Chelator Ethylenediaminetetraacetic Acid Research Articles

Unraveling the Impact of Ethylenediaminetetraacetic Acid Chelating Agents on the Oil Recovery Processes: An Insight into Its Role in Fluid-Fluid and Rock-Fluid Interactions.

In recent years, chelating agents have garnered increasing attention due to their unique capabilities in addressing challenges associated with chemically enhanced oil recovery materials. Most previous studies have primarily focused on examining the influence of chelating agents on rock-fluid interactions. However, their effects on fluid-fluid interactions, specifically on interfacial tension (IFT) characteristics under various conditions, remain relatively unknown. This study investigates the effect of crucial reservoir parameters on the performance of ethylenediaminetetraacetic acid (EDTA) chelating agents in the IFT between crude oil and brine. Furthermore, the study evaluated the impact of varying concentrations of this agent on rock wettability alteration, zeta potential, and spontaneous imbibition. The results illustrated that introducing EDTA at high concentration into seawater (SW) solution reduced the IFT by 85%. Additionally, while higher pH levels contributed to IFT reduction due to increased hydroxyl ions, excessive salinity levels resulted in elevated IFT. Raising the temperature from 30 to 75 °C further decreased the IFT, changing the IFT for optimal EDTA concentration from 20.43 to 2.56 mN/m (∼88% reduction). The changes in zeta potential and contact angle measurements indicated that solutions of 5 and 7 wt % EDTA shifted rock wettability from oil-wet to strongly water-wet, resulting in the wettability alteration index of 1.01 and 1.02, respectively. Inductively coupled plasma analysis, on the other hand, revealed substantial chelation of metal ions from both the solution and rock when EDTA was added to the rock/SW system. This resulted in a significant increase in Ca2+ ions and a decrease in Mg2+ ions, attributed to the multi-ion exchange phenomenon.

High performance Mn/Mg co-modified calcium-based material via EDTA chelating agent for effective solar energy storage

Calcium-based material is a very promising candidate energy storage material for next generation concentrated solar power (CSP) plants with operation temperatures above 700 °C. However, performance decay and poor solar absorption capacity limit the large utilization of calcium-based material. Here, ethylene diamine tetraacetic acid (EDTA)-assisted sol–gel method is first employed to modify CaO with magnesium (Mg) and manganese (Mn) elements. MgO and Ca2MnO4 nanoparticles are attached to the surface of CaO particles to separate grains spatially to inhibit sintering. In addition to the external separation effect, Mn elements are found to be doped successfully into CaO crystal lattice rather than simply mixed, which restrains atomic diffusion and agglomeration inside CaO and thus further inhibits sintering more efficiently. The Mg and Mn co-doped sample (Ca:Mn:Mg = 9:1:2) synthesized by EDTA demonstrates exceptional thermal stability at 800 °C. The performance decay is only 6.3 % after 100 cycles and mainly manifests in the first ten cycles (4 %). Furthermore, by combining two-step calcination to avoid agglomeration and uneven doping, we also obtain the co-doped sample (Ca:Mn:Mg = 9:1:1) with nearly no performance decay in 100 cycles. The proposed materials possess an average solar absorptance of 67 %, about 4 times that of pure calcium material. This work not only designs energy storage materials with excellent performance expected to be applied in the next generation CSP plant but also provides a lattice doping route for calcium-based material modification.

Task specific microextraction column based on monolith for magnetic field-assisted in-tube solid phase microextraction of vanadium species in complex samples prior to online chromatographic analysis

The dominant species of vanadium (V) are V(IV) and V(V) which exhibit different toxicity and biological effects. Thus, speciation of V(IV) and V(V) is highly essential. Efficient sample preparation is the core step in the quantification of V(IV) and V(V). In the present study, a new task specific microextraction column based on monolith mingled with Fe3O4 nanoparticles (MBMC) was in situ synthesized in capillary and utilized as the extraction phase of magnetic field-assisted in-tube solid phase microextraction (MA-IT-SPME) of V(IV) and V(V) species which were coordinated with ethylene diamine tetraacetic acid (EDTA). The prepared MBMC presented porous and superparamagnetic properties, and possessed abundant functional groups. Results revealed that the exertion of magnetic field during adsorption and eluting steps boosted the extraction efficiency of V(IV)-EDTA and V(V)-EDTA chelates from 65.1 % to 55.7 %–90.0 % and 80.1 %, respectively. Under the beneficial extraction parameters, the established MA-IT-SPME was online hyphenated with HPLC/DAD to perform speciation of trace vanadium in water and vegetable samples, the achieved limits of detection were 0.054–0.060 μg/L and 1.4–1.5 μg/kg in water and vegetable samples, respectively, and the spiked recoveries varied from 82.5 to 118 %. In addition, relevant extraction mechanism under magnetic field was explored. In comparison with existing methods, the developed MA-IT-SPME technique displays some attractive merits such as automation, good anti-interference ability, high extraction efficiency, low cost and less use of organic solvent, in the capture of V species. The established online MBMC@MA-IT-SPME-HPLC/DAD system can become a competitive approach for sensitive speciation of V(IV) and V(V) at trace levels in complex samples.

LANTHANIDE CONTRACTION IN CHELATES OF ETHYLENEDIAMINETETRAACETIC ACID BASED ON CRYSTALLOGRAPHIC DATA: A SHORT REVIEW

The lanthanide (Ln) series has been attracted so much attention not only for its physical properties but also for its applications in organic synthesis and biomedical engineering. In the lanthanide chemistry, lanthanide contraction is a crucial concept meaning the gradual decrease in ionic radii as the atomic number of the Ln series increases. As a prominent chelator, ethylenediaminetetraacetic acid (EDTA) has been well-known to give stable complexes with various metals including Ln ions, resulted in forming (EDTA−4H)4− anion by deprotonation; over 100 kinds of Ln-EDTA complexes have hitherto been synthesized and structurally characterized using X-ray crystallography. While the lanthanide contraction phenomenon has been extensively studied in certain complexes of Ln, systematization on the Ln-EDTA remains inadequate though the chelates of EDTA are commonly used. Thus, this study presents a comprehensive analysis based on the data from the Cambridge Crystallographic Data Centre (CCDC). In mononuclear EDTA complexes X[Ln(EDTA−4H)(H2O)m]·nH2O (X+ = NH4+and its analogues) systematic lanthanide contraction depending on their coordination number are presented except for a few cases. However, in the case of non-mononuclear complexes or coordination polymers, the compositions become more complicated, and a greater variation in atomic bond length occurs, which is unusual for the lanthanide contraction studies in previous research. These varieties are considered to be influenced by different types of counter-cations, inorganic anions, solvent molecules and bridging O atoms from another EDTA anions. This suggests the flexibility and versatility of EDTA as a ligand. Such findings in the Ln-EDTA complexes could potentially provide us further development of a novel function in the future.

Elucidating the Role of a Calcium-Binding Loop in an x-Prolyl Aminodipeptidase from Lb. helveticus.

Prolyl aminodipeptidase (PepX) is an α/β hydrolase that cleaves at penultimate N-terminal prolyl peptide bonds. The crystal structure of PepX from Lactobacillus helveticus exhibits a calcium-binding loop within the catalytic domain. The calcium-binding sequence of xDxDxDGxxD within this loop is highly conserved in PepX proteins among lactic acid bacteria, but its purpose remains unknown. Enzyme activity is not significantly affected in the presence of the metal chelator ethylenediaminetetraacetic acid (EDTA), nor in the presence of excess calcium ions. To eliminate calcium binding, D196A and D194A/D196A mutations were constructed within the conserved calcium-binding sequence motif. Enzyme activity and stability of the D196A mutant were comparable to the wild-type enzyme by colorimetric kinetic assays and protein thermal shift assays. However, the D194A/D196A mutant was inactive though it retained native-like structure and thermal stability, contradicting the EDTA and calcium titration results. This suggests calcium binding to PepX may be essential for activity.

A lignin-derived material improves plant nutrient bioavailability and growth through its metal chelating capacity

The lignocellulosic biorefinery industry can be an important contributor to achieving global carbon net zero goals. However, low valorization of the waste lignin severely limits the sustainability of biorefineries. Using a hydrothermal reaction, we have converted sulfuric acid lignin (SAL) into a water-soluble hydrothermal SAL (HSAL). Here, we show the improvement of HSAL on plant nutrient bioavailability and growth through its metal chelating capacity. We characterize HSAL’s high ratio of phenolic hydroxyl groups to methoxy groups and its capacity to chelate metal ions. Application of HSAL significantly promotes root length and plant growth of both monocot and dicot plant species due to improving nutrient bioavailability. The HSAL-mediated increase in iron bioavailability is comparable to the well-known metal chelator ethylenediaminetetraacetic acid. Therefore, HSAL promises to be a sustainable nutrient chelator to provide an attractive avenue for sustainable utilization of the waste lignin from the biorefinery industry.

Differences in the Shiga Toxin (Stx) 2a Phage Regulatory Switch Region Influence Stx2 Localization and Virulence of Stx-Producing Escherichia coli in Mice.

Shiga toxin (Stx)-producing Escherichia coli (STEC) is a major cause of foodborne illness globally, and infection with serotype O157:H7 is associated with increased risk of hospitalization and death in the U.S. The Stxs are encoded on a temperate bacteriophage (stx-phage), and phage induction leads to Stx expression; subtype Stx2a in particular is associated with more severe disease. Our earlier studies showed significant levels of RecA-independent Stx2 production by STEC O157:H7 strain JH2010 (stx2astx2c), even though activated RecA is the canonical trigger for stx-phage induction. This study aimed to further compare and contrast RecA-independent toxin production in Stx2-producing clinical isolates. Deletion of recA in JH2010 resulted in higher in vitro supernatant cytotoxicity compared to that from JH2016ΔrecA, and the addition of the chelator ethylenediaminetetraacetic acid (EDTA) and various metal cations to the growth medium exacerbated the difference in cytotoxicity exhibited by the two deletion strains. Both the wild-type and ΔrecA deletion strains exhibited differential cytotoxicity in the feces of infected, streptomycin (Str)-treated mice. Comparison of the stx2a-phage predicted protein sequences from JH2010 and JH2016 revealed low amino acid identity of key phage regulatory proteins that are involved in RecA-mediated stx-phage induction. Additionally, other STEC isolates containing JH2010-like and JH2016-like stx2a-phage sequences led to similar Stx2 localization, as demonstrated by JH2010ΔrecA and JH2016ΔrecA, respectively. Deletion of the stx2a-phage regulatory region in the wild-type strains prevented the differential localization of Stx2 into the culture supernatant, a finding that suggests that the stx2a-phage regulatory region is involved in the differential ΔrecA phenotypes exhibited by the two strains. We hypothesize that the amino acid differences between the JH2010 and JH2016 phage repressor proteins (CIs) lead to structural differences that are responsible for differential interaction with RecA. Overall, we discovered that non-homologous stx2a-phage regulatory proteins differentially influence RecA-independent, and possibly RecA-dependent, Stx2 production. These findings emphasize the importance of studying non-homologous regulatory elements among stx2-phages and their influence on Stx2 production and virulence of STEC isolates.

Rapid, Cost-Efficient, Enzyme-Free Passaging of Human Pluripotent Stem Cells on Feeder Cells by Ethylenediaminetetraacetic Acid-Mediated Dis-Adhesion.

Human pluripotent stem cells (human embryonic stem cells, hESCs, and human induced pluripotent stem cells, hiPSCs) were originally cultured on different types of feeder cells for maintenance in an undifferentiated state in long-term culture. This approach has been supplanted to a large extent by feeder-free culture protocols, but these involve more costly reagents and can promote a transition to a primed state, which restricts the cells' differentiation capacity. In both feeder and feeder-free conditions, the harvesting of hESC or hiPSC colonies for passaging is a necessary procedure for expanding the cultures. To provide an easy and high-yield procedure for passaging hESCs/hiPSCs cultured on feeder cells, we have established a harvesting method using dis-adhesion elicited by the calcium chelator ethylenediaminetetraacetic acid (EDTA). We have assessed the yield and quality of the resultant passaged cells by comparing this approach to the original mechanical harvesting approach, in which colonies are isolated with a scalpel under a microscope (mechanical harvesting was chosen as a comparator to avoid the reagent variability associated with enzymatic harvesting). In one set of experiments, two different hESC lines were maintained on a feeder cell layer of human foreskin fibroblasts. Each line was subjected to multiple passages using EDTA-based or mechanical harvesting and assessed forcolony size and morphology, cell density, stemness marker expression, differentiation to the three germ layers in embryoid bodies, and genomic aberrations. In another set of experiments, we used EDTA-based harvesting on two different hiPSC lines and obtained similar results. EDTA-induced dis-adhesion saved time and gave a higher yield of colonies of a more favorable size and more uniform morphology compared to mechanical harvesting. It was also faster than enzymatic harvesting and not prone to enzyme batch variability. The EDTA-induced dis-adhesion method also facilitates the transfer of hESC/hiPSC lines from feeder cell-based culture to feeder-free conditions if desired for downstream use and analysis.

Staged purification of phosphogypsum using pH-dependent separation process.

Phosphogypsum (PG) is an industrial by-product of the transformation of phosphate rocks. For decades, PG has been a source of environmental concern due to the massive amount produced thus far, i.e., 7 billion tons, with a current production rate of 200-280 million tons per year. Phosphate minerals contain various impurities that precipitate and concentrate within PG. These impurities hinder PG usability in various sectors. This paper aims to purify PG using an innovative process based on staged valorization of PG. Initially, PG dissociation by ethylenediaminetetraacetic acid (EDTA) was optimized. After screening of different parameters and monitoring the ionic conductivity of solutions, it was disclosed that a pH-dependent solubilization process in the presence of EDTA resulted in high solubility of PG, up to 11.82g/100mL at pH > 11. Subsequently, a recovery of the purified PG by selective precipitation of calcium sulfate dihydrate (CSD) from obtained filtrate through pH adjustment to 3.5 were investigated. An abatement of 99.34% Cr, 97.15% Cd, 95.73% P2O5, 92.75% Cu, 92.38% Al2O3, 91.16% Ni, 74.58% Zn, 72.75% F, 61.43% MgO, 58.8% Fe2O3, 56.97% K2O, and 55.41% Ba was achieved. The process relied on the variation of EDTA chelation properties towards monovalent, divalent, and trivalent cations at different pHs. According to the findings of this study, a staged purification process in the presence of EDTA is an effective method for removing impurities from the industrial PG.

Experimental Investigation and Modeling of Fluid and Carbonated Rock Interactions with EDTA Chelating Agent during EOR Process

The injection of chemical fluids into oil reservoirs is gaining widespread attention in light of the declining conventional oil resources by recovering more hydrocarbons. This study is focused on using a chemical called ethylenediaminetetraacetic acid (EDTA) chelating agent in a carbonate reservoir to shed light on contact angle differences of 625 aged thin sections and rock dissolution under the influence of different pHs, temperatures, chelating times, and various chelating agent concentrations in seawater. According to a rock dissolution test, at least 5 wt % of EDTA chemical is needed to obtain oil recovery. A ζ potential test and scanning electron microscopy (SEM) images revealed that the mechanism of adsorption at low pH values and the expansion of the electrical double layer (EDL) at high pH values were responsible for wettability alteration, and an increase in EDTA concentration intensified each mechanism. Interfacial tension (IFT) measurements also showed that adding 1 and 10 wt % of the EDTA to the seawater solution reduced the IFT by 67.75% and 76.08%, respectively. The contact angle experiments demonstrated an increase in the mechanism that leads rock to behave more hydrophilically as pH, solution temperature, and chelating agent concentration in saltwater increased. Artificial neural network (ANN) methods also led to the introduction of a model to predict the contact angle employing multilayer perceptron neural networks (MPNN) and cascade feedforward neural networks (CFFNN). The CFFNN with two hidden neurons and trained by the Levenberg–Marquardt backpropagation algorithm is the most accurate model when comparing the accuracy of models for predicting contact angle values. The CFFNN model indicated that the weight percentage of the chelating chemical, which has a share of about 90%, had the greatest influence on the contact angle, and chelating time, with a share of less than 10%, had the least.

Are Reactive Oxygen Species (ROS) the Main Mechanism by Which Copper Ion Treatment Degrades the DNA of Mycobacterium avium subsp. paratuberculosis Suspended in Milk?

Mycobacterium avium subsp. paratuberculosis (MAP) is the causal agent of paratuberculosis. This pathogen is able to survive adverse environmental conditions, including the pasteurization process. Copper, a well-studied metal, is considered an important antibacterial tool, since it has been shown to inactivate even MAP in treated milk through unknown mechanisms. The aim of the present study is to show the effect of copper ions, and reactive oxygen species (ROS) generated in response to oxidative stress, on the damage to MAP DNA when exposed to a copper ion challenge in cow's milk. Spiked milk with different MAP bacterial loads was supplemented with blocking agents. These were either the copper chelators ethylenediaminetetraacetic acid (EDTA) and batocuproin (BCS) or the ROS quenchers D-mannitol, gallic acid and quercetin. The DNA protection, MAP viability and ROS production generated after exposure to a copper challenge were then measured. In a bacterial load of 104 cells mL-1, blocking effects by both the copper chelators and all the ROS quenchers offered significant protection to MAP DNA. In a concentration of 102 cells mL-1, only D-mannitol and a mix of quenchers significantly protected the viability of the bacteria, and only at a concentration of 106 cells mL-1 was there a lower production of ROS when supplementing milk with gallic acid, quercetin and the mix of quenchers. Based on these findings, it may be concluded that MAP DNA damage can be attributed to the combined effect of the direct copper ions and ROS generated. Nevertheless, taking into account the antioxidant environment that milk provides, the direct effect of copper could play a prominent role.

Neuron Protection by EDTA May Explain the Successful Outcomes of Toxic Metal Chelation Therapy in Neurodegenerative Diseases.

Many mechanisms have been related to the etiopathogenesis of neurodegenerative diseases (NDs) such as multiple sclerosis, amyotrophic lateral sclerosis, Parkinson’s disease, and Alzheimer’s disease. In this context, the detrimental role of environmental agents has also been highlighted. Studies focused on the role of toxic metals in the pathogenesis of ND demonstrate the efficacy of treatment with the chelating agent calcium disodium ethylenediaminetetraacetic acid (EDTA) in eliminating toxic metal burden in all ND patients, improving their symptoms. Lead, cadmium, aluminum, nickel, and mercury were the most important toxic metals detected in these patients. Here, I provide an updated review on the damage to neurons promoted by toxic metals and on the impact of EDTA chelation therapy in ND patients, along with the clinical description of a representative case.

Thermal decomposition characterization and kinetics of copper, iron, manganese and zinc chelates of ethylenediaminetetraacetic acid in air atmosphere

The analysis of the thermal stability of Cu, Fe, Mn, and Zn-EDTA (copper, iron manganese, and zinc chelates of ethylenediaminetetraacetic acid) chelates indicates a high complexity of occurring decomposition processes, ranging from two to three simplified stages of the decomposition process. Obtained results reports that the thermal stability decreased in the following order: Zn-EDTA > Mn-EDTA > Cu-EDTA > Fe-EDTA. The initial model-free kinetic analysis suggested that three out of four chelates had a multi-step first stage of the decomposition. Model-fitting methodology resulted in the best fit in the first stage of decomposition of the studied EDTA chelates that corresponded to An (nth-dimensional nucleation) or Cn (nth-order autocatalytic reaction) models with correlation coefficients within 0.9951 to 0.9991. The activation energy values were within the range 126.27–253.25 kJ·mol−1. The least stable chelates, Cu and Fe, were defined by using competitive An and Cn reaction types, while the most stable, Zn, has a single-step Cn first stage of the decomposition process. The study showed the initial possibility of using EDTA chelates of zinc, manganese, and possibly copper in fertilizer production.

Mechanistic insights into Ca-alginate gel-associated membrane fouling affected by ethylene diamine tetraacetic acid (EDTA)

While transparent exopolymer particles (TEP) is a major foulant, and ethylene diamine tetraacetic acid (EDTA) is a strong chelating agent frequently used for fouling mitigation in membrane-based water treatment processes, little has been known about TEP-associated membrane fouling affected by EDTA. This work was performed to investigate roles of EDTA addition in TEP (Ca-alginate gel was used as a TEP model) associated fouling. It was interestingly found that, TEP had rather high specific filtration resistance (SFR) of 2.49 × 1015 m−1·kg−1, and SFR of TEP solution firstly decreased and then increased rapidly with EDTA concentration increase (0–1 mM). A series of characterizations suggested that EDTA took roles in SFR of TEP solution by means of changing TEP microstructure. The rather high SFR of TEP layer can be attributed to the big chemical potential gap during filtration described by the extended Flory-Huggins lattice theory. Initial EDTA addition disintegrated TEP structure by EDTA chelating calcium in TEP, inducing reduced SFR. Continuous EDTA addition decreased solution pH, resulting into no effective chelating and accumulation of EDTA on membrane surface, increasing SFR. It was suggested that factors increasing homogeneity of TEP gel will increase SFR, and vice versa. This study revealed the thermodynamic mechanism of TEP fouling behaviors affected by EDTA, and also demonstrated the importance of EDTA dosage and pH adjustment for TEP-associated fouling control.

Rapid and sensitive detection of metal chelator ethylenediamine tetraacetic acid

A colloidal gold-labeled monoclonal antibody nano-probe for metal chelator ethylenediamine tetraacetic acid (EDTA) was synthesized. Based on the probe, an immunochromatographic assay that was highly sensitive, convenient, and one-step competitive to detect EDTA, was developed. Then the immunochromatographic assay was applied for the detection of water samples. The goat anti-mouse IgG was immobilized on the nitrocellulose membrane as a control line. And the detection conjugate (isothiocyanobenzyl-EDTA-BSA) was immobilized on the nitrocellulose membrane as a detection line. EDTA in water samples would compete with the immobilized isothiocyanobenzyl-EDTA-BSA to bind with the colloidal gold probe. The visual detection limit of EDTA was detected to be about one ppm. The immunochromatographic assay in the present study does not need any equipment and complicated sample preparation and can be performed within 10 min. The EDTA concentrations in local water samples were successfully detected by the immunochromatographic assay, which is rapid, low cost, and suitable for testing on-site.

Reinforcing effect of surface-modified steel fibers in ultra-high-performance concrete under tension

The direct tensile behavior of ultra-high-performance surface-modified steel fiber-reinforced concrete was evaluated in this study. Various chemical modifications were applied to steel fibers, including acetone washing, hydrochloric acid washing, zinc phosphating, silica coating, and chelation using an ethylenediaminetetraacetic acid (EDTA) electrolyte solution, which improved the tensile strength, tensile strain, and g-value to a maximum of 17.76 MPa, 1.22%, and 144.51 kJ/m3, respectively. Acetone washing and EDTA chelating were the most effective methods for improving the tensile strength, whereas silica coating was the best for improving the strain capacity and energy absorption capacity. The optimal treatment time for EDTA chelation treatment was approximately 6 h, and the tensile performance decreased considerably after 12 h of treatment. Comparing these results with those of pullout experiments revealed that a high shear stress should be maintained after the fiber has fully debonded to effectively enhance the post-cracking tensile performance.

Metal Chelators Ethylenediaminetetraacetic acid (EDTA) and N,N,N′,N′‐tetrakis(2‐pyridinylmethyl)‐1,2‐ethanediamine (TPEN) Interfere with Carbonic Anhydrase (CA) Activity in Wilbur‐Anderson Assay (WAa)

In our effort to set up a laboratory for undergraduate students with the tentative title ”Studying enzymatic activity of Carbonic Anhydrase”, we successfully determined carbonic anhydrase activity and demonstrated its inhibition by Acetazolamide, a potent CA inhibitor, using the Wilbur‐Anderson assay (WAa) using 6 experimental set‐ups with a class of 24 students.WAa hinges upon determining the time T (in seconds) required for 4 mL of saturated with carbon dioxide (CO2) water to lower pH from 8.3 to 6.3 of the mixture when added to 6 mL of 0.02M Tris buffer at 0°C without (T0) and with enzyme (TE). Activity (A) is defined as A = 2*(T0/TE‐1) assay units (AU). In n = 16 blank trials, T0 = 75.0±10.7s (Mean±Standard deviation), and with 0.001mg of CA in n = 12 trials, TE = 50.2±8.1s, A = 0.99±0.66 AU (p < 0.001). When for a test we used EDTA, a carboxylic high‐affinity metal ion chelator, to inactivate this Zn2+‐containing enzyme, we unexpectedly encountered that in the presence of the sodium salt of EDTA (Na2EDTA): 1) T was significantly slowed in a concentration‐dependent manner: for 5µM, 50µM, and 500µM, T was 84.3±7.9s (n = 10, p < 0.05), 108.5±.6s (n = 7, p < 0.001), and 130.8±22.7s (n = 10, p < 0.001), respectively; and 2) unexpectedly, in the context of the previous finding, Na2EDTA significantly enhanced CA activity (TE = 38.5±4.0s, A = 1.84 AU, n = 10, p < 0.001) in the presence of 5µM Na2EDTA that was abrogated by 10µM Acetazolamide, a potent CA inhibitor (T = 138.3±10.4s, n = 7, p < 0.001). TPEN, a pyridinic non‐carboxylic metal ion chelator that is more potent in metal ion chelation that EDTA, significantly slowed T0 (99.5±15.9s, n = 4) similar to Na2EDTA, and significantly enhance CA activity (TE = 41.1±3.8, n = 4, p < 0.05) with equal potency.This indicates that principally chemically different metal ion chelators EDTA and TPEN interfere with the determination of CA activity in the context of WAa. Studies to explain these phenomena are underway with the hypotheses that the contaminating metal ions that catalyze CO2 hydration/dehydration without CA are responsible for the observed phenomena.

Evaluation of Chelating Agents Used in Phytoextraction by Switchgrass of Lead Contaminated Soil.

Soil lead (Pb) contamination is a recognized environmental and global health problem. Phytoextraction of Pb using switchgrass (Panicum virgatum L.), a second-generation biofuel crop, is typically enhanced by soil chelation. The effectiveness of four different chelating agents, phytic acid (inositol hexaphosphate), citric acid, NTA (nitrilotriacetic acid), and EDTA (ethylenediaminetetraacetic acid) was examined in pot culture. Plants treated with EDTA (1 mM) showed significantly higher shoot Pb concentrations compared to control plants and plants treated with other chelates. Lead-solubility following phytoextraction was examined by soil washing using 0.01 and 0.05 M acetic acid as an extractant solution revealed no significant differences in Pb concentrations in soil among different chelate treatments and control. Furthermore, the effects of different concentrations (1, 2, 5 and 10 mM) of NTA on Pb phytoextraction of switchgrass were examined. Plants receiving 5 mM and 10 mM NTA had significantly higher foliage concentrations of Pb compared to plants treated with lower levels (1 and 2 mM) of NTA. Moreover, the effect of NTA application alone was significantly improved by a combined application of Triton X-100, an alkyl polyglucoside (APG); the Pb concentration in the foliage of switchgrass was more than doubled when treated with NTA combined with APG. The use of NTA combined with APG has great potential in improving phytoextraction efficiencies of switchgrass on Pb-contaminated soils.

Attenuation of ischemia–reperfusion injury by intracoronary chelating agent administration

Ischemia–reperfusion (IR) injury accelerates myocardial injury sustained during the myocardial ischemic period and thus abrogates the benefit of reperfusion therapy in patients with acute myocardial infarction. We investigated the efficacy of intracoronary ethylenediaminetetraacetic acid (EDTA) administration as an adjunctive treatment to coronary intervention to reduce IR injury in a swine model. We occluded the left anterior descending artery for 1 h. From the time of reperfusion, we infused 50 mL of EDTA-based chelating agent via the coronary artery in the EDTA group and normal saline in the control group. IR injury was identified by myocardial edema on echocardiography. Tetrazolium chloride assay revealed that the infarct size was significantly lower in the EDTA group than in the control group, and the salvage percentage was higher. Electron microscopy demonstrated that the mitochondrial loss in the cardiomyocytes of the infarcted area was significantly lower in the EDTA group than in the control group. Echocardiography after 4 weeks showed that the remodeling of the left ventricle was significantly less in the EDTA group than in the control group: end-diastolic dimension 38.8 ± 3.3 mm vs. 43.9 ± 3.7 mm (n = 10, p = 0.0089). Left ventricular ejection fraction was higher in the EDTA group (45.3 ± 10.3 vs. 34.4 ± 11.8, n = 10, respectively, p = 0.031). In a swine model, intracoronary administration of an EDTA chelating agent reduced infarct size, mitochondrial damage, and post-infarct remodeling. This result warrants further clinical study evaluating the efficacy of the EDTA chelating agent in patients with ST-segment elevation myocardial infarction.

Effects of the Reservoir Environment and Oilfield Operations on the Iron Mineral Surface Charge Development: An Insight into Their Role in Wettability Alteration

Iron minerals are hydrophobic minerals predominately found in sandstone formations with their role in wettability alteration not fully understood. With the reservoir rock being a complex system of multiple minerals, the control of wettability alterations becomes difficult to manage due to the different surface chemistry of constituent minerals. This study presents for the first time the surface charge development of pyrite, magnetite, and hematite minerals in native reservoir environments and the effect of oilfield operations such as acidizing, water injection, polymerization, surfactant flooding, and alkaline flooding on iron minerals, surface charge development. This was achieved using zeta potential measurement, which depicts the type of surface charge and infers the propensity of precipitation. The experimental results show that pyrite, magnetite, and hematite behave similarly under reservoir conditions with all the minerals being positively charged although pyrite and hematite are negatively charged in seawater (SW). Results also show that the surface charge development is controlled by the electrical double-layer effect and ion adsorption on the mineral surfaces. These findings provide key insights into the role of iron minerals in wettability alteration as they provide surfaces that serve as a precursor for polar crude component adsorption. Also, the design of an ion-engineered fluid to control the surface charge of iron minerals was implemented, and the results showed that they behave differently. Furthermore, the effect of low-salinity water on the mineral surface charge was examined. The findings revealed that low-salinity water can produce a negatively charged surface, however, cannot mitigate the iron mineral precipitation challenge as the observed zeta potential values are near zero. Finally, slug and continuous injection of the ethylenediaminetetraacetic acid chelating agent was implemented as an iron mineral precipitation control strategy, with the continuous injection observed to significantly improve the colloidal stability of the iron minerals in the reservoir native state and after SW injection.