Nilanjal Misra

Cellulose based cationic adsorbent fabricated via radiation grafting process for treatment of dyes waste water.

A cationized adsorbent was prepared from cellulosic cotton fabric waste via a single step-green-radiation grafting process using gamma radiation source, wherein poly[2-(methacryloyloxy) ethyl]trimethylammonium chloride (PMAETC) was covalently attached to cotton cellulose substrate. Radiation grafted (PMAETC-g-cellulose) adsorbent was investigated for removal of acid dyes from aqueous solutions using two model dyes: Acid Blue 25 (AB25) and Acid Blue 74 (AB74). The equilibrium adsorption data was analyzed by Langmuir and Freundlich isotherms, whereas kinetic data was analyzed by pseudo first order, pseudo second order, intra particle diffusion and Boyds models. The PMAETC-g-cellulose adsorbent with 25% grafting yield exhibited equilibrium adsorption capacities of ∼ 540.0mg/g and ∼ 340.0mg/g for AB25 and AB74, respectively. Linear and nonlinear fitting of adsorption data suggested that the equilibrium adsorption process followed Langmuir adsorption isotherm model, whereas, the kinetic adsorption process followed pseudo-second order model. The multi-linearities observed in the intra-particle kinetic plots suggested that the intraparticle diffusion was not the only rate-controlling process in the adsorption of acid dyes on the adsorbent, which was further supported by Boyds model. The adsorbent could be regenerated by eluting the adsorbed dye from the adsorbent and could be repeatedly used.

A horseradish peroxidase immobilized radiation grafted polymer matrix: a biocatalytic system for dye waste water treatment

Horseradish peroxidise (HRP) enzyme, an industrially and environmentally relevant biocatalyst, was covalently immobilized onto epoxy functionalized polypropylene (PP) films, fabricated via 60Co-gamma radiation induced mutual irradiation grafting of 2,3-epoxypropyl methacrylate (EPMA) on to PP matrix. The effect of the grafting parameters, such as radiation dose and monomer concentration, on the grafting yield was studied in order to optimize the radiation grafting process. Poly(EPMA)-g-PP films were characterized by grafting yield determination, FTIR, SEM and XPS. The catalytic activity of the immobilized enzyme HRP system was spectrophotometrically assayed using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) as a substrate. The immobilized HRP system was investigated for repeatability, storage, thermal and pH stability with respect to the free enzyme. The practical applicability of immobilized HRP in the treatment of textile dye waste water was examined by studying the repeated catalytic degradation of Basic Red 29 (BR29) dye. The immobilized enzyme system was found to cause ∼90% degradation of BR29 over a period of 20 days and was observed to be reusable for five cycles without substantial loss in activity.

Studies on production of fructo-oligosaccharides (FOS) by gamma radiation processing of microbial levan

Microbial levan, a natural polymer of fructose, was produced and purified by alcohol precipitation from culture supernatants of Bacillus megaterium type 1 grown in an optimized liquid sucrose medium. GPC analysis showed that the yield of the major fraction of levan having molecular weight ~5000 D increased with increase in sucrose concentration in the broth. Levan subjected to (60)Co-gamma radiation as well as acid hydrolysis was investigated by rheometry, UV-visible spectrophotometry and gel permeation chromatography (GPC) techniques. Unlike most of the polysaccharides, levan powder exhibited good radiation degradation stability up to 150 kGy. Gamma irradiation of 10% levan aqueous solution at 250 kGy yielded 63.0% fructo-oligosaccharide (FOS) with an average molecular weight of 1250 D. Acid hydrolysis of levan using 0.5 N HCl for 60 min treatment time gave rise to the desired FOS with lower yield (23.1%) as compared to that obtained in gamma radiolysis process.

Radiation engineered copper nanoparticles immobilised catalytic reactor (Cu-NICaR) system

A robust and reusable Copper Nanoparticles Immobilised Catalytic Reactor (Cu-NICaR) system was fabricated by immobilising Copper Nanoparticles (Cu NPs) onto a radiation functionalized polymer support. Gamma radiation induced simultaneous irradiation grafting process was employed for introducing poly-glycidyl methacrylate (poly(GMA)) chains onto non woven PE-PP matrix. Optimization of the grafting process was carried out by studying the effect of experimental parameters, such as absorbed dose, monomer concentration and solvent polarity on grafting yield. The poly(GMA)-g-PE-PP matrix was used as a functional polymer support for Cu NPs, synthesised under optimized conditions using NaBH4 as reducing agent. Characterization of the samples was carried out by UV-Visible spectrophotometer, Fourier Transform Infrared (FTIR) Spectroscopy, X-ray fluorescence (XRF), Thermogravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM). Catalytic activity of Cu NPs immobilised poly(GMA)-g-PEPP catalytic system was studied by spectrophotometrically monitoring the catalytic reduction of p-nitrophenol (PNP), using NaBH4 as reducing agent. The Cu NPs-immobilised-poly(GMA)-g-PE-PP was observed to exhibit excellent catalytic activity both in batch process (12 cycles over a period of 30 days) as well as in fixed bed column reactor mode, without significant loss of activity. Copyright

Radiolytically Synthesized Noble Metal Nanoparticles: Sensor Applications

Nanotechnology is a discipline that has grown exponentially over the last few decades. The unique properties of nanomaterials, including optical, thermal, electromagnetic etc., make them a highly attractive proposition for a vast array of applications, ranging from medical science to defense technologies. The singular optical properties of noble metal nanoparticles, in particular, have helped develop highly sophisticated sensor systems for estimating trace levels of various analytes. This chapter brings into focus some of the recent developments in the field of sensors based on the Localized Surface Plasmon Resonance (LSPR) properties of Gold (Au) and Silver (Ag) nanoparticles. The use of ionizing radiation, such as 60Co gamma, for fabrication of polymer stabilized Au and Ag nanoparticles via radiolytic route has proved to be one of the most attractive and convenient techniques for nanosynthesis. Using gamma radiation, Au and Ag nanoparticles have been synthesized and successfully employed as LSPR based sensors for estimation of trace levels of analytes such as H2O2, Hg2+, dopamine and Uric Acid. In a nutshell, the chapter highlights how the wedlock between radiation and nanotechnology is fast emerging as a powerful tool to design new materials that can cater to high end applications.