Navin Chandra

Synthesis and characterization of nano-sized zirconia powder synthesized by single emulsion-assisted direct precipitation

For the first time, single reverse microemulsion-assisted direct precipitation route has been successfully used to synthesize tetragonal zirconia nanoparticles in narrow size range. The synthesized powder was characterized using FT-IR, XRD and HRTEM techniques. The zirconia nanoparticles obtained were spherical in shape and has narrow particle size distribution in the range of 13-31nm and crystallite size in the range of 13-23nm.

Adsorption of cyanide from aqueous solutions at pyrophyllite surface

The adsorption of cyanide from aqueous solutions at pyrophyllite mineral surface has been studied by investigating the effect of initial concentration of adsorbate, amount of adsorbent, pH and temperature of test solutions. The adsorption efficiency is observed to be 99% in dilute solutions but decreases down to 40% with increase in cyanide concentration to 10 ppm. The adsorption is observed to be maximum from neutral solutions and is observed to increase with increase in temperature. The adsorption data have been fitted in Langmuir and Freundlich isotherms and the adsorption has been found to be endothermic in nature in the temperature range 30–60°C.

Removal of Zn (II) from aqueous solution by using hybrid precursor of silicon and carbon.

Hybrid precursor (HP) of silicon and carbon was synthesized from rice hulls by a novel low temperature method, using sol-gel route. The potential of hybrid precursor to remove Zn (II) ions from aqueous solutions was investigated under different experimental conditions. Hybrid precursor removes Zn (II) ions with efficiency higher than 95% at low concentration. The data revealed that initial uptake was rapid and equilibrium was established in 30min. Pseudo first order, Pseudo second order and Intraparticle diffusion kinetic models were applied to the kinetic data and it was found that adsorption process followed pseudo second order with activation energy of 1.093kJmol(-1). Zn (II) removal was quantitatively evaluated using Langmuir and Freundlich isotherm model and monolayer sorption capacity show the value 28.76mg/g indicating the affinity of HP for Zn (II) ions. The negative value of Gibbs free energy obtained in this study with hybrid precursor confirms the feasibility and spontaneous nature of adsorption process.

Determination of aliphatic amines by gas chromatography-mass spectrometry after in-syringe derivatization with pentafluorobenzoyl chloride.

A simple and highly sensitive gas chromatographic method has been developed for the determination of low molecular weight short-chain aliphatic amines (SCAAs) after their simultaneous extraction and in-syringe derivatization with pentafluorobenzoyl chloride (PFBOC). Derivatization of the low molecular weight aliphatic amines in bicarbonate buffer of pH 10.5 with PFBOC was followed by immersed solvent microextraction. Derivatization conditions, including reagent concentration, reaction pH, ionic concentration of buffer, reaction time, stirring rate, reaction temperature and extraction solvent, have been investigated for method optimization. Linearity was studied within range of 0.15 pg ml⁻¹-50 ng ml⁻¹. The correlation coefficients were between 0.9934 and 0.9999. Detection limit of derivatized amines proved to be in the range of 0.117-1.527 pg ml⁻¹, and the intraday and interday relative standard deviation (RSD) values were less than 8% with respect to peak area. The method was applied for analysis of lake, river and industrial waste water. The recoveries of extraction from lake, river and industrial waste water samples, which have been spiked with different levels of aliphatic amines, were in the range of 68-99%, 63-102% and 62-105%, respectively.

Removal of lead from aqueous solution by hybrid precursor prepared by rice hull

Use of low-cost hybrid precursor, prepared from rice hull has been studied as a sorbent for the removal of Pb(2+) from aqueous solutions. Effect of contact time, initial concentration, pH and temperature has been studied. The effect of temperature (30, 40, 50 and 60 degrees C) on adsorption phenomena has been studied and data have been analyzed using Langmuir isotherm. The change in enthalpy (Delta H) (-14.6179 kJ/mol), free energy (Delta G) and entropy (DeltaS) has also been evaluated. The negative values of Delta G and Delta H indicate the adsorption of lead ions on the surface of hybrid precursor to be spontaneous and exothermic under the experimental condition.

Manganese recovery from secondary resources: A green process for carbothermal reduction and leaching of manganese bearing hazardous waste

During the hydrometallurgical extraction of zinc by electrowinning process, a hazardous solid waste called anode mud is generated. It contains large quantity of manganese oxides (55-80%) and lead dioxide (6-16%). Due to the presence of a large quantity of lead, the anode mud waste is considered hazardous and has to be disposed of in secure landfills, which is costly, wastes available manganese and valuable land resources. For recovery of manganese content of anode mud, a process comprising of carbothermal treatment using low density oil (LDO) followed by sulphuric acid leaching is developed.

Synthesis and characterization of iron oxide nanoparticles by solvothermal method

In the present work iron oxide nanoparticles have been synthesized by alkaline solvo thermal method using anhydrous ferric chloride, sodium hydroxide, polyethylene glycol and cetyl trimethyl ammonium bromide and characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Energy-dispersive X-ray Spectroscopy (EDX) and Thermal Gravimetric Analysis (TGA). XRD indicated that the product is a mixture of different phases of iron oxide viz. gamma-Fe2O3 (maghemite, tetragonal), Fe2O3 (maghemite, cubic), Fe3O4 (magnetite, cubic) and ɛ-Fe2O3(epsilon iron oxide). FESEM studies indicated that size of the particles is observed in the range of about 19.8 nm to 48 nm. EDX spectral analysis reveals the presence of carbon, oxygen, iron in the synthesized nanoparticles. The FTIR spectra indicated absorption bands due to O-H stretching, C-O bending, N-H stretching and bending, C-H stretching and Fe-O stretching vibrations. TGA curve represented weight loss of around 3.0446 % in the sample at temperature of about 180°C due to the elimination of the water molecules absorbed by the nanoparticles from the atmosphere.

A NOVEL PROCESS FOR MAKING ALKALINE IRON OXIDE NANOPARTICLES BY A SOLVO THERMAL APPROACH

In the present work alkaline iron oxide nanoparticles are synthesized by a novel solvo thermal approach and characterized exhaustively by various complementary techniques. Field emission scanning electron microscopy (FESEM) studies reveal that the size of nanoparticles is in the range of 31.5 nm to 96.9 nm. Energy-dispersive X-ray spectroscopy spectral analysis reveals the presence of oxygen, carbon, iron, and sodium. The X-ray diffraction studies confirm the formation of tetragonal NaFeO2 as the major phase along with orthorhombic NaFeO2·H2O and rhombohedral FeCO3 (siderite) as the minor phases. Fourier transform infrared spectroscopy exhibits peaks due to the stretching and bending vibrations of O-H, C=O, CH3-N, CH3, C-H, C-N, and Fe-O groups. Differential scanning calorimetry (DSC) results display an endothermic peak at 100.85°C and a very small endothermic peak at 791.56°C with 819.73 mJ and 349.28 mJ energies respectively. These DSC peaks can be correlated with thermal gravimetric analysis (TGA) peaks representing 31.04% weight loss and 7.70% weight loss respectively in the sample at around 160°C and 980°C respectively.