Poly(2-acrylamido glycolic acid-co-acryloyl morpholine) and poly(2-acrylamido glycolic acid-co-acrylamide): Synthesis, characterization, and retention properties for environmentally impacting metal ions

Poly(2-acrylamido glycolic acid-co-acrylamide), P(AGA-co-AAm), and poly(2-acrylamido glycolic acid-co-4-acryloylmorpholine), P(AGA-co-AMo), were synthesized by radical polymerization. The water-soluble polymers containing tertiary amine, amide, hydroxyl, and carboxylic acid groups were investigated as polychelatogen, in view of their metal ion binding properties by using the liquid-phase polymer-based retention technique under different experimental conditions. The retention properties for the following metal ions were investigated: Ag⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Pb²⁺, Al²⁺, Cr³⁺ and Fe³⁺. P(AGA-co-AMo) showed a selective retention for tri-valent cation Al³⁺ at pH 3, but no retention at higher pH. P(AGA-co-AAm) showed the highest metal ion retention capability, specially at pH 5 and pH 7 with values close to 100% to di-valent cations.     

Aminodiacetic water-soluble polymer-metal ion interactions

The retention properties for metal ions, the maximum retention capacity, the antibacterial and mutagenic activity of water-soluble metal ion complexes from water-soluble poly[2-hydroxy-(3-methacryloyloxypropyl)aminodiacetic acid] P(HMPADA) were studied. HMPADA was synthesized by radical polymerization in aqueous solution. The water-soluble polymer (WSP) P(HMPADA), containing ester, hydroxy, tertiary amine, and two carboxylic acid groups in every monomeric unit was investigated as polychelatogen in view of its potential metal ion binding properties using the liquid-phase polymer based retention (LPR) technique under different experimental conditions. The water-soluble complexes were investigated as biocides. Metal ions investigated at pH 3, 5, and 7 were: Ag⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Pb²⁺, Al³⁺, Cr³⁺, and Fe³⁺. Depending on pH, P(HMPADA) showed a different interaction affinity, where the highest interaction occurred at pH 7. Polymer-metal ion interaction showed the following affinity order: tri-valent >di-valent >mono-valent ion. Maximum retention capacity (MRC) ranged between 17.2 and 342.2 mg metal ion/g polymer for Cu²⁺ and Ag⁺, respectively. FT-IR showed a variation in νCO, νΟ−CO, νOH absorption signals, and Far-IR showed new signals corresponding to metal-O and metal-N interaction, indicating a participation of carboxylic acid, amine, and hydroxy groups of polymer-metal ion complexes. Antibacterial activity of Ag⁺, Cu²⁺, Zn²⁺, and Cd²⁺ complexes were studied. These complexes presented a higher biocide activity against Staphylococcus aureus (Gram-positive) than for Escherichia coli (Gram-negative) with a lowest minimum inhibitory concentration (MIC) of 4 mg/mL for polymer-Cd²⁺ complex. Scanning electron microscopy (SEM) showed the interaction between polymer-metal ion complexes and bacteria surface. All samples showed low genotoxic activity.     

Water-soluble Polyelectrolytes Contaning Sulfonic Acid Groups with Metal Ion Binding Ability by Using the Liquid Phase Polymer Based Retention Technique

Water-soluble polyelectrolytes from 2-acrylamido-2-methyl-1-propane sulfonic acid (APSA) were obtained by radical polymerization with different comonomers which contain weak acid and neutral groups. These copolymers were investigated as polyelectrolytes and polychelatogens, in view of their metal ion binding properties using the liquid-phase polymer-based retention (LPR) technique under different experimental conditions. The metal ions investigated were: Ag(I), Co(II), Cu(II), Zn(II), Cd(II), and Pb(II). APSA allowed increase metal ion interaction of weak acid, meanwhile did not improve the metal ion interaction of neutral monomers at these experimental conditions. Results indicated that retention capability depended strongly on the structure of the polyelectrolyte, arrangement of comonomers at main chain, pH, and the filtration factor, Z.     

Metal ions recovery with alginic acid coupled to ultrafiltration membrane

Alginic acid (AA) is a natural polysaccharide derived from brown algae. Naturally AA is present in cellular wall forming insoluble complexes with ions as calcium, magnesium, and sodium. This polymer is composed of uronic acids as d-manuronic acid and l-guloronic acid (units differing in C5 configuration) which are disposed in blocks or alternating on principal chain due its spatial configuration. In its structure only hydroxy and carboxylic acid are present, with a pK_{a alginic acid} = 3.45. At pH = 4.3 this polymer is completely soluble in water. Metal ion retention was evaluated using liquid-phase polymer-based retention (LPR) technique elution method, and metal ions studied were Ag⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, and Pb²⁺ at different pH and filtration factor. A high efficiency for all metal ions at all pH was reveled with a maximum at pH = 4.5 of 100% of majority of metal ions. To evaluate the maximum retention capacity (MRC) of AA, LPR technique concentration method was used. Metal ion/polymer ratio from 48 to 325 mg/g for Zn²⁺ and Ag⁺ were studied, respectively. Homopolymer and polymer-metal ion complexes were characterized using FT-IR, Far-IR spectroscopy, dynamic light scattering (DLS), and thermogravimetric analysis. FT-IR revealed relevant shifts between AA and PMC, which involve carboxylic acid, hydroxy, and ether groups. DLS shows non-pH-dependent sizes of alginic acid-silver complexes.     

Indirect ultraviolet detection of alkaline earth metal ions using an imidazolium ionic liquid as an ultraviolet absorption reagent in ion chromatography

A convenient and versatile method was developed for the separation and detection of alkaline earth metal ions by ion chromatography with indirect UV detection. The chromatographic separation of Mg²⁺, Ca²⁺, and Sr²⁺ was performed on a carboxylic acid base cation exchange column using imidazolium ionic liquid/acid as the mobile phase, in which the imidazolium ionic liquid acted as an UV‐absorption reagent. The effects of imidazolium ionic liquids, detection wavelength, acids in the mobile phase, and column temperature on the retention of Mg²⁺, Ca²⁺, and Sr²⁺ were investigated. The main factors influencing the separation and detection were the background UV absorption reagent and the concentration of hydrogen ion in ion chromatography with indirect UV detection. The successful separation and detection of Mg²⁺, Ca²⁺, and Sr²⁺ within 14 min were achieved using the selected chromatographic conditions, and the detection limits (S /N = 3) were 0.06, 0.12, and 0.23 mg/L, respectively. A new separation and detection method of alkaline earth metal ions by ion chromatography with indirect UV detection was developed, and the application range of ionic liquids was expanded.     

Synthesis of poly(hydroxamic acid) ligand from polymer grafted corn‐cob cellulose for transition metals extraction

Poly(hydroxamic acid) ligand was synthesized using ester functionalities of cellulose‐graft‐poly(methyl acrylate) copolymer, and products are characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, high‐resolution transmission electron microscopy, and X‐ray photoelectron spectroscopy analysis. The poly(hydroxamic acid) ligand was utilized for the sensing and removal of transition metal ions form aqueous solutions. The solution pH is found a key factor for the optical detection of metal ions, and the reflectance spectra of the [Cu‐ligand]ⁿ⁺ complex were observed to be the highest absorbance 99.5% at pH 6. With the increase of Cu²⁺ ion concentration, the reflectance spectra were increased, and a broad peak at 705 nm indicated that the charge transfer (π‐π transition) complex was formed. The adsorption capacity with copper was found to be superior, 320 mg g^?1, and adsorption capacities for other transition metal ions were also found to be good such as Fe³⁺, Mn²⁺, Co³⁺, Cr³⁺, Ni²⁺, and Zn²⁺ were 255, 260, 300, 280, 233, and 223 mg g^?1, respectively, at pH 6. The experimental data show that all metal ions fitted well with the pseudo‐second‐order rate equation. The sorption results of the transition metal ions onto ligand were well fitted with Langmuir isotherm model (R² > 0.98), which implies the homogenous and monolayer character of poly(hydroxamic acid) ligand surface. Eleven cycles sorption/desorption process were applied to verify the reusability of this adsorbent. The investigation of sorption and extraction efficiency in each cycle indicated that this new type of adsorbent can be recycled in many cycles with no significant loss in its original detection and removal capability. Copyright © 2016 John Wiley & Sons, Ltd.     

Swelling Behavior and Metal-Ion Uptake Capacity of pH-Responsive Hydrogels of Poly(N-acryloyl-N′-ethylpiperazine)

New hydrogels based on N-acryloyl-N′-ethylpiperazine (AcrNEP) and N,N-methylene bisacrylamide (MBA) were prepared by thermal initiated solution polymerization. The hydrogels swelled extensively in buffer solutions of low pH due to protonation of the amine functions of the monomers, while the swelling was less significant in buffer solutions of high pH. The increased swelling of the gel in low pH is due to the development and interaction of fixed charges within the gel network. As a result of the electrostatic repulsion between the charges the elastic constraint of the gel is modified which leads to pronounced swelling and hence to high water uptake. Water transport in the hydrogel both in buffer solutions of pH 2.6 and pH 8.4 was non-Fickian due to polymer relaxation (anomalous process). The gels demonstrated good uptake of divalent metal ions such as Ni²⁺, Co²⁺, and Zn²⁺, with high selectivity for Ni²⁺ ions due to the formation of a more stable ligand-metal complex. The metal uptake capacity increased with increase in pH of the solution, while an increase in the crosslinker amount of the hydrogel reduced its metal uptake capacity. In the presence of metal ions the swelling of the hydrogel reduced considerably due to the formation of additional physical crosslinks within the hydrogel network. The metal ion loaded hydrogels could be stripped and regenerated with 1 M sulfuric acid without any loss in swelling or metal uptake capacities.     

Polymeric hydrogels modified with ornithine and lysine: Sorption and release of metal cations and amino acids

A novel, convenient synthesis, using copper ions, is described for the multigram‐scale preparation of acryloyl and methacryloyl ornithine and lysine without the need to use protecting groups and chromatographic purifications. Three methods of removing the copper ions from the amino acid derivatives were examined. The obtained acryloyl and methacryloyl ornithine and lysine were copolymerized with N‐isopropylacrylamide and N,N′‐methylenebisacrylamide as crosslinking agents, resulting in a series of hydrogels with varying incorporated amino acid content. The relative content of a given amino acid was estimated from the ¹H NMR data and compared with its molar fraction used in the polymerization process. We investigated the influence of the amount of amino acid groups incorporated into the polymer network on the swelling behavior of the gels in the presence of metal ions of different ability to form complexes (Cu²⁺, Co²⁺, and Ca²⁺) with α‐amino acid groups and the sorption of copper ions. Next, the presence of α‐amino acid groups attached to the polymer network was used to bond the compounds which can cocomplex metal ions. Phenylalanine was selected for examination of its cocomplexation of Cu²⁺ with the polymer‐network amino acids and its consecutive release from the gel after appropriate change of pH. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Study of Bulk Membrane Transport of Some Heavy Metal Cations Using Three Macrocyclic Ligands Containing Oxygen and Nitrogen Heteroatoms

The transport experiments of Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Ag⁺ and Pb²⁺ metal cations were carried out by dibenzo-18-crown-6 (DB18C6), dibenzyl-diaza-18-crown-6 (Dibenzyl-diaza-18C6) and di-tert-butyl-dibenzo-18-crown-6 (Di-tert-butyl-DB18C6) using chloroform (CHCl₃), 1,2-dichloroethane (1,2-DCE) and nitrobenzene (NB) organic solvents as liquid membranes. The source phase contained equimolar concentration of these metal cations and the source and receiving phases being buffered at pH=5 and pH=3, respectively. The obtained results show that the selectivity and the efficiency of transport for these heavy metal cations change with the nature of the ligand and also the organic solvents, which were used as liquid membranes in these experiments. A good selectivity was observed for silver (I) ion by dibenzyl-diaza-18C6 in all membrane systems. Dibenzo-18C6 and di-tert-butyl-DB18C6 showed the highest transport efficiency for cobalt (II) ion. The effect of stearic acid on transport efficiency was also investigated and the results show that the efficiency of transport of the heavy metal cations increases in the presence of this organic acid.     

Analysis of Nonionic Surfactants by High Performance Liquid Chromatography

Abstract

This review discusses the principles of immobilized metal ion affinity chromatography (IMAC) and its applications to protein separations. IMAC functions by binding the accessible electron-donating pendant groups of a protein - such as histidine, cysteine, and tryptophan - to a metal ion which is held by a chelating group covalently attached on a stationary support. A common chelating group is iminodiacetate. The ions commonly used are of borderline or soft metals, such as Cu²⁺, Ni²⁺, Co²⁺, and Zn²⁺. Protein retention in IMAC depends on the number and type of pendant groups which can interact with the metal. The interaction is affected by a variety of independent variables such as pH, temperature, solvent type, salt type, salt concentration, nature of immobilized metal and chelate, ligand density, and protein size. Proteins are usually eluted by a decreasing pH gradient or by an increasing gradient of a competitive agent, such as imidazole, in a buffer. There are still several unresolved issues in IMAC. The exact structures of protein-immobilized metal complexes need to be known so that retention behavior of proteins can be fully understood and sorbent structures can be optimized. Engineering parameters, such as adsorption/desorption rate constants, sorbent capacities, and intraparticle diffusivities, need to be developed for most protein systems. Engineering analysis and quantitative understanding are also needed so that IMAC can be used efficiently for large scale protein separations.     

Chelation ion-exchange properties of salicylic acid-urea-formaldehyde copolymers

Chelation ion-exchange properties of copolymers prepared from salicylic acid, urea and formaldehyde by condensation in presence of acid catalyst were studied for Cu²⁺, Fe³⁺, UO²⁺, Mn²⁺,Zn²⁺ and Co²⁺ ions. A batch equilibration method was adopted to study the selectivity of metal ion uptake. This method involved the measurement of distribution of a given metal between the copolymer sample and a solution containing the metal ions. The study was carried out over a wide pH range and in media of various ionic strengths. The copolymer showed a higher selectivity for UO₂ ²⁺, Cu²⁺ and Fe³⁺ ions than Mn²⁺, Co²⁺ and Zn²⁺ ions.     

Preparation of hydrazinodeoxycellulose and carboxyalkyl hydrazinodeoxycelluloses and their adsorption behavior toward heavy metal ions

Nitrogen-containing cellulose derivatives hydrazinodeoxycellulose (HDC) and carboxyalkyl hydrazinodeoxycelluloses (α- and β-CAHDCs) were prepared from 6-chlorodeoxycellulose (CDC). Their adsorption of divalent transition metal ions was determined from dilute aqueous solutions and compared with that of aminoalkyl celluloses (AmACs) reported previously. HDC scarcely adsorbs metal ions in the pH range of 1–2, whereas α- and β-CAHDCs adsorb metal ions in this pH range. However, the adsorption of metal ions on HDC increases rapidly with increasing pH and HDC more effectively adsorbs metal ions than α- and β-CAHDCs in weakly acidic conditions. The ability to adsorb Cu²⁺ ions was in the order of AmAC (carbon number in the diamine moiety m = 2) > HDC > α-CAHDC > β-CAHDC in the weakly acidic region. These adsorbents selectively adsorb Cu²⁺ ions from the solutions containing other metal ions such as Mn²⁺, Co²⁺, and Ni²⁺, and the Irving–Williams series is obeyed in these adsorbent/metal ion systems. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3359–3363, 1997     

Advanced oxidation processes for decolorization of aqueous solution containing acid red G azo dye

Some investigations concerning the decolorization of Acid Red G azo dye by photooxidation with hydrogen peroxide were performed. The influences of pH, oxidant concentration, and the presence of Fe²⁺ or other metal ions (Co²⁺, Cu²⁺, Ni²⁺, Mn²⁺) as potential catalysts, were investigated. The best results were obtained in the presence of ferrous ions in acid and neutral media. The other ions are not as effective as Fe²⁺ for dye decolorization. Co²⁺ and Cu²⁺ ions have a catalytic action, at low concentration, within a wide range of pH. Ni²⁺ and Mn²⁺ ions have no catalytic effect in photooxidation with hydrogen peroxide at acid Ni²⁺ and Mn²⁺ ions have no catalytic effect in photooxidation with hydrogen peroxide at acid pH values, but show a weak action in alkaline media.     

Metal Ion Removal from Aqueous Solution by Liquid Phase Polymer-Based Retention Technique

Summary: Water-soluble poly[3-(dimethylamino)propylacrylate] is synthesized by radical polymerization with a yield of 87%. The polymer structure is confirmed by FT-IR and ¹H-NMR spectroscopies. The polymer lost only 3% of weight up to 100 °C. The narrowest molecular weight distribution is observed with the fraction between 3,000 and 10,000 Da. P(DAPA) presents a high affinity for the metal ions Pb²⁺ and Cu²⁺, while the other metal ions are not significantly retained. By increasing the filtration factor, Z, metal ion affinity decreases, indicating a very weak ligand-metal interaction and the possibility of its destruction when washed with water at the filtration cell's pH. For Z = 10, the retention values of Pb²⁺ and Cu²⁺ at pH 5 are 76.5% and 48.5%, respectively, while the values for Cu²⁺ and Cd²⁺ at pH 7 are 89.5% and 40.4%, respectively.     

Control of a photoswitching chelator by metal ions: DFT,NBO, and QTAIM analysis

Ability of aroylhydrazones to change conformation upon interaction with light makes them promising candidates for molecular switches. Isomerization can be controlled through complexation with selected metal ions which bind with different affinity. N′‐[1‐(2‐hydroxyphenyl)ethyliden]iso‐nicotinoylhydrazide (HAPI) is an example of a dual‐wavelenght photoswitching molecule, whose complexation with metal ions was recently experimentally investigated (Franks et al. J. Inorg. Chem. 2014, 53, 1397). In this contribution, complexes between HAPI and K⁺, Ca²⁺, Mn²⁺, Fe²⁺, Fe³⁺, Cu⁺, Cu²⁺, and Zn²⁺ ions were investigated using Density Functional Theory, Natural Bond Order analysis, and Quantum Theory of Atoms in Molecules. The most important parameters that determine complex stability are found to be ion radius and charge transferred from ligands to the ion: smaller ion radii and larger CT values characterize formation of more stable complexes. Our results explain experimentally observed effect of different metal ions on photoisomerization through determination of metal ion affinity (MIA): photoisomerization is inhibited if MIA exceeds 100 kcal/mol; for MIA between 50 and 100 kcal/mol excess of metal ions prevents isomerization, whereas in case of MIA below 50 kcal/mol metal ions have no influence on light–HAPI interaction. © 2015 Wiley Periodicals, Inc.     

Preconcentration and Determination of Copper(II) by Novel Solid-Phase Extraction and High-Resolution Continuum Source Flame Atomic Absorption Spectrometry

Amberlite XAD-4 modified with N-para-anisidine-3,5-di-tert-butylsalicylaldimine was investigated as a new chealting sorbent for the selective separation and preconcentration of Cu(II). The metal ion was retained by chemical sorption on the modified resin, eluted by hydrochloric acid, and determined by high-resolution continuum source flame atomic absorption spectrometry. The prepared resin was characterized for the solid-phase extraction of Cd²⁺, Co²⁺, Cr³⁺, Cu²⁺, Fe³⁺, Mn²⁺, Ni²⁺, Pb²⁺, and Zn²⁺ in a column. The influence of the pH, the mass of solid phase, eluent, flow rate, and sample volume was optimized. Using the optimum conditions, only Cu(II) showed quantitative sorption at the 95% confidence level, and the recoveries of the other metal ions were below 80%. A preconcentration factor 125 was obtained for Cu(II) with a limit of detection of 0.56?µg?L^?1. The method was used for the determination of Cu(II) in tap water, river water, tomato leaves, and fish. The relative standard deviation and the relative error were lower than 7%.     

Thermal and ion-exchange studies on chelating terpolymer resins derived from o cresol urea formaldehyde

Terpolymers prepared by condensation of o cresol and urea with formaldehyde in presence of acid catalyst (2 M HCl) proved to be selective chelating ion exchange resins for certain metal ions. The molecular weights of the synthesised terpolymers were determined by GPC Technique. TGA analysis was employed to study the thermal stability and the kinetic data like activation energy of the terpolymer resins. Chelation ion exchange properties of these terpolymers were studied for Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Pb²⁺ and Cd²⁺ ions. A batch equilibrium method was employed in the study of the selectivity of metal ion uptake involving the measurements of distribution of a given metal ion between the polymer samples. The study was carried out over a wide pH range and in media of various ionic strengths.     

Complexation of metal ion with poly(1-vinylimidazole) resin prepared by radiation-induced polymerization with template metal ion

Poly(1-vinylimidazole) (PVI) resin was prepared with Ni²⁺, Co²⁺, or Zn²⁺ as a template to study the adsorption of metal ions. The metal-1-vinylimidazole complex was copolymerized and crosslinked with 1-vinyl-2-pyrrolidone by γ-ray irradiation and the template metal ion was removed by treating the polymer complex with an acid. These PVI resins adsorbed metal ions more effectively than the PVI resin prepared without the template. The number of adsorption sites (As) and the stability constant (K) of Ni²⁺ complex were larger for the PVI resin prepared with the Ni ion template, caused by the smaller dissociation rate constant of Ni ion from the resin. The composition of the Ni²⁺ complex in the resin remained constant. This suggests that the complexation proceeded via a one-step mechanism.     

Untersuchung der Komplexierung von Na+, K+, Ca2+ und Ba2+ mit einigen elektrisch neutralen Liganden durch Messung von 13C-chemischen Verschiebungen und Spin-Gitter-Relaxationszeiten

Investigation of the complexing of Na⁺, K⁺, Ca²⁺ and Ba²⁺ with some uncharged ligands by ¹³C-chemical shift and spin-lattice relaxation time measurements The influence of Na⁺, K⁺, Ca²⁺ and Ba²⁺ ions on ¹³C chemical shifts and on spin-lattice relaxation times of some electrically neutral ion carriers was investigated. In the solvents CD₃CN and CD₃OD and in presence of an excess of metal ions ligand 4 (see the Scheme) forms complexes of 1:1 stoichiometry. All four oxygen atoms of the ligand as well as solvent molecules take part in the coordination. In CDCl₃ as solvent, for all ions investigated except sodium, only 1:2 complexes (metal/ligand) were observed with 4 . Sodium ions form both 1:1 and 1:2 complexes in this solvent. In the 1:2 complexes of the investigated monovalent ions only one, in those of the divalent ions both amide carbonyl groups of ligand 4 take part in the coordination.     

Metal‐Ion‐Mediated Tuning of Duplex DNA Binding by Bis(2‐(2‐pyridyl)‐1H‐benzimidazole)

Studies of double‐stranded‐DNA binding have been performed with three isomeric bis(2‐(n‐pyridyl)‐1H‐benzimidazole)s (n=2, 3, 4). Like the well‐known Hoechst 33258, which is a bisbenzimidazole compound, these three isomers bind to the minor groove of duplex DNA. DNA binding by the three isomers was investigated in the presence of the divalent metal ions Mg²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺. Ligand–DNA interactions were probed with fluorescence and circular dichroism spectroscopy. These studies revealed that the binding of the 2‐pyridyl derivative to DNA is dramatically reduced in the presence of Co²⁺, Ni²⁺, and Cu²⁺ ions and is abolished completely at a ligand/metal‐cation ratio of 1:1. Control experiments done with the isomeric 3‐ and 4‐pyridyl derivatives showed that their binding to DNA is unaffected by the aforementioned transition‐metal ions. The ability of 2‐(2‐pyridyl)benzimidazole to chelate metal ions and the conformational changes of the ligand associated with ion chelation probably led to such unusual binding results for the ortho isomer. The addition of ethylenediaminetetraacetic acid (EDTA) reversed the effects completely.