractant solutions of EDDS and DTPA resulted in the lowest and highest levels of Cu (0.06 and 0.14 mg·L−1, respectively) and Fe (4.3 and 13.1 mg·L−1, respectively) in extract solutions. Overall, these results suggest that there are no negative implications for the use of FeEDDS with peat-based substrate in terms of horticultural crop production based on substrate Fe solubility, which was not different from FeEDTA.

Phytoremediation of lead by jack beans on a Rhodic Hapludox amended with EDTA

A greenhouse study was conducted to evaluate the effects of ethylenediamine tetraacetic acid (EDTA) addition to soils on the lead (Pb) phytoextraction potential of jack beans (Canavalia ensiformis L.). In a pot experimentSoil samples (dystrophic Rhodic Hapludox) were treated with six Pb rates (0, 100, 200, 350, 1,200, and 2,400 mg kg-1 soil) applied as Pb(NO3)2 without and with EDTA application (0 and 0.5 g kg-1, respectively). Lead, Cl-, NO3-, NH4+, SO4(2-), H2PO4-, Zn2+, Cu2+, Fe3+, Al3+, Ca2+, Mg2+, K+ and DOC (dissolved organic carbon) concentrations obtained in a saturation soil extract (soil:water ratio of 1:0.3) were used for Pb speciation by means of the software Visual-Minteq 2.30. Soil Pb-availability was assessed with Diethylene triamine pentaacetic acid (DTPA) extraction. EDTA treated soils showed higher Pb (as PbEDTA2-), and Fe (as FeEDTA-) concentrations in soil solution leading to higher uptake of these elements by the jack bean. On the other hand, it decreased the concentration of stable complexes as Pb-DOC and Fe-DOC. EDTA also induced better nutrition to plants building up the concentration of non target metals (Ca, K, Mg, Zn, Cu, Fe and Mn) in shoots. Shoot dry matter yield remained constant even at the highest Pb rates after EDTA treatment. Jack bean can be considered as a potential Pb-phytoextractor. In addition, the DTPA solution was effective to assess Pb availability to the plants at all applied Pb rates.

Kinetics of DTPA extraction of zinc from calcareous soils

Abstract The kinetics of Zn extraction by diethylenetriaminepentaacetic acid (DTPA) from the ≤ 2 mm fraction of 12 calcareous soils was investigated using surface soil (0–30 cm) samples. Soils were equilibrated with 0.005 M, DTPA solution for 0.25 to 192 h. Zero-, first-, second-, third-order, parabolic diffusion and simple Elovich equations did not adequately describe Zn extraction kinetics. The best model for describing extraction data for all soils was the exponential rate equation ( q = a t b ). q is the amount of Zn desorption (mg Zn kg − 1 ), a is the Zn desorption magnitude constant (mg Zn kg − 1 h − 1 ) and b is the desorption rate constant. Constant a ranged from 21 to 79.8 with a mean of 41.4 and b from 0.19 to 0.33 with a mean of 0.25. The differences in a value presumably reflect the quite different properties and constituents of these soil types. The magnitude constant a , was positively correlated ( r = 0.76⁎⁎) to organic carbon content and negatively to pH ( r = − 0.67⁎). The rate constant b was not related to any of the measured soil properties such as pH, cation exchange capacity, carbonate calcium equivalent, active calcium carbonate equivalent, clay content, organic carbon and specific surface area or to any combination of these properties.

Reação do solo e disponibilidade de micronutrientes, em solo de textura média, tratado com lodo de esgoto e cultivado com milho

The evaluation of micronutrient availability in agricultural soil treated with sewage sludge was developed in field with maize cultivation on a Dystrophic Red Latosol. The experiment used a randomized complete block design, with the treatments in a split-plot scheme, in time, with six doses of sewage sludge (main-plot treatment) in relation to the five sampling periods for the soil (subplot treatment), with four replications. The sewage sludge was applied in the superficial layer (0-20 cm). The micronutrients Fe, Cu, Mn and Zn were extracted from the soils using a DTPA (diethylenetriaminepentaacetic acid) solution. The same micronutrients were analyzed in the plant tissue after the nitric-perchloric decomposition of the maize samples by spectrometric atomic absorption. The results showed an increasing amount of Fe, Mn, Zn, Cu, Cation Exchange Capacity (CEC) and a decreasing pH in the soil. The increasing doses of sewage sludge increased the Fe, Mn, Cu and Zn availability in the soil solution, and the uptake amount by maize plants were always greater than the control values.

The mechanism and kinetics of DTPA-promoted dissolution of barite

Abstract The dissolution rate of natural barite, BaSO 4 , was measured in solutions of DTPA (diethylene triamine penta-acetic acid) to investigate the mechanism of ligand-promoted dissolution using a strong chelating agent. Experiments were carried out over a range of DTPA concentrations 0.5–0.0001 M solutions, at room temperature (22 °C), as well as a range of temperatures, 22–80 °C at 1 atm. The dissolution rate is inversely related to the DTPA concentration in solution. A more dilute DTPA solution is shown to be more efficient as a solvent in terms of the approach to the equilibrium saturation value for the dissolution of Ba 2+ . An analysis of the temperature dependence of the dissolution rate at high pH by the determination of activation energies indicates that the reaction is probably controlled by the pre-exponential term in the rate constant. This indicates that reaction frequency mostly controls differences in reactivity and suggests an explanation for the results in terms of stearic hindrance due to adsorbed DTPA molecules at the barite surface. The effect of DTPA on the solvation of the Ba 2+ ion may also influence the dissolution rate.