A. P. Gupta

Studies on a new heteropolyacid-based inorganic ion exchanger; zirconium(IV) selenomolybdate

Abstract A new heteropolyacid-based cation exchanger zirconium(IV) selenomolybdate has been synthesized, characterized using I.R., X-ray, TGA, DTA techniques. Its composition was found to be Zr:Se:Mo::2.5:0.7:1.6 and it is quite chemically stable. It exhibits 0.94 meq/g ion-exchange capacity for Na + ions. Its distribution behavior for 16 metal ions has been studied and its utility has been employed by achieving separations Zn 2+ –Cd 2+ , Zn 2+ –Co 2+ , Ni 2+ –Cd 2+ and Ni 2+ –Co 2+ on its column.

Investigation of some kinetic parameters for M2+H+ exchanges on zirconium(IV) tungstophosphate — a cation exchanger

Abstract The kinetics and mechanism for the ion-exchange processes Mg 2+ H + , Ca 2+ H + , Sr 2+ H + , Ba 2+ H 2+ , Zn 2+ H + , Cd 2+ H + , and Pb 2+ H + at 25°C, 33°C, 45°C, 65°C (±1°C) temperatures on zirconium(IV) tungstophosphjate were studied using approximated Nemst-Planck equation under the particle diffusion controlled phenomenon. Some physical parameters, i.e. fractional attainment of equilibrium U ( τ ) , self diffusion coefficients ( D o ), energy of activation ( E a ) and entropy of activation ( δS * ) have been estimated. These investigations reveal that the equilibrium is attained faster at higher temperature probably due to availability of thermally enlarged matrix of zirconium(IV) tungstophosphate cation exchanger.

Preparation and Characterization of Potato Starch Based Low Density Polyethylene/Low Density Polyethylene Grafted Maleic Anhydride Biodegradable Polymer Composite

Polysaccharide-filled plastics have attracted immense interest from research scientists as a means to develop a biodisintegrable polymer. The objective of the present study is to develop a biodisintegrable polymer composite using potato starch, which may be a step toward an alternative user friendly polymer composite. Keeping in mind the compatibility issue between potato starch and polyethylene, we used a base material with a polar group in its low density polyethylene (LDPE) backbone. Polymer composite sheets with a combination of potato starch, LDPE, and LDPE grafted maleic anhydride (LDPE-g-mA) were prepared. The LDPE and LDPE-g-mA were used in equal amounts and as a base material. The starch contents varied between 0 and 30%. The composites so prepared were tested for their thermal and mechanical properties. The results show that the thermal stability and melting temperature of these composites did not change significantly with various combinations of potato starch. The mechanical testing results show that tensile strength of material could be maintained at up to 15% mixing of potato starch in composites, and at up to 5% mixing of potato starch the percentage elongation was intact.

Studies on tetracycline hydrochloride sorbed zirconium tungstophosphate; La(III)-selective chelating ion exchanger

Abstract Tetracyclines are powerful chelating agents. One of its salt tetracycline hydrochloride has been sorbed over zirconium tungstophosphate (ZWP) and the studies of tetracycline-sorbed zirconium tungstophosphate (TCZWP) has been carried out as a chelating ion exchanger. The sorption of tetracycline has been supported by IR and its distribution studies on 17 metal ions have been calculated in DMW 1 × 10 −5 M HNO 3 , 1 × 10 −3 M HNO 3 , 1 × 10 −2 M NH 4 NO 3 and 1 × 10 −2 M NH 4 NO 3 in 1 × 10 −5 M HNO 3 . On account of Kd values it was found selective for lanthanum(III) and separations from others have been successfully achieved on its column.

Synthesis and ion-exchange properties of niobium arsenate

Abstract Eight samples of niobium arsenate with different ratios of niobium to arsenic have been prepared, and their stabilities and compositions have been determined. The results of thermogravimetry and X-ray studies are reported and compared with those for niobium pentoxide. The separations of Mg 2+ from Al 3+ and Mn 2+ , of Ga 3+ from Al 3+ and of Hg 2+ from Cd 2+ are achieved. A plot of p K sp · r 0 vs. K d is a straight line.

Synthesis and Characterization of Novel Chain-Linked Biodegradable Polymers

The synthesis of high-molecular-weight lactic-acid-based polymers by chain-linked polymerization was investigated. A lactic-acid-based hydroxyl-terminated telechelic pre-polymer was synthesized and then it was chain-linked with methylene diphenyldiisocyanate (MDI). All polymerizations were carried out in the melt, using tin octoate as catalyst. The products were characterized by dynamic mechanical analyzer, Fourier transform infrared spectroscopy, thermogravimetric analysis and viscometry. With the increase in diisocyanate concentration, increases in the viscosity, storage modulus and glass transition temperature were observed.

Preparation and characterization of carboxymethyl guar gum nanoparticles.

Carboxymethyl guar gum nanoparticles (CMGGNPs) were synthesized by nanoprecipitation and sonication method. This method was used for the first time for the synthesis of carboxymethyl guar gum nanoparticles. It was found that the formation of nanoparticles might depend upon the sonication time, solvent, and stirring time. Nanoparticles were characterized by SEM, TEM, XRD and FTIR. The sizes of the particles in suspension have been found in the range 12-30nm. It was concluded that such type of nanoparticles may be used in pharmaceutical and drug delivery.

Studies on the Effect of Coupling Agent on Glass Fiber Filled Polypropylene

Blends of polypropylene reinforced with glass fiber and chemical coupling agent were prepared by melt blending techniques. Maximum improvement in the mechanical and thermal properties was observed with one percent coupling agent, and these properties were further enhanced with increasing concentration of glass fiber, except impact strength and elongation at break, which decreased with an increased percentage of glass fiber.

Ion exchange behaviour of crystalline niobium antimonate towards alkali metal ions

Abstract The potentiometric ion-exchange titrations of niobium antimonate have been performed for the systems Li + /H + , Na + /H + , K + /H + and NH 4 + /H + . Samples at each step of exchange have been characterised by X-ray diffraction analysis. It is concluded that the alkali metal ion exchange in niobium antimonate occurs without phase transition and the exchanger shows a trifunctional acid behavior. The ion exchange capacity of the material is 3.69 meq g −1 . At pH 7 the proton exchange by Li + , Na + , K + and NH 4 + is 1.05, 1.70, 1.25 and 1.60 meq g −1 respectively. Thus the exchanger produces a wide range of acidities as is found in noncrystalline or semicrystalline ion exchange materials. The column ion-exchange capacity for the univalent metal ions has been determined and compared with those of a batch experiment. The low ion exchange capacity—observed in column operation has been interpreted in terms of slow kinetics of the ion exchange process.

Morphological and Impact Properties of Thermo-oxidative Degraded Polypropylene/Metallocene Linear Low Density Polyethylene Blend Systems

Thermo-oxidative degradation of the blends of polypropylene (PP) with metallocene linear low density polyethylene (mLLDPE), has been examined. The samples were exposed in the air-oven for a period of 120 days at 150°C. Scanning Electron Microscopy (SEM) and Light Microscopy (LM) were used for the study of morphology and the measurement of impact properties, to assess the embrittlement of the blend systems. In case of PP, surface cracks appeared spontaneously after 30 days of thermal aging. However, it has been observed that thermal stability of PP has significantly improved by blending it with mLLDPE even after 120 days of thermal aging. Similarly impact strength of PP has shown deterioration after 30 days while there is not much reduction in impact strength in case of PP/mLLDPE blends. The presence of stabilizer in both materials has not shown much difference in impact strength and morphology. Therefore the stabilizer ratio can be optimized vis-à-vis appropriate PP/mLLDPE blend composition.