EDTA Molecules Research Articles

Chloride ion enhanced oxidant-free in situ degradation of Ni-EDTA by electrochemical process with boron-doped diamond electrodes

Conventional advanced oxidation processes were used to treat heavy metal complexes. However, a considerable amount of oxidants was required to enable effective oxidative degradation, which led to a significant increase of the treatment costs and subsequent difficulties in the sludge disposal. Based on the abundance of anions in heavy metal wastewater, the effects of anions on the in-situ degradation of Ni-EDTA in an oxidant-free electrochemical system with boron-doped diamond (BDD) as the anode were investigated. The presence of Cl- was found to exert a significant effect on improving the degradation process. Moreover, pH had little effect on the removal of nickel (Ni) and Ni-EDTA within a specific pH range (1 < pH < 9). The removal efficiencies of Ni and TOC reached 100 % and 77.45 %, respectively, at pH 2.16 with 0.4 M NaCl electrolyte, 2 mM Ni-EDTA concentration, and a current density of 50 mA/cm2. •OH and Cl• played crucial roles in the removal of Ni-EDTA by disrupting the chelation sites of Ni and EDTA molecules. The released Ni2+ ions could active the H2O2 in-situ generated at the cathode to produce •OH. The formation of the precipitation products such as NiOOH, Ni(OH)2, and NiCO3 in the Cl-/BDD system were conform based on the XRD and XPS analyses, which suggested the possible pathways for the removal of Ni2+ and Ni3+. Finally, the possible degradation pathways of Ni-EDTA were proposed based on the identification of intermediate products using UPLC-MS.

ANALYSIS OF SPECIALTIES OF CRYSTAL STRUCTURE FOR NON-­CHELATE CONFORMATIONS OF ETHYLENE-DIAMINETETRAACETIC ACID AND ITS SALTS WITH ALKALI AND ALKALINE EARTH METALS

In the present study, the crystal structures of non-chelating EDTA molecules and their non-chelation salts in a zwitterionic state, along with the EDTA-chelates of alkali and alkaline earth metals, were searched and overviewed. 25 non-chelating molecules of EDTA, and zwitterions of ethylenediammonium-diacetate diacetic acid HOOC-CH2-(-OOC-CH2-)NH+-CH2-CH2-NH+(-CH2-COO-)-CH2-COOH and their salts (ethylenediammonium-tetraace­tic acid (HOOC-CH2-)2NH+-CH2-CH2-NH+(-CH2-COOH)2, ethylenediammonium-acetate triacetic acid (HOOC-CH2-)2NH+-CH2-CH2-NH+(-CH2-COO-)-CH2-COOH, and ethylenediammonium-tetraacetate (-OOC-CH2-)2NH+-CH2-CH2-NH+(-CH2-COO-)2 with counterions), as well as 17 types of EDTA-chelates of alkali metal ions (Li+, Na+, K+, Rb+) and alkaline earth metal ions (Mg2+, Ca2+, Sr2+, Ba2+) were analyzed using data from the Cambridge Crystallographic Data Center (CCDC). Each intramolecular contact distance between nitrogen and oxygen atoms (NH+···O) has been examined and found to be around 2.7 Å. Investigation on the distribution of the intramolecular NH+··· NH+-distances of EDTA and non-chelated salts thereof also revealed that bulky counterion and certain crystal solvent molecules correspond to change in crystal packing, and that they influenced the conformers of EDTA mo­lecules among gauche form to anti form. In the existing crystalline EDTA-chelates of alkali metals as well as alkaline earth metals, various coordination numbers (CN) and the denticity (к) of EDTA anions are displayed; CN 5 to 9, and tri- and hexadentate fashions. Intramolecular contact N···O and N···N distances correspond to the metal ion radii except for the case of Sr-EDTA chelate, probably due to differences of crystal packings in addition to the number of counterions and crystal solvent molecules. The existing data on crystalline EDTA and its salts have been gathered herein, which contributes to a further understanding and exploring applications hereafter.

The Effect of EDTA Functionalization on Fe3O4 Thermal Behavior

The surface of Fe3O4 nanoparticles is very reactive and can oxidize to γ-Fe2O3 (maghemite) and α-Fe2O3 (hematite) structures. Based on this, the oxidation process of Fe3O4 nanoparticles must be prevented, and one of the strategies is surface functionalization with organic or inorganic molecules. Thus, this study analyzed the thermal behavior of Fe3O4 and Fe3O4-EDTA nanoparticles using X-ray diffraction (XRD), simultaneous thermogravimetry-differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC). Results showed that γ- Fe2O3 was obtained as an intermediate in Fe3O4 and Fe3O4-EDTA decomposition, as confirmed by TG-DTA and DSC curves. Moreover, Fe3O4-EDTA exhibited a temperature peak (Tp = 573.5°C) of phase transformation (γ-Fe2O3 → α-Fe2O3) higher than that of Fe3O4 (Tp = 533.0°C), confirming that EDTA molecules stabilized the nanoparticles efficiently. The kinetic behavior of samples changed, and the activation energy for functionalized samples decreased.

Effective removal of the heavy metal-organic complex Cu-EDTA from water by catalytic persulfate oxidation: Performance and mechanisms

It is difficult to remove heavy metal-organic complexes from water by chemical precipitation because of the strong complexation ability between heavy metal ions and organics. In this study, the removal of the Cu-ethylenediaminetetraacetic acid (Cu-EDTA) complex using autocatalytic persulfate (PS) oxidation was investigated. The Cu-EDTA removal efficiency reached up to 96.57% after 90 min of treatment by PS oxidation. A higher PS concentration favored Cu-EDTA removal; An increase in the initial concentration of Cu-EDTA benefited PS activation, and a greater removal performance was obtained at a lower Cu-EDTA initial concentration (0.1 mmol L−1). Excessive Cu2+ accelerated Cu-EDTA removal, while superfluous EDTA suppressed it. Relatively lower initial solution pH value favored Cu-EDTA removal. SO4•-, •OH, and 1O2 displayed significant roles in the Cu-EDTA removal process, as they destroyed the chelating sites of the Cu(II) and EDTA molecules; finally small molecular organic acids, alcohols, and NO3− were produced. The released Cu(II) existed in the precipitates in the forms of Cu-based carbonates, Cu-based hydroxides, and copper oxide. A possible decomposition pathway of Cu-EDTA was proposed. Overall, multipathway activation of PS induced by heavy metal complexes could be an effective technique for the removal of the heavy metal complexes.

Removal of As(V), Cr(VI) and Cu(II) using novel amine functionalized composite nanofiltration membranes fabricated on ceramic tubular substrate

Novel amine functionalized composite membranes were prepared over tubular ceramic substrate using facile dip-coating and cross-flow filtration approach. The two fabricated membranes, P-60S and P-60S-EDTA with polyethyleneimine (PEI) and EDTA-modified PEI as functional layers respectively, were characterized in terms of EDX, FTIR, XPS, FESEM, AFM and contact angle analyses which confirmed their stable physical and chemical structure for use in high pressure application. Clean water permeability and MWCO study revealed the superior permeability and rejection efficiency of the P-60S-EDTA compared to the P-60S membrane. Incorporation of bulky EDTA molecules in the membrane functional layer simultaneously decreased pore size and increased membrane hydrophilicity. The removal of As(V), Cr(VI) and Cu(II) heavy metals by both membranes were found to be highly pH dependent and overall rejection improved in case of P-60S-EDTA membrane [99.82% for Cu(II), 96.75% for As(V) and 97.22% for Cr(VI)]. Interestingly, rejection of As(V) and Cr(VI) was significantly improved in presence of Cu(II) due to volume resistance provided by EDTA-Cu(II) complex towards the passage of other heavy metal ions. Excellent stability of P-60S-EDTA membrane in continuous operation of 36 h in both ideal and practical water environment suggests its promising application in real field heavy metal contaminated waste water treatment.

Formation Reactivity on the Organometallic Complexes of HFE-7100 Solvent Analogues That Can Protect a DNA Molecule

Ether계 HFE-7100 용매분자(R1-X-R2; R1=CH 3 ) 중 헤테로(X) 원자가 서로 다른 4종의 유사체 (A; ether, B; amine, C; thioether 및 D; disulfide)들에 대한 금속 착화합물의 DNA 분자보호 조건들을 탐색하기 위하여 경계분자궤도함수(FMO) 이론에 적용한 전산화학적인 연구결과는 다음과 같다. 리간드(L; ligand) 분자로서 4종의 유사체(A-D)는 헤테로(X) 원자의 음하전 크기(X: NH≫ O > S > S2> S1) 의 순서로 2차 amine 분자가 제일 높은 금속 착화합물 화 반응성을 나타내었다. R2-치환체와 금속염 (ZnCl 2 및 CuCl 2)과의 착화합물 화 반응성은 전자밀게(σ I < 0)인 alkyl group (1-7)이 전자끌게(σ I > 0)인 fluoroalkyl group (8-14)보다 약 1.3배 높았다. 금속 착화합물 화 반응 및 DNA 가수분해 반응성에 관한 FMO에너지 도표 분석결과로부터 수화된 금속 착 화합물([ZnL n (H 2 O) n ] 2+ )내 물 분자의 숫자(NWM) 가 증가함에 따라서 DNA분자의 가수분해 반응성이 증가하였다. 그러나 methyl t-butylamine (B7)의 비 수화된 금속 착 화합물(Zn(L) 6 )이나 EDTA분자가 DNA분자를 보호할 수 있음을 시사하였다. 또한, HFE-7100용매의 대체물질로는 me-too approach 방법에 따라서 2차 amine (B)계 methyl n-nonafluorobutyl amine (B12) 및 그의 이성질체(B13)가 선택되었다.To search the protect conditions of DNA molecule and the formation reactivity on the metal complexes of hetero atom (X) in HFE-7100 solvent molecule (R1-X-R2; R1=CH 3 ) as ether family compound differ from 4 analogues (A; ether, B; amine, C; thioether, & D; disulfide), the results from the applied to the frontier molecular orbital (FMO) theory in computational chemistry studies were as followings. The secondary amine molecules showed the most highest complexation reactivity in order of negative charge scale (X: NH≫ O>S>S2>S1) of hetero atoms (X) in 4 analogues (A-D). The metal complexations between R2-substituents as ligand (L) molecules and metal salt (ZnCl 2 & CuCl 2 ) are processed based on the inductive effect (σ I ) by R2-substituents, and the alkyl groups (1-7) as electron donor (σ I <0) ca. 1.3 times higher than the fluoroalkyl groups (8-14) as electron withdrawing (σ I >0) in R2-substituents. From the FMO energy diagram on the znic complexation of 4 analogues and decomposition reaction of DNA molecule, the hydrolysis reactivity of DNA molecule increased in a fairly constant manner as the number of the water molecules (NWM) in metal aqua complexes ([ZnL n (H 2 O) n ] 2+ ) increases. But all the results suggested that the non-hydrated metal complex (Zn(L) 6 ) with methyl t-butylamine (B7) or EDTA molecule can protect a DNA molecule. And HFE-7100 solvent molecule can be substituted that it was selected the methyl n-nona fluorobutylamine (B12) and their isomer (B13) as secondary amine (B) family by me-too approach.

Investigation of adverse effect of coexisting aminopolycarboxylates on the determination of rare earth elements by ICP-MS after solid phase extraction using an iminodiacetate-based chelating-resin

When iminodiacetic acid chelating-resin solid phase extraction (SPE) was used for the preconcentration of rare earth elements (REEs) in river water samples around sewage treatment plant (STP), low recovery values for heavy REEs were observed. In order to find out the reason for the low recovery, in the present paper, organic ligands in the STP effluent, which may compete with iminodiacetic acids, were analyzed by GC-NPD. It was found that EDTA was contained in the STP effluent at several-100 nM level and interfered with the adsorption of REEs, especially heavy REEs (present at pM level) on the chelating-resin due to the formation of stable complexes. Therefore, acid treatment was applied to decompose EDTA molecules. As a result of acid treatment with HNO3 and H2O2 at 170 °C for 4 h, all REEs were almost quantitatively recovered from the STP effluent with chelating-resin SPE with good reproducibility. After the acid treatment and subsequent 40-times preconcentration with SPE, all REEs in river water samples were precisely determined by ICP-MS at several-10 to sub pg mL−1 levels.

A highly sensitive EDTA-based senor for detection of disease biomarker and drug

In this study, a fascinating photocatalytic property of EDTA under light irradiation was observed, much the same as that of natural horseradish peroxidase. The small EDTA molecules enable it easily attaches to amine terminal on antibody surface, an ELISA-like assay may be fabricated through combining with gold nanoparticles (AuNPs) in suspensions can exhibit various colors. The labeled EDTA on the proteins which may catalyze decomposition of hydrogen peroxide and in situ mediate the growth of hydrogen peroxide-induced formation of AuNPs, displaying various color nanoparticle dispersion as a read-out means. A straightforward plasmonic sensor was accordingly designed to enable naked-eye observation and quantitative determination of ultra-trace target analytes based on peroxidase-like EDTA. The highly sensitive assay was utilized to determine cancer antigen 15-3 (CA15-3, a breast cancer biomarker) and methamphetamine, and their limit of detection CA15-3 and methamphetamine are 7.5×10−15U/mL and 2.8×10−20mg/mL by naked eyes, respectively. Furthermore, practical applications for detection of CA15-3 and MA in human blood samples were also carried out. The results of detecting CA15-3 of breast cancer serum samples are close agreement with those given by hospital, implying this sensor with high accuracy. This assay has a great potential to be developed into a platform to quantitatively determine analytes as long as the specific antibodies against them were available. Its versatile features will broaden the applicability toward the ultrasensitive detection of target molecules in clinical diagnosis, environmental monitoring, and food quality control only using naked eyes.

Chemical synthesis, structural, optical, magnetic characteristics and enhanced visible light active photocatalysis of Ni doped CuS nanoparticles

In this paper, we report systematic investigations on the effects of Ni doping on the structural, optical, magnetic and photocatalytic characteristics of CuS nanoparticles synthesized by simplistic wet chemical co-precipitation route via EDTA molecules as templates. XRD studies confirmed that accurate phase formation of synthesized nanoparticles and chemical composition were obtained by EDX. Magnetic measurements revealed that 3% Ni doped CuS nanoparticles show signs of good ferromagnetism at room temperature and transition of magnetic signs from ferromagnetic to paramagnetic nature by increasing the Ni dopant concentration in CuS host matrix. The photocatalytic degradation efficiency of the prepared pure and Ni doped CuS nanoparticles were evaluated as a function of simulated sunlight irradiation via RhB organic dye pollutant as a test molecule. Particularly, in the presence of 3% Ni doped CuS nanoparticles in pollutant solution 98.46% degradation efficiency was achieved within 60 min of sunlight irradiation; meanwhile bare CuS attained only 83.22%. Further, after five cycles 3% Ni doping CuS nanoparticles exhibit good photocatalytic stability with very negligible catalyst loss. We believe that the investigations in this study provides adaptable pathway for the synthesizing of various diluted magnetic semiconductor nanoparticles and their applications in spintronic devices as well as sunlight-driven photocatalysts intended for wastewater purification.

Multifunctional adhesive polymers: Preactivated thiolated chitosan-EDTA conjugates

AimThe aim of this study was to synthesis preactivated thiolated chitosan-EDTA (Ch-EDTA-cys-2MNA) conjugates exhibiting in particular high mucoadhesive, cohesive and chelating properties. MethodsThiol groups were coupled with chitosan by carbodiimide reaction and further preactivated by attachment with 2-mercaptonicotinic acid (2MNA) via disulfide bond formation. Determinations of primary amino and sulfhydryl groups were performed by TNBS and Ellman’s tests, respectively. Cytotoxicity was screened by resazurin assay in Caco-2 cells. Mucoadhesive properties and bivalent cation binding capacity with Mg2+ and Ca2+ in comparison to chitosan-EDTA (Ch-EDTA) and thiolated Ch-EDTA (Ch-EDTA-cys) were evaluated. ResultsDetermination of 2MNA and total sulfhydryl groups indicated that 80% of thiol groups were preactivated. The results from cytotoxicity studies demonstrated that Ch-EDTA-cys and Ch-EDTA-cys-2MNA were not toxic to the cells at the polymer test concentration of 0.25% (w/v) while cell viability decreased by increasing the concentration of Ch-EDTA. Although EDTA molecule was modified by thiolation and preactivation, approximately 50% of chelating properties of the conjugates were maintained compared to Ch-EDTA. Ch-EDTA-cys-2MNA adhered on freshly excised porcine intestinal mucosa up to 6h while Ch-EDTA adhered for just 1h. ConclusionAccording to the combination of mucoadhesive and chelating properties of the conjugates synthesized in this study, Ch-EDTA-cys-2MNA might be useful for various mucosal drug delivery systems.

On the Synthesis of Au Nanoparticles Using EDTA as a Reducing Agent

The synthesis of gold nanoparticles (Au NPs) from HAuCl4 by using EDTA as a reducing agent is investigated for the first time using UV–vis spectroscopy, transmission electron microscopy (TEM), and dynamic light scattering (DLS). We show that the size of resulting Au NPs is dictated by the reactivity of ionic Au(III) species and the charge density of EDTA molecules with pH. Moreover by varying the pH of the reaction media, the size of Au NPs can be tuned from 25 to 100 nm. Investigation of the nucleation and growth of Au NPs by time-resolved UV–vis and TEM revealed the presence of nanowires that progressively increase in size at the same time the connected network is fragmented into small segments before the final spherical particles are formed. The identification of reaction intermediates and final products resulting from the reduction of Au(III) by EDTA was possible by recording several 1D- and 2D-nuclear magnetic resonance (NMR) spectra. Our results show that Au(III) reduction to Au(0) NPs by EDTA is ac...

Application of displacement principle for detecting heavy metal ions and EDTA using microcantilevers

A microcantilever sensor based on a reversible displacement reaction was developed. The demonstration was performed with the Ni–NTA–EDTA sample system. Ni ions, a typical heavy metal, were injected and adsorbed onto a NTA-functionalized AFM cantilever in a fluid cell. This adsorption resulted in tensile stress which was detected by monitoring the corresponding deflection of the microcantilever. In the next step, EDTA was injected into the cell to release the adsorbed Ni ions from the surface of the cantilever. Since EDTA molecules have a stronger affinity for Ni ions compared to NTA, they compete with and eventually replace the NTA molecules and take over the binding positions on Ni. The displacement of Ni ions from the cantilever by EDTA, followed by water flow removes the tensile stress and restores the cantilever deflection to its original value. In this way, both heavy metal ions and EDTA can be specifically recognized. From the cantilever deflection, the concentration of Ni ions and EDTA can be quantified. The detection limits are presently at the micromolar level. Another weaker Ni ion binder, imidazole, was unable to dissociate Ni ions from NTA and produce similar effects. The demonstrated principle can be used for microcantilever sensors which are capable of regeneration for multiple uses. The method presented can be generalized to detect other reactants.

Flaky and Porous Rod-Like MgO Powders Prepared by Molten Salt Synthesis

Flaky and porous rod-like MgO powders were prepared by molten salt synthesis with MgCl2, CaCO3, NaNO3and KNO3as raw materials. TG-DSC, XRD and SEM were used to investigate the reacion process and characterize the resulting products. The results indicated that Ca2+was displaced by Mg2+and dolomites were formed and finally converted into magnesium carbonates during the molten salt synthesis. Fibrous Mg(OH)2formed in PEG solution and flaky Mg(OH)2formed in EDTA-PEG solution illustrated that EDTA and PEG molecules could define the growth direction of Mg(OH)2. The porous rod-like MgO powders with 20-80 nm in diameter and 40-100 in length-to-width ratio were obtained by the decomposition of fibrous Mg(OH)2at 600 °C, while the flaky MgO powders were prepared by the decomposition of flaky Mg(OH)2at 600 °C. Flaky MgO powders were platelike, with 30-50 nm in thickness, 200-500 nm in diameter, and up to 1.0 µm2in a single slice surface area.

Study on the adsorption of Ca 2+, Cd 2+ and Pb 2+ by magnetic Fe 3O 4 yeast treated with EDTA dianhydride

Magnetic Fe 3O 4 baker's yeast biomass (FB) was prepared by combining baker's yeast biomass and nano-Fe 3O 4 using glutaraldehyde as a cross-link agent, and was chemically treated with ethylenediaminetetraacetic dianhydride (EDTAD). The EDTAD-treated magnetic Fe 3O 4 baker's yeast biomass (EFB) was investigated by Fourier transform infrared spectroscopy (FTIR), potentiometric titration, zeta potential, and magnetic response analysis. The results revealed that the EFB possessed not only the super-paramagnetic characteristic of nano-Fe 3O 4, but its surface also had plenty of carboxyl and amino groups introduced by the EDTA molecules. The adsorption properties of EFB for Pb 2+, Cd 2+, and Ca 2+ ions were also evaluated. The results showed that the uptakes of EFB for the three metal ions were higher than that of FB, and the adsorption capability of Pb 2+, Cd 2+, and Ca 2+ ions increased with an increase in pH. The adsorption process was followed by the pseudo-second-order kinetic model and Langmuir isotherm equation. The maximum adsorption capacities of 99.26 mg/g for Pb 2+ at pH 5.5, 48.70 mg/g for Cd 2+ at pH 6.0, and 33.46 mg/g for Ca 2+ at pH 6.0 were observed at 30 °C. The regeneration experiments showed that the EFB could be successfully reused.

EDTA Surface Capped Water-Dispersible ZnSe and ZnS:Mn Nanocrystals

ZnSe and ZnS:Mn nanocrystals were synthesized via the thermal decomposition of their corresponding organometallic precursors in a hot coordinating solvent (TOP/TOPO) mixture. The organic surface capping agents were substituted with EDTA molecules to impart hydrophilic surface properties to the resulting nanocrystals. The optical properties of the water-dispersible nanocrystals were analyzed by UV-visible and room temperature solution photoluminescence (PL) spectroscopy. The powders were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), and confocal laser scanning microscopy (CLSM). The solution PL spectra revealed emission peaks at 390 (ZnSe-EDTA) and 597 (ZnS:Mn-EDTA) nm with PL efficiencies of 4.0 (former) and 2.4% (latter), respectively. Two-photon spectra were obtained by fixing the excitation light source wavelengths at 616 nm (ZnSe-EDTA) and 560 nm (ZnS:Mn-EDTA). The emission peaks appeared at the same positions to that of the PL spectra but with lower peak intensity. In addition, the morphology and sizes of the nanocrystals were estimated from the corresponding HR-TEM images. The measured average particle sizes were 5.4 nm (ZnSe-EDTA) with a standard deviation of 1.2 nm, and 4.7 nm (ZnS:Mn-EDTA) with a standard deviation of 0.8 nm, respectively.

The encapsulation of idarubicin within liposomes using the novel EDTA ion gradient method ensures improved drug retention in vitro and in vivo

The purpose of this study was to design a new stable liposomal formulation for the anticancer drug idarubicin. Idarubicin is a relatively hydrophobic member of the anthracycline family. It exhibits pronounced bilayer interactions leading to rapid in vivo drug release from liposomes. This rapid drug leakage is due to the presence of cholesterol and charged lipids in the liposomal bilayer. Therefore, a novel method of remote drug loading was developed to prevent rapid drug release from PEGylated cholesterol-containing liposomes. This method uses EDTA disodium or diammonium salt as an agent to form low solubility complexes between the drug and EDTA molecules inside the liposomes, thus yielding improved drug retention. The efficiency of idarubicin encapsulation is close to 98% at a drug to lipid molar ratio of 1:5. An in vitro long-term storage experiment confirmed the high stability of the liposomes. The in vivo studies also showed the superiority of the new idarubicin formulation over the recently used remote loading methods. The plasma level of idarubicin was much higher when EDTA liposomes were used. The presented results fully demonstrate the superiority of the proposed method of idarubicin encapsulation over existing methods. The method offers the possibility of encapsulating not only all the anthracyclines, but also other weakly amphiphilic bases within the liposomes.

Hydrothermal synthesis of cuboidal PbSe microcrystals via an EDTA reduction route

Cuboidal lead selenide (PbSe) microcrystals have been successfully synthesized via a novel EDTA reduction route in which EDTA molecules serve as both chelating reagent and reductant. Hereafter EDTA is the abbreviation for ethylenediaminetetraacetic acid tetrasodium salt dihydrate (C 10H 12N 2Na 4O 8·2H 2O). The unique cuboidal PbSe microcrystals have eight symmetric arms along the < 111> directions. The edge of a cuboidal PbSe microcrystal extends outwards from its core with a tiny cubic center leaving step-like faces. The whole synthetic system provides an appropriate crystal growth environment for the formation of these microcrystals. Furthermore cuboidal PbSe microcrystals with different concave faces can be obtained at different reaction stages.

A New Pb2+ Ion-selective Hybrid Cation-exchanger — EDTA–Zirconium Iodate: Synthesis, Characterization and Analytical Applications

An amorphous sample of the new hybrid cation-exchanger EDTA–zirconium iodate was synthesized by the combination of the inorganic ion-exchanger zirconium iodate with the organic EDTA molecule, thereby providing a new class of organic–inorganic hybrid ion-exchangers with better mechanical and granular properties, good ion-exchange capacity (e.g. 2 mequiv Na+/g dry exchanger), good reproducibility, a higher stability and demonstrating selectivity towards heavy metal ions. The physicochemical properties of this material were examined by instrumental analyses, viz. FT-IR spectroscopy, X-ray diffraction studies and TGA/DTA investigations. Assessments of the elution and distribution behaviour were made and pH titrations undertaken to obtain an understanding of the ion-exchange behaviour of the material. On the basis of the distribution studies, the material was found to be highly selective towards the Pb2+ ion, a highly toxic environmental pollutant. Its selectivity was assessed by examining its use for some imp...

Effect of organic complexation on the toxicity of Cu to the earthworm Eisenia fetida

The relationship between Cu speciation in solution and mortality and tissue Cu concentrations in Eisenia fetida was investigated. E. fetida were exposed to solutions containing 0.009, 0.049 and 0.125 mg Cu L −1and 0, 0.15, 0.35 and 50 mg EDTA L −1. Mortalities of 100, 60, 50 and 25% were recorded in the 0.125 mg Cu L −1 solutions containing 0, 0.15, 0.35 and 50 mg EDTA L −1, respectively. Similarly tissue body burden decreased with increasing EDTA concentration. Complexation capacity of the solution increased with EDTA concentration. In the 0.125 mg Cu L −1 solution labile Cu concentration decreased with increasing EDTA concentration. These trends are attributed to complexation of free Cu ions with EDTA molecules, and the non-bioavailable nature of the resultant Cu–EDTA complex.

Preparation of Rhombic MgO Nanoflakes from Dolomites

Rhombic magnesia flakes with multi interspaces were prepared by calcining magnesium hydrate.The precursor of MgO could be obtained via acid immersing twice and ammonia depositing from dolomites.The structure,morphology,and composition of MgO and its precursor were characterized by means of XRD,FT-IR,SEM,and TEM methods.The results indicated that EDTA and PEG molecules were possessed of the effect directing the radial epitaxial growth of Mg(OH)2 flakes.The rhombic magnesia nanoflakes with 10-20 nm in thickness and up to 1 μm2 in area of main surface are single crystal with cubic crystal structure.It grows with a preferred orientation along the [100] direction and inherits the features of radial epitaxial growth of Mg(OH)2.The orientated growth mechanism of the MgO nanoflakes was studied based on corresponding thermodynamics and dynamics theories.