Modification of poly acrylic acid using calix[4]arene derivative for the adsorption of toxic heavy metals

Poly acrylic acid (PAA) was grafted with p‐t‐butyl calix[4]arene diamine (distal cone) (2) to adsorb toxic heavy metal and alkali metal cations. The grafting method includes the amidation reaction of PAA with calixarene diamine derivative 2 which was carried out in N,N‐dimethylformamide (DMF) and N–methyl‐2‐pyrrolidone (NMP) as solvents. The modified PAAs (PAA‐C1 and PAA‐C2) were characterized by FTIR, ¹H‐NMR, thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). PAA‐C1 and PAA‐C2 were used to evaluate the sorption properties of some toxic heavy metal cations (Co²⁺, Cu²⁺, Cd²⁺, Hg²⁺), alkali metal cations (Na⁺, K⁺, Cs⁺), and Ag⁺. Results showed that the modified PAAs were good sorbents for heavy metal and alkali metal cations. The main goal of this project is to design hydrophobically modified PAA that is suitable for ion selective membranes and chemical sensor devices for adsorption of toxic heavy metals. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characterization of calix[4]arene-based copolyethers and polyurethanes. Ionophoric properties and extraction abilities towards metal cations of polymeric calix[4]arene urethanes

Copolyethers and polyurethanes containing lower and upper rim calix[4]arene units in the fixed cone conformation were prepared in good yield by polycondensation reactions of distal calix[4]arene diols with bisphenol-A/dibromomethane and 2,4-tolylendiisocyanate (TDI), respectively. In a similar way were prepared calix[4]arene-crown-5 and -crown-6 polyurethanes in the fixed 1,3-alternate conformation by condensation of TDI with lower rim calixcrown-5 and calixcrown-6 diols. However, the poor solubility in common organic solvents of the copolyether derivatives (M_w=11,100-11,600 g/mol) hampered further studies on their ionophoric properties. Aiming to obtain model compounds for the investigation of both extraction abilities and ionophoric properties of the polyurethane materials, several bis-urethanes were also synthesized by reaction of the calix[4]arene diols with p-tolylisocyanate (TI). The extraction ability measurements of monomeric and polymeric calix[4]arene urethanes (M_w=12,300-83,500 g/mol) towards alkali metal cations (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺) and Ag⁺showed a remarkable efficiency and selectivity of calixcrown-6 polyurethane toward Rb⁺, Cs⁺and Ag⁺.     

Alkoxymethyl-Substituted 18-Crown-6 and 21-Crown-7 Ligands: Synthesis,Complexation Properties,and Metal Ion Membrane Separations

Abstract

Three novel alkoxymethyl-substituted 18-crown-6 (8–10) and one new alkoxymethyl-substituted 21-crown-7 (11) ligands have been prepared. First, 1-O-tritylpropanetriol (1) and penta- or hexaethylene glycol ditosylate were cyclized in the presence of an alkali metal hydride. The resulting trityloxymethyl-substituted crowns were deprotected to give the hydroxymethyl-substituted 18-crown-6 (6) and hydroxymethyl-substituted 21-crown-7 (7). The latter compounds were alkylated using sodium hydride and the appropriate l-bromoalkane to form 8–11. Complexation properties of these new ligands with the alkali metal cations were studied by a calorimetric titration technique. Compared with the parent 18-crown-6 and 21-crown-7 ligands, the substituted 18-crown-6 ligands demonstrate superior selectivity for K⁺, while the substituted 21-crown-7 ligand demonstrated less selectivity for Cs⁺ over other alkali cations. Solvent extraction and membrane separation experiments using these new ligands were also carried out. The results demonstrated that the structural features of these new ligands have a significant influence on cation complexation selectivity and separations potential.     

Liquid–Liquid Extraction of Alkali Metal Cations by Calix[4]crowns with Pendant Groups

Abstract

The selective liquid–liquid extraction of alkali metal cations from the aqueous phase to the organic phase was carried out by using calix[4]crowns bearing two pendant groups with donor sites. It was found that calix[4]crown‐4 and calix[4]crown‐5 extractants with two pendant groups exhibit higher extraction efficiency than the parent compounds and possess obvious selectivity for Na⁺ and K⁺, respectively.     

C,N‐Pyridylpyrazole‐Based Ligands: Synthesis and Preliminary Use in Metal Ion Extraction

Abstract

The synthesis of new N‐donor pyridylpyrazole ligands with a functionalized arm is described. The complexation capabilities of these compounds towards bivalent metal ions (Hg²⁺, Cd²⁺, Pb²⁺, Cu²⁺, and Zn²⁺) and alkali metal ions (K⁺, Na⁺, and Li⁺) were investigated using the liquid‐liquid extraction process. The percentage limits of extraction were determined by atomic absorption measurements.     

Synthesis and characterization of new monomeric and polymeric phthalocyanines

Monomeric (M = 2Li or 2H) and polymeric (M = 2H, Zn, Cu, Co, or Ni), where M is metal or hydrogen, phthalocyanines were prepared by the tetramerization reaction of bisphthalonitrile monomer with appropriate materials. The electrical conductivities of the polymeric phthalocyanines, which were measured as gold sandwiches, were found to be 10⁻¹⁰–10⁻⁷ S/cm in vacuo and in air. The binding property of a Co‐containing polymeric phthalocyanine ( 10 ) toward alkali, alkaline‐earth, and some heavy cations was studied in tetrahydrofuran. The extraction affinity of 10 for K⁺ was found to be the highest in the heterogeneous phase extraction experiments. The disaggregation property of a Ni‐containing polymeric phthalocyanine ( 11 ) was investigated with K⁺, Na⁺, and NH₄⁺ cations. The intrinsic viscosities of all polymers were also measured by means of viscometry. All the novel compounds were characterized with elemental analysis, ultraviolet–visible, Fourier transform infrared, NMR, and mass spectrometry spectral data, and differential thermal analysis/thermogravimetry. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Functionalized graphene sheets coordinating metal cations

Interactions of metal cations such as Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺, Sr²⁺, Cr³⁺, Mn²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺ with ammonia-treated graphene sheets (G) and thermal stability of metal cations coordinated with oxygen- and nitrogen-containing functional groups on G were investigated by rinsing G coordinated with metal cations (G-Metal) in 2-propanol using sonication and by heating G-Metal at 773 K, respectively. Monovalent alkali metal cations, divalent alkaline-earth metal cations, divalent transition metal cations such as Mn²⁺, and the other metal cation such as Zn²⁺ were removed by rinsing because of either no interaction or weak interactions between metal cations and G including various thermally stable nitrogen- and oxygen-containing functional groups. Trivalent transition metal cations such as Cr³⁺ and Fe³⁺ were agglomerated by heat treatment at 773 K, whereas divalent transition metal cations such as Co²⁺, Ni²⁺, and Cu²⁺ remained without severe agglomeration. Phenanthroline-like groups on edges of graphene showed the strongest interaction with Ni²⁺ among all of investigated nitrogen- and oxygen-containing functional groups as results of density functional theory calculation. The thermal stability of NNi bonding was confirmed as above 873 K as results of heat treatment of a standard compound (Ni phthalocyanine) in a glass ampoule.     

ION EXCHANGE PROPERTIES OF THE SODIUM PHLOGOPITE AND BIOTITE

ABSTRACT

The ion exchange behavior of three sodium micas (phlogopite, Ward's Sci.; phlogopite, Suzorite Inc., biotite, Ward's Sci.) towards Li⁺, K⁺, Rb⁺, Cs⁺, Mg²⁺. Ca²⁺, Sr²⁺, Ba²⁺, Pb²⁺ Hg²⁺, Co²⁺, Cu²⁺ Cd²⁺ and Zn²⁺ ions has been studied. The ion exchange isotherms of alkali, alkaline earth and some other divalent cations were determined and concentration equilibrium constants as a function of metal loading and temperature were analyzed. Sodium micas exhibit high affinity for heavy alkali metals with the selectivity order Rb⁺ > Cs⁺ > K⁺. By studying the cesium uptake in the presence of NaNO₃, CaCl₂, NaOH, NaOH+KOH, HNO₃ electrolytes (in the range of 0.01–6 M) it was found that sodium micas could remove cesium efficiently in neutral and alkaline media, which make them promising for certain types of nuclear waste treatment.     

Preparation and characterization of fluorescent hyperbranched polyether

A new kind of fluorescent hyperbranched polymers was prepared by an end-capping approach, i.e., the hyperbranched poly(hydroxyl ether) was end capped with p-N,N-dimethylaminobenzaldehyde. The resulting polymers fluoresce yellow-green in solid and in solution. The maximum excitation and emission wavelengths in ethanol are 310 ± 10 and 360 ± 10 nm, respectively. Hyperbranched polyethers with various densities of chromophore groups showed different fluorescence intensities at the same concentration of chromophore groups. The fluorescent hyperbranched polyether with a high density of chromophore groups can form intramolecular excimers. The fluorescence signal of the resulting polymer increases with pH and passes through a maximum at 7.2–8.5 and then decreases gradually. Furthermore, the peak at 360 nm shifts to 405 nm with increasing pH. The fluorescence can be quenched by transition metal cations such as Cu²⁺ and Fe³⁺, while the alkali and alkaline earth metal cations and Ni²⁺ and Co²⁺ have little effect on the fluorescence intensity.     

Effect of Receiving Phase Anion on Macrocycle-Mediated Cation Transport Rates and Selectivities in Water—Toluene—Water Emulsion Membranes

Abstract

Relative transport rates of metal nitrates (Na⁺, K⁺, Rb⁺, Cs⁺, Ag⁺, T1⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Zn²⁺, and Pb²⁺) were measured alone and in combination with either Pb²⁺, Ag⁺, or T1⁺ in a water-toluene-water emulsion membrane system. The toluene phase contained the surfactant Span 80 and the crown ether dicyclohexano-18-crown-6 (DC18C6). The aqueous receiving phase contained the lithium salt of one of the following anions: pyrophosphate, thiosulfate, hydroxide, chloride, formate, nitrate. In the case of the metal combinations, chloride and formate ions were not studied. Unless significant complexation occurred both between the transported cation and the anion in the receiving phase and between the cation and DC18C6 in the membrane phase, there was little or no transport of the cation from the source phase to the receiving phase. Selective removal of Pb²⁺ and of Ag⁺ from binary mixtures of these cations with each of the cations listed was demonstrated using the emulsion membrane.     

Synthesis,metal ion complexation and antibacterial activities of some thiapodands with lipophilic amide and ester end groups

A series of acyclic analogues of thiacrown ethers (podands) 7–12 with lipophilic amide and ester end groups were synthesized in high yield and in a simple way. Their transition metal ions complexation was studied using a conductometric method in acetonitrile at 25°C. Podands 7 and 11 showed a continuous decrease in the molar conductances in their complexation with Ag⁺, Cu²⁺, Cd²⁺, Hg²⁺, Zn²⁺ and Pb²⁺ which begins to level off at a mole ratio of 1:1 podand to metal indicating the formation of a stable 1:1 complexes. On the other hand, podand 9 also showed the formation of 1:1 complexes with above metal cations except with Hg²⁺ ion, which formed a 1:2 podand-to-metal ratio complex. An influence of end groups on metal ion selectivity is evident. Podands having ethoxy end groups (podands 8, 10 and 12 exhibit pronounced metal ion selectivity over podands having amino end groups (podands 7, 9 and 11). Compounds 10 and 12 with dithiaethylene units and ethoxy end groups provide the best selectivity for Hg²⁺ and Ag⁺ ions. These results suggest that podands 10 and 12 could be useful for the selective removal of Hg²⁺ and Ag⁺ ions from industrial waste that may contain a variety of toxic heavy and transition metal ions. The in vitro antibacterial activity of the investigated compounds was tested against several microorganisms such as Bacillus subtilis (ATCC 6633), Micrococcus luteus (ATCC 10240), Staphylococcus aureus (ATCC 43300), Escherichia coli (ATCC 25922) and Enterobacter aerogenes (ATCC 13048). The antibacterial activity of podand 10 is significant for M. luteus and B. subtilis compared with other podands under investigation.     

NEW NITROGEN-CONTAINING MACROCYCLIC LIGANDS COVALENTLY ATTACHED TO SILICA GEL AND THEIR USE IN SEPARATING METAL CATIONS

Several polyaza-crowns and cyclams, each containing an allyl-oxymethyl or other monofunctional group capable of further reaction to attach it to silica gel, have been prepared. As an example of an attachment of a crown to silica gel, allyloxymethyl-substituted diaza-18-crown-6 was reacted with triethoxysilane to form the crown-substituted triethoxysilane This crown-silane material was heated on silica gel to effect a covalent attachment of the crown. The silica gel-bound macrocyclic ligands were found to interact with various metal cations with log K ( H2O) values similar to those of the same cations with unbound macrocycles. A tetraaza-crown bound to silica gel was found to quantitatively remove toxic heavy metal ions, such as Pb²⁺, Hg²⁺ Cd²⁺ Ag⁺and others at the ppb level, from large volumes of aqueous solutions containing those metal ions and much larger amounts of Na⁺Mg²⁺and Ca²⁺ions     

SYNTHESIS AND CHARACTERIZATION OF THE ION EXCHANGE PROPERTIES OF A SPHERICALLY GRANULATED SODIUM ALUMINOPHOSPHATESILICATE

ABSTRACT

Spherically granulated sodium aluminosilicophosphate (APS) of the empirical formula Na₄Al₄PS₁₈O_46.5 18H₂O was synthesized by a gel method. The APS was characterized by elemental analysis, X-ray diffraction, TGA and ²⁷AI, ²⁸Si and ³¹P MAS NMR spectroscopy methods. Ion exchange of alkali, alkaline earth and some other divalent metal cations by APS was studied in batch conditions. It was found that the APS has a cation exchange capacity of 2.5 meq/g and exhibits rapid kinetics of ion exchange. The ion exchange isotherms of alkali, alkaline earth and some other divalent cations were determined and the corrected selectivity coefficients as a function of metal loading were analyzed. It was found that APS exhibits a high affinity for cesium ion, a moderate affinity for some heavy metal cations (Pb²⁺, Zn⁺) and a low affinity for alkali and alkaline earth metal ions. A testing of the APS in complex solutions suggests that it could be a promising exchanger for treatment of some specific nuclear waste and contaminated environmental and biological liquors from radioactive cesium and toxic heavy metal ions.     

Separation and extraction of some heavy and toxic metal ions from their wastes by grafted membranes

Preparation and characterization of a series of ion‐exchange membranes for the purpose of separation and extraction of some heavy and toxic metal ions from their wastes were studied. Such ion‐exchange membranes were prepared by γ‐radiation grafting of acrylonitrile (AN) and vinyl acetate (VAc) in a binary monomer mixture onto low‐density polyethylene (LDPE) using the direct technique of grafting. The reaction conditions at which the grafting process proceeds successfully were determined. Many modification treatments were attempted for the prepared membranes to improve their ion‐exchange properties. The possibility of their practical use in waste‐water treatment to remove some heavy and toxic metal ions such as Pb²⁺, Cd ²⁺, Cu²⁺, Fe³⁺, Sr²⁺, and Li⁺ were investigated. These grafted membranes showed great promise for possible use in the field of extraction and removal of some heavy and toxic metals from their wastes. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 849–860, 2001     

Metallo-supramolecular Polymers: Versatile DNA Binding and Their Cytotoxicity

Metallo-supramolecular polymers (RuL1, RuL2, RuL3, FeL3, and FeL4) prepared by complexation of bis(terpyridine) derivatives with Ru²⁺ or Fe²⁺ ions with octahedral coordination structures showed high binding ability to several DNAs (calf thymus DNA, herring sperm DNA, [poly(dA-dT)]₂, and [poly(dG-dC)]₂), which were revealed by UV–Vis absorption titration experiments. The electrostatic interactions between the metal cations of the polymers and phosphate anions of DNA led to formation of conjugate structure. The binding constant observed reached 3.7 × 10⁷ M^?1, which is the highest among values reported for metal complexes to date. Based on a long strand structure of the polymer, groove binding is most possible binding mode. Cell viability experiments showed that RuL3 and FeL3 displayed highly statistical significance (**p<0.01) to human non small cell lung cancer cell lines (NCI-H460).     

Preparation of polysulfonebenzylthiourea-reactive ultrafiltration plate membranes and their rejection properties for heavy toxic metal cations

The asymmetric membranes were prepared via phase inversion method, by using chloromethyl polysulfone as membrane materials, polyethylene glycol (PEG) as pore forming agent to improve the morphology and function of resultant membranes, N,N-dimethylacetamide as solvent, and water as the extraction solvent. Then the highly qualified polysulfonebenzylthiourea-reactive ultrafiltration plate membrane was prepared successively through the reactions between the chloromethyl polysulfone matrix membrane and thiourea. The thiourea-functionalized polysulfone plate reactive ultrafiltration membrane was used for the rejection of heavy toxic metal cations such as Cd²⁺ and Zn²⁺ through the coordination of the thiourea group and heavy toxic metal cations, in which the effects of the morphological and the structure of the membrane on the rejection properties were investigated. The rejection conditions, including the concentration of heavy toxic metal cations, temperature and pH of the solution had significant effects on the rejection capacity of polysulfonebenzylthiourea-reactive ultrafiltration membrane. The reactive ultrafiltration membrane containing thiourea group can be conveniently recovered by dilute hydrochloric acid for coordination of heavy toxic metal cations, which would have wide application for the treatment of waste-water-containing heavy toxic metal cations. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Lichen Substances Affect Metal Adsorption in <Emphasis Type="Italic">Hypogymnia physodes</Emphasis>

Lichen substances are known to function as chelators of cations. We tested the hypothesis that lichen substances can control the uptake of toxic metals by adsorbing metal ions at cation exchange sites on cell walls. If true, this hypothesis would help to provide a mechanistic explanation for results of a recent study showing increased production of physodalic acid by thalli of the lichen Hypogymnia physodes transplanted to sites with heavy metal pollution. We treated cellulose filters known to mimic the cation exchange abilities of lichen thalli with four lichen substances produced by H. physodes (physodic acid, physodalic acid, protocetraric acid, and atranorin). Treated filters were exposed to solutions containing seven cations (Ca²⁺, Cu²⁺, Fe²⁺, Fe³⁺, Mg²⁺, Mn²⁺, and Na⁺), and changes to the solution concentrations were measured. Physodalic acid was most effective at influencing metal adsorption, as it increased the adsorption of Fe³⁺, but reduced the adsorption of Cu²⁺, Mn²⁺, and Na⁺, and to a lesser extent, that of Ca²⁺ and Mg²⁺. Reduced Na⁺ adsorption matches with the known tolerance of this species to NaCl. The results may indicate a possible general role of lichen substances in metal homeostasis and pollution tolerance.     

Synthesis and binding properties of polymeric calix[4]arene nitriles

Two new polymers containing pendant calix[4]arene units with nitrile functionalities at their lower rim have been synthesized via radical initiated reactions involving a vinylic monomer 6 {5,11,17,23-tetra-tert-butyl-25,26,27-tris(cyanomethoxy)-28-(2-acryloyloxy) ethoxycalix[4]arene} and with styrene. A five atom spacer group was incorporated between the bulky calixarene core and the acrylate moiety in order to minimize steric interactions which proved to impede the polymerization. The complexation studies were made by using liquid–liquid extraction procedures. It has been deduced from the observations that both polymers show a good selectivity towards Hg²⁺ like their precursor 5,11,17,23-tetra-tert-butyl-25,26,27-tricyanomethoxy-28-(2-hydroxy)ethoxycalix[4]arene 5, which supports their utility as adsorbents or potential candidate materials for fabricating membranes and sensors, which can separate or detect Hg²⁺ metal ions in a high selectivity.     

Effect of ultraviolet irradiation on the selective transport of alkali metal ions through 2,3-epithiopropyl methacrylate–methacrylic acid copolymer membrane

Cationic exchange membranes were prepared with 2,3-epithiopropyl methacrylate (ETMA)–methacrylic acid (MAc) copolymer. Transport of alkali metal ions against their concentration gradient through the membranes was investigated by using the system which contains HCl (left side) and alkali metal solution including two kinds of alkali hydroxides (right side). The effect of ultraviolet (UV) irradiation on the selective transport of alkali metal ions through the ETMA–MAc copolymer membranes was investigated. The membranes were irradiated with a 6-W low pressure mercury lamp at a distance of 10 cm at room temperature in air. The transport selectivity could be increased by using UV-irradiated membranes and the selectivity increased with increasing irradiation time up to 2–3 h, although the transport rate of alkali metal ions decreased with increasing time of UV irradiation. The maximum selectivity of K⁺/Na⁺, Na⁺/Li⁺, and K⁺/Li⁺ were 1.7, 2.0, and 4.2, respectively. In order to explain this phenomena, the effect of UV irradiation on the properties of the membranes was studied. It was concluded that the increase of the selectivity is attributed to the formation of the dense membrane by photocrosslinking of the membrane by UV irradiation.     

Rapid Separation of Tl+ and Pb2+ from Various Binary Cation Mixtures Using Dicyclohexano-18-crown-6 Incorporated into Emulsion Membranes

Abstract

Relative transport rates of metal cation nitrates (Na⁺, K⁺, Rb⁺, Cs⁺, Ag⁺, Tl⁺, Ca²⁺, Sr²⁺, Ba²⁺, and Pb²⁺) in a water-toluene-water emulsion membrane system were measured. The toluene component contained the surfactant Span 80 and the crown ether dicyclohexano-18-crown-6. The aqueous receiving phase contained Li₄P2O₇. When each metal cation was individually present in the aqueous source phase, metal extraction was complete within 10 min with the order of extraction being Tl⁺ > Cs⁺ > Ag⁺ > Rb⁺ > K⁺ ≥m Na⁺ and Pb⁺ > Ca²⁺ > Sr²⁺ > Ba²⁺ for uni-and bivalent cations, respectively. Significant extraction was found for all cations except Na⁺, K⁺, and Ba²⁺. Some metal ions were concentrated nearly 10-fold in a 10-min period. Relative transport rates were determined when binary cation mixtures of either Tl⁺ or Pb²⁺ were present at equal concentrations with each of the remaining metal ions in the source phase. Tl⁺, when present with either Na⁺, Cs⁺, or Rb⁺, was selectively extracted from the source phase. Complete and nearly exclusive extraction of Pb²⁺ was observed in the presence of all cations including Tl⁺. The enrichment ratios of Pb²⁺ in the binary mixtures were approximately 10 while those of the second cation were less than 0.5 except for Sr²⁺ which was 0.86. Corresponding separation factors for Pb²⁺ ranged from 1000 to > 6000.