Ethylenediaminetetraacetic Acid Dianhydride Research Articles

Synthesis and characterization of a new multifunctional aliphatic poly(amic acid): An efficient polymeric adsorbent for removing the heavy metal ions

The heavy-metal ions in wastewater have attracted intense attention due to environmental issues, including their toxicity, bioaccumulation tendency, and persistency in nature. Despite other strategies for heavy metal removal from wastewater, adsorption is one of the most promising methods, owing to its simplicity and efficiency. To conserve the carboxyl and amine functional groups and prevent amidation reaction, a new aliphatic tertiary poly(amic acid) with linear and cyclic spacers was synthesized via the catalyst-free process. The ring opening of ethylenediaminetetraacetic acid dianhydride (EDTADA) by piperazine, a bifunctional cyclic secondary diamine, was conducted in a polar solvent (DMF) in a nitrogen atmosphere for 3 h. The characterization was conducted by FTIR and NMR, and their morphology and elemental composition were investigated by field emission scanning electron microscopy and energy dispersive X-ray (FESEM-EDX). As-synthesized aliphatic tertiary poly(amic acid) could be separated as a white powder with an O/N ratio of 0.93 ± 0.03 and morphology of woven fiber. The white powder showed an average molecular weight (M̅w) of ∼12,000 and a polydispersity index (PDI) of 1.52 ± 0.05. In addition, the poly(amic acid) TGA/DTA analysis showed a high thermal stability with stepwise degradation with the onset of 346 °C. The poly(amic acid) DSC profile displayed a high glass transition at 124 °C. The Brunauer–Emmett–Teller (BET) surface area and pore volume were determined to be 146.05 m2/g and 0.78 cm3/g. The poly(amic acid) contains the mesopores and macropores based on its pore size distribution curve. Regarding an acidic pH and abundance of functional groups, as-prepared tertiary poly(amic acid) was employed as a heterogeneous adsorbent of different types of heavy-metal ions, including Ag (I), Cr (III), and Cu (II). A removal efficiency > 90 % after 10 min for three heavy metal ions demonstrates a strong chelating capacity of as-prepared tertiary poly(amic acid). An adsorption capacity of > 50 mg per gram of poly(amice acid) was recorded for three heavy-metal ions with a pH of 3 or higher than 3. Poly(amic acid) exhibited good recyclability. This work exhibited the applicability of novel poly(amic acid) as an efficient adsorbent for the heavy metal ions removal from wastewater.

Insight into a novel circulation system combined with coordination leaching and biosorption for Cu(II) efficient recycling from electroplating sludge

A novel circulation system combined with coordination leaching and biosorption process was successfully used for the direct recycling of Cu2+ from the electroplating sludge. Cu2+ was firstly efficiently leached out from the sludge by the choosing organic acid, and then it was selectively adsorbed onto a modified sorbent from the lixivium containing other co-ions including Zn2+, Ca2+, Fe3+, Cr3+, and Mg2+ under dynamic adsorption condition. The results of static leaching experiments and DFT calculations showed that citric acid showed the best leaching performance for Cu2+ among the studied organic acids and the traditional inorganic acid (HCl). To selective recovery of Cu2+ from the lixivium, ethylenediamine tetraacetic acid dianhydride (EDTAD) modified bagasse was prepared, and it had high adsorption capacity, selectivity, and good reusability toward Cu-citric acid complex. The adsorption isotherm for Cu matched with the Langmuir model with a maximum adsorption capacity of 52.2 mg/g. XPS and EXAFS analysis illustrated that the Cu-citric acid complex was broken by EDTA on the modified bagasse, and Cu2+ enriched on the sorbent while citric acid was released into the lixivium again. In the combined leaching and sorption circulation system, Cu2+ was simultaneously absorbed on the modified bagasse fixed bed column once it was leached out. Benefitting the recycling of citric acid and the continuous adsorbing of Cu of the circulation system, the leaching efficiency could be increased from 75.0 % to 92.4 %, even in the very dilute citric acid solutions (concentration of 0.01 mol/L). The combined methods could increase Cu recovery efficiency from the sludge at a low concentration of the leaching agent, which had great potential in the practical application.

Electrospun cellulose acetate/activated carbon composite modified by EDTA (rC/AC-EDTA) for efficient methylene blue dye removal

The present study fabricated regenerated cellulose nanofiber incorporated with activated carbon and functionalized rC/AC3.7 with EDTA reagent for methylene blue (MB) dye removal. The rC/AC3.7 was fabricated by electrospinning cellulose acetate (CA) with activated carbon (AC) solution followed by deacetylation. FT-IR spectroscopy was applied to prove the chemical structures. In contrast, BET, SEM, TGA and DSC analyses were applied to study the fiber diameter and structure morphology, the thermal properties and the surface properties of rC/AC3.7-EDTA. The CA was successfully deacetylated to give regenerated cellulose nanofiber/activated carbon, and then ethylenediaminetetraacetic acid dianhydride was used to functionalize the fabricated nanofiber composite. The rC/AC3.7-EDTA, rC/AC5.5-EDTA and rC/AC6.7-EDTA were tested for adsorption of MB dye with maximum removal percentages reaching 97.48, 90.44 and 94.17%, respectively. The best circumstances for batch absorption experiments of MB dye on rC/AC3.7-EDTA were pH 7, an adsorbent dose of 2 g/L, and a starting MB dye concentration of 20 mg/L for 180 min of contact time, with a maximum removal percentage of 99.14%. The best-fit isotherm models are Temkin and Hasely. The outcome of isotherm models illustrates the applicability of the Langmuir isotherm model (LIM). The maximal monolayer capacity Qm determined from the linear LIM is 60.61 for 0.5 g/L of rC/AC3.7-EDTA. However, based on the results from error function studies, the generalized isotherm model has the lowest accuracy. The data obtained by the kinetic models’ studies exposed that the absorption system follows the pseudo-second-order kinetic model (PSOM) throughout the absorption period.

Versatile crosslinking synthesis of an EDTA-modified UiO-66-NH2/cotton fabric composite for simultaneous capture of heavy metals and dyes and efficient degradation of organophosphate

The metal-organic frameworks/cotton fabric composites (MOFs/CFCs) have emerged as a new type of prospective materials for environmental cleanup, due to their convenient recyclability and high removal efficiency towards hazardous pollutants. However, their practical applications are limited by complicated synthetic conditions, insufficient interface bonding and poor adsorption capacity. Herein, for the first time, a robust ethylenediaminetetraacetic acid (EDTA)-functionalized MOFs/CFC is prepared based on UiO-66-NH2 crystals by using EDTA dianhydride as the cross-linking agent, and applied for simultaneous removal of heavy metals and dyes, as well as degradation of chemical warfare agents. The as-prepared EDTA-UiO-66-NH2/CFC shows extraordinary monocomponent adsorption performance with maximum adsorption capacity of 158.7, 126.2, 131.5, 117.4 and 104.5 mg/g for Cd(II), Cu(II), methylene blue, crystal violet and safranin O, respectively. Interestingly, in metal-dyes binary system, the uptake of Cu(II) by EDTA-UiO-66-NH2/CFC increases significantly when co-existing high concentration of dyes. The results indicate that the synergistic and simultaneous removal of both dyes and metal from complex systems can be realized by EDTA-UiO-66-NH2/CFC via multiple mechanisms. The EDTA-UiO-66-NH2/CFC also exhibits an outstanding catalytic performance for degrading dimethyl 4-nitrophenylphosphate. Besides, it can be reused for several times without obvious decrease of its adsorption and catalysis efficiencies. More impressively, the cross-linking reaction approach can not only anchor UiO-66-NH2 crystals firmly onto cotton fabric, but also facilitate in-situ formation of abundant adsorption sties on the adsorbent surface. Therefore, this work offers a simple and versatile synthetic strategy to develop high-performance environmental material for multiple pollutants remediation.

Exploring the Corrosion Inhibition Properties of an Anionic Gemini Surfactant Based on an Ethylenediaminetetraacetic Acid Derivative on AZ31 Alloy

AbstractNovel sodium 2,2′‐(7,16‐dihexyl‐8,15‐dioxo‐7,10,13,16‐tetraazadocosane‐10,13‐diyl)diacetate was prepared by treating ethylenediaminetetraacetic acid dianhydride with N‐dihexylamine. The surfactant was used as a corrosion inhibitor on AZ31 alloy. FT‐IR spectroscopy, NMR spectroscopy and LC‐MS techniques were used to characterize the synthesized anionic inhibitor. The theoretical studies, performed by using the DFT simulations revealed in‐depth information on the frontier molecular orbitals and electronic properties of the inhibitor. Potentiodynamic polarization and electrochemical impedance spectroscopy methods were used to determine the corrosion inhibition ability of the synthesized surfactant. The adsorption of the surfactant on the surface of AZ31 Mg alloy obeyed Langmuir isotherm with predominantly physical adsorption and partial chemisorption. SEM‐EDX and XPS were used to understand the surface morphologies of the corroded AZ31 alloy. The quantum chemical simulations were used to get the correlation between their structural, molecular geometry, and experimental results.

Biosorption of Cd2+ and Pb2+ from apple juice by the magnetic nanoparticles functionalized lactic acid bacteria cells

The pollution of heavy metals in fruit juice is still increasing and becoming a significant food safety issue worldwide nowadays. In this work, twelve strains of lactic acid bacteria (LAB) were evaluated for the biomass and their capability to adsorb Cd2+ and Pb2+. One strain of LAB capable of efficiently adsorbing heavy metals in apple juice was screened. The obtained LAB was functionalized by magnetic Fe3O4 nanoparticles (MNPs) and modified by Ethylenediaminetetraacetic acid dianhydride (EDTAD) for generation EDTAD-MNPs-LAB (EMB) adsorbent, which was further characterized by Scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The results indicated that the strain of LAB was successfully functionalized and modified by MNPs and EDTAD. The maximum adsorption capacity of EMB adsorbent for Cd2+ and Pb2+ in apple juice was 0.57 mg/g and 0.17 mg/g, respectively. The EMB adsorbent could be rapidly separated from the sample solution with the help of magnetic field and the adsorption process has no significant impact on the quality of fruit juice. The regeneration experiments revealed that the EMB adsorbent could be successfully reused. The research provides a new insight and strategy for the effective adsorption and removal of heavy metals from juice.

Chelating Effect of Cellulose Acetate Hydrogel Crosslinked with EDTA Dianhydride Used as a Platform for Cell Growth

The use of biomaterials capable of achieving controlled release of drugs or chemical and physical interactions with living organisms causes these new materials to be studied in depth to better target their future applications. An example of this is the use of materials that have in their physical structure elements with chelating effects, capable of interacting with the ions and cations present in the cell culture media, drugs, and other elements capable of interacting with the human body. In this work, cellulose acetate hydrogel (HAC) crosslinked with EDTAD (ethylenediaminetetraacetic acid dianhydride) showed a significant chelating effect capable of altering the adhesion of mesenchymal cells in the first days of in vitro tests. This result became our main question in this work, and by using new cell viability assays, it was verified that the hydrogel interacted with the culture medium, removed the salts present, such as Ca2+ and Mg2+, and promoted a decrease in the amount of cells adhered to the material but not cell death. After saturation of Ca2+ and Mg2+, we obtained an improvement in cell adhesion. Electrochemical impedance spectroscopy (EIS) results also verified the dynamics of linked or mobile loads in the volume and interface regions of HAC-EDTA and the presence of characteristic bands related to the interaction between calcium and magnesium present in the culture medium with HAC-EDTA. The DMA traction test showed that there was no dynamic-mechanical change in the structure of the material at temperatures between 20 and 60°C, which is ideal for this studied biomaterial. The purpose of these tests is to aid in the characterization of future biomaterials, where the physicochemical interaction of some of them is often confused with a false cytotoxicity, which in fact may only be an easily identifiable and adaptable structural feature.

New benzyloxyethyl cellulose (BEC) crosslinked EDTA: synthesis, characterization and application for supramolecular self-assembling nanoencapsulation of Pb (II)

Abstract Cellulosic derivatives-modification by Ethylenediaminetetraacetic acid dianhydride (EDTAD) leads to an advanced state of the crosslinking degree, which often limits the adsorbent-metal ion interactions at the superficial level. Moreover, the specific area decreases by increasing crosslinking degree, resulting in a degradation of the adsorptive properties of the materials. In the present work, a new synthesis strategy of crosslinkedcellulose derivative with Ethylenediaminetetraacetic acid (EDTA) was proposed. The preparation of the adsorbent was based on the hydrophobation of hydroxyethyl cellulose (HEC) by partial benzylation (DS ∼ 1). This helped to obtain a new cellulose derivative (Benzyloxyethyl cellulose (BEC)) soluble in the majority of the usual solvents, and the EDTA grafting reaction was performed under homogeneous conditions to ensure homogenous distribution of the chelating sites. The resulting BEC-EDTA material was then characterized by FT-IR, SEM and TGA. Thus, the Pb (II)-adsorption behavior on the bio-adsorbent was studied at the supramolecular level and the study of changes in adsorbent morphology before and after modification was performed based on SEM images and EDX spectra. Effect of Pb (II) on BEC-EDTA morphology was investigated as well. However, a self-assembly of BEC-EDTA as nanometric rods in the presence of Pb (II) ions was a strong indication of the Pb (II) nano-encapsulation in a stable polymer network.

Synthesis of polyhedral oligomeric silsesquioxane nano‐crosslinked poly(ethylene glycol)‐based hybrid hydrogels for drug delivery and antibacterial activity

AbstractThe synthesis is reported of novel hybrid hydrogels based on ethylenediaminetetraacetic acid dianhydride and poly(ethylene glycol) (PEG) with octa‐aminopropyl polyhedral oligomeric silsesquioxane hydrochloride salt (OA‐POSS) as a nano‐crosslinker under solvent‐free conditions. The molecular weight of PEG was varied between 600 and 1000 Da. The synthesized hydrogels were characterized using various techniques. Further, the swelling behavior and antibacterial activity of the hydrogels and release kinetics of metronidazole (MTZ) as a model drug from them were evaluated. Experimental results demonstrate that hydrogels with tunable properties can be synthesized by varying the PEG molecular weight and type of crosslinker (hybrid or organic). Among the synthesized hybrid hydrogels, that crosslinked by OA‐POSS with long PEG chains (1000 Da) showed the highest swelling degree (2000%), drug encapsulation efficiency (88%) and extent of MTZ release (96%). © 2018 Society of Chemical Industry

Adsorption of ethylenediaminetetraacetic dianhydride modified oxalate decarboxylase on calcium oxalate

We used ethylenediaminetetraacetic acid dianhydride (EDTAD) to modify oxalate decarboxylase (OXDC) to improve its adsorption on calcium oxalate stones. The modified sites were identified by Ultra performance liquid chromatography-mass spectrometry (UPLC-MS) and the adsorption mechanism of the EDTAD-modified OXDC on calcium oxalate (CaOx) was investigated. We investigated adsorption time, initial enzyme concentration, temperature and solution pH on the adsorption process. Data were analyzed using kinetics, thermodynamics and isotherm adsorption models. UPLC-MS showed that EDTAD was attached to OXDC covalently and suggested that the chemical modification occurred at both the free amino of the side chain and the α-NH2 of the peptide. The adsorption capacity of the EDTAD-OXDC on calcium oxalate was 53.37% greater than that of OXDC at the initial enzyme concentration of 5 mg/ml, pH = 7.0, at 37° C. The modified enzyme (EDTAD-OXDC) demonstrated improved oxalate degradation activity at pH 4.5−6.0. Kinetic data fitting analysis suggested a pseudo second order kinetic model. Estimates of the thermodynamic parameters including ΔG0, ΔH0 and ΔS0 of the adsorption process showed it to be feasible, spontaneous and endothermic. Isotherm data fitting analysis indicated that the adsorption process is reduced to monolayer adsorption at a low enzyme concentration and to multilayer adsorption at a high enzyme concentration. It may be possible to apply OXDC to degradation of calcium oxalate stones.

Dynamics and interactions of ibuprofen in cyclodextrin nanosponges by solid-state NMR spectroscopy.

Two different formulations of cyclodextrin nanosponges (CDNS), obtained by polycondensation of β-cyclodextrin with ethylenediaminetetraacetic acid dianhydride (EDTAn), were treated with aqueous solutions of ibuprofen sodium salt (IbuNa) affording hydrogels that, after lyophilisation, gave two solid CDNS-drug formulations. 1H fast MAS NMR and 13C CP-MAS NMR spectra showed that IbuNa was converted in situ into its acidic and dimeric form (IbuH) after freeze-drying. 13C CP-MAS NMR spectra also indicated that the structure of the nanosponge did not undergo changes upon drug loading compared to the unloaded system. However, the 13C NMR spectra collected under variable contact time cross-polarization (VCT-CP) conditions showed that the polymeric scaffold CDNS changed significantly its dynamic regime on passing from the empty CDNS to the drug-loaded CDNS, thus showing that the drug encapsulation can be seen as the formation of a real supramolecular aggregate rather than a conglomerate of two solid components. Finally, the structural features obtained from the different solid-state NMR approaches reported matched the information from powder X-ray diffraction profiles.

Chemically Modified Cellulose Filter Paper for Heavy Metal Remediation in Water

A chemically modified cellulose filter paper with ethylenediaminetetraacetic acid (EDTA) is described as a device for metal remediation. This new material was prepared by esterification of the paper with EDTA dianhydride. The high hydrophilicity of cellulose paper associated with the strong chelating properties of the EDTA moieties for metals allow the treatment of water samples containing various metal cations, including Ag(I), Pb(II), Cd(II), Ni(II), Zn(II), Sn(II), and Cu(II), with 90–95% removal efficiency. The mechanism of adsorption was deeply studied with the support of kinetic experiments and adsorption isotherms. As a practical feature, one can note that the cellulose–EDTA material works at a wide range of pH values and can be used either as a solid adsorbent or a membrane for continuous wastewater treatment.

Anomalous diffusion of Ibuprofen in cyclodextrin nanosponge hydrogels: an HRMAS NMR study.

Ibuprofen sodium salt (IP) was encapsulated in cyclodextrin nanosponges (CDNS) obtained by cross-linking of β-cyclodextrin with ethylenediaminetetraacetic acid dianhydride (EDTAn) in two different preparations: CDNSEDTA 1:4 and 1:8, where the 1:n notation indicates the CD to EDTAn molar ratio. The entrapment of IP was achieved by swelling the two polymers with a 0.27 M solution of IP in D2O, leading to colourless, homogeneous hydrogels loaded with IP. The molecular environment and the transport properties of IP in the hydrogels were studied by high resolution magic angle spinning (HRMAS) NMR spectroscopy. The mean square displacement (MSD) of IP in the gels was obtained by a pulsed field gradient spin echo (PGSE) NMR pulse sequence at different observation times td. The MSD is proportional to the observation time elevated to a scaling factor α. The α values define the normal Gaussian random motion (α = 1), or the anomalous diffusion (α < 1, subdiffusion, α > 1 superdiffusion). The experimental data here reported point out that IP undergoes subdiffusive regime in CDNSEDTA 1:4, while a slightly superdiffusive behaviour is observed in CDNSEDTA 1:8. The transition between the two dynamic regimes is triggered by the polymer structure. CDNSEDTA 1:4 is characterized by a nanoporous structure able to induce confinement effects on IP, thus causing subdiffusive random motion. CDNSEDTA 1:8 is characterized not only by nanopores, but also by dangling EDTA groups ending with ionized COO− groups. The negative potential provided by such groups to the polymer backbone is responsible for the acceleration effects on the IP anion thus leading to the superdiffusive behaviour observed. These results point out that HRMAS NMR spectroscopy is a powerful direct method for the assessment of the transport properties of a drug encapsulated in polymeric scaffolds. The diffusion properties of IP in CDNS can be modulated by suitable polymer synthesis; this finding opens the possibility to design suitable systems for drug delivery with predictable and desired drug release properties.

Synthesis and properties of hydrophilic polymers, part 11: Synthesis, biodegradability, and metal complexation of copolymers of ethylenediaminetetraacetic acid dianhydride and lactose

AbstractThe synthesis and characterization of poly(ethylenediaminetetraacetic acid‐co‐lactose) of high molar mass (132 kg mol−1) is described. The polycondensate with pendant carboxylic groups was shown to be hydrolytically and microbiologically degradable by using conventional microbiological methods. The metal complexing properties of the polyester were studied for Cr(III), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Sr(II), Cd(II), Pb(II), and Al(III) ions in aqueous solution using the liquid‐phase polymer‐based retention (LPR) method. In addition, the complexing capacity of the Cu(II)‐saturated copolymer was determined by TGA to be 182 mg g−1 polymer. According to the retention profiles determined as a function of filtration factor by using LPR in conjunction with inductively coupled plasma spectrometry, Cr(III) and Fe(III) showed a strong interaction with this polymer under these conditions, indicated by retention values of 100% at pH 5. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2932–2939, 2007

A Pluronic-coupled metal-chelating ligand for membrane affinity chromatography

A technique for bio-specific affinity chromatography using synthetic nonporous membranes and a new metal-chelating Pluronic surfactant is described. Synthetic polymeric poly(vinyldiene fluoride) membranes were fabricated for use as solid, hydrophobic adsorption membrane matrices. An ethylene diamine tetraacetic acid dianhydride was coupled to the terminal hydroxyl end groups of Pluronic ® F108 via a two-step reaction at 40 °C, to create a new metal affinity ligand, Pluronic- N,N-dicarboxymethyl-3,6-diazaoctanedioate (Pluronic-DMDDO). The hydrophobic poly(propylene oxide) moiety of Pluronic allowed non-covalent adsorption of the ligand to the hydrophobic membrane matrix. The protein repellent properties of the hydrophilic poly(ethylene oxide) brush layer of Pluronic, served to preserve the bio-specific activity of the ligand and to increase ligand accessibility. Proton-induced X-ray emission (PIXE) analysis was used to determine the metal binding capacity, stability and surface homogeneity of this immobilised metal affinity membrane system and to generate surface homogeneity maps of the chelated metal ions. The chelate capacity of Pluronic-DMDDO was determined under non-competitive conditions and was of the order (Zn 2+ > Ni 2+ > Cu 2+). An amino terminal hex-histidine-tagged recombinant Escherichia coli pantothenate kinase was used as a test protein. Histidine-tagged pantothenate kinase bound strongly to Pluronic-DMDDO-treated membranes specifically in the presence of Ni 2+. Eluted immobilised histidine-tagged proteins retained their biochemical activity and the membranes were capable of being regenerated and re-used.

Synthesis and properties of hydrophilic polymers. IX. Synthesis, biodegradability, and metal complexation of copolymers of ethylenediaminetetraacetic acid dianhydride and lactose

AbstractThe synthesis and characterization of poly(ethylenediaminetetraacetic acid‐co‐lactose) with pendant carboxylic groups of high molar mass (132 kg mol−1) is described. The polycondensate was hydrolytically and microbiologically degradable with conventional microbiological methods. The metal‐complexing properties of the polyester were studied for Cr(III), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Sr(II), Cd(II), Pb(II), and Al(III) ions in aqueous solution with the liquid‐phase polymer‐based retention (LPR) method. In addition, the complexing capacity of the Cu(II)‐saturated copolymer was determined by thermogravimetric analysis to be 182 mg g−1 of polymer. According to the retention profiles determined as a function of the filtration factor with LPR in conjunction with inductively coupled plasma spectrometry, Cr(III) and Fe(III) showed a strong interaction with this polymer under these conditions, as indicated by retention values of about 100% at pH 5. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 650–657, 2003

Synthesis and characterization of lithium and magnesium complexes based on [EDTA][PEG400] 2 and [EDTA] 3 [PEG400] 7

Two distinct types of host polymers, [EDTA]3-[PEG400]7 and [EDTA][PEG400]2, consisting of polyether chains linked together by ethylenediaminetetraacetic acid (EDTA) chelating units, were synthesized from EDTA acetate esters and poly(ethylene glycol) 400 (PEG400). Their structures were revealed by analytical analyses, viscosimetric measurements, NMR and FT-IR studies. Direct dissolution of δ-LiCl and δ-MgCl2 in these prepared host polymers resulted in the following complexes: [EDTA]3-[PEG400]7/(LiCl)6.39, [EDTA]3[PEG400]7/(MgCl2)8.23, [EDTA]3[PEG400]7/(LiCl)6.39(MgCl2)6.16, [EDTA][PEG400]2/ (LiCl)2.26, [EDTA][PEG400]2/(MgCl2)1.98 and [EDTA]-[PEG400]2/(LiCl)2.26(MgCl2)1.98. Mid- and far-FT-IR spectroscopic studies revealed the following properties for all six complexes: a) the polyether chains are in the trans–gauche–trans conformation; b) the Mg2+ ion could be hexa- or heptacoordinated to the chelating sites of EDTA; c) the Li+ ion is preferentially coordinated by the oxygen atoms of the residual acetate groups and polyether moieties. Results of conductivity measurements at room temperature indicated that the proposed Mg products might be very useful for the development of electrochemical transducers for measuring water hardness. Esterification of EDTA dianhydride with PEG400; (2): Synthesis of the complexes (MXn = LiCl/MgCl2).

A Novel Biodegradable Carboxy-Functional Lactose Copolymer

The synthesis of the first lactose main-chain copolymer was achieved by means of solution polyreaction of ethylenediaminetetraacetic acid dianhydride with D-lactose. The water-soluble carboxy-functional material based on EDTA with a high molar mass is shown to be biodegradable. The metal complexing properties of the polymer based on the liquid-phase polymer-based retention (LPR) method showed a strong interaction with Cr(III), Fe(III), and Sr(II) ions.

Metal-chelating properties and biodegradability of an ethylenediaminetetraacetic acid dianhydride modified soy protein hydrogel

The heavy-metal chelating properties of a soy protein based hydrogel, prepared by crosslinking an ethylenediaminetetraacetic acid dianhydride (EDTAD) modified soy protein isolate (SPI), have been studied. The equilibrium binding capacities of the divalent calcium, zinc, mercury, and lead ions by the gel were 0.70, 0.65, 0.95, and 0.70 mmol per gram of dry gel, respectively. The distribution ratio of metal ions between the gel and the solution was in the range of 370 to 15,000 mL/g, depending on the initial metal concentration. A positive relationship between the carboxyl group content of EDTAD-modified SPI and the metal-binding ability of the gel was observed; the optimum metal binding occurred at 25°C. The metal-binding ability increased with increasing pH, in the range where the solubility of the metal ions was not affected by the pH. In binary metal ion solutions, the metal ions adsorbed to the gel in a competitive fashion, influenced by the initial ion concentration. The EDTAD-modified protein hydrogel was readily degraded by proteolytic enzymes and was biodegraded in a fungal overgrowth test. The EDTAD-SPI hydrogel was completely degraded after a 28-day incubation with fungal spores. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 891–901, 1997

Synthesis and Relaxivity of Polyamide Paramagnetic Metal Complexes for Magnetic Resonance Imaging

A new class of paramagnetic macromolecular magnetic resonance imaging contrast agents has been developed. Eight new polyamide ligands were synthesized by copolymerization of ethylenediaminetetraacetic acid dianhydride or diethylenetriaminepentaacetic acid dianhydride and diamine monomers. Their gadolinium(III), manganese(II) and iron(III) complexes were also synthesized. All polyamide ligands and metal complexes were characterized by 1H nuclear magnetic resonance, infrared spectra and elemental analyses. Relaxivity studies showed that the polyamide paramagnetic metal complexes had obviously higher relaxation effectiveness as compared to corresponding simple monomeric paramagnetic metal complexes.