Radiation-induced Polymerization Research Articles

Evaluation of a cesium adsorbent grafted with ammonium 12-molybdophosphate

Abstract A fibrous cesium (Cs) adsorbent was developed using radiation-induced graft polymerization with a cross-linked structure containing a highly stable adsorption ligand. The ligand, ammonium 12-molybdophosphate (AMP), was successfully introduced onto the fibrous polyethylene trunk material. The resulting Cs adsorbent contained 36% nonwoven fabric polyethylene (NFPE), 1% AMP, 2% triallyl isocyanurate (TAIC) and 61% glycidyl methacrylate (GMA). The adsorbent's Cs adsorption capacity was evaluated using batch and column tests. It was determined that the adsorbent could be used in a wide pH range. The amount of desorbed molybdenum, which can be used as an estimate for AMP stability on the Cs adsorbent, was minimized at the standard drinking water pH range of 5.8–8.6. Based from the inspection on the adherence of these results to the requirements set forth by the Food Sanitation Act by a third party organization, it can be concluded that the developed Cs adsorbent can be safely utilized for drinking water.

Grafting of thermo-sensitive N-vinylcaprolactam onto silicone rubber through the direct radiation method

The modification of silicone rubber films (SR) was performed by radiation-induced graft polymerization of thermosensitive poly(N-vinylcaprolactam) (PNVCL) using gamma rays from a Co-60 source. The graft polymerization was obtained by a direct radiation method with doses from 5 to 70kGy, at monomer concentrations between 5% and 70% in toluene. Grafting was confirmed by infrared, differential scanning calorimetry, thermogravimetric analysis, and swelling studies. The lower critical solution temperature (LCST) of the grafted SR was measured by swelling and differential scanning calorimetry.

Alternative Alkaline Conditioning of Amidoxime Based Adsorbent for Uranium Extraction from Seawater

Alkaline conditioning of the amidoxime based adsorbents is a significant step in the preparation of the adsorbent for uranium uptake from seawater. The effects of various alkaline conditioning parameters such as the type of alkaline reagent, reaction temperature, and reaction time were investigated with respect to uranium adsorption capacity from simulated seawater (spiked with 8 ppm uranium) and natural seawater (from Sequim Bay, WA). An adsorbent (AF1) was prepared at the Oak Ridge National Laboratory by radiation-induced graft polymerization (RIGP) with acrylonitrile and itaconic acid onto high-surface-area polyethylene fibers. For the AF1 adsorbent, sodium hydroxide emerged as a better reagent for alkaline conditioning over potassium hydroxide, which has typically been used in previous studies, because of higher uranium uptake capacity and lower cost over the other candidate alkaline reagents investigated in this study. Use of sodium hydroxide in place of potassium hydroxide is shown to result in a 21...

Enhancing Uranium Uptake by Amidoxime Adsorbent in Seawater: An Investigation for Optimum Alkaline Conditioning Parameters

A high-surface-area polyethylene-fiber adsorbent (AF160-2) has been developed at the Oak Ridge National Laboratory by radiation-induced graft polymerization of acrylonitrile and itaconic acid. The grafted nitriles were converted to amidoxime groups by treating with hydroxylamine. The amidoximated adsorbents were then conditioned with potassium hydroxide (KOH) by varying different reaction parameters such as KOH concentration (0.2, 0.44, and 0.6 M), duration (1, 2, and 3 h), and temperature (60, 70, and 80 °C). Adsorbent screening was then performed with simulated seawater solutions containing sodium chloride and sodium bicarbonate, at concentrations found in seawater, and uranium nitrate at a uranium concentration of ∼7–8 ppm and pH 8. Fourier transform infrared spectroscopy and solid-state NMR analyses indicated that a fraction of amidoxime groups was hydrolyzed to carboxylate during KOH conditioning. The uranium adsorption capacity in the simulated seawater screening solution gradually increased with co...

Radiation induced graft polymerization of multi-walled carbon nanotubes for superhydrophobic composite membrane preparation

Highly soluble multi-walled carbon nanotubes (MWNTs) were prepared by radiation-induced free radical graft polymerization of vinyl acetate (VAc) onto pristine MWNT surfaces. High resolution transmission electron microscopy (HR-TEM), Fourier transform infrared (FTIR) spectroscopy, and micro-Raman spectroscopy were used to confirm that poly(vinyl acetate) (PVAc) had been successfully grafted onto the surface of the MWNTs. The effects of experimental parameters on the degree of grafting (DG) of PVAc were also investigated, including adsorbed dose, dose rate, initial monomer concentration, and solvents. The grafted MWNTs (MWNTs-g-PVAc) exhibited good solubility in common organic solvents at high mass fraction. In addition, a superhydrophobic composite membrane could be readily fabricated by vacuum filtration of MWNTs-g-PVAc onto a supporting membrane, as was confirmed by water contact angle testing and visualization by scanning electron microscopy.

Preparation of a Proton-Exchange Me mbrane with -SO3H Group Based on Polyethylene and Poly(vinylidene fluoride) Film by Radiation-Induced Graft Polymerization for Proton-Exchange Fuel Cell.

This paper reports the preparation of a proton-exchange membrane (PEM) with sulfonic acid (-SO3H) groups based on polyethylene (PE) films and poly(vinylidene fluoride) (PVdF) films by the radiation-induced graft polymerization (RIGP) of sodium styrene sulfonate (NaSS) in the presence of the polymerizable access agents, such as acrylic acid and pyrollidone in a methanol solution. A PEM with -SO3H based on PE and PVdF films were confirmed by ATR, XPS and contact angle measurements. The water uptake (%), graft yield (%), ion-exchange content (mmol/g), and proton conductivity (S/cm), as well as the current density (mA/cm2), and power density (mW/cm) for PEM with -SO3H groups prepared by RIGP were evaluated. The PEM prepared with the -SO3H groups based on PE and PVdF films can be used as a proton-exchange fuel cell membrane.

Influencing Factors for Organic Spill Recovery Performance with a Novel Polypropylene-Methacrylate Sorbent.

Insoluble organic matter released to the water body through accidental spillage imposes serious damage on the environment. Polypropylene (PP) fiber and methacrylate resin, however, end up in certain morphology or low sorption capacity after a single use. In this study, a novel sorbent was prepared by radiation-induced graft polymerization of butyl methacrylate (BMA) onto PP fiber matrix to retain the advantages of both PP fibers and methacrylate resins to overcome the shortcomings of each used alone. The different parameters including irradiation power, irradiation time and monomer concentration that effect the grafting degree of grafted fiber were studied. The resulting grafted fibers (PP-g-BMA) were evaluated in this study in terms of sorption capacity, retention behaviors and reusability properties. The investigation revealed that the homopolymerization rate, organic matter temperature and pH values of organic-over-water aqueous solution are the most important factors in the sorption performance of polypropylene grafted fiber sorbent.

Radiation-induced graft polymerization of chitosan onto poly(3-hydroxybutyrate)

Chitosan is among the most studied biopolymers and offers important advantages, such as biodegradability, biocompatibility and nontoxicity. In this study, this polysaccharide was grafted onto poly(3-hydroxybutyrate) using the simultaneous gamma-irradiation-initiated polymerization method. The polyester was immersed in diverse solvents, which allowed the preparation of graft copolymers with different yields and crystallinities. A successful synthesis and the estimation of the degree of crystallinity were verified by spectroscopic and calorimetric techniques. The most suitable method was found to be the thermoanalytical approach because it displayed a linear relationship between the degree of crystallinity and the increasing degree of grafting. The results also indicated that the lowest degree of grafting was seen for acetic acid (14.27%), while the highest degree corresponded to ethyl acetate (32.11%). The mechanism of grafting was proposed on the basis of the experimental results.

Modification of microcrystalline cellulose by gamma radiation-induced grafting

Abstract Modified microcrystalline cellulose (MCC) was prepared through gamma radiation-induced graft polymerization of glycidyl methacrylate (GMA). Simultaneous grafting was employed wherein MCC with GMA in methanol was irradiated with gamma radiation in nitrogen atmosphere. The effects of different experimental factors such as monomer concentration, type of solvent and absorbed dose on the degree of grafting, Dg, were studied. The amount of grafted GMA, expressed as Dg, was determined gravimetrically. Information from grafted samples subjected to Fourier transformed infrared spectroscopy (FTIR) in attenuated total reflectance (ATR) mode showed peaks corresponding to GMA which indicates successful grafting. The X-ray diffraction (XRD) analysis revealed that the crystalline region of MCC was not adversely affected after grafting with GMA. The thermogravimetric analysis (TGA) data showed that the decomposition of grafted MCC occurred at higher temperature compared to the base MCC polymer.

WE-D-210-04: Radiation-Induced Polymerization of Ultrasound Contrast Agents in View of Non-Invasive Dosimetry in External Beam Radiation Therapy

Purpose: Ultrasound contrast agents (UCA’s) based on gas-filled microbubbles encapsulated by an amphiphilic shell are well established as safe and effective echo-enhancers in diagnostic imaging. In view of an alternative application of UCA’s, we investigated the use of targeted microbubbles as radiation sensors for external beam radiation therapy. As radiation induces permanent changes in the microbubble’s physico-chemical properties, a robust measure of these changes can provide a direct or indirect estimate of the applied radiation dose. For instance, by analyzing the ultrasonic dispersion characteristics of microbubble distributions before and after radiation treatment, an estimate of the radiation dose at the location of the irradiated volume can be made. To increase the radiation sensitivity of microbubbles, polymerizable diacetylene molecules can be incorporated into the shell. This study focuses on characterizing the acoustic response and quantifying the chemical modifications as a function of radiation dose. Methods: Lipid/diacetylene microbubbles were irradiated with a 6 MV photon beam using dose levels in the range of 0–150 Gy. The acoustic response of the microbubbles was monitored by ultrasonic through-transmission measurements in the range of 500 kHz to 20 MHz, thereby providing the dispersion relations of the phase velocity, attenuation and nonlinear coefficient. In addition, the radiation-induced chemical modifications were quantified using UV-VIS spectroscopy. Results: UV-VIS spectroscopy measurements indicate that ionizing radiation induces the polymerization of diacetylenes incorporated in the microbubble shell. The polymer yield strongly depends on the shell composition and the radiation-dose. The acoustic response is inherently related to the visco-elastic properties of the shell and is strongly influenced by the shell composition and the physico-chemical changes in the environment. Conclusion: Diacetylene-containing microbubbles are polymerizable under influence of ionizing radiation and are a promising design concept within the development of a novel non-invasive in-vivo radiation dosimeter for external beam radiation therapy. This work was funded by the Research Foundation - Flanders (FWO).

Tribological and Mechanical Properties of Poly[(R)-3-hydroxybutyric acid] Grafted with Vinyl Compounds: Insight into Possible Application

Biodegradable graft copolymers were prepared by gamma radiation-induced graft polymerization of two vinyl monomers, vinyl acetate and vinyl alcohol, onto poly[(R)-3-hydroxybutyric acid]. Success of the grafting reaction was verified by Fourier-transform infrared and nuclear magnetic resonance spectroscopy. Thermal remolding was used to create membranes from the copolymers. We determined tribological and mechanical properties of the membranes obtained. The lowest elongation at break in tensile testing is seen for P(3HB) and the highest for P(3HB-g-VA). Up to 5 N or so, the highest scratch resistance is exhibited by P(3HB-g-VA). Piezoelectric behavior is seen for P(3HB-g-VA) while P(3HB-g-VAc) and plain P(3HB) showed no electric response. Explanation of the piezoelectric behavior in terms of molecular structures is provided.

Polymeric nanocomposite proton exchange membranes prepared by radiation-induced polymerization for direct methanol fuel cell

Abstract The vinyl group-modified montmorillonite clay (F-MMT), vinyl group-modified graphene oxide (F-GO), and vinyl group-modified multi-walled carbon nanotube (F-MWNT) were first prepared by ion exchange reaction of 1-[(4-ethylphenyl)methyl]-3-butyl-imidazolium chloride in order to use the materials for protection against methanol cross-over in direct methanol fuel cell (DMFC) membrane. Then polymeric nanocomposite membranes with F-MMT, F-GO, and F-MWNT were prepared by the solvent casting method after radiation-induced polymerization of vinyl monomers in water-methanol mixture solvents. The proton conductivity, water uptake, ion-exchange capacity, methanol permeability, and DMFC performance of the polymeric nanocomposite membranes with F-MMT, F-GO, and F-MWNT were evaluated.

Enhancement of immobilized lipase activity by design of polymer brushes on a hollow fiber membrane

A polymer brush possessing aminoethanol (AE) functional groups for lipase immobilization was grafted onto a hollow fiber membrane by radiation-induced graft polymerization. Almost the AE groups-grafted polymer brushes unfold through positive charge repulsion between the AE groups, enabling multi-layer immobilization of lipase. The hydroxyl groups in AE can also retain water molecules around hydrophilic part of the lipase. In this study, we controlled the length and density of the polymer brushes consisting of the glycidyl methacrylate (GMA) by changing the concentration of GMA monomer during radiation-induced graft polymerization. Immobilized lipase showed the highest activity on the grafted membrane when 5wt% of glycidyl methacrylate as monomer for the radiation-induced graft polymerization was used. Consequently high efficiency esterification (approximately 1600mmol/h/g-membrane) was achieved in five-layer lipase on AE polymer brush than that in monolayer lipase on the polymer brush possessing only hydroxyl groups. Moreover, the polymer brush possessing AE functional groups for lipase immobilization maintained high activity on the reuse for several times.

Radiation-chemical and optical properties of a radio-fluorogenic gel

The radiation-induced polymerization and fluorescence intensity of a radio- fluorogenic medium consisting of tertiary-butyl acrylate (TBA) with ca 100 ppm maleimido- pyrene (MPy) display a super-linear dependence on dose and a close to inverse square root dependence on dose rate over the range from 2 to 30 Gy/min. In contrast with the fluorescence, the clarity and optical absorption remain unchanged on irradiation up to at least 17% monomer conversion for which the medium is a rigid gel.

Adsorption behavior of samarium(III) from aqueous solutions onto PAN@SDS core-shell polymeric adsorbent

Abstract Adsorption behavior of samarium(III) radionuclides from aqueous solutions onto a novel polyacrylonitrile coated with sodium dodecyl sulfate (PAN@SDS), prepared by gamma radiation-induced polymerization, was studied in this work. The developed polymeric adsorbent was characterized by FT-IR, X-ray diffraction and N2 adsorption-desorption. The influence of some experimental parameters such as pH, initial samarium(III) concentration, SDS concentration, temperature, ionic strength and contact time on the adsorption efficiency of samarium(III) was evaluated. Results showed that adsorption efficiency of about 97% was attained for samarium(III) in the pH range 3.8–7.5. The kinetic study showed that samarium(III) was efficiently removed within 10 min and equilibrium was attained at around 30 min. Six isotherm models; Freundlich, Langmuir, Generalized, Redlich–Peterson, Toth and Sips, were used to fit the adsorption equilibrium data, and the best-fit three-parameter isotherms suggest that adsorption capacity of PAN@SDS for samarium(III) to be 97.73 mg g –1, which is a markedly high value compared to most of the other adsorbents reported for other metal ions. Using the Dubinin–Kaganer–Radushkevich (DKR) model, the mean free energy E was calculated as 1.569 kJ mol-1, which suggested that adsorption of samarium(III) was dominated by physisorption. Results of the thermodynamic parameters, ΔGo, ΔSo and ΔHo, showed that adsorption of samarium(III) onto PAN@SDS was feasible, spontaneous and exothermic in nature. Of the various studied kinetic models, the experimental kinetic data were best fitted to the modified multiplex model, and the adsorption process was mainly controlled by particle diffusion. Desorption studies showed that 95% of samarium(III) loaded on PAN@SDS were recovered using 2 mol L –1 HCl.

ICONE23-1873 Radioactive Strontium Removal from Seawater and Groundwater with Adsorptive Fibers Prepared by Radiation-Induced Graft Polymerization

The Great East Japan Earthquake and the tsunami that followed caused the meltdown of three reactors of the TEPCO Fukushima Daiichi nuclear power station (NPS), resulting in the emission of radionuclides such as cesium-137 and strontium-90 to the environment. Radioactive strontium was detected in seawater and groundwater at concentrations of 1.8 × 10^2 and 5.5 × 10^5 Bq/L, respectively, on October 7th 2014. Nonradioactive strontium dissolves at a concentration of 8 mg/L in seawater. No adsorbent can distinguish radioactive strontium from nonradioactive strontium; therefore, the adsorbent must collect both ions which coexist with other alkaline-earth metal ions such as magnesium and calcium ions. Inorganic compounds and chelate-forming resins are candidate adsorbents for strontium removal. However, It is difficult to use these adsorbents to process a large volume of water contaminated with radionuclides because of their granule and bead forms. We have prepared two kinds of adsorptive fiber by radiation-induced graft polymerization and subsequent chemical modifications: (1) sodium-titanate-impregnated fiber (ST fiber) and (2) iminodiacetate-group-immobilized fiber (IDA fiber). The preparation scheme of the ST fiber consisted of four steps. First, a commercially available 6-nylon fiber was irradiated with γ-rays to produce radicals. Second, sodium styrene sulfate was graft-polymerized onto the irradiated fiber. Third, a titanium species [Ti(OH)_2^<2+>]was bound to the sulfonic acid group of the grafted polymer chain. Finally, the titanium species was converted into sodium titanate with sodium hydroxide, and the resulting precipitate was impregnated onto the fiber. On the other hand, the IDA fiber was prepared as follows. An epoxy-group-containing vinyl monomer, glycidyl methacrylate, was graft-polymerized onto a previously γ-ray-irradiated 6-nylon fiber. Subsequently, the epoxy group was converted into an iminodiacetate group as a chelate-forming group by a reaction with disodium iminodiacetate. The former and latter fibers are applicable to strontium removal from seawater and groundwater, respectively.

ICONE23-1872 Radioactive Cesium Removal from Seawater Using Adsorptive Fibers Prepared by Radiation-Induced Graft Polymerization

The meltdown of three reactors of the TEPCO Fukushima Daiichi nuclear power station (NPS) caused by the Great East Japan Earthquake on March 11th 2011 resulted in the emission of radionuclides such as cesium-137 and strontium-90 to the environment. For example, radioactive cesium exceeding the legal discharge limit (90 Bq/L, 2×10^<-13> M) was detected in the seawater of the seawater-intake area of the NPS at the end of September 2014. Adsorbents with a high selectivity for cesium ions over other alkali metal ions such as sodium and potassium ions are required for cesium removal from seawater because sodium and potassium ions dissolve respectively at much higher concentrations of 5×10^<-1> and 1×10^<-2> M than cesium ions (2×10^<-9> M). In addition, the simple operations of the immersion in seawater and the recovery of the adsorbents from seawater are desirable at decontamination sites. We prepared a cobalt-ferrocyanide-impregnated fiber capable of specifically capturing cesium ions in seawater by radiation-induced graft polymerization and chemical modifications. First, a commercially available 6-nylon fiber was irradiated with γ-rays. Second, an epoxy-group-containing vinyl monomer, glycidyl methacrylate, was graft-polymerized onto the γ-rayirradiated nylon fiber. Third, the epoxy ring of the grafted polymer chain was reacted with triethylenediamine to obtain an anion-exchange fiber. Fourth, ferrocyanide ions, [Fe(CN)_6]^<4->, were bound to the anion-exchange group of the polymer chains. Finally, the ferrocyanide-ion-bound-fiber was placed in contact with cobalt chloride to precipitate insoluble cobalt ferrocyanide onto the polymer chains. Insoluble cobalt ferrocyanide was immobilized at the periphery of the fiber. However, the impregnation structure remains unclear. Here, we clarified the structure of insoluble cobalt ferrocyanide impregnated onto the polymer chain grafted onto the fiber to ensure the chemical and physical stability of the adsorptive fiber in various contaminated waters. The adsorption rate and capacity of the fiber for cesium ions were compared with those of a zeolite as a conventional adsorbent.

Development of an Adsorbent for Cs Removal Synthesized by Radiation-Induced Graft Polymerization

Development of an Adsorbent for Cs Removal Synthesized by Radiation-Induced Graft Polymerization

Impregnation Process of Insoluble Cobalt Ferrocyanide onto Anion-Exchange Fiber Prepared by Radiation-Induced Graft Polymerization

Impregnation Process of Insoluble Cobalt Ferrocyanide onto Anion-Exchange Fiber Prepared by Radiation-Induced Graft Polymerization

Batch Studies for Sorption of Ga(III), Cu(II), Ni(II) and Zn(II) Ions onto Synthetic Polymeric Resins

Poly(acrylamide-acrylic acid-dimethyl amino ethylmethacrylate), p(AM-AA-DMAEM) and Poly(acrylamide-acrylic acid)-ethylene diamine tetracetic acid disodium, p(AM-AA)-EDTANa2 were prepared by gamma radiation-induced template polymerization technique. The prepared polymeric materials were used for the sorption of Ga(III), Cu(II), Ni(II) and Zn(II) in aqueous solution. The effect of pH, weight of resins, metal ion concentrations and contact time on the sorption of these metal ions were studied.