Recovery of uranium from seawater. VI. Uranium adsorption ability and stability of macroporous chelating resin containing amidoxime groups prepared by the simultaneous use of divinylbenzene and ethyleneglycol dimethacrylate as crosslinking reagent

Macroporous chelating resins (RNH-DVB-1G) containing amidoxime groups with various degrees of crosslinking were synthesized by varying the amount of divinylbenzene (DVB) and ethyleneglycol dimethacrylate (1G). It was confirmed that the content of amidoxime group decreased with an increase in the degree of crosslinking. On the other hand, the amount of amidoxime group hydrolyzed by acid treatment showed a tendency to decrease with an increase in degree of crosslinking. From the measurement of specific surface area and pore size distribution, it was found that the macropore of RNH-DVB-1G with the same degree of crosslinking was remarkably affected by the composition of crosslinking reagent (DVB and 1G). The RNH-DVB-1G prepared in the present work were applied to the recovery of uranium from seawater. It was found that the uranium adsorption ability of RNH-DVB-1G with the same degree of crosslinking was remarkably affected by the proportion of DVB and 1G, although each RNH-DVB-1G had the same content of amidoxime group. In the case of RNH-DVB-1G prepared with 25 mol% of crosslinking reagent, the resin prepared with 10 mol% of DVB and 15 mol% of 1G showed the high adsorption ability for uranium in seawater. These results indicate that the simultaneous use of DVB and 1G contributes to the formation of effective macropore and micropore for recovery of uranium from seawater and the increase of chemical and physical stability.     

Recovery of uranium from seawater. XII. Preparation and characterization of lightly crosslinked highly porous chelating resins containing amidoxime groups

A number of lightly cross-linked poly(acrylonitrile-co-divinylbenzene) beads (RN-5) have been synthesized by suspension polymerization. The use of solvating diluents such as chloroform, dichloroethane, and tetrachloroethane resulted in copolymer beads having highly porous structures. The chelating resins containing amidoxime as a functional group (RNH-5) have been prepared by the reaction of copolymer beads with 3% hydroxylamine in methanol. A detailed analysis is made of the pore structure of lightly cross-linked copolymers of acrylonitrile–divinylbenzene and their amidoxime derivatives in the anhydrous state including pore-size distribution, specific surface area, and pore structure in the aqueous media by means of gel permeation chromatography (GPC). A set of experiments have been performed to ascertain the potential of the resins for the adsorption of uranium from seawater. Because of their modified pore structures, the chelating resins exhibited a marked adsorption rate for uranium in seawater as high as 23 μg of U/cm³ of resin/day without alkaline treatment.     

Preparation of Chelating Resins Containing a Pair of Neighboring Carboxylic Acid Groups and the Adsorption Characteristics for Heavy Metal Ions

Abstract

For the functional enhancement of chelating resins containing carboxylic acids, copolymer beads were prepared by suspension polymerization of styrene (St), methyl methacrylate (MMA), and divinylbenzene (DVB) in the presence of toluene as diluent. The phenyl rings of the beads were directly chloromethylated, and the carboxylic ester groups of the beads were converted into hydroxymethyl groups by reduction followed by chlorination to give chloromethyl groups, respectively. The chelating resins containing a pair of neighboring carboxylic acid groups (NCAGs) were obtained by the alkylation of chloromethyl groups in copolymer beads with diethyl malonate in the presence of sodium hydride followed by hydrolysis using aqueous alkali solution. Accordingly, the structural effects of the resins on the adsorption of heavy metal ions were investigated. Poly(St‐co‐DVB)‐based chelating resin containing NCAGs showed adsorption abilities toward heavy metal ions like Pb²⁺, Cd²⁺, and Cu²⁺, whereas poly(MMA‐co‐DVB)‐based chelating resin containing NCAGs showed adsorption abilities toward heavy metal ions like Cu²⁺, Cd²⁺, and Co²⁺. On the other hand, poly(St‐co‐MMA‐co‐DVB)‐based chelating resin containing NCAGs showed adsorption abilities toward heavy metal ions like Pb²⁺, Cd²⁺, Hg²⁺, Co²⁺, and Cu²⁺: a synergistic effect on the adsorption of heavy metal ions like Pb²⁺, Cd²⁺, Hg²⁺, and Co²⁺ was observed. The adsorption ability of poly(St‐co‐MMA‐co‐DVB)‐based chelating resin among three kinds of chelating resins was relatively good.     

Recovery of uranium from sea water. IV. Influence of crosslinking reagent of 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 ethyleneglycol dimethacrylate (1G), dimethyleneglycol dimethacrylate (2G), triethyleneglycol dimethacrylate (3G), tetraethyleneglycol dimethacrylate (4G), and nanoethyleneglycol dimethacrylate (9G) as crosslinking reagent. The effect of crosslinking reagents on the pore structure, ion exchange capacity, swelling ratio, and adsorption ability for uranium of RNH was investigated. RNH (RNH–1G) prepared by using 1G were showed to have macroreticular structures by the measure of specific surface area. RNH–1G had the high adsorption ability and physical stability. Though RNH (RNH–4G) obtained by using 4G have little macroreticular structure (macropore), these resins showed the high adsorption ability for uranium by the treatment with 0.1 mol dm^?3 NaOH at 30°C for 15 h (alkali treatment). These results suggest that the formation of not only the favorable macropore but also the micropore is important for the effective recovery of uranium in sea water, whereas RNH–4G was defined to be low physical and chemical stability. For the preparation of RNH which have effective pore structure for the recovery of uranium, chemical, and physical stability, the simultaneous use of divinylbenzene (DVB) and 1G or 4G as crosslinking reagent was examined (abbreviated as RNH–DVB–1G and RNH–DVB–4G). The specific surface area of RNH–DVB–1G increased with an increase of 1G used. These RNH–DVB–1G have been shown the high adsorption ability for uranium. On the other hand, the specific surface area and adsorption ability for uranium of RNH–DVB–4G decreased with an increase of 4G used. Repeated use did not cause the deterioration of both RNH–DVB–1G and RNH–DVB–4G. This result suggests that the simultaneous use of DVB and 1G or 4G contributed the improvement of chemical and physical stability. In particular, RNH–DVB–1G has the effective macropore and micropore for the recovery of uranium.     

大孔偕胺肟树脂的合成及其对镓的吸附性能

采用悬浮聚合法先合成出了丙烯腈(AN)-二乙烯基苯(DVB)交联骨架,制备了具有偕胺肟基团的大孔螯合树脂,表征了其结构和形貌,并用于拜耳溶液中镓的吸附. 研究了二乙烯苯含量、油相稀释剂种类及用量、第三单体、胺肟化反应条件对树脂吸附镓的性能的影响. 结果表明,螯合树脂的吸附性能随DVB含量增加先增加后降低,DVB含量为8%(w)时吸附性能最好,选用60%(w)甲苯和30%(w)航油作油相稀释剂,树脂的吸附率最大,分别为46%和52%. 添加少量(2%)第三单体甲基丙烯酸甲酯使树脂吸附率提高到57%.     

Preparation of macroreticular chelating resins containing dihydroxyphosphino and/or phosphono groups and their adsorption ability for uranium

The macroreticular chelating resins (RSP, RSPO, RCSP, and RCSPO) containing dihydroxy-phosphino and/or phosphono groups were prepared and their adsorption capacity for UO₂²⁺ and the recovery of uranium from sea water were investigated. RSP and RCSP were prepared by phosphorylation of macroreticular styrene–divinylbenzene copolymer beads and the chloromethylated copolymer beads, respectively. RSPO and RCSPO were prepared by oxidation of RSP and RCSP, respectively. The order of recovery of uranium from sea water with these four resins is as follows: RCSPO ? RCSP > RSPO > RSP. The adsorption of uranium in sea water was not only affected by the chemical structure, but also by physical structure of the resins. Uranium absorbed on the resins was eluted with 0.25 ～ 1 mol·dm^?3 Na₂CO₃ or NaHCO₃ solution by batch and column methods. The average recovery ratios of uranium from sea water with Na-form and H-form RCSP on 10 recycles were 84.9% and 90.5%, respectively, when 20 dm³ of sea water was passed through the column (resin 4 cm³, 10 mm ? × 50 mm) at the space velocity of 60 h^?1. RCSP has a high physical stability and resistance against acid and alkali solution.     

Recovery of Uranium from Seawater

Abstract

Seawater contains various elements in solution. Deuterium, lithium, and uranium are the important ingredients for energy application at present and in the future. This paper deals with the recovery of uranium from seawater, with emphasis on the development of an adsorbent with high selectivity and rate of adsorption for uranium.

Polyacrylamidoxime chelating resins were synthesized from various co-polymers of acrylonitrile and cross-linking agents. The resulting resins with the chelating amidoxime group showed selective adsorption for uranium in seawater. The amount of uranium adsorbed from seawater at room temperature reached 3.2 mg/g resin after 180 days.

Polyacrylamidoxime fiber, which was prepared from polyacrylo-nitrile fiber and hydroxylamine, showed a high rate of adsorption for uranium. The polyacrylamidoxime fiber conditioned with 1 M HCl and 1 M NaOH adsorbed 4 mg U/g fiber from seawater in ten days.     

Kinetic Behavior of Lightly Crosslinked Chelating Resins Containing Amidoxime Groups for Batchwise Adsorption of UO2 2+

Abstract

Lightly crosslinked poly(acrylonitrile-co-divinylbenzene) beads (RN-5) have been synthesized by suspension polymerization. The use of dichloroethane and chloroform as a porogen produced lightly crosslinked copolymer beads having highly porous structures. The chelating resins containing amidoxime groups (RNH-5) have been prepared by the reaction of copolymer beads with NH₂OH in MeOH. The resulting chelating resins have been used in the batchwise adsorption of UO₂ ²⁺ from nitrate solutions containing 0.01 mol·dm^?3 UO₂ ²⁺ at pH 3.25. In order to get some measure of the relative performance of each resin in kinetic terms, the extraction of UO₂ ²⁺ was monitored with time and some adsorption profiles were obtained. An increase in porogen content resulted in a marked increase in the batchwise adsorption of UO₂ ²⁺. Alkaline treatment allowed a high swelling and hence rapid accessibility of UO₂ ²⁺ to the ligands. Even after 30 minutes, the alkali-treated resins were 50% loaded.     

Parametric studies on the synthesis of amidoximated adsorbent resins

The main goal of this study was to obtain acrylonitrile (AN)‐divinylbenzene (DVB) copolymer beads that can serve as the matrix for preparation of amidoxime resins. AN‐DVB amidoxime resin was synthesized via suspension polymerization and the effect of different parameters such as the speed of stirrer, the amounts of suspending agent, hydrophilic agent, diluent agent, and initiator on its properties was investigated by fractional factorial (Taguchi) experimental design method. This method gives much‐reduced variance for the experiments with optimum control parameters setting and provides a set of minimum experiments compared to the conventional methods. The results showed that the most effective parameters on the amidoximation of resins were hydrophilic agent content, speed of stirrer, and the amount of suspending agent, respectively. Furthermore, anion‐exchange capacity of the amidoxime resins was utilized as a criterion for the evaluation of amidoxime adsorbent groups and the adsorption potential of the synthesized resins was determined by cation‐exchange capacity. The amount of methylacrylate as a hydrophilic agent had the most significant effect on the ion‐exchange capacity of the final product. Swelling ratio was also measured to evaluate the adsorption capacity of the synthesized resin. The results showed that the amounts of hydrophilic and diluent agents had significant effects on swelling ratio of resin. Finally, cation‐exchange capacity and swelling ratio of amidoxime resin were changed greatly because of alkaline treatment, but it had no significant effect on the anion‐exchange capacity of the synthesized resin. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Water‐swellable hydrophobic porous copolymer resins based on divinylbenzene and acrylonitrile. II. Pore structure and adsorption behavior

By using purified divinylbenzene (DVB, 98.8%) or technical DVB (79.3%), the hydrophobic, but water‐wettable or swellable porous copolymer resins based on DVB and acrylonitrile (AN) could be prepared with a wide range of pore structures under certain conditions. The specific surface area for the resulting AN/DVB resin, with an AN/DVB ratio of 40/60 (by mole), could reach a value of 704 m²/g, while such a resin is still water wettable or swellable by direct contact with water. The adsorption behavior of the AN/DVB resins was investigated by focusing on the comparison between the resins with and without prewetting, using caffeine and phenol as model adsorbates. Adsorption behavior of the AN/DVB resins, without prewetting, correlates well with the wetting ability of the resins in water, suggesting that a well water‐wettable hydrophobic porous AN/DVB resin could be directly applied, in a dry state, to the adsorption in an aqueous medium, almost without diminishing the ability of the resin to adsorb the solutes. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2050–2056, 2004     

Synthesis and metal ion adsorption studies of chelating resins derived from macroporous glycidyl methacrylate‐divinylbenzene copolymer beads anchored schiff bases

Two novel chelating resins are prepared by anchoring diethylenetriamine bis‐ and mono‐furaldehyde Schiff bases onto the macroporous GMA‐DVB copolymer beads and utilized for the adsorption towards Cu(II), Co(II), Ni(II), and Zn(II). FTIR spectra show that Schiff base groups have been successfully introduced into the polymer matrix and the chelating resins can form complexes with the metal ions. The chelating resins show a higher adsorption capacity toward Cu(II). The conductivity method can be used for determining the adsorption kinetics of the resins towards metal ions. The results show that the adsorption rates towards Cu(II) are much higher than those towards other ions and pseudo second‐order and intraparticle diffusion models can be applied to treat the adsorption amount‐time data. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Modification of porous copolymers network based on acrylonitrile

Summary The preparation of a chelating ion-exchange network based on acrylonitrile was carried out by chemical modification with hydroxylamine. The beads of resin were synthesized by aqueous suspension copolymerization of acrylonitrile (AN), styrene (STY) and divinylbenzene (DVB). The influence of diluent used in the suspension polymerization on the structure of the resulting copolymers was evaluated. The diluents employed were heptane (HEP), toluene (TOL) and anisole (ANI). It was found that the AN incorporation into copolymer structure was dependent on the diluent used. Conversion of nitrile groups into the amidoxime was conducted by treatment with hydroxylamine under alkaline solution. The resins were characterized by apparent density, surface area, average pore diameter, elemental analysis (CHN), FTIR and optical microscopy. Based on the results obtained, it was possible to control the porosity by diluent employed in the synthesis and to modify chemically a resin containing nitrile groups by hydroxylamine reaction. Received: 6 October 2001/Revised version: 2 April 2002/ Accepted: 11 April 2002     

Water‐swellable hydrophobic porous copolymer resins based on divinylbenzene and acrylonitrile. I. Water‐swelling behavior

Hydrophobic porous copolymer resins based on divinylbenzene (DVB) and acrylonitrile (AN) could be prepared as directly swellable in water by using purified DVB (98.8%) and technical DVB (79.3%) in the presence of 1,2‐dichloroethane as porogen. Compared with the resins based on DVB and methyl acrylate (MA/DVB resins), the AN/DVB resins thus obtained are water‐swellable over a wider range of copolymer compositions, and the swelling ability of the AN/DVB resins in water was further confirmed by investigating the water‐swelling behavior of the AN/DVB resins undergoing solvent treatment. The copolymer composition (AN and DVB contents) of the resins and the property of the porogen affect the water‐swellable behavior of the AN/DVB resins profoundly. The results in this paper provide additional evidence to support the hypothesis that the swelling ability of a hydrophobic porous copolymer in water originates from the existence of the inner stresses in the strained polymer network of the resins and the weak interaction between polymer and water that is negligible in the case of a conventional hydrophobic polymer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2041–2049, 2004     

Pore structure of water‐wettable hydrophobic resins based on divinylbenzene and methyl acrylate

Hydrophobic, but water‐wettable porous resins based on divinylbenzene (DVB) and methyl acrylate (MA) were prepared with a wide range of pore structures by suspension copolymerization under different conditions. By using purified DVB (98.8%), the specific surface area for the resulting MA/DVB resins could reach high values at high DVB levels, while these resins are wettable by direct contact with water. An increased content of MA significantly increases the porosity of the resins, whereas the solvating power of the porogen affects both pore structure and water‐wettability of the MA/DVB resins profoundly. Treating these MA/DVB resins with ferric chloride in the presence of dichloroethane gives products with larger surface areas and an enhanced water‐wettability. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2681–2688, 2004     

Antibacterial activity of resin-containing triethylenetetramine side chains and/or thiol groups–metal complexes

Four chelating resins containing triethylenetetramine side chains and/or thiol groups were made from macroreticular 2,3-epithiopropyl methacrylate, styrene–divinylbenzene (DVB), or methyl methacrylate–DVB copolymer beads, and then the resins bearing metal ions such as Ag⁺, Cu²⁺, and Zn²⁺ were made. The antibacterial activity of the resins bearing metal ions against Escherichia coli (E. coli) or Staphylococcus aureus (S. aureus) was investigated. The resins containing thiol groups showed the higher adsorption capacity for silver ions than for other metal ions. The resins, which contain both triethylenetetramine side chains and thiol groups, bearing silver ions (RE-TTA-Ag) exhibited high antibacterial activity against bacteria, especially E. coli, without the residual silver ions in water after contacting with bacteria. The activity of the RE-TTA-Ag did not decrease even after reusing several time. © 1996 John Wiley & Sons, Inc.     

Pore structure and water‐swelling behavior of porous resins based on methyl acrylate and different divinylbenzene isomers

Porous resins based on divinylbenzene (DVB) and methyl acrylate (MA) were prepared with m‐DVB (98.3%) or p‐DVB (99.1%) in the presence of toluene as a porogen. The MA/DVB resins thus obtained with a wide range of pore structures were hydrophobic in nature and were swellable by direct contact with water. The behavior of m‐DVB and p‐DVB as a crosslinker in the MA/DVB monomer system was different from that in the styrene (ST)/DVB system and was influenced by the amount of MA in the MA/DVB monomer system. As a result, a larger specific surface area and pore volume were observed for MA/DVB resins derived from p‐DVB than for those derived from m‐DVB, which was opposite to that observed for resins based on DVB and ST. The different behaviors of m‐DVB and p‐DVB in the MA/DVB monomer system also resulted in different swelling abilities of the resins in water. Compared with the MA/DVB resins derived from m‐DVB, the p‐DVB derived resins swelled faster in water and were water‐swellable when the resins had a higher DVB content and, therefore, a stronger hydrophobicity and a larger specific surface area. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2071–2078, 2005     

Effect of water content of hydrophilic amidoxime polymer on adsorption rate of uranium from seawater

Amidoxime polymers crosslinked with tetraethylene glycol dimethacrylate (40 wt%) and with differing water contents were prepared by poly(acrylonitrile) treatment in various quantities of toluene with hydroxylamine. Adsorption rates of uranium on the amidoxime polymers from seawater were examined in relation to their porosity. The amidoxime polymer prepared from poly(acrylonitrile) in an increasing quantity of toluene exhibits a significantly increasing water content. On the basis of mercury intrusion measurements, the increasing water content was revealed to be predominantly owing to the enhancement of porosity. The adsorption rate of uranium from seawater increased steadily with an increase of porosity, suggesting the dependence of the adsorption rate on a diffusion process of uranium into the pore domain.     

Kinetics of Adsorption of Uranium on Amidoxime Polymers from Seawater

Abstract

Distributions of uranium adsorbed on amidoxime polymers crosslinked with tetraethyleneglycol dimethacrylate (4EGDM) and/or divinylbenzene (DVB) from seawater were examined by x-ray microanalysis in order to elucidate the diffusion behavior of uranium into the polymer matrix. The uniform distribution of the ligands on the polymers was confirmed by the distribution of Cu(II) adsorbed from copper(II) dichloride solutions. It was found that the distribution of uranium adsorbed is changed significantly by the composition of 4EGDM and DVB. Thus, the polymer crosslinked with 4EGDM exhibits a uniform distribution of uranium; however, as the ratio of DVB to 4EGDM increases, a more predominant distribution of uranium near the periphery of the polymer particle appears and the intensity decreases. This suggests that the adsorption rate of uranium is governed by the diffusion of uranium into the polymer matrix, explaining well the dependence of the adsorption rate on the hydrophilicity of the polymer. On the basis of these results, the diffusion constant of uranium into the polymer matrix was estimated to be 3.3 × 10^?-7 cm²/s.     

Preparation and characterization of amidoxime resins based on poly(acrylonitrile-co-vinylidene chloride-co-divinylbenzene)

The poly(acrylonitrile-co-vinylidene chloride-co-divinylbenzene) beads with macroporous morphology were synthesized by suspension polymerization. The use of dichloroethane as a solvating diluent resulted in copolymer beads having highly porous structures. These have been reacted with hydroxylamine in methanol, which generates amidoxime groups. The precursory resins were readily functionalized within 0.5–1 h. A detailed analysis is made of the pore structure of resins in the anhydrous state including pore size distribution and specific surface area. © 1994 John Wiley & Sons, Inc.     

Chelating resins for mercury extraction based on grafting of polyacrylamide chains onto styrene–divinylbenzene copolymers by gamma irradiation

Chelating resins for mercury adsorption were prepared by grafting polyacrylamide chains onto styrene–divinylbenzene (Sty–DVB) copolymers by applying gamma radiation. Sty–DVB copolymers were synthesized by aqueous suspension polymerization employing different synthesis conditions. The copolymers were characterized by apparent density, surface area, pore size distribution and swelling capacity. The copolymers were irradiated using a ⁶⁰Co-γ source at room temperature in the presence of acrylamide solution in methanol. The grafting reaction was evaluated with the aid of elemental analysis, FTIR and thermogravimetric analysis (TGA). Hg(II) uptake measurements were carried out in batch experiments. The results showed that these resins can be successfully used for Hg(II) adsorption at ppm levels. The porosity degree of the copolymers influences the grafting yield as well as the Hg(II) complexation capacity of the chelating resins.