C. V. Chaudhari

Electron Beam Grafted Polymer Adsorbent for Removal of Heavy Metal Ion from Aqueous Solution

Abstract An electron beam grafted adsorbent was synthesized by post irradiation grafting of acrylonitrile (AN) on to a non‐woven thermally bonded polypropylene (PP) sheet using 2 MeV electron beam accelerator. The grafted poly(acrylonitrile) chains were chemically modified to convert a nitrile group to an amidoxime (AMO) group, a chelating group responsible for metal ion uptake from an aqueous solution. The effect of various experimental variables viz. dose, dose rate, temperature, and solvent composition on the grafting extent was investigated. PP grafted with the amidoxime group (AMO‐g‐PP) was tested for its suitability as an adsorbent for removal of heavy metal ions such as Co2+, Ni2+, Mn2+, and Cd2+ from aqueous solution. Langmuir and Freundlich adsorption models were used to investigate the type of adsorption of these ions. The adsorption capacities of the adsorbent for the metal ions were found to follow the order Cd2+>Co2+>Ni2+>Mn2+. The kinetics of adsorption of these ions indicated that the rate of adsorption of Cd2+ was faster than that of other ions studied.

Polychloroprene rubber/ethylene-propylene diene monomer/multiple walled carbon nanotube nanocomposites: synergistic effects of radiation crosslinking and MWNT addition

Synergistic effect of MWNT induced reinforcement and high energy radiation induced crosslinking on the physico-mechanical and thermal characteristics of polychloroprene rubber (PCR)/ethylene-propylene diene rubber (EPDM)/MWNT elastomeric nanocomposites was investigated. The extent of reinforcement, as assessed using the Kraus equation suggested high reinforcement of the blend on MWNT addition; though, the thermal stability and glass transition of the PCR and EPDM components were not significantly affected by MWNTs. The elastic modulus increased with the radiation dose as well as with the increase in MWNT content. The reinforcing mechanism of the nano-composites was studied by various micromechanics models all of which predicted higher moduli than the experimentally observed results, indicating agglomeration in the nano-composites. Nevertheless, in all the composites synergistic effect of radiation crosslinking and MWNT induced reinforcement were seen, suggesting radiation induced crosslinking between polymer and MWNT interface.

Correlation between surface energy and uptake behavior of radiation-grafted methacrylic acid-g-LDPE

An efficient and low-cost effluent adsorbent has been developed by grafting an ionizable monomer onto polyolefin surface and its efficacy was tested for dyes and metal ion uptake from aqueous medium. The grafted matrix was synthesized by optimizing various experimental parameters such as irradiation dose, dose rate, monomer concentration, inhibitor concentration, surfactant concentration, and backbone thickness. Grafting yield decreased with dose rate and thickness and increased with the concentration of methacrylic acid and inhibitor. Grafting kinetics studies indicated that grafting rate is comparatively much affected by dose rate that monomer concentration. Surface energy of the grafted surface was accessed from dynamic contact angle measurements. Uptake study of Basic Red 29, Methylene Blue showed high correlation with grafting yield and polar component of the surface energy; however, metal ion uptake was exceptionally high at ~25 grafting (%), highlighting anomalous behavior of MAA-g-LDPE with respect to surface energy and total ion uptake capacity.

Radiation Processed Styrene-Butadiene Rubber/Ethylene-Propylene Diene Rubber/Multiple-Walled Carbon Nanotubes Nanocomposites: Effect of MWNT Addition on Solvent Permeability Behavior

Different compositions of SBR/EPDM 50:50 blends containing multiple-walled carbon nanotubes (MWNT) as nanoparticulate fillers (0.5%–10%) were evaluated for radiation sensitivity and solvent permeability. The efficiency of radiation ***cross-linking was analyzed by gel-content and Charlesby–Pinner parameter measurements. ***Gamma-radiation-induced cross-linking extent was found to increase with radiation dose and MWNT concentration, which was reflected in different extents of swelling. Rigorous analysis of swelling and diffusion data, on the basis of the transport exponent (n) values and diffusion/relaxation rate indicated anomalous diffusion behavior for most of the nanocomposites. The swelling extent in different solvents was found to be a function of polymer-solvent interaction as well as stearic hindrance due to the structure/size of the solvent molecules. Polymer-filler interaction investigated by a Kraus plot indicated high reinforcement of the SBR/EPDM matrix on MWNT addition. There was no significant change in surface energy or hydrophilicity of the SBR/EPDM matrix on introduction of MWNT into it.

Swelling response of radiation synthesized 2-hydroxyethylmethacrylate-co-[2-(methacryloyloxy)ethyl] trimethylammonium chloride hydrogels under various in vitro conditions.

High-energy 60Co gamma radiation has been used to synthesize 2-hydroxyethylmethacrylate-co-[2-(methacryloyloxy)ethyl]trimethylammonium chloride (HEMA-co-MAETC) polyelectrolyte hydrogels. HEMA-co-MAETC co-polymer gels were characterized and investigated for swelling behaviour in different swelling conditions. Fourier transformed infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) techniques were used to characterize the co-polymer gels. Swelling extent of the gels was found to be a linear function of MAETC content in the gels. The effect of ionic strength, temperature, pH, some solutes of biological importance like glucose, urea, and surfactants such as Triton-X and deoxycholic acid on swelling behavior have been reported. The swelling of gels at higher temperature enhanced the swelling rates but not the swelling extent. HEMA-co-MAETC hydrogel exhibited an excellent responsive characteristic to the ionic strength of the swelling medium. It was found that the swelling of the co-polymer gel at 60°C reduced the swelling–deswelling cycle time by approx. 30% without altering the swelling extent. The gels were also investigated for their swelling in aqueous solutions of anionic dyes, acid blue 25 (AB25), acid blue (AB74) and acid yellow 99 (AY99), and were found to be suitable for dye uptake applications.

Polymers, Blends and Nanocomposites for Implants, Scaffolds and Controlled Drug Release Applications

Polymer blends and nanocomposites are widely explored for different biomedical applications such as biodegradable scaffolds, biosensors, implants and controlled drug release. Both, synthetic and semi-synthetic polymers are used in medical applications and have their inherent advantages and disadvantages. Synthetic polymers offer flexibility of varying monomer unit, molecular weight, branching and thus offer a diverse set of physico-mechanical properties, whereas natural polymers offer superior biocompatibility and biodegradation profile. Availability of polymer blending techniques adds another dimension to the property set that polymers can offer, and therefore polymer blending is often used to tailor biodegradability and physico-mechanical properties. Polymers, in general, have poor mechanical properties when compared to metals and ceramics, putting a load bearing limit on polymer-based medical implants. The addition of reinforcing/functional filler is expected to overcome such disadvantages of polymers. Polymers composites are heterogeneous systems wherein polymers are compounded with micron or nano-size particles to render high strength, electrical conductivity or any other functional attribute. This chapter describes the technological aspects of polymer blends and nanocomposites with a specific reference to synthesis, characteristics and applications of multi-phasic polymer systems as implants, scaffolds, and controlled drug release matrices. A detailed account of synthetic and natural polymer nanocomposites along with a brief discussion on important nano-fillers used in medical applications and interface modification techniques is presented. Few examples of recently explored novel polymer blends and composites that displayed promising properties as implants, scaffolds, biosensors and control release matrices have also been discussed.

Phosphate functionalized radiation grafted Teflon for capturing and quantifications of U(VI) and Pu(IV) ions at ultra-trace concentration in aqueous samples

A phosphate groups bearing thin polymer film has been anchored on Teflon by radiation induced grafting and subsequent chemical modification. Thus formed phosphate-g-Teflon (Ph-g-T) sheet has been characterized appropriately and studied for its selectivity towards Pu(IV) and U(VI) ions at different acidities. Depending upon acidity dependent selectivity of Ph-g-T toward actinides ions, the solid state nuclear track detector based methods was developed to quantify Pu(IV) and U(VI) at ultra-trace concentration in a variety of aqueous samples.