Evidence for a differential translocation of actinides across human lung epithelial cell monolayer in vitro according to their physicochemical properties and the presence of a chelating agent

The epithelial cell plays a key role in the transfer of radionuclides from lungs to blood following pulmonary exposure. The present study was designed to evaluate the transfer across human lung epithelial cells of various actinides (plutonium, americium and uranium), the influence of the physicochemical properties of plutonium compounds and of the chelating agent diethylene triamine pentaacetic acid (DTPA). To address this question, Calu-3 cells grown in a bicameral culture system were used. The integrity of the epithelial barrier was evaluated by measuring transepithelial electrical resistance (TEER) and the passage of a fluorescent marker, lucifer yellow. Activity measurement in basal compartment following periodic collection of culture medium was made from 2 h to seven days. To facilitate data handling and analysis, the statistical tool STATBIODIS was used. The results indicate differences in transfer for the different elements, and according to Pu physicochemical properties. Though to various extents, the chelating agent DTPA always increased the transfer of Pu and Am across the epithelial cells, without altering the integrity of the epithelial barrier. This in vitro cell culture model, by mimicking translocation of actinides from lungs to blood, can represent a valuable tool to further understand the underlying mechanisms and properties controlling this process.

Decontamination of radioactive hazardous materials by using novel biodegradable strippable coatings and new generation complexing agents

Eight different types of complexing agents were employed for the development of new biodegradable decontamination solutions that are able to form strippable coatings after they are dispersed and allowed to dry on a variety of surfaces contaminated with ⁶⁰Co, ¹³³Ba, ¹³⁷Cs and ²⁴¹Am radioactive isotopes. The new generation of eco-friendly chelators with superior biodegradability, utilized for the first time in such applications, can easily replace the non-biodegradable and carcinogenic complexing agents that are still in use today, due to their decontamination performances. Furthermore, besides the complexing action over the radionuclides, the solutions contain two types of clays, Bentonite (BT) and Saponite (SP), which have the capacity to adsorb specific ions, improving the decontamination efficiency of the solutions. Our research revealed that it is preferable to replace BT with SP, due to its better dispersibility, thermal stability, next to superior ability to gel and better thermal stability (Miles, 2011). The solutions showed a decontamination factor superior to 95% for ¹³⁷Cs (on all surfaces), over 90% for ⁶⁰Co and ¹³³Ba, and more than 72% ²⁴¹Am (on all surfaces), except for galvanized metal plates, where lower decontamination factors were obtained: over 70% for ¹³³Ba, maximum 41.87% for ²⁴¹Am and 43.19% for ⁶⁰Co.

Biodegradable chelating agent improves the survival of early larvae for shellfish aquaculture

The toxicity of heavy metals commonly impacts the survival of crustacean and bivalve larvae in hatchery culture, and this has led to the widespread use of EDTA to decrease this toxicity. Since EDTA has a very poor biodegradability leading to potential persistent environmental effects, alternative methods to prevent heavy metal toxicity to shellfish larvae are needed. EDDS is a biodegradable potential alternative to EDTA for this application and was tested as a treatment of the seawater used for rearing aquaculture Greenshell™ mussel (Perna canaliculus) larval embryos in this study. Mussel embryos reared with EDTA or EDDS had significantly better survival than without. The concentrations and spatial distributions of heavy metals in D-veliger larvae as determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and X-ray Fluorescence Microscopy (XFM) suggested that chelating agents increased the levels of calcium in larvae while they reduced the concentration of zinc. In addition, where decreased accumulation of the other heavy metals was not observed, chelating agents affected their distribution within the larvae, especially for copper and arsenic. This is the first study to test the use of EDDS for aquaculture hatchery application and shows that EDDS is an effective biodegradable alternative to EDTA that can mitigate the effects of heavy metals for shellfish larval rearing.

Impact of humic acid on degradation of benzo(a)pyrene polluted Haplic Chernozem triggered by modified Fenton-like process

In this study, the applicability of a modified Fenton reaction for remediation of polycyclic aromatic hydrocarbons (PAHs) was demonstrated in chernozem soil. The main aim was to investigate the impact of variation of humic acid (HA) on the modified Fenton capabilities to degrade of benzo(a)pyrene (BaP). Experimental was designed with two independent variables, including hydrogen peroxide (H₂O₂) and hematite (α-Fe₂O₃), to determine the most effective BaP treatment conditions with exploring natural and an extra added amount of HA. For modified Fenton reaction at Haplic Chernozem, the best BaP degradation conditions resulted in an overall degradation of 68% with the following conditions: 0.95 M H₂O₂; 17.54 mg/g hematite; pH 7.8 without adjustment; 24 h; unsaturated (soil: water ratio 1:0.5). In the soil supplemented with 1% HA, Fenton-like reaction was found to perform better and resulted in 76% BaP degradation with less amount of hematite dosage (16.71 mg). The fact that HA, a significant class of naturally occurring compounds in soil, supports the Fenton reaction has strong relevance in the field of enhancing PAHs degradation field to obtain a more economical route.

Data on metal-chelating, -immobilisation and biosorption properties by Gordonia rubripertincta CWB2 in dependency on rare earth adaptation

Recent studies have shown that the metal adaptation of Actinobacteria offers a rich source of metal inducible environmentally relevant bio-compounds and molecules. These interact through biosorption towards the unique cell walls or via metal chelating activity of metallophors with trace elements, heavy metals and even with lanthanides to overcome limitations and toxic concentrations. Herein, the purpose is to investigate the adaptation potential of Gordonia rubripertincta CWB2 in dependence of the rare earths and to determine if we can utilize promising metallophore metal affinities for metal separation from aquatic solutions. For details on data interpretation and applicability of siderophores we refer to the related article entitled "Cultivation dependent formation of siderophores by Gordonia rubripertincta CWB2" [1]. The respective workflow comprises a metal adaptation method to demonstrate effects on bacterial growth, pH, metallophore production, and metabolic change. All this was evaluated by LC-MS/MS and effects on biosorption of rare earths was verified by ICP-MS. Furthermore, we were able to carry out batch metal adsorption and desorption studies of metallophores entrapped in inorganic polymers of tetramethoxysilane (TMOS) to determine metal chelating capacities and selective enrichment effects from model solutions. The adaptation potential of strain CWB2 at increased erbium and manganese concentrations was verified by increased chelating activity on agar plates, in liquid assays and demonstrated by the successful enrichment of erbium by metallophore-functionalized TMOS-polymers from an aquatic model solution. Furthermore, the number of detected compounds in dependency of rare earths differ in spectral counts and diversity compared to the wild type. Finally, the biosorption of rare earths for the selected adaptation was increased significantly up to 2-fold compared to the wild-type. Overall a holistic approach to metal stress was utilised, integrating a bacterial erbium adaptation, metal chelating, biosorption of lanthanides and immobilization as well as enrichment of metals using metallophore functionalized inorganic TMOS polymers for separation of metals from aquatic model solutions.

A novel strategy for accelerating the recovery of a Fe(II)-inhibited anammox reactor by intermittent addition of betaine: Performance, kinetics and statistical analysis

In this manuscript, Fe(II) inhibition of anammox and its recovery were investigated, and the performance, kinetics and statistical features were comprehensively studied simultaneously. Anammox was suppressed and completely inhibited by the addition of 109.29 and 378.57 mg/L Fe(II), respectively, via uncompetitive inhibition. Nitrite inhibition of anammox was best fitted by the Edwards model and Aiba model. EDTA-2Na wash (0.5, 1.0, 1.5, and 2.0 mM) had a limited effect on anammox recovery, while the addition of 2.0 mM betaine accelerated anammox recovery. Prolonged betaine addition caused an unintended reduction of anammox activity, though it self-recovered after the withdrawal of betaine. The modified Boltzmann model most accurately simulated the processes of anammox recovery using the EDTA-2Na wash, betaine regulation and self-recovery, and the modified Stover-Kincannon model was able to assess the results of anammox recovery. The one-sample t-test was successfully applied to determine the effects of these three recovery strategies on inhibited anammox, which were short-term disinhibition or long-term recovery effects. The above-mentioned results demonstrate that an intermittent addition of betaine, which is a better alternative to frequently-used but poorly-degradable EDTA, may be a useful and environmentally friendly recovery strategy for Fe(II)-inhibited anammox reactor.

Effect of different chelating agents and their surface tension on the amount of apically extruded debris

Background/purpose

During root canal preparation apical extrusion is an undesirable situation that can cause postoperative complications. The aim of the present study is to evaluate the effect of the presence of different chelators in root canals during preparation on the amount of apically extruded debris and to investigate the effect of surface tension of irrigant on the apical extrusion.

Materials and methods

Ninety extracted mandibular incisor teeth were included. Prior to canal preparation, the teeth were mounted to Eppendorf tubes. Root canals of the samples were prepared with Reciproc instruments in the presence of different chelating agents (17% EDTA-liquid, 17% EDTA-gel, 7% maleic acid, 2.25% peracetic acid, 10% citric acid) and 5% NaOCl. Apically extruded debris was collected in Eppendorf tubes and weighted with an electronic balance. The surface tension of solutions was calculated with the ring method using a du Noüy ring digital tensiometer. The statistical analysis was performed with Tamhane's T2 test for apical extrusion and the Tukey for surface tension. The correlation between apical extrusion and surface tension was compared using Pearson's coefficient.

Results

The least amount of apically extruded debris was with EDTA-gel, peracetic acid and citric acid which were similar to each other. NaOCl had the highest surface tension whereas peracetic acid and EDTA-liquid had the lowest. There was no significant correlation exists between apical extrusion and surface tension.

Conclusion

The presence of EDTA-gel, citric acid and peracetic acid in root canals during preparation decreased the amount of apically extruded debris compared to other solutions. The investigated irrigation solutions have no significant effect on the amount of apical debris extrusion.

Ecotoxicity assessment of sodium dimethyldithiocarbamate and its micro-sized metal chelates in Caenorhabditis elegans

Sodium dimethyldithiocarbamate (SDDC) is a widely used heavy metal chelating agent in harmless treatment of wastewater and hazardous waste, but SDDC and its heavy metal chelates may leak into the environment and bring potential ecological risks. In this study, the model organism Caenorhabditis elegans was used to evaluate the toxic effect of SDDC and its heavy metal Cu, Pb chelates. Multiple endpoints were investigated by subacute exposure to SDDC (0.01-100 mg/L) and micro-sized Cu, Pb chelates of SDDC (1-100 mg/L). Our data indicated that the LC₅₀ value of SDDC was 139.39 mg/L (95% Cl: 111.03, 174.75 mg/L). In addition, SDDC was found that concentration of 1 mg/L is a safe limit value for nematode C. elegans, and concentration above 1 mg/L caused adverse effects on the survival, growth, locomotion behaviors and reactive oxygen species (ROS) production of exposed nematodes. Furthermore, all tested SDDC-Cu and SDDC-Pb chelates had obviously lower toxic effect than untreated Cu, Pb metals. These two chelates also had a lower toxic effect than SDDC agent due to its more stable structure. Moreover, SDDC-Cu had a higher toxic effect than SDDC-Pb at the same concentration. Thus, our results suggest that SDDC as a kind of chelating agent applied in harmless treatment of heavy metals, the safe addition limit should not be exceeded.

Calcium elution from cement kiln dust using chelating agents, and CO2 storage and CaCO3 production through carbonation

In this study, indirect carbonation was carried out by using cement kiln dust (CKD), an alkaline industrial by-product, and three chelating agents (citrate, malonate, and adipate salts) as solvents at the room temperature and atmospheric pressure. We derived the optimum conditions for eluting Ca from CKD, as well as those for storing CO₂ and producing CaCO₃ through carbonation. The most important factor affecting the Ca elution from CKD was the solvent concentration and that for the carbonation was the end-of-carbonation pH. Under the optimum conditions of Ca elution, the molar ratios of Ca and solvent in eluates were 1:1, 1:2, and 1:2, respectively, using citrate, malonate, and adipate solvents. Based on the results, we propose that one molecule of Ca ion and one molecule citrate that is tridentate are combined to form a complex. The bidentate malonate and adipate, on the other hand, form complexes by combining one molecule of Ca ion and two molecules of each solvent. It is essential to raise the pH while simultaneously minimizing the amount of free chelating agent in solution to produce more CaCO₃ and prevent its dissolution. Besides, it is absolutely necessary to terminate the carbonation reaction at a pH of about 10.5 to improve the reuse efficiency of the chelating agent. CaCO₃ produced through carbonation reaction started to dissolve at pH approximately 10.5. All of the CaCO₃ produced was calcite with a purity of 98%. The efficiency of Ca elution from CKD using three solvents increased significantly with increasing stability constant of a Ca-ligand complex, but the efficiency of carbonation was the same for all solvents.

The effect of phosphate on the heat resistance of spores of dairy isolates of Geobacillus stearothermophilus

In this study, we show that phosphate decreases the spore heat resistance by accelerating the rate of loss of cations from spores. Heat resistance of spores of Geobacillus stearothermophilus A1, D1, P3 and ATCC 12980 were determined in distilled water containing varying concentrations (0.1, 1 and 2% w/v) of di‑sodium phosphate. The average decimal reduction times (D value) for strains A1, D1, P3 and ATCC 12980 in distilled water were 5.8, 6.8, 5.7 and 9 min at 110 °C respectively. On the addition of 0.1, 1 and 2% w/v of di‑sodium phosphate, the average D₁₁₀ values of all the strains in distilled water were lowered by 50, 61 and 70% respectively. Addition of 0.05% w/v of Na-EDTA to distilled water resulted in lowering of the average D₁₁₀ value of all the strains by 55%. Heat resistance of spores of A1, D1, P3 and ATCC 12980 was found to be associated with the Dipicolinic Acid (DPA) content whose concentrations were 0.25, 0.30, 0.27 and 1.6 pg per spore respectively. Analysis by atomic absorption spectroscopy revealed that the phosphate present in the heating medium causes excess release of calcium from spores with 2% w/v phosphate being highly effective, thus confirming the chelating effect of phosphate. This study provides insight into the heat resistance and the increased heat sensitivity of spores of G. stearothermophilus A1, D1 and P3 in the presence of phosphate, which can be used in the design of Cleaning in Place (CIP) systems involving phosphate based cleaning agents to combat biofilms and spores in the dairy industry.

Evaluation method for the measuring comprehensive suitability of chelating agents: a study of the temporal dynamics of heavy metal activation

The effects of chelating agents on heavy metal activation in Cd- and Pb-contaminated soils were studied through a dynamic activation experiment. An evaluation method for the measuring comprehensive suitability of chelating agent was established by calculating indexes for the degree of activation effect suitability and activated heavy metals' half-life suitability. The following results were obtained: in Cd- and Pb-contaminated soils, heavy metal activation effects reached or approached maximum activating effects within 1 d and subsequently showed different levels of decline in all chelating agent treatment conditions. Declines in activation effects similarly subjected to the law of exponents over time and to the goodness of fit in DTPA, NTA, and GLDA ranged from 0.80 to 0.98. For Cd- and Pb-contaminated soils, chelating agents' levels of comprehensive suitability (H) were recorded as follows: NTA(1.40) > GLDA(1.31) > DTPA(1.14) > EDTA(1.00) > EDDS(0.14) > CA(0.06) and GLDA(1.56) > DTPA(1.48) > EDTA(1.00) > NTA(0.78) > EDDS(0.26) > CA (0.02). GLDA and DTPA are both suitable for Cd and Pb phytoextraction. Moreover, NTA and GLDA are optimal chelating agents for Cd and Pb phytoextraction, respectively.

Heavy metal toxicity: An update of chelating therapeutic strategies

AIM

This review illustrates heavy metals toxicity, currently available therapies and the role and efficacy of chelation therapy for its management.

SUMMARY

Heavy metals are necessary for various biological processes, but they become harmful in excess. Specifically, they induce oxidative stress by generating free radicals and reducing antioxidant levels. Heavy metals also alter the confirmation of protein and DNA and inhibit their function. Chelation therapy is commonly used to treat metals toxicity. Chelation is a chemical process that occurs when interaction between a central metal atom/ion and ligand leads to formation of a complex ring-like structure. The ligand has a donor ion/molecule, which has a lone pair of electrons and may be monodentate to polydentate. Each metal has a different reactivity with a ligand, so a specific chelation agent is required for each metal. Combination therapy with a chelating agent and an antioxidant led to improved outcome.

CONCLUSION

Heavy metal poisoning is a common health problem because of mining, smelting, industrial, agricultural and sewage waste. Heavy metals can be efficiently excreted from the body following treatment with proper chelation agents.

Amine-terminated dendritic polymers as a multifunctional chelating agent for heavy metal ion removals

In this study, amine-terminated hyperbranched PAMAM (polyamidoamine) polymer (AT-HBP) was synthesized as a multifunctional chelating agent to remove two heavy metal ions (Cr(III) and Cu(II)) from the simulated wastewater solutions. The AT-HBP was characterized by Fourier transformed infrared (FTIR), dynamic light scattering (DLS), and proton nuclear magnetic resonance (¹H NMR) analysis. The removal process was carried out in two different methods, centrifuged process and ultrafiltration. The concentration of heavy metal ions before and after removal was measured by inductively coupled plasma (ICP) instrument. The removal processes were evaluated by changing different parameters such as solution pH, AT-HBP dosage, and metal ion concentration. To evaluate the extend of binding of heavy metal ions in the presence of AT-HBP the presence of salt in the solution was also examined on the performance of the removal system. The overall results indicated that removal percentages higher than 98% for Cr(III) and 86% for Cu(II) were achieved for heavy metal concentrations of 100 mg/L for both removal process methods. Furthermore, the function of second generation of polypropylenimine (PPI) was compared to AT-HBP. The results reveal that the removal of Cr(III) and Cu(II) ions by AT-HBP were approximately 20% and 10% higher compared to PPI, respectively. Finally, hyperbranched dendritic polymer with lower expenses to synthesize compared to dendrimer underlined favorable properties as a multifunctional chelating agent and enhancement of ultrafiltration process for wastewater treatment. Graphical abstract.

A quick and simple in vitro assay to predict bioavailability of actinides following accidental exposure

Physicochemical properties of actinides highly influence internal intake and biodistribution. An a priori knowledge of the dissolution properties of compounds involved in accidental exposure would be of great help in early dose assessment. However, this information is rarely available, leading to difficulties in interpreting excretion data from contaminated victims. We developed an in vitro acellular assay to predict in vivo bioavailability of actinides and improve medical handling of the victims. Various actinides of different physicochemical properties were used to validate the reliability of the assay to mimic in vivo behavior of the contaminants. Our assay was designed as a dynamic muticompartmental system in which an agarose gel represents the retention compartment of actinides and a dynamic phase the transfer compartment. Relevant physiological conditions were obtained by introducing various components both in the static and dynamic phases. The proposed model may provide a good prediction of in vivo behavior and could be used as a first assessment to predict the fraction of actinides that could be potentially transferred from retention compartments, as well as the fraction available to chelating drugs.

A novel phytoextraction strategy based on harvesting the dead leaves: Cadmium distribution and chelator regulations among leaves of tall fescue

The treatment of large amount of hazardous plant residues from phytoextraction is costly and has been a burden for the society. This experiment was designed to evaluate the possibility of cadmium (Cd) phytoextraction by harvesting the dead leaves instead of the whole plant in tall fescue (Festuca arundinacea). Results showed that Cd was preferentially distributed in the senescent and dead leaves. EDTA, DTPA and EGTA enhanced Cd accumulations in the dead leaves which could be associated to the increase of the water-soluble inorganic Cd and Cd-organic acid complexes in shoots. The dead leaves were only 12.6-16.3% of the total shoot biomass but accumulated 73.4-87.2% of the total shoot Cd. The results indicate that a novel strategy of Cd phytoextraction based on harvesting the dead leaves is feasible to save the high treatment cost of hazardous plant residues while maintaining the acceptable phytoextraction efficiency.

Enhanced remediation of arsenic and chromium co-contaminated soil by eletrokinetic-permeable reactive barriers with different reagents

The present work focused on the effects of different reagents on the remediation of arsenic and chromium co-contaminated soil by electrokinetic technology coupled with permeable reactive barrier (EK-PRB). In a running of EK-PRB, reductant (ascorbic acid, sodium citrate) and chelating agent (EDTA-2Na) were used to pretreat contaminated soil together with CaAl-LDH as reactive materials for PRB. As a result, the chelating agent improved the removals of As and Cr in co-contaminated soil. However, the reducing agent only increased As removal. When 0.05 M sodium citrate was used in pretreatment, the As removal attained the maximum of 50.5%, although Cr removal was only 44.1% at the same time. When the contaminated soil was pretreated with 0.01 M EDTA-2Na, the Cr removal increased to 54.28%, although As removal was only 26.3%. After EK-PRB, the As and Cr were efficiently captured by CaAl-LDH, resulting in maximal fixed amounts of 126.5 mg/kg (As) and 1507.6 mg/kg (Cr). The XRD and FITR analyses of LDH indicated that As was mainly adsorbed on the surface of LDH. As for Cr, it was mainly intercalated into interlayer of LDH.

Ni tolerance and its distinguished amelioration by chelating agents is reflected in root radius of B. napus cultivars

The negative effect of excess nickel (Ni) on plants is well investigated but there is only little information on its influence on root anatomy and a possible amelioration by chelating agents. In this study, we utilized light microscopy to observe anatomical changes in canola (Brassica napus) roots and investigated the element content by X-ray microanalysis. Ni-tolerant (Con-II) and Ni-sensitive cultivars (Oscar) were selected for this purpose. The plants were treated with 30 ppm NiSO₄. Then, citric acid and ethylene-diamine-tetra-acetic acid (EDTA) (alone or in combination) were applied to observe the influence of chelating agents in metal stress amelioration. Ni treatment led to significant swelling of the roots in the Con-II variety as compared to the cultivar Oscar. Application of EDTA reduced the root radius of Con-II plants and this effect for Ni tolerance is discussed. According to X-ray microanalyses, Ni ions were more dispersed in the sensitive cultivar as indicated by metal adsorption to the cell wall. We investigate the hypothesis that an enhanced capacity of binding metals to the cell wall allows the plants to tolerate more heavy metals.

Effect of EDTA and NTA on Arsenic Bioaccumulation and Translocation Using Phytoremediation by Mimosa pudica L. from Contaminated Soils

This study aimed to investigate the effects of Nitrilotriacetic acid (NTA) and Elthylenediaminetetraacetic acid (EDTA) on the bioaccumulation and translocation of arsenic (As) by Mimosa pudica L. using soils with 5 mg/kg of added As and NTA and EDTA concentrations of 50, 100, and 200 mg/kg. Soil and plant samples were collected every 30-120 days to analyze the As concentrations in the soil, underground part of the plants (root), and aboveground parts of the plants (shoots and leaves). The results showed that the plants with EDTA concentrations of 100 mg/kg had the highest As accumulation. At 120 days, M. pudica L. had a higher accumulation in the underground parts (29.71 mg/kg) than in the aboveground parts (6.32 mg/kg), with statistical significance (p < 0.05). The As translocation factor in the aboveground parts was less than 1, indicating As accumulation in the underground part only. With EDTA concentrations of 50 and 100 mg/kg, M. pudica L. had the highest bioaccumulation potential of As of 8.00 and 8.44, respectively. However, this research did not examine the reaction between As and any growth promoters. Further research should investigate the details of such a reaction at the molecular level, as well as explore how fertilizer factors might affect the As absorption of M. pudica L.

Modifying aroylhydrazone prochelators for hydrolytic stability and improved cytoprotection against oxidative stress

BSIH ((E)-N'-(2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzylidene)isonicotinohydrazide) is a prodrug version of the metal chelator SIH ((E)-N'-(2-hydroxybenzylidene)isonicotinohydrazide) in which a boronate group prevents metal chelation until reaction with hydrogen peroxide releases SIH, which is then available for sequestering iron(III) and inhibiting iron-catalyzed oxidative damage. While BSIH has shown promise for conditionally targeting iron sequestration in cells under oxidative stress, the yield of SIH is limited by the fact that BSIH exists in cell culture media as an equilibrium mixture with its hydrolysis products isoniazid and 2-formylphenyl boronic acid. In the current study, several BSIH analogs were evaluated for their hydrolytic stability, reaction outcomes with H₂O₂, and prochelator-to-chelator conversion efficiency. Notably, the para-methoxy derivative (p-OMe)BSIH ((E)-N'-(5-methoxy-2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzylidene)isonicotinohydrazide) and the meta-, para-double substituted (MD)BSIH ((E)-N'-((6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzo[d][1,3]dioxol-5-yl)methylene)isonicotinohydrazide) showed 1.3- and 1.9-fold improved hydrolytic stability compared to BSIH, respectively, leading to a 22 and 50% increase in chelator released. Moreover, both prochelators were found to protect retinal pigment epithelial cells stressed with either H₂O₂ or paraquat insult.

The effect of olive husk extract compared to the edta on Pb availability and some chemical and biological properties in a Pb-contaminated soil

It was found that using chelating agents increases the efficiency of heavy metal extraction, however, they may have negative effects on soil ecosystem quality. A pot experiment was conducted in a completely randomized design with three replications in order to evaluate the effect of EDTA and Olive Husk Extract (OHE) on some chemical and biological properties of the Pb-contaminated soil. The experimental treatments included EDTA (2 g Na₂EDTA salt per kg soil), OHE (2 g TDS of OHE per kg soil) and control (without the chelating agent). The results revealed that the EDTA and OHE treatments increased the Pb availability by 17.7% and 5.5% in comparison to the control treatment, respectively. Although EDTA was more effective in increasing the Pb availability but decreased the soil biological quality index (SBQI). The EDTA treatment significantly decreased the dehydrogenase (DH) activity and germination index (GI). The OHE application significantly increased the available-P, available-K, total N and organic carbon content by 339.92%, 40.79%, 20.9%, and 29.7% compared with control treatment, respectively. Furthermore, OHE considerably increased SBQI from 18.96 to 53.48. Compared to the control treatment higher values of soil respiration activity, DH activity, and carbon availability index (CAI) were observed in OHE treatment.

High monomeric sugar yields from enzymatic hydrolysis of soybean meal and effects of mild heat pretreatments with chelators

Defatted soybean meal has 30-35% oligo-/polymeric carbohydrates and approximately 50% proteins. Enzymatic carbohydrate monomerization enables easy separation to enrich protein content, reduces indigestibility concerns, and facilitates use of carbohydrate as fermentation feedstock. Among soybean carbohydrates, pectin and glucan are more recalcitrant to hydrolyze. To destabilize Ca2+-bridged junctures in pectin, effects of 3 chelators ethylenediaminetetraacetic acid (EDTA), sodium hexametaphosphate (HMP) and citric acid under 2-h 90 °C pretreatments were investigated here. Citric acid was the most effective while EDTA decreased enzymatic hydrolysis. In a 3-factor 2-level factorial study, heat (90 °C, 2 h) and citric acid (10 g/L) pretreatments and cellulase supplementation (10 FPU/g) were found to increase yields of all monosaccharides, to 86.8 ± 5.2% glucose, 98.1 ± 1.6% xylose, 87.5 ± 5.2% galactose, 83.6 ± 1.6% arabinose, and 91.4 ± 3.1% fructose + mannose. The largest percentage improvements were for arabinose (382%), mannose (113%) and glucose (51%). Achieving high monosaccharide yields greatly increases value of soybean carbohydrate as fermentation feedstock.

Detection of Fe(III)EDTA by using photoluminescent carbon dot with the aid of F- ion

Iron(III) ethylenediaminetetraacetate (Fe(III)EDTA) is widely used in iron fortification for reducing iron deficiency, and its determination is urgently needed. The present work developed a fluorescent method to straightforwardly determine Fe(III)EDTA by using photoluminescent carbon dots (C-dots) with the aid of F^- ions as the masking agent of free Fe³⁺ ions. In the presence of F^- ions, only Fe(III)EDTA selectively quenched the photoluminescence of C-dots, and both Fe³⁺ and Fe²⁺ as well as other carboxylic acids have no effect on the emission of C-dots. The sensing mechanism was attributed to the ligand-tailored electron transfer process from C-dots to Fe³⁺. Under optimum conditions, this method showed a linear calibration plot over the Fe(III)EDTA range of 1.0-200 μmol L^-1 and a detection limit of 0.4 μmol L^-1. The proposed method was successfully applied to determine Fe(III)EDTA in real samples with acceptable recoveries of spikes (95%-110%) and repeatability (RSD, 4.2%-9.5%).

Glyphosate, a chelating agent-relevant for ecological risk assessment?

Glyphosate-based herbicides (GBHs), consisting of glyphosate and formulants, are the most frequently applied herbicides worldwide. The declared active ingredient glyphosate does not only inhibit the EPSPS but is also a chelating agent that binds macro- and micronutrients, essential for many plant processes and pathogen resistance. GBH treatment may thus impede uptake and availability of macro- and micronutrients in plants. The present study investigated whether this characteristic of glyphosate could contribute to adverse effects of GBH application in the environment and to human health. According to the results, it has not been fully elucidated whether the chelating activity of glyphosate contributes to the toxic effects on plants and potentially on plant-microorganism interactions, e.g., nitrogen fixation of leguminous plants. It is also still open whether the chelating property of glyphosate is involved in the toxic effects on organisms other than plants, described in many papers. By changing the availability of essential as well as toxic metals that are bound to soil particles, the herbicide might also impact soil life, although the occurrence of natural chelators with considerably higher chelating potentials makes an additional impact of glyphosate for most metals less likely. Further research should elucidate the role of glyphosate (and GBH) as a chelator, in particular, as this is a non-specific property potentially affecting many organisms and processes. In the process of reevaluation of glyphosate its chelating activity has hardly been discussed.

Degradation of the earthy and musty odorant 2,4,6-tricholoroanisole by persulfate activated with iron of different valences

2,4,6-Trichloroanisole (TCA) is an odorous compound that is often detected in tap water and is difficult to be removed via water treatment. In this study, the transformation efficiency of TCA in the presence of persulfate (PS) activated by iron (Fe²⁺, Fe⁰, and Fe³⁺) was investigated for the first time. The effects of the activator dosage, oxidant dosage, pH, dosing method, chelating agents, humic acid, and temperature were evaluated. The degradation rate of TCA increased with increasing PS dosages (0.12-0.48 mM) and initial Fe²⁺ concentrations (0.12-0.96 mM), while it decreased with higher Fe²⁺ concentrations. Fe²⁺/PS and Fe⁰/PS systems achieved their best TCA removal efficiency at pH 7 and 2.5, respectively. According to the results of electron paramagnetic resonance (EPR), the contribution of SO₄^-• to TCA degradation was much higher than that of •OH. Gradual addition of Fe²⁺ improved TCA degradation compared to single addition. Citric acid (CA) promoted TCA degradation under Fe²⁺/PS at the beginning of the reaction, but inhibited it after 10 min. Ethylenediaminetetraacetic acid (EDTA) improved the TCA removal rate with an EDTA/Fe²⁺ molar ratio of 0.5:1, while it decreased it at higher EDTA/Fe²⁺ molar ratios. Oxalic acid (OA) negatively affected TCA degradation with increasing OA/Fe²⁺ molar ratios. Among all of the chelating agents, only CA increased TCA degradation by Fe⁰/PS. Humic acid promoted TCA degradation by Fe²⁺/PS at the proper dosage (1 mg/L). Under our specific conditions and over the temperature ranging from 10 to 25 °C, no change was observed in the reaction kinetics. It was found that 2,4,6-trichlorophenol (TCP) was the only detected oxidation product. The presence of an Fe²⁺-Fe³⁺ redox cycle in iron-activated PS systems was confirmed by TCA degradation under the Fe³⁺/PS system.

Phytoextraction of heavy metals from a multiply contaminated dredged sediment by chicory (Cichorium intybus L.) and castor bean (Ricinus communis L.) enhanced with EDTA, NTA, and citric acid application

The remediation of contaminated dredged sediments is necessary to eliminate the risk towards human beings or the environment when there is disposal on land. A greenhouse experiment was carried out to evaluate the chemically assisted phytoextraction to clean up dredged sediment contaminated with Cr, Cu, Pb, and Zn. The ability of castor bean and chicory to absorb, translocate, and accumulate metals from sediment to root and shoot was evaluated by applying EDTA (5 mM), NTA (5 mM), and citric acid (60 mM) to sediment, before the harvest. Citric acid 60 mM was the most effective treatment in increasing Cr, Cu, and Pb in castor bean and chicory shoot. Chicory could accumulate 1730 mg Cr kg-1 in shoot, and had greater values than one for the bioaccumulation and translocation factors when citric acid was added to the sediment. But, the Cr percentages removed per harvest of chicory were 0.05% and were lower for Cu, Pb, and Zn due to low biomass obtained. Citric acid-assisted phytoextraction with chicory can be a promising short time solution to reduce Cr concentration in sediment and reach the Cr level guide for industrial land use only if suitable agronomic practices could be implemented to increase crop yield.