Preparation and Analytical Application of a New Chelating Ion Exchange Resin Containing Thioglycolic Acid

Starting from copolymerization of acrylonitrile and divinylbenzene by emulsion polymerization technique, a macroporous, crosslinked polyacrylonitrile copolymer was synthesized. The nitrile groups on the copolymer resin were converted into carboxylic acid groups by hydrolysis with strong alkaline solution of sodium hydroxide to obtain the resin matrix with carboxylic acid groups. A new chelating ion exchange resin containing alkylthioglycolate was prepared by esterification of carboxylic acid groups on the resin matrix and thioglycolic acid with 1,6-hexanediol as binding part. After studies of the basic characters, ion exchange ability, exchange rate and acidity of the medium, it was found that the new resin obtaind was highly selective for silver(I), mercury(II), gold(III) and bismuth(III) in acidic-aqueous solution. Separation of these metal ions from each other and concentration of these metal ions from very dilute solution were studied by liquid chromatography using a short column of this new resin. The analytical applications of this new resin are reported.     

Extraction of metal ions by N-phenyl-, N-methyl-, and N-unsubstituted hydroxamic acid resins

Procedures are described for preparing macroreticular chelating resins with hydroxamic acid or N-methylhydroxamic acid functional groups. The chelating properties of the resins are compared with each other and with an N-phenylhydroxamic acid resin reported earlier. The extraction of 19 metal ions was studied as a function of pH for the N-methylhydroxamic acid resin. Several analytical applications of this resin have been demonstrated including the purification of chemical reagents, concentration of trace metal ions, and chromatographic separation of metal-ion mixtures.     

Synthesis, characterization and analytical application of a hydroxamic acid resin

A chelating ion-exchange resin with hydroxamic acid functional groups was synthesized from styrene-maleic acid co-polymer cross-linked with divinylbenzene. A resin prepared from equimolar amounts of styrene and maleic anhydride with 0.75 mole% divinylbenzene gives the best sorption characteristics. The selectivity of the resin for metal ions is copper(II) > cobalt(II) > zinc(II) > nickel(II) > manganese(II) > chromium(III) > iron(III) > vanadium(V). Copper(II), chromium(III) and iron(III) in chromium plating baths can be separated by use of the resin and determined spectrophotometrically.     

Synthesis and properties of poly(hydroxamic acid) from crosslinked poly(methacrylate)

Poly(hydroxamic acid) chelating ion-exchange resin was prepared from crosslinked poly(methacrylate) beads. The starting polymer was prepared by a suspension polymerization of methacrylate and divinyl benzene. Conversion of the ester groups into the hydroxamic acid was carried out by treatment with hydroxylamine in an alkaline solution. Hydroxamic acid capacity of the product was 2.71 mmol/g. The resin exhibited high affinity towards Fe(III) and Pb ions and its capacities for Fe(III), Pb, Cu, Ni and Co ions were pH dependent. The ability of the resin to carry out the separation of Fe(III)CuCo/Ni and PbNi ions is also reported.     

一步法合成大孔丙烯酸交联树脂

悬浮聚合;二乙烯苯;一步法合成大孔丙烯酸交联树脂     

The synthesis of poly(hydroxamic acid) from poly(acrylamide)

Poly(hydroxamic acid) in gel or water soluble from was prepared from the reaction of poly(acrylamide) and hydroxylamine in basic aqueous solution (pH > 12) at room temperature. The polymers were composed of 70% hydroxamic acid groups, less than 5% carboxylic acid groups, and 25% unreacted amide groups. The polymers exhibited high affinity to iron(III) and copper(II) in the pH range of 1 to 5 with a high binding rate. A binding of 3 mmol/g for both metals was achieved. Preliminary tests demonstrated the urease inhibitory activity of both linear and crosslinked poly(hydroxamic acids).     

Crosslinking network structure governing particle shape and size distribution by one-step emulsion polymerization in the presence of particle coagulation

In this study, sub-200?nm, crosslinked latex particles with a narrow particle size distribution were prepared by one-step emulsion polymerization in the presence of particle coagulation. The relationship between the particle shape and particle coagulation was investigated by varying the time of crosslinking network structure formation and particle coagulation. Particles with irregular shapes such as doublet, triplet, and ellipsoid were obtained using divinylbenzene (DVB) and ethylene glycol dimethacrylate (EGDMA) as the crosslinking agents, because the crosslinking network structure of particles was formed before the particle coagulation. In contrast, latex particles with a uniform spherical shape were also prepared using triallyl isocyanurate (TAIC) or dihydrodicyclopentadienyl acrylate (DCPA) as the crosslinking agents by delaying the time of crosslinking network structure formation. Alternatively, uniform spherical latex particles were prepared by bringing forward the particle coagulation time using cationic initiator, 2, 2′-azobis (2-methylpropionamidine) dihydrochloride (AAPH). This study presents a new idea that would further broaden the application of particle coagulation in emulsion polymerization.     

Influence of the Nature of Crosslinking Agent on the Oxidation Behavior of Crosslinked Polystyrene‐Supported Polyoxyethylene Bound Permanganate

Abstract

Polystyrene‐supported polyoxyethylene (PSPOE) bound permanganate with varying crosslinking agents have been prepared and used as a new class of recyclable oxidizing agents for low molecular weight alcohols and aldehydes. The effect of the nature of crosslinking agents on the oxidation reactions was studied in detail. The crosslinking agents used were ethyleneglycol dimethacrylate (EGDMA), 1,4‐butanediol dimethacrylate (BDDMA), and 1,6‐hexanediol diacrylate (HDODA). Polymer supports were synthesized by free radical suspension polymerization. Chloromethylation was done using the Friedel‐Crafts reaction. A cyclic polyether type compound was developed by the reaction of functionlized resin with polyethylene glycol (PEG₆₀₀) and sodium. Polystyrene‐supported polyoxyethylene was equilibrated with potassium permanganate in benzene to give the oxidizing agent. The results reveal that the reactivity of HDODA‐crosslinked system shows higher reactivity than the BDDMA, and EGDMA‐crosslinked systems. This is due to higher flexibility of the HDODA‐crosslinked system compared to the BDDMA, and EGDMA‐crosslinked systems. The effect of solvent, temperature, and molar concentration of the reagent on oxidation were carried out using benzoin to benzil as the model reaction. For a less flexibile EGDMA‐crosslinked resin, tetrahydrofuran (THF) is the best solvent, for BDDMA‐crosslinked system dioxane and for the highly flexible HDODA‐crosslinked system CHCl₃ is found to be best. In all cases, the reactivity of the reagent increased with an increase in temperature and molar excess of the reagent.     

Microgel formation in the free radical crosslinking polymerization of ethylene glycol dimethacrylate (EGDMA). I. Experimental

An important feature of free radical crosslinking polymerization of ethylene glycol dimethacrylate (EGDMA) resin is the formation of heterogeneous structure through intramolecular reaction. Such structure formation affects not only the cure behavior and rheological changes of the resin but also the physical properties of the formed polymers. In this study, the reaction kinetics, morphological changes, and characteristics of formed polymers were examined by a differential scanning calorimeter, a Rheometrics Dynamic Analyzer, a dynamic light scattering goniometer, and a Fourier transfer infrared spectrometer. Experimental data showed the formation of bimodal polymers before gelation. These polymers are partially crosslinked and can be considered as microgel particles. © 1995 John Wiley & Sons, Inc.     

Synthesis and rheology of methacrylic acid-ethyl acrylate crosslinked polymers

The rheological behaviour of methacrylic acid-ethyl acrylate copolymers (MAA 61.9–78.5 mol%) and terpolymers with two crosslinking agents, i.e. ethylene glycol dimethacrylate (EGDM, 0.23–4.83 mol%) or N, N′-methylene bisacrylamide (MBAM, 0.29–1.48 mol%) has been studied. The effect of pH, shear rate, solid content of the solution, and the addition of electrolyte on the viscosity has been reported. As the viscosity is a function of neutralization of carboxylic acid groups, it was found to be highly dependent on pH. Addition of electrolytes (0.5–1.5%) led to a drastic drop in the viscosity. The influence of different crosslinking agents on the viscosity was also studied and N, N′-methylene bisacrylamide was found to be more efficient than ethylene glycol dimethacrylate. The gel content of the crosslinked polymers was determined to obtain an idea of the degree of crosslinking of the polymers.     

SYNTHESIS AND PROPERTIES OF ACRYLIC-BASED SUPERABSORBENTS WITH ENHANCED CROSSLINKING ON PARTICLE SURFACE

A series of acrylic-based superabsorbent resins were synthesized by inverse suspension polymerization, using potassium persulfate as the initiator, N, N＇-methylene bisacrylamide （BIS） and divinylbenzene （DVB） as the multiple crosslinking agents. The morphology of the resulting superabsorbent resins revealed by SEM demonstrated that a hard shell layer was indeed formed due to surface crosslinking. The swelling and deswelling properties, and the mechanical strength of superabsorbents were investigated. The results indicated that the adding time of DVB and the amount of DVB participated in the crosslinking show a significant influence on the properties of superabsorbents. When DVB was added in polymerization later, the amount of DVB participated in reaction decreases and the surface crosslinked shell becomes thinner. It is suitable for DVB to be introduced in the later stage of the polymerization process, because the absorption rate of resin is efficiently improved in conjunction with higher water absorption. Furthermore, it was found that the mechanical strength of swollen superabsorbent with surface crosslinking was indeed enhanced in comparison with that of the conventional one.     

Synthesis of dihydroxamic acid chelating polymers and the adsorptive property for uranium in sea water

Preparation of new chelating polymers bearing dihydroxamic acid groups and the adsorptive ability for uranium in sea water are described. Chloromethylated polystyrene crosslinked with divinylbenzene was treated with diethyl malonate in N, N-dimethylformamide to give the polymer having diethyl malonate groups. This polymer was then treated with hydroxylamine in methanol to afford the dihydroxamic acid polymer. The presence of hydroxamic acid groups was confirmed by the appearance of IR absorption band at 1680 cm^?1. The dihydroxamic acid polymer contained carboxylic acid groups as well as hydroxamic acid ones, and the contents of carboxylic acid and hydroxamic acid groups were estimated from elemental analysis to be 2–3 and 2–4 mmol/g, respectively. The polymer showed the adsorptive ability of 40 μg-U/g in 8 days for uranium in sea water. In addition, the polymer showed the selective adsorptivity for iron, nickel, copper, and zinc as well as uranium. The macroreticular-type polymer showed much higher adsorption rate for uranium in sea water than the gel-type ones did, suggesting that the rate depends on the diffusion of the uranium in the polymer support.     

THE SYNTHESIS AND CHARACTERIZATION OF Ba-CROSSLINKED POLYMER ANTI-RADIATION MATERIALS

Crosslinked poly(methyl methacrylate) and polystyrene with barium dimethacrylate [Ba(MA)_2] as crosslinking agent have been synthesized. The relationship between X-ray absorbability and the content of Ba(MA)_2 in polymers was investigated. TGA and DSC results indicated that the crosslinked polymers containing barium dimethacrylate have a much better heat stability than pure PMMA or PS. The mechanical properties of the polymers containing barium are improved in comparison with the pure PMMA.     

Adsorption Behavior of Metal Ions by Amidoxime Chelating Resins

In this work, the acrylonitrile (AN) – divinylbenzene (DVB) –methylacrylate (MA) resin was synthesized via suspension polymerization in the presence of toluene as diluent, and benzoylperoxide (BPO) as initiator. The effect of MA, toluene and alkaline treatment on the exchange capacity of the resin were investigated. The results showed that the anion exchange capacity decreased with an increase in the amount of MA, while alkaline treatment had no significant effect. Also, the cation exchange capacity increased with an increase in the amount of hydrophilic agent and reached a maximum point. The sorption equilibrium was achieved relatively fast within 40 mins, and the resin exhibited affinity towards lead (II), copper (II) and in particular uranium (VI). The adsorption of uranium was directly depended up on the pH value. Furthermore, the macroreticular chelating resin, containing amidoxime group had higher adsorption of uranium (VI) in comparison to other metal ions studied. Finally, the alkaline treatment enhanced the potential for much faster adsorption characteristics and the highly porous chelating resin provided a more favorable pore structure for the rapid rate of diffusion of metal ions.     

二乙烯苯交联聚(2-羟乙基硫甲基苯乙烯)树脂的相转移催化合成

 研究了固-液-液体系中相转移催化的交联氯甲基化聚苯乙烯与2-巯基乙醇的反应,合成了一种含有硫和氧的新型螯合树脂二乙烯苯交联聚(2-羟乙基硫甲基苯乙烯)(PSME). 用FT-IR监测手段,研究了反应时间、反应温度、相转移催化剂、溶剂极性以及反应物摩尔比对转化率的影响. 结果表明,当温度为298 K,2-巯基乙醇与氯甲基化聚苯乙烯的摩尔比为6,十四烷基三甲基溴化铵为相转移催化剂时,在苯/NaOH水溶液中氯的转化率可达到91.2%. 用FT-IR,XPS,EDX,SEM和元素分析法对树脂的结构进行了表征,引入功能基之后,树脂的孔隙明显增大.     

New fluorinated hydroxamic acid reagents for the extraction of metal ions with supercritical CO2

Research to date on the supercritical fluid extraction (SFE) of metal ions has focused on the use of dithiocarbamates and β-diketones. Hydroxamic acids are well known as effective chelating agents for a broad range of transition metal ions. Much attention has centred in inorganic chemistry on the effect of N-substitution on metal chelate stability and selectivity, and in analytical chemistry on the immobilisation of the chelating agents to the chosen solid supports such as silica. In this paper, the synthesis of selected fluorinated mono hydroxamic acids and their N-substituted derivatives is reported. The new reagents are applied in the SFE of metal ions in particular Fe(III) using unmodified supercritical CO₂. Metal extraction is monitored using atomic absorption spectroscopy and visible spectrophotometry. The extraction efficiencies were determined as a function of pressure and temperature. The new ligands synthesised and applied were perfluorooctanohydroxamic acid (PFOHA), heptafluorobutyrichydroxamic acid (HFBHA) and their N-methylhydroxamic acid derivatives. Of the synthesised reagents, PFOHA was the most soluble and effective extractant of Fe(III) from spiked filter paper, reaching 97% extraction of the metal ion under optimised conditions. The selectivity of this ligand for Fe(III) in the presence of Cu(II), Ni(II), Pb(II) and Zn(II) is also demonstrated.     

Purification of the specific immunoglobulin G1 by immobilized metal ion affinity chromatography using nickel complexes of chelating porous and nonporous polymeric sorbents based on poly(methacrylic esters). Effect of polymer structure

Ni2+ complexes of the chelating nonporous and porous bead sorbents based on methacrylic esters crosslinked with ethylene dimethacrylate were used in isolation of the horseradish peroxidase-specific immunoglobulin IgG1 from the crude mouse ascitic fluid by immobilized metal ion affinity chromatography (IMAC). Iminodiacetic and aspartic acids were attached to porous poly(glycidyl methacrylate) beads differing in size, morphology and chemical composition. Ethylenediaminetriacetic acid and quinolin-8-ol chelating groups were attached mainly to the surface hydroxyl groups in nonporous poly(diethylene glycol methacrylate) beads through spacers. The latter sorbents exhibited better kinetic characteristics than the former but a very low IgG1 sorption capacity. In a single-step IMAC procedure, the best efficiency in the specific IgG1 purification was obtained with porous sorbents (recovery 92%, purity 73%). Differences in IMAC separations are discussed from the point of view of morphology of polymer beads as well as of the type and concentration of chelating ligands.     

EFFECT OF THE DEGREE OF DVB CROSSLINKING ON THE METAL ION SPECIFICITY OF POLYACRYLAMIDE-SUPPORTED GLYCINES

Metal ion specificity studies of divinylbenzene (DVB)-crosslinked polyacrylamide-supported glycines in different structural environments were investigated. The effect of the degree of crosslinking on the specific rebinding of the desorbed metal ion was investigated towards Co(II), Ni(II), Cu(II), and Zn(II) ions. The metal ion-desorbed resins showed specificity for the desorbed metal ion and the specificity characteristics increases with an increasing degree of the crosslinking agent. The polymeric ligands and metal complexes were characterized by IR, UV-visible and EPR spectra, and by SEM analysis. The swelling and solvation characteristics of the crosslinked polymers, polymeric ligands and metal complexes, the effect of the pH dependence on metal ion binding and rebinding and the kinetics of metal ion binding and rebinding were also followed. The complexation resulted in the downfield shift of the carboxylate peak in the IR spectra. The EPR parameters are in agreement with a distorted tetragonal geometry. The Cu(II) ion-desorbed resins selectively rebinds Cu(II) ions from a mixture of Cu(II) and Co(II) and Cu(II) and Ni(II) ions. The resin could be regenerated several times without loss of capacity and effective for the specific and selective rebinding of Cu(II) ions.     

Influence of Crosslinking and Porosity on the Uranium Adsorption of Macroreticular Chelating Resin Containing Amidoxime Groups

Macroreticular chelating resins (RNH) containing amidoxime groups with various degrees of crosslinking were synthesized by using various amounts of divinylbenzene (DVB) or/and poly(ethylene glycol) dimeth-acrylate [ethylene glycol dimethacrylate (IG), diethylene glycol dimethacrylate (2G), triethylene glycol dimethacrylate (3G), tetraethylene glycol dimethacrylate (4G), and nanoethylene glycol dimethacrylate (9G)] as crosslinking reagent. The effects of crosslinking reagents on the pore structure, ion-exchange capacity, swelling ratio, and adsorption ability for uranium of RNH were investigated. The adsorption ability of RNH for uranium was tested by use of natural seawater or U-spiked seawater. RNH-1G samples prepared by using 1G were shown to have macroreticular structures by measuring the specific surface area. RNH-1G had high adsorption ability and good physical stability. Though RNH-4G samples obtained by using 4G had little macroreticular structure (macropore), these resins showed high adsorption ability for uranium on treatment with 0. 1 M NaOH at 30°C for 15 h. RNH-4G was found to have low physical and chemical stability. For the preparation of RNH with effective pore structure for the recovery of uranium, as well as chemical and physical stability, the simultaneous use of DVB and 1G or 4G as crosslinking reagent was examined (abbreviated as RNH-DVB-1G and RNH-DVB-4G). The RNH-DVB-1G showed high adsorption ability for uranium. Repeated use did not cause deterioration of either RNH-DVB-1G or RNH-DVB-4G. RNH-DVB-1G samples with various degrees of crosslinking were prepared, and the uranium recovery of the resins was also investigated by a column method. Although the RNH-DVB-1G samples with the same degree of crosslinking had almost the same content of amidoxime groups, the uranium recovery of each RNH-DVB-1G sample was considerably different and increased by treatment with alkali solution. These results indicate that the adsorption ability of RNH-DVB-1G for uranium in seawater was not only affected by the macropores but also by the micropores formed by swelling of the resins.     

Preparation and analytical properties of a chelating resin functionalized with 1-hydrazinophthalazine ligand

A poly[styrene-co-(divinylbenzene)] resin (XAD-4) functionalized with 1-hydrazinophthalazine ligand has been prepared and its analytical properties investigated. The pH dependence of sorption of metal ion on the resin has been determined for Cu(II), Ni(II), Co(II), Zn(II), Cd(II), Pb(II), Fe(III) and Cr(III). Trace amounts of these metal ions were quantitatively retained on the resin and recovered by eluting with 1 mol l(-1) hydrochloric acid. The resin was found to be selective for Fe(III) and its separation from other metal ions was carried out effectively. Metal ions concentrations were determined using AAS.