Radiation Grafting Research Articles

Adsorption of Zn(II) from aqueous solution and separation of zinc isotopes by displacement chromatography using chelating adsorbent

The removal of zinc ions (Zn(II)) in water and the separation of zinc isotopes were fully investigated in this study. Imidodiacetic acid (IDA) type adsorbent (named PSGI) based on polystyrene spheres (PS) was synthesized by simultaneous irradiation grafting. By adsorption method, the removal of Zn(II) from water by the chelating adsorbent was studied in batch experiments. Under optimized condition, PSGI showed the removal efficiency of more than 98 % for Zn(II) and the adsorption capacity of 70.1 mg/g. Langmuir isothermal and pseudo-second-order kinetic model fitted the experimental results better, indicating that the adsorption is dominated by chemical adsorption. The spent adsorbent (PSGI-Zn) was used for further zinc isotope separation by displacement chromatography using EDTA-NH4 solution as eluent. Due to the mass effect of isotopes, 70Zn was found to preferentially fractionated into the front-end effluents with the highest front enrichment values of 70Zn/64Zn. By extending the migration distance to 20 m, we obtained the best isotope enrichment with the front maximum enrichment values as 1.0949, 1.0739 and separation coefficient values as 1.977 × 10−3, 8.33 × 10−3 corresponding to the isotope pairs 66Zn/64Zn, 68Zn/64Zn.

Aryl ether-free polymer electrolytes for electrochemical and energy devices.

Anion exchange polymers (AEPs) play a crucial role in green hydrogen production through anion exchange membrane water electrolysis. The chemical stability of AEPs is paramount for stable system operation in electrolysers and other electrochemical devices. Given the instability of aryl ether-containing AEPs under high pH conditions, recent research has focused on quaternized aryl ether-free variants. The primary goal of this review is to provide a greater depth of knowledge on the synthesis of aryl ether-free AEPs targeted for electrochemical devices. Synthetic pathways that yield polyaromatic AEPs include acid-catalysed polyhydroxyalkylation, metal-promoted coupling reactions, ionene synthesis via nucleophilic substitution, alkylation of polybenzimidazole, and Diels-Alder polymerization. Polyolefinic AEPs are prepared through addition polymerization, ring-opening metathesis, radiation grafting reactions, and anionic polymerization. Discussions cover structure-property-performance relationships of AEPs in fuel cells, redox flow batteries, and water and CO2 electrolysers, along with the current status of scale-up synthesis and commercialization.

Preparation of a Novel Proton Exchange Membrane Using Radiation Grafted ETFE Film for Fuel Cell

For many different applications, functional polymeric materials are extremely important in electrochemical reactions. The development of polymer electrolytes, such as those used in fuel cells, depends heavily on these functional materials. One of the most significant sources of power for applications in numerous industries is provided by fuel cells. In this study, a proton exchange membrane (PEM) was developed using ethylene tetrafluoroethylene (ETFE) film with binary blends of acrylic acid (AA) and sodium styrene sulfonate (SSS), while NaCl served as an additive. As the monomer concentration increased, the degree of grafting (DG) increased. Gravimetric analyses, Fourier Transform Infrared (FTIR) spectroscopy, mechanical characteristics, and surface morphology (SEM) have all supported the radiation grafting. The physical and chemical durability of 60% DG of ETFE-g-AA-SSS film made it an ideal PEM for this study since it is more durable than other grafted samples of ETFE-g-AA-SSS film. The 60% DG of PEM's ion-exchange capacity (IEC) was determined to be 0.26 mmol g-1. They demonstrated excellent thermal, mechanical, and acid stability characteristics. In H2O2 solutions, they are highly stable, and they display significant water uptake. It is therefore applicable to acidic fuel cells.

Bioremediation of Synthetic Polyacrylic acid via radiation graft copolymerization with natural based polymers

Bioremediation of Synthetic Polyacrylic acid via radiation graft copolymerization with natural based polymers

Radiation crosslinking and grafting of chitosan: Conversion of biowaste to an efficient adsorbent for removal of cationic dyes

By the mutual radiation grafting technique using Co60 gamma radiation, a novel anionic adsorbent “CRChitosan-g-SSS” was developed where in p-Sodium Styrene Sulphonate was covalently grafted onto crosslinked chitosan backbone. The synthesized radiation-grafted adsorbent was tested for the adsorptive removal of cationic dyes: methylene blue, malachite green and Congo red from aqueous solutions. The adsorbed amount of the respective dyes was 89.12, 73.13, and 29.14 (mg/g) respectively, which could be better described with Langmuir isotherm and pseudo-second-order reaction according to the correlation coefficient values, indicating favorable and feasible adsorption. Various factors influencing the adsorption capacity of“CRChitosan-g-SSS” like initial dye concentration, contact time, solution pH, and temperature were also studied. Different thermodynamic parameters such as standard free energy, standard enthalpy, and standard entropy were calculated which revealed the adsorption process to be exothermic and spontaneous. The radiation-grafted anionic adsorbent showed promising properties for the removal of toxic cationic dyes (i.e. Methylene blue, Malachite green, and Congo red).

Efficient Removal of Cr(VI) by Protonated Amino-Bamboo Char Prepared via Radiation Grafting: Behavior and Mechanism

Biochar is considered to be the most promising substrate for the preparation of environmentally functional materials. The modification of bamboo char can significantly improve the removal rate of toxic ions from wastewater; however, there are few reports that focus on the radiation grafting method. Here, glyceride methacrylate (GMA) is successfully grafted onto bamboo char through electron beam radiation, followed by amination using the existing epoxide group in diethyltriamine, and finally, treated with hydrochloric acid to obtain protonated diethyltriamine-functionalized bamboo char (CDGBC). The results of IR, TG, XRD, and SEM prove the successful fabrication of a CDGBC biosorbent. The results show that the solution pH has a great effect on the adsorption capacity, and a maximum adsorption capacity of 169.13 mg/g is obtained at pH = 2 for Cr(VI). In addition, the adsorption behavior of Cr(VI) onto CDGBC is demonstrated to obey the pseudo-second-order kinetic and Freundlich isotherm models, and thermodynamic analysis exhibits that Cr(VI) adsorption is an endothermic spontaneous process. A possible adsorption mechanism based on the electrostatic interaction, reduction, and surface complexation is proposed, according to the obtained results. This work confirms that radiation-induced grafting modification can effectively transform biochar into a high-performance adsorbent for Cr(VI) removal, offering a new approach to synthesizing an efficient biosorbent.

Obtaining hybrid absorbents by grafting acrylamide onto chitosan chains under gamma irradiation

Hybrid hydrogels have been synthesized by radiation grafting of acrylamide to chitosan chains. The structure of the acrylamide-grafted chitosan was examined using FTIR spectroscopy, X-ray diffraction and simultaneous thermal analysis. It has been determined that both hydroxyl and amino groups of the polysaccharide are the grafting centers of growing polyacrylamide chains on the chitosan macromolecules. The effect of the reagents ratio on the sorption and rheological properties of the obtained hydrogels has been studied. Hydrogels based on acrylamide-grafted chitosan were modified chemically by alkaline hydrolysis, and the effect of hydrolysis on the sorption capacity of hydrogels with respect to water and Cu(II) ions was examined.

Radiation synthesized carboxyl-functionalized covalent organic framework adsorbent for efficient heavy metal decontamination

Carboxyl groups exhibit great potential in the field of heavy metal decontamination due to their good coordination ability. In this work, acrylic acid was grafted onto covalent organic framework (COF) by using a γ-ray radiation grafting approach. A carboxyl-functionalized adsorbent designated AA-TbDa-COF with high performance for multiple heavy metal removal was obtained. Infrared spectroscopy and thermogravimetric analysis proved the successful carboxyl modification. The porous nanofiber morphology and high accessibility of carboxyl functional groups give the resultant AA-TbDa-COF ultra-fast adsorption kinetics. The capacity for Pb2+, Cd2+ and Cu2+ decontamination was 127.9, 60.6 and 39.8 mg/g, respectively. The preparation of functional COFs by radiation method is extended to the field of heavy metal treatment, proving the great potential of radiation-prepared materials in environmental governance.

CO2 adsorption-desorption in batch and continuous conditions by using a nano-fibrous polyacrylonitrile radiation grafted adsorbent under response surface methodology

This research presents a comprehensive study on the modification of polymer nanofibers. Polyacrylonitrile nanofibers were prepared from industrial polyacrylonitrile (PAN) material using electrospinning. Then, the grafting of glycidyl methacrylate monomer on the PAN surface was successfully performed using the radiation grafting method. Also, the modification procedure was carried out using the amination approach with ethanolamine (EA). The influence of essential parameters for adsorbent synthesis, including radiation dose (10–50 kGy), monomer concentration (0–50 %), and ethanolamine concentration (0–100 %), was examined using the response surface methodology (RSM) based on the central composite design (CCD) approach. The synthesis results showed that the optimal adsorbent (NF-PAN/Rad/GMA/EA) showed a maximum bond degree (DG %) equal to 323.45 %, and a degree of amination (DA %) equal to 170.88 %. The highest adsorption capacity with NF-PAN/Rad/GMA/EA adsorbent equal to 3.23 mmol/g was obtained under ambient conditions, a flow rate of 100 ml/min, and a concentration of 5 % CO2. The highest fit was obtained with the Pseudo-second-order model in evaluating the traditional adsorption model. The Langmuir isotherm showed that the adsorption process is performed as a monolayer on the adsorbent surface. The recovery of NF-PAN/Rad/GMA/EA adsorbent at 80 °C and a low time of 15 min confirm the applicability of this novel adsorbent.

New generation radiation-grafted PVDF-g-VBC based dual-fiber electrospun anion exchange membranes

Anion Exchange Membranes (AEM) have the potential to solve the cost issues of fuel cell technologies due to their basic environment that can allow the use of cheaper components. However, there is still a need to develop an ideal inexpensive, mechanically robust AEM with high ionic conductivity and ion exchange capacity (IEC). In this work, we present various dual-fiber electrospun membranes based on a novel radiation-grafted copolymer. First, the synthesis route of radiation-induced grafting of vinyl benzyl chloride (VBC) onto poly (vinylidene fluoride) (PVDF) to prepare PVDF-g-VBC was optimized. Then, PVDF-g-VBC powders were used to fabricate dual-fiber electrospun mats with inert PVDF and commercial Fumion-FAA-3 ionomer. Dual-fiber electrospun mats were hot-pressed and then quaternized with trimethylamine. Finally, mechanical properties, ion exchange capacity, ionic conductivity, and morphology of these prepared dual-fiber electrospun membranes were investigated. The dual-fiber membrane prepared with PVDF-g-VBC (88% of the total weight of the membrane) and PVDF: Fumion-FAA-3 (1:2) mix (12 wt%) realized ionic conductivity of 4.67 mS/cm at 25 °C, high ion exchange capacity of 1.35 mmol/g with Young's Modulus of 761 MPa. The membrane based on the combination of radiation grafting and dual-fiber electrospinning was prepared for the first time in literature and offers the prospect of tuning and fine-control of mechanical and physicochemical properties of AEMs.

Tailoring Acid Free-Paper based Analytical Devices (Af-PADs) via radiation assisted modification of cellulose paper

A novel green fabrication approach is being proposed based on radiation assisted modification of Whatman filter paper 1 (WFP) for development of Acid Free-Paper based Analytical Devices (Af-PADs). Af-PADs exude immense potential as handy tools for on-site detection of toxic pollutants such as, Cr(VI), boron, etc., which have established detection protocols involving acid mediated colorimetric reactions that necessitate external acid addition. The proposed Af-PAD fabrication protocol asserts its novelty through elimination of external acid addition step, making the detection process safer and simpler. To achieve this, poly(acrylic acid) (PAA) was grafted onto WFP via a single step, room temperature process of gamma radiation induced simultaneous irradiation grafting, introducing acidic -COOH groups in the paper thereon. Grafting parameters namely, absorbed dose and concentrations of monomer, homopolymer inhibitor and acid were optimized. The -COOH groups incorporated in PAA-grafted-WFP (PAA-g-WFP) provide localized acidic conditions for colorimetric reactions between pollutants and their sensing agents, anchored on the PAA-g-WFP. Af-PADs loaded with 1,5-diphenylcarbazide (DPC) have been ably demonstrated for visual detection and quantitative estimation of Cr(VI) in water samples using RGB image analysis, with LOD value of 1.2 mg.L−1 and a measurement range comparable to that of commercially available PADs based Cr(VI) visual detection kits.

CellUSorb: A high-performance, radiation functionalized cellulose based adsorbent for Uranium (VI) remediation in ground water

A state of the art, phosphate functionalized cotton cellulose based green U(VI) adsorbent has been synthesized via single step, 60Co gamma radiation mediated simultaneous irradiation grafting process, wherein bis(2-methacryloxyethyl) phosphate (B2MEP) was grafted onto cotton cellulose fabric. Samples were characterized using 13C NMR, FTIR, EDXRF, XRD and SEM techniques. Poly(B2MEP)-g-cellulose adsorbent (CellUSorb) was tested for removal of Uranyl (U(VI)) ions from water, adsorption capacities being 79.9 mg.g−1 and 135.9 mg.g−1 in batch and column modes, respectively. The equilibrium adsorption data were analyzed using Langmuir, Freundlich and Redlich-Peterson isotherm models, and kinetic data using pseudo first order, pseudo second order, intra-particle diffusion and Boyd’s models. The adsorbent viability was enhanced through regeneration achieved using ammonium oxalate as eluent, ensuring reusability for five cycles with < 20 % attrition loss/cycle. A standalone, portable water treatment set up, housing a ∼ 100 g CellUSorb cartridge (maximum theoretical U(VI) adsorption capacity ∼ 27,200L for [U(VI)] = 500 µg.L−1), has been conceptualized, fabricated and successfully tested for U(VI) removal to < 30 µg.L−1 (WHO permissible limit) from contaminated water. With potential upscaling for large scale, onsite U(VI) remediation, CellUSorb is a promising prospect that spotlights the role of cellulose in accomplishing UNO’s Sustainable Development Goal of “clean water for all” (SDG6).

Radiation grafting of 4-vinylpyridine and 2-hydroxyethyl methacrylate onto silicone rubber films, quaternization and antimicrobial properties

A novel antibacterial system was synthesized by surface modification of silicone rubber films SR with an antimicrobial quaternized 4-vinylpyridine (4VP) and one antibiofouling 2-hydroxyethylmethacrylate (HEMA) by radiation grafting in two steps. The modification was carried out by preirradiation oxidative grafting of HEMA, then direct 4VP radiation grafting and further quaternization. The optimum grafting conditions were obtained and quaternization with alkyl bromide of the pyridine groups of the synthesized systems were realized to study the antimicrobial properties. The modified films were characterized by FTIR spectroscopy, swelling behavior, TGA, SEM and AFM.Studies on antibacterial activity with Gram-positive S. aureus and Gram-negative E. coli were determined; systems with quaternized 4VP presented more than 90% of inhibition for gram positive bacteria, and only one sample (SR-g-4VP) reached 45% of inhibition for gram negative.

Effective CO2 capture by using poly (acrylonitrile) nanofibers based on the radiation grafting procedure in fixed-bed adsorption column

In this study, a new adsorbent was investigated for CO2 adsorption in the fixed-bed column. Poly (acrylonitrile) nanofibers were prepared by electrospinning, then grafting under gamma irradiation with glycidyl methacrylate (GMA). Then, the nanofibers were modified with ethanolamine (EA), diethylamine (DEA) and triethylamine (TEA) to adsorb carbon dioxide molecules. Dynamic adsorption experiments were performed with a mixture of CH4, CO2 in a constant bed column at ambient pressure and temperature and CO2 feed concentration (5%). The maximum adsorption capacity is 2.84 mmol/g for samples with 172.26% degree of grafting (DG) in 10 kGy. Also, the degree of amination with ethanolamine was achieved equal to 170.83%. In addition, the reduction of the regeneration temperature and the stability of this adsorbent after four cycles indicated the high performance of this adsorbent for CO2 adsorption.

Green preparation of silver nanocluster composite AgNCs@CF-g-PAA and its application: 4-NP catalytic reduction and hydrogen production.

4-Nitrophenol (4-NP) is a serious organic environmental pollutant. Conversion of 4-nitrophenol to 4-aminophenol (4-AP) by catalytic hydrogenation is an effective solution. In this work, a catalyst (AgNCs@CF-g-PAA) loaded with silver nanoclusters (AgNCs) was prepared by radiation technique. Firstly, the template polyacrylic acid (PAA) was grafted onto the cotton fiber (CF) by radiation grafting technique to obtain a solid template (CF-g-PAA). After that, AgNCs were synthesized in situ on CF-g-PAA by radiation reduction, and the composite material AgNCs@CF-g-PAA was obtained directly. AgNCs@CF-g-PAA has an obvious photoluminescence phenomenon, which is attributed to the stable AgNCs binding to the carboxyl on the PAA molecular chain. Due to the extremely small size of AgNCs, AgNCs@CF-g-PAA has good catalytic characteristics. The prepared AgNCs@CF-g-PAA catalyst has a very high catalytic rate for the hydrogenation of 4-NP. Even at high concentrations of 4-NP, AgNCs@CF-g-PAA can still maintain a high catalytic rate. At the same time, the AgNCs@CF-g-PAA catalyst can also be used to catalyze the rapid hydrolysis of sodium borohydride, which is conducive to hydrogen production. In summary, we have prepared a practical catalyst AgNCs@CF-g-PAA with high catalytic performance based on cheap raw materials and a simple synthesis route, which provides a catalyst candidate for the treatment of water contaminant 4-NP and the production of hydrogen from sodium borohydride.

Electron beam irradiation modified carboxymethyl chitin microsphere-based hemostatic materials with strong blood cell adsorption for hemorrhage control.

Timely control of coagulopathy bleeding can effectively reduce the probability of wound infection and mortality. However, it is still a challenge for microsphere hemostatic agents to achieve timely control of coagulopathy bleeding. In this work, the CCM-g-AA@DA hemostatic agent based on carboxymethyl chitin microspheres, CCM, was synthesized using electron beam irradiation-induced grafting polymerization of acrylic acid and coupling with dopamine. Irradiation grafting endowed the microspheres with excellent adsorption performance and a rough surface. The microspheres showed a strong affinity to blood cells, especially red blood cells. The maximum adsorption of red blood cells is up to approximately 100 times that of the original microspheres, the CCM. The introduction of dopamine increased the tissue adhesion of the microspheres. At the same time, the microspheres still possessed good blood compatibility and biodegradability. Furthermore, the CCM-g-AA@DA with Fe3+ achieved powerful procoagulant effects in the rat anticoagulant bleeding model. The bleeding time and blood loss were both reduced by about 90% compared with the blank group, which was superior to that of the commercially available collagen hemostatic agent Avitene™. In summary, the CCM-g-AA@DA hemostatic agent shows promising potential for bleeding control in individuals with coagulation disorders.

Electron beam irradiation grafting of metal-organic frameworks onto cotton to prepare antimicrobial textiles.

Textiles modified with antimicrobial nanomaterials have excellent comprehensive performance. However, the shedding of nanoparticles often occurs in actual use. This not only reduces the service life of antimicrobial textiles, but also causes potential harm. Here, we report a new method to covalently immobilize a zinc-imidazolate MOF (ZIF-8) onto cotton fabric by electron beam irradiation to prepare antimicrobial textiles with excellent durability. A series of characterization analysis showed the electron beam irradiation did not damage the structure of the ZIF-8 nanoparticles and the particles were successfully introduced onto cotton fibers via poly hydroxyethyl acrylate (PHEA). The modified cotton fabric exhibited >99% inhibition of Escherichia coli, Staphylococcus aureus and Candida albicans. The results of dry cleaning and rub resistance tests showed that the prepared antimicrobial cotton fabric had significant durability which was attributed to the strong covalent binding between the MOF and textile.

Silver nanoparticles-immobilized-radiation grafted polypropylene fabric as breathable, antibacterial wound dressing

In this work, a simplistic approach for developing an antibacterial and hydrophilic non-woven polypropylene (NWPP) fabric with excellent breathability has been presented via a two-step process. In the first step, acrylic acid was introduced onto NWPP fabric using simultaneous irradiation graft polymerization and pre-irradiation graft polymerization methods. Different grafting parameters, e.g., absorbed dose, monomer concentration, homopolymer inhibitor, reaction time, etc., were studied to optimize the grafting process. Subsequently, the acrylic acid grafted NWPP (NWPP-g-AA) fabric was immobilized with silver nanoparticles (Ag NPs), prepared from silver nitrate using trisodium citrate as reducing agent. After optimizing the grafting parameters, the NWPP-g-AA and Ag NPs-(NWPP-g-AA) samples were thoroughly characterized by grafting yield, FTIR, SEM, TEM, water contact angle, water vapor transmission rate (WVTR) and mechanical properties. The Ag NP-(NWPP-g-AA) fabric samples exhibited desired hydrophilicity, breathability and mechanical strength. Ag NP-(NWPP-g-AA) fabric samples were tested for antibacterial activity using plate count method after serial dilution, and exhibited excellent antibacterial efficacy against S.aureus (gram positive) and E.coli (gram negative) bacteria. This strategy demonstrated that a hydrophilic NWPP fabric having long-lasting antimicrobial activity was developed by gamma radiation-induced graft polymerization, which offers an ideal material for antibacterial wound dressing applications.

Highly selective adsorption of Pt(IV) from spent catalyst by polyethyleneimine functionalized polyethylene/polypropylene non‐woven fabric

AbstractAiming at efficient recovery of platinum (Pt) from aqueous solution, the aminated polyethylene/polypropylene non‐woven fabric (PE/PP NWF) was synthesized via radiation grafting of glycidyl methacrylate (GMA), followed by ring‐opening reaction with polyethyleneimine (PEI). The effects of different parameters, including pH, sorption time, initial Pt(IV) concentration, competing ions and adsorbent dosage on the Pt(IV) adsorption performance were investigated by batch adsorption tests. A high Pt(IV) adsorption capacity of 485.0 mg g−1 (initial concentration: 263.5 mg L−1) was achieved, and the adsorption kinetics and isotherm conformed to the pseudo‐second‐order model and the Langmuir isotherm model, respectively. Moreover, the PEI functionalized PE/PP NWF exhibited excellent adsorption performance over the wide pH range (1–6), and also good selectivity for Pt(IV) over multiple coexisting metal cations (Ni, Cu, Co, Pb, Mg, and Zn). The recovery ratio of Pt from spent proton exchange membrane fuel cell (PEMFC) catalysts reached 89.7% after three cycles of regeneration.

Green synthesis of loofah-based biosorbent via radiation grafting for effective removal of methylene blue

A new loofah-based biosorbent with high adsorption capacity for cationic dye was synthesized by a one-step co-radiation grafting method. The successful grafting of sodium 4-vinylbenzene sulfonate (SSS) onto loofah sponge (LFs) through electron beam radiation can significantly improve the remove capacity of methylene blue in wastewater. The biosorbent with a 409.67 mg/g of uptake capacity for methylene blue (MB), was higher than most of the loofah based adsorbents reported. FT-IR, elemental analysis, XRD, SEM and TG were used to analyze the changes in the functional group composition, element content, morphology, thermal stability of the obtained biosorbent. The pH, contact time, temperature and the effect of dosage on adsorption were also investigated. The results showed that the adsorption behavior well accorded with the pseudo-second-order kinetic and Langmuir adsorption model, which proved that the adsorption was a single-layered and chemisorption process. The thermodynamic parameters suggested a spontaneous and endothermic process. XPS analysis confirmed a potential adsorption mechanism was based on hydrogen bond interaction, electrostatic interaction and π-π stacking. Additionally, the adsorbent owned outstanding reusability, which could be reused five times with a slight reduction of removal rate. Overall, this research enriches the MB trapping agent and provides a new methods for the reuse of waste natural loofah sponge, and it will be a valuable research with the advantages of low cost and less environmental pollution.