Addition Of Ethylenediaminetetraacetic Acid Research Articles

Supercritical hydrothermal synthesis of ultra-fine Cu powders

ABSTRACT Ultra-fine Cu powders were synthesized using supercritical water as a reaction medium and formic acid as a reducing agent. The effects of reducing agent, reaction temperature, and complexing agent on the phase constituents, particle size distributions and morphology of the synthesized ultra-fine Cu powders were investigated. A complex mixture of Cu2O and Cu powders formed by pure supercritical water while high purity homogeneous ultra-fine Cu powders can be synthesized by supercritical water with formic acid as a reducing agent. Moreover, fine tuning of particle size and morphology can be realized by the addition of Ethylenediamine tetraacetic acid (EDTA). The modification mechanism of EDTA on the surfaces of ultra-fine Cu powders was investigated by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. EDTA adsorbed on the surfaces of nanoparticles by the dehydration reaction of carboxyl groups in the molecule of EDTA and hydroxyl groups on surfaces of copper nanoparticles (CuOH).

Effects of lanthanum and ethylenediamine tetraacetic a cid

Using nickel-tungsten as active metals and TiO₂-Al₂O₃ as the support, Ni-W/TiO₂-Al₂O₃ catalysts for the hydrodesulfurization of heavy oil were prepared by wetness impregnation. The effects of the modification of lanthanum, ethylenediamine tetraacetic acid (EDTA)and La in cooperation with EDTA on the structure and hydrodesulfurization performance of the catalysts were investigated. The catalysts were characterized by XRD, BET, H₂-TPR and SEM. The results indicated that La and EDTA could weaken the interaction between support and active component, facilitate the reduction of active component, and benefit the formation of Ni-W-S phase. Addition of La or EDTA could increase the surface area and suppress the agglomeration of active metals on surface, forming smaller and highly dispersed active phase particles. The La, EDTA and combined La and EDTA modified catalysts possessed higher HDS activity than Ni-W sample, Ni-W-La-E catalyst had the highest HDS activity, and its thiophene conversion reached 99.7%.

Oxide-Encapsulated Silver Electrocatalysts for Selective and Stable Syngas Production from Reactive Carbon Capture Solutions.

Electrolysis of bicarbonate-containing CO2 capture solutions is a promising approach towards achieving low-cost carbon-neutral chemicals production. However, the parasitic bicarbonate-mediated hydrogen evolution reaction (HER) and electrode instability in the presence of trace impurities remain major obstacles to overcome. This work demonstrates that the combined use of titanium dioxide (TiO2) overlayers with the chelating agent ethylene diamine tetra-acetic acid (EDTA) significantly enhances the selectivity and stability of Ag-based electrocatalysts for bicarbonate electrolysis. The amorphous TiO2 overlayers suppress the HER by over 50% at potentials more negative than -0.7 V vs. RHE, increasing the CO faradaic efficiency (FE) by 33% (relative). In situ surface-enhanced Raman spectroscopy (SERS) measurements reveal the absence of near-surface bicarbonate species and an abundance of CO2 reduction intermediates at the Ag|TiO2 buried interface, suggesting that the overlayers suppress HER by blocking bicarbonate ions from reaching the buried active sites. In accelerated degradation tests with 5 ppm of Fe(III) impurity, the addition of EDTA allows stable CO production with >47% FE, while the electrodes rapidly deactivate in the absence of EDTA. This work highlights the use of TiO2 overlayers for enhancing the CO:H2 ratio while simultaneously protecting electrocatalysts from impurities likely to be present in "open" carbon capture systems.

Dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) is a cellular receptor for delta inulin adjuvant.

Delta inulin, or Advax, is a polysaccharide vaccine adjuvant that significantly enhances vaccine-mediated immune responses against multiple pathogens and was recently licensed for use in the coronavirus disease 2019 (COVID-19) vaccine SpikoGen. Although Advax has proven effective as an immune adjuvant, its specific binding targets have not been characterized. In this report, we identify a cellular receptor for Advax recognition. In vitro uptake of Advax particles by macrophage cell lines was substantially greater than that of latex beads of comparable size, suggesting an active uptake mechanism by phagocytic cells. Using a lectin array, Advax particles were recognized by lectins specific for various carbohydrate structures including mannosyl, N-acetylgalactosamine and galactose moieties. Expression in nonphagocytic cells of dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN), a C-type lectin receptor, resulted in enhanced uptake of fluorescent Advax particles compared with mock-transfected cells. Advax uptake was reduced with the addition of ethylenediaminetetraacetic acid and mannan to cells, which are known inhibitors of DC-SIGN function. Finally, a specific blockade of DC-SIGN using a neutralizing antibody abrogated Advax uptake in DC-SIGN-expressing cells. Together, these results identify DC-SIGN as a putative receptor for Advax. Given the known immunomodulatory role of DC-SIGN, the findings described here have implications for the use of Advax adjuvants in humans and inform future mechanistic studies.

Oral sericin ameliorates type 2 diabetes through passive intestinal and bypass transport into the systemic circulation

Ethnopharmacological relevanceBoiled silkworm cocoons have been used to treat 'Xiaoke disease' (diabetes mellitus) recorded in Chinese medicine for over 800 years. In recent years, it has been found that the active substance silk sericin (SS) has therapeutic benefits in treating type 2 diabetes mellitus (T2DM). SS promotes pancreatic islet signalling, the proliferation of pancreatic islet cells, and insulin secretion. It is inferred that SS enters the bloodstream after oral administration and plays a role in the body's circulation. As a natural protein, SS needs to resist digestion by proteases in the gastrointestinal tract and cross the gastrointestinal barrier after oral administration. It is currently unclear how SS crosses the gastrointestinal barrier and whether it exerts therapeutic effects on T2DM by entering the circulation. Aim of the studyTo study how SS crosses the gastrointestinal barrier and whether it enters the body circulation to exert a therapeutic effect on T2DM. Materials and methodsSS was extracted from silkworm cocoons using an alkaline method with sodium carbonate. The antidigestive capacity of SS was detected using SDS-PAGE gel electrophoresis experiments. The mode of uptake and translocation of orally consumed SS in vivo was analysed using the AP-side to BL-side and BL-side-AP-side translocations, apparent Permeability coefficient (Papp), and Exocytosis rates (ER). The study compared the differences between the adSS group and the adSS + EDTA group by using Ethylenediaminetetraacetic acid (EDTA) to separate the tight junctions between Caco-2 cells. The aim was to analyze whether the transport mode of oral filaggrin proteins in vivo could be absorbed by bypass transport. By administering SS through oral and intraperitoneal injection to type 2 diabetic mice, we measured its concentration in the blood, as well as blood glucose and insulin levels, to determine its effectiveness in treating diabetes and its ability to enter the body's circulation for treatment. ResultsThe molecular weight of SS decreased from 10k∼25 kDa to 10k∼15 kDa after in vitro simulated gastrointestinal fluid digestion, indicating its good antidigestive properties. The apparent Papp was greater than 1 × 10−6 cm·s-1, and the ER was between 0.5 and 1.5, indicating that adSS was well-absorbed and mainly passively transported. The Caco-2 cell model showed that the addition of EDTA promoted the transport of adSS, resulting in significantly larger Papp and ER values, indicating that adSS was absorbed by bypass transport. After oral administration of SS, the concentration of SS in the blood was lower than after intraperitoneal injection, which is 60% of intraperitoneal administration. Mice with a T2DM model who were administered SS for 5 weeks showed significant improvement in insulin resistance and glucose tolerance. Additionally, the pancreatic tissue appeared more regular. In the treatment of T2DM, injections of SS have been shown to be more effective than oral administration. Both oral and intraperitoneal injections have been partially involved in the circulation. ConclusionsSS is enzymatically cleaved by proteolytic enzymes in the gastrointestinal tract. The smaller molecules are partially absorbed into the body's circulation through passive and paracrine transport, exerting a therapeutic effect on T2DM.

Growth and cadmium and nickel uptake of maize (Zea mays L.) in a cadmium and nickel co‑contaminated soil and phytoremediation efficiency using ethylenediamine tetraacetic acid

Background: Anthropogenic activities release cadmium (Cd), nickel (Ni), and other heavy metals into soil. Zea mays can clean up contaminated soils, but little is known about how Cd and Ni co-contamination stress affects ethylenediamine tetraacetic acid (EDTA)-based phytoextraction and phytoremediation, hence this study was conducted. Methods: The experiment involved nine treatment levels (0, 5, 10, 15, and 20 mg kg-1 Cd and 0, 15, 30, 45, and 60 mg kg-1 Ni), grouped into three categories: CT as the control group, P as Cd + Ni only, and CAP as Cd + Ni + EDTA (n=3). The treatments used (CH3COO)2Cd•2H2O and NiSO4 as the source of Cd and Ni, respectively, and EDTA was applied at two rates (0 and 0.5 g/kg). After the experimental period, measurements were taken for shoot length, biomass, and metal concentrations in both the roots and shoots using established procedures. Results: The concentrations of metals in plants' roots and shoots increased as the concentrations in soil increased, but shoot length, biomass, bioconcentration factor (BCF), and translocation factor (TF) values decreased with increasing soil metal content. The application of EDTA increased metal uptake but led to greater root and shoot biomass loss. Generally, TF values for Cd and Ni were less than 1 but most of the BCF values were greater than 1. Conclusions: The study found that phytostabilization is the main mechanism for phytoremediation of Cd-Ni-co-contaminated soils with Zea mays, with EDTA addition enhancing metal accumulation and reducing biomass yield.

Eco-friendly approach to decrease the harmful effects of untreated wastewater on growth, yield, biochemical constituents, and heavy metal contents of carrot (Daucus carota L.).

Here, the impact of irrigation using untreated wastewater (WW) on carrots (Daucus carota L.) was examined. We hypothesized that the addition of ethylenediaminetetraacetic acid (EDTA), dry algal powder (Spirulina platensis or Chlorella vulgaris), and Salix alba leaves powder would function as chelators for harmful contaminants in wastewater. The findings showed that irrigation of carrot plants with the sampled untreated wastewater led to significant decreases in the shoot lengths, fresh, dry weights of shoots and roots at stage I, the diameter of roots, pigment content, carotenoids, total soluble carbohydrate content, and soluble protein content. Furthermore, a significantly increased level of proline, total phenols, and the activities of polyphenol oxidase (PPO), peroxidase (POX), superoxide dismutase (SOD), and catalase (CAT) was identified in stage I samples. In contrast to the stage I, the length of the roots, the number of leaves on each plant, wet and dry weights of the stage II roots were all greatly enhanced. In spite of the increased yield due to the wastewater irrigation, carrot roots irrigated with wastewater had significantly more cadmium (Cd), nickel (Ni), cobalt (Co), and lead (Pb) than is considered safe. Our data clearly show that the application of Spirulina platensis, Chlorella vulgaris, EDTA, and leaves powder of salix was able to alleviate the toxicity of wastewater on carrot plants. For example, we recorded a significant decrease in the accumulation of carrot's Cd, Ni, Co, and Pb contents. We conclude that the treatments with Spirulina platensis and Chlorella vulgaris can be utilized as eco-friendly tools to lessen the damaging effects of wastewater irrigation on carrot plants.

New insights into the effect of EDTA on pyrite oxidation and N2O emission during pyrite autotrophic denitrification

Pyrite autotrophic denitrification (PAD) is crucial for removing nitrate in groundwater and advanced wastewater treatment. While disulfide is typically seen as the electron donor, the role of iron in pyrite oxidation is often ignored. In this study, Ethylene Diamine Tetraacetic Acid (EDTA) had been proven to have the potential to facilitate pyrite oxidation by promoting the solubility of iron in solution, thereby enhancing the kinetics of pyrite autotrophic denitrification. Firstly, EDTA could improve PAD performance, i.e. the nitrate removal rate at EDTA addition of 5 mM was 0.69 mg N/L•h and twice that of the control. However, high concentrations of EDTA inhibited the activity of the nitrous oxide reductase, resulting in the maximum accumulation of N2O reaching 13.26 mg N/L with an EDTA concentration of 15 mM. Furthermore, the X-ray Photoelectron Spectroscopy (XPS) result indicated that the EDTA addition promoted the production of bioavailable sulfur, with the concentration of S0 at 15 mM EDTA being more than twice higher than that of the control. Transmission electron microscopy (TEM) analysis indicated that EDTA could relieve the damage of iron encrustation on cell activity because it was difficult for EDTA-chelated ferrous iron to penetrate the cell membrane. Microbial community analyses showed an increase abundance of iron oxidizing bacteria, suggesting that EDTA addition promoted the bioavailability of iron for Fe(II) autotrophic denitrification. Overall, this study will provide insights into the understanding of oxidation mechanism of PAD process and the practical application for efficient nitrogen removal and N2O mitigation.

Synergistic effects of EDTA and lysozyme on the properties of hydroxypropyl starch nano antibacterial films

Hydroxypropyl starch (HPS) nano antibacterial films incorporating Ethylene Diamine Tetraacetic Acid (EDTA) and lysozyme (LY) were fabricated via solvent casting method. The synergistic effects of EDTA and LY on the microstructure, component interactions, color, optical, mechanical, barrier and antibacterial properties of HPS nano antibacterial films were evaluated. The results indicated that EDTA and LY were well dispersed in the matrix of the HPS nano antibacterial films, the film-forming substrates have good compatibility, resulting in a dense multi-layer structure of the HPS nano antibacterial films. The addition of EDTA and LY increased the color parameters (L*, a*, b* and △E*) of the HPS nano antibacterial films. The synergistic effects of EDTA and LY significantly decreased the light transmission of the HPS nano antibacterial films. The presence of EDTA and LY increased the tensile strength (TS) and the elongation at break (EAB) of the HPS nano antibacterial films. The TS and EAB of E2.5L1 reached the highest values of 6.329 MPa and 50.24 %, respectively. The incorporation of EDTA and LY had positive effects on the improvement of water vapor permeability (WVP) and oxygen permeability (OP). The WVP and OP of E2.5L1 reached the highest values of 0.9350 × 10−12 g cm/cm2•s•Pa and 0.297 × 10 −2 g m/m2 •d, respectively. In addition, EDTA and LY had significant synergistic effects on the antibacterial activity against S. aureus (Gram-positive bacteria) and E. coli (Gram-negative bacteria). E2.5L1 exhibited the highest antibacterial activity and the inhibition zone diameters of S. aureus and E. coli were 3.69 mm and 4.28 mm, respectively. The HPS nano antibacterial films incorporating EDTA and LY are potential functional packaging materials.

The enhanced flotation separation of magnesite and dolomite by introducing chelating reagent EDTA

In pulp environment, due to the migration and transformation of dissolved calcium ions, the surface properties of magnesite and dolomite tend to become similar, which in turn leads to difficulties in their flotation separation. In this paper, the chelating reagent EDTA is introduced to eliminate the adverse influence of calcium species and to restore the selectivity of magnesite-dolomite separation using sodium hexametaphosphate (SHMP) as depressant. Flotation experiments demonstrate that, in the presence of ethylenediaminetetraacetic acid (EDTA), the flotation recovery of magnesite increased by 22.14 % compared to using only the depressant SHMP. Zeta potential experiments combined with solution chemistry analysis indicate that the negatively charged hydrolysis species of EDTA can form soluble and stable chelates with positively charged Ca2+ and Ca(OH)+ species, effectively preventing the adsorption and transformation of calcium ions on the magnesite surface. Adsorption measurements directly confirm from a macroscopic perspective that the addition of EDTA reduces the adsorption of the depressant SHMP on the magnesite surface. X-ray photoelectron spectroscopy (XPS) measurements further confirm the phenomenon of calcium ion migration and transformation from the surface of magnesite to dolomite at the microscale, as well as the adsorption mechanisms of EDTA and SHMP on the surfaces of both minerals. Based on the experimental and analytical results, a flotation separation model of the system is established.

Pattern of Lead Accumulation in Two Vegetable Plants Due to EDTA Treatment

Phytoextraction and phytostabilization are the most consistent patterns or mechanisms of action of phytoremediation. One of the elements influencing the mechanism of action of heavy metal absorption by plant species is Ethylene Diamine Tetraacetic Acid (EDTA). Therefore, this study aimed to determine the pattern of phytoremediation in water spinach and spinach due to the addition of EDTA in the soil. The treatments tested by factor 1 were water spinach (T1) and spinach (T2), and factor 2 was the concentration of EDTA consisting of 3 levels, 0, 3, and 6 g/polybag. Each treatment was repeated three times on five sample plants. Furthermore, growth evaluation was carried out in the first six days after planting and conducted every 3 days. It was carried out on variables such as changes in plant height, leaves area, total root length, Pb content in the soil, fresh and dry weight of shoots and roots, shoot, seeds, and Translocation Factor (TF). The results showed that water spinach and spinach had different mechanisms of action due to the application of EDTA in Pb-contaminated media. Furthermore, water spinach and spinach have a mechanism of phytoextraction and phytostabilization, respectively. Therefore, spinach is safer than water spinach when grown in Pb-polluted land.

Phytoremediation efficacy of Nerium oleander L. for removal of Cd, Ni, and Pb- contaminated soil

A pot experiment was conducted to assess the effectiveness of Nerium oleander L. in phytoremediation of cadmium (Cd), nickel (Ni), and lead (Pb)- contaminated soil. This evaluation included the application of ethylene diamine tetra-acetic acid (EDTA) and a nutrient solution containing NPK. The results revealed that the inclusion of EDTA and NPK, in combination with varying metal concentrations, significantly increased the dry weight of the plants. The results demonstrated that oleander, when aided by EDTA and NPK, exhibited a high capacity to efficiently absorb and accumulate Pb without any amendments. The addition of EDTA increased Pb concentrations in both aerial parts and roots (84.9 mg kg-1 and 80.2 mg kg-1, respectively). For Nickel, in the presence of NPK, the concentration in roots was 80,2 mg kg-1. Cd accumulation was highest in the treatment with 100 mg kg-1 EDTA, reaching 72.9 mg kg-1 in the aerial parts. Particularly, NPK reduced Ni levels in aerial parts, while EDTA enhanced root metal uptake. The Translocation Factor (TF) was greater than 1 for Cd and Ni treatments, indicating oleander's remarkable ability to absorb and accumulate these heavy elements. The treatment involving Pb50+EDTA displayed the highest Bioaccumulation Factor (BAF) value at 1.7. Furthermore, for Pb50, Ni50 and Cd50, the NPK treatment exhibited the highest Bioconcentration Factor (BCF) values, ranging from 0.3 to 1.69. Nerium oleander L. exhibits promise for both Ni phytoextraction and Cd and Pb phytostabilization, suggesting its potential as an effective phytoremediation agent. Future research should focus on optimizing metal uptake conditions and investigating long-term plant health and soil impacts to refine sustainable strategies for mitigating metal pollution in contaminated environments.

Process design and optimization of EDTA-biojarosite – a treatment approach in the Box–Behnken framework

Abstract A study was conducted to investigate the performance of biojarosite as a catalyst in Fenton oxidation with and without the presence of the chelating agent ethylene diamine tetra acetic acid (EDTA). The addition of EDTA resulted in increased iron dissolution, confirming the role of EDTA as a chelating agent. The heterogeneous catalytic properties of jarosite were confirmed by the removal efficiencies of 93.5 and 83.4%, with and without EDTA, respectively. The Box–Behnken method was employed as a Design of Experiments tool to identify suitable experimental runs. Both Fenton oxidation and EDTA-based Fenton oxidation were examined separately, with PCP removal being the response variable. In the case of Fenton oxidation, the optimization process resulted in the selection of 0.1–1 g/L of iron catalyst, 100–1,000 mg/L of H2O2, and a pH range of 2.5–3.5. On the other hand, for EDTA-based Fenton oxidation, the optimal conditions were determined to be 0.1–1 g/L of iron catalyst, 100–1,000 mg/L of H2O2, and a pH range of 6.5–7.5. ANOVA was conducted to analyze the results, and the model fit was examined.

Enhancing the Photovoltaic Performance of Cd(1−x)ZnxS Thin Films Using Seed Assistance and EDTA Treatment

This research article provides a comprehensive investigation into the optoelectronic characteristics of three distinct types of cadmium sulfide (CdS) thin films, namely: (a) conventionally prepared CdS thin films using chemical bath deposition (CBD-CdS), (b) CdS thin films produced via chemical bath deposition with the inclusion of zinc (CBD-Cd(1−x)ZnxS, x = 0.3), and (c) CdS thin films synthesized using a seed-assisted approach, treated with ethylenediaminetetraacetic acid (EDTA), and incorporating zinc (ED/CBD + EDTA-Cd(1−x)ZnxS). The investigation reveals that the crystallite size of these thin films decreases upon the addition of EDTA to the reaction solution, leading to an increase in the inter-planar spacing and dislocation density. Furthermore, a blue shift in the transmittance edge of the ED/CBD + EDTA-Cd(1−x)ZnxS samples compared to CBD-CdS implies modifications in the band gaps of the deposited films. The incorporation of Zn2+ into the reaction solution results in an increased band gap value of up to 2.42 eV. This suggests that Cd(1−x)ZnxS thin films permit more efficient photon transmission compared to conventional CdS. Among the three types of films studied, ED/CBD + EDTA-Cd(1−x)ZnxS exhibits the highest optical band gap of 2.50 eV. This increase in the optical band gap is attributed to the smaller crystallite size and the splitting of the tail levels from the band structure. Additionally, the increment in the optical band gap leads to reduced light absorption at longer wavelengths, thereby enhancing the electrical properties. Notably, ED/CBD + EDTA-Cd(1−x)ZnxS thin films demonstrate improved photovoltaic performance in a photoelectrochemical (PEC) cell, characterized by enhanced open-circuit voltage (363 mV, VOC), short-circuit current (35.35 μA, ISC), and flat-band voltage (−692 mV, Vfb). These improvements are attributed to the better adhesion of CdS to the fluorine-doped tin oxide (FTO) substrate and improved inter-particle connectivity.

Improve corrosion resistance of steel bars in simulated concrete pore solution by the addition of EDTA intercalated CaAl-LDH

The main perspective of this paper is to prepare an eco-friendly corrosion inhibitor suitable for reinforced concrete. The properties of CaAl-LDHs loaded with ethylenediaminetetraacetic acid (EDTA) synthesized under different conditions were studied and the optimal condition was determined. Electrochemical tests showed that CaAl-EDTA-LDH had excellent anti-corrosion properties for steel bars in the simulated concrete pore (SCP) solution. Mechanistically, the dual protection mechanism of CaAl-EDTA-LDH on steel bars was mainly due to the fact that the organic corrosion inhibitor adsorbed on the surface of steel bars to form a protective film while consolidating chlorides.

Effect of EDTA-modified alumina composite abrasive on the CMP performance of sapphire substrate

Sapphire is one of the most widely used substrate materials for semiconductor lighting. With the improvement of chemical mechanical polishing (CMP) processing technology for sapphire substrate, mass production, and cost control requires faster polishing efficiency and better surface quality. In CMP, alumina abrasive is widely used for its high polishing rate, but it also has the disadvantages of easy agglomeration and poor polishing quality. Therefore, ethylenediamine tetraacetic acid (EDTA)-grafted alumina composite abrasives were produced by a two-step process for the sapphire substrate CMP. As demonstrated by time of flight secondary ion mass spectrometry and fourier transform infrared spectroscopy, EDTA has been successfully grafted onto the surface of alumina particles. As shown by the scanning electron microscope, particle size distribution, and zeta potential analyses, the modified alumina composite abrasives exhibit superior dispersion properties than pure alumina particles. CMP experiment results show that the material removal rate (MRR) of the alumina composite abrasives can reach up to 2.6 μm/h, and the surface roughness (Sa) of the sapphire substrate can be reduced to 0.89 nm, which is 53 % higher and 66 % lower than pure alumina, respectively. According to X-ray photoelectron spectroscopy, the chemical etch of modified abrasive particles was strengthened, and the complex reaction occurred throughout the CMP process to generate the C–O–Al structural compound. Meanwhile, the friction coefficient test and contact angle test were combined to create the contact wear model. It shows that the addition of EDTA expands the contact area between the composite abrasives and the surface of substrates, improving the mechanical interaction during CMP. The chemical reaction and mechanical action combine and promote each other to enhance the CMP performance.

Effects of EDTA on the leaching behaviors of Cs(I) and Co(II) from cement waste forms

Cementation is extensively employed for immobilizing radionuclides in low- and intermediate-level radioactive wastes generated during the decommissioning of nuclear power plants. Ethylenediaminetetraacetic acid (EDTA), used as a decontamination agent during the decommissioning process, can be introduced into the cement waste form containing radionuclides. This study investigated the effects of the EDTA present in simulated radioactive decommissioning wastes on the leaching behaviors of Co and Cs immobilized in the cement waste form. Co leaching was facilitated by the formation of highly mobile Co–EDTA complexes. However, Cs leaching was impeded by the competition for leaching with other metal–EDTA complexes. Moreover, the EDTA-induced carbonated layer with a dense pore structure played a crucial role as a retardation barrier for the Cs leaching. The calcite contents of the samples with 8 wt% EDTA were approximately three times higher than those of the samples without EDTA. The introduced EDTA affected the leaching behaviors of both Co and Cs, as well as the microstructure evolution of the cement waste form. Nevertheless, the addition of EDTA had a relatively low positive effect on the efficiency of Cs immobilization, but also an obvious negative effect on the efficiency of Co immobilization, regardless of the concentration of EDTA. Finally, an EDTA dosage of 1 wt% in the cement waste forms containing Co or Cs is suggested as a potential waste acceptance criterion for solidified low- and intermediate-level radioactive waste.

Enhanced photocatalytic reduction of Cr(VI) from aqueous solution using Fe0/TiO2-based polymeric nanocomposites.

The combination of zerovalent iron (Fe0) and titanium dioxide (TiO2) has been investigated as a promising method for environmental remediation. However, it is a challenge to prepare conveniently desirable Fe0/TiO2 nanocomposites with excellent efficiency and reusability. Here, a novel nanocomposite material, Fe0/TiO2@D201, was synthesized to enhance the removal of Cr(VI) from an aqueous system by impregnating Fe0 and TiO2 inside a commercial anion exchanger (D201). The proposed structure and Cr(VI) removal mechanism of Fe0/TiO2@D201 were confirmed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analysis. Compared to the monometallic samples (Fe0-D201 and TiO2-D201), Fe0/TiO2@D201 showed outstanding Cr(VI) removal and the removal ratio reached up to 97.30% after 120min of UV light irradiation. The removal of Cr(VI) by Fe0/TiO2@D201 remained high (91.70%) even after four cycles, indicating the stability of the nanocomposites toward Cr(VI) removal and their strong potential for practical applications. The addition of ethylenediaminetetraacetic acid (EDTA) positively affected the Cr(VI) reduction process, whereas the addition of Na2S2O8 negatively affected the Cr(VI) process. The XPS results revealed that the photocatalytic reduction of Cr(VI) by Fe0/TiO2@D201 involved the capture of photoexcited electrons and Fe0 reduction. A path for the photogenerated electrons engaging in the reduction reaction to improve the utilization of Fe0 was proposed. These results demonstrate that Fe0/TiO2@D201 is a promising alternative composite catalyst for the efficient Cr(VI) removal from contaminated water.

Strengthening desilication of coal fly ash by alkaline leaching with the addition of ethylene diamine tetraacetic acid

Pre-desilication, as a treatment to improve the mass ratio of alumina to silica of aluminosilicate materials, is one of the essential procedures for alumina extraction from coal fly ash (CFA). In this work, a new method for strengthening desilication efficiency of CFA was proposed by alkaline leaching with the addition of ethylene diamine tetraacetic acid (EDTA). The effects of alkaline leaching conditions on the desilication efficiency of CFA were investigated; meanwhile, the strengthening pre-desilication mechanism was further clarified by means of scanning electron microscopy-energy dispersive spectroscopy, laser particle size analysis, x-ray diffraction and nuclear magnetic resonance, etc. The results showed that the desilication efficiency of CFA was significantly increased from 38 % to 50 % with the addition of EDTA during the alkaline leaching process. The mass ratio of alumina to silica of desilicated CFA was increased from 1.41 to 1.66, accordingly. During this process, the dissolved Al(OH)4- in the desilicated solution would be complexed by the additional EDTA, which makes it not to largely consume the dissolved H2SiO42- to form an insoluble by-product of hydroxysodalite (Na8Al6Si6O24(OH)2(H2O)2). Both the reduction of cumulative amount of hydroxysodalite on the desilicated CFA and the continuous exposure of new reaction interface on the desilicated CFA contribute to the improvement of desilication efficiency.

Enhancing corrosion resistance of the CaCO3/MgO coating via ultrasound-assisted chemical conversion with addition of ethylenediamine tetra-acetic acid (EDTA) on AZ41 Mg alloy

In order to enhance the corrosion resistance of the AZ41 Mg alloy used as concrete formwork, a bilayer CaCO3/MgO coating was fabricated on the surface of AZ41 Mg alloy with addition of Ca-EDTA in the chemical conversion solutions. Effect of different Ca-EDTA concentrations on the surface morphology of as-prepared CaCO3/MgO coating and corrosion resistance in simulated concrete pore solutions with 3.5 wt% NaCl were investigated. SEM, XPS and XRD were combined to investigate the morphology and composition of the coatings. Electrochemical methods and immersion tests were used to assess the anticorrosion performance of the as-prepared coatings. Results show that an integrated bilayer CaCO3/MgO coating can be prepared on AZ41 Mg alloy by the addition of Ca-EDTA. Electrochemical tests reveal that the CaCO3/MgO coating prepared at 0.01 M Ca-EDTA possesses the best corrosion resistance at varying concentrations of Ca-EDTA. Ca-EDTA accelerates the release of Mg2+ and further affects both nucleation and growth of CaCO3 particles. Appropriate addition of Ca-EDTA can simultaneously preserve the stability of CaCO3 and enhance coating density.