Bhanudas Naik

A review on chemical methodologies for preparation of mesoporous silica and alumina based materials.

The discovery of novel family of molecular sieves called M41S aroused a worldwide resurgence in the field of porous materials. According to IUPAC definition inorganic solids that contain pores with diameter in the size range of 20-500 A are considered mesoporous materials. Mesoporous silica and alumina based materials find applications in catalysis, adsorption, host- guest encapsulation etc. This article reviews the current state of art and outline the recent patents in mesoporous materials research in three general areas: Synthesis, various mechanisms involved for porous structure formation and applications of silica and alumina based mesoporous materials.

Preparation of a magnetically separable CoFe2O4 supported Ag nanocatalyst and its catalytic reaction towards the decolorization of a variety of dyes

This study deals with the exploration of CoFe2O4 supported Ag nanoparticles as a catalyst for the decolorization of various dyes (such as 4-nitrophenol, Congo red, rhodamine B) and dye mixtures by employing a reduction reaction with excess NaBH4 in an aqueous medium. Nanocatalysts with 10 wt% Ag loading (10Ag@CoFe2O4) exhibited very high catalytic activity and dye solutions were found to be decolorized within 4 to 6 minutes. A simple method for the preparation of a catalyst (10Ag@CoFe2O4) was reported, which exhibited very high catalytic efficiency towards the decolorization of dyes with different chemical structures as well as demonstrating its magnetic properties for easy separation from reaction mixtures and its reusability.

Development of simple chemical method for synthesis of single phase Ni–Zn ferrite nanopowders

Abstract A precursor based method has been developed for the synthesis of nanostructured, single phase Ni–Zn ferrite powders (Ni1–xZnxFe2O4 with x=0·20, 0·35, 0·50 and 0·60). Precursor powders were synthesised by reacting aqueous solutions of metal nitrates and ethylene diamine tetraacetic acid and then evaporating them to dryness. The precursors were calcined in air for 2·30 h at different temperatures ranging from 250 to 450°C. The powders synthesised in this manner were characterised by using X-ray diffraction, thermogravimetric differential scanning calorimetric analysis, Brunauer–Emmett–Teller surface area measurement and SEM. Magnetic characterisation was performed by using a vibrating sample magnetometer. The method provides a simple and cost effective route to produce single phase, Ni–Zn ferrite nanopowders, with average crystallite size of ∼25 nm, at comparatively low temperature.

Preparation of TiO2, Ag-doped TiO2 nanoparticle and TiO2–SBA-15 nanocomposites using simple aqueous solution-based chemical method and study of their photocatalytical activity

Nanocrystalline TiO2, Ag-doped TiO2 and TiO2–SBA-15 nanocomposites have been synthesised using a simple aqueous solution-based chemical method. Nanocrystalline TiO2 was synthesised by calcining the precursor prepared by using ethylenediamine tetraacetic acid and TiCl3 in aqueous medium. Formation of crystalline phase (anatase, rutile or mixed phase) and crystallite size were found to be dependent on calcination temperature. To enhance the photocatalytic activity, Ag-doped TiO2 was synthesised by doping of Ag during the synthesis step of TiO2. TiO2–SBA-15 nanocomposites were synthesised by impregnation method. Pure anatase TiO2 nanoparticle was formed in the amorphous matrix of the silicate SBA-15, even though the loading of the TiO2 in the silicate matrix was as low as 5 wt%. The synthesised materials were characterised using thermal analysis, powder X-ray diffraction method, surface area and porosimetry analysis, diffuse reflectance analysis and transmission electron microscopy. The photocatalytic property of the synthesised materials was investigated towards the degradation of methyl orange under sunlight exposure and monitored by UV–visible spectrophotometer. Ag-doped TiO2 exhibited enhanced photocatalytic activity than undoped TiO2. TiO2–SBA-15 nanocomposites showed impressive photocatalytic activity even with 10 wt% TiO2 loading.

Preparation of polybenzoxazine–Ni–Zn ferrite magnetic nanocomposite and its magnetic property

Abstract The synthesis of a new type, high performance polybenzoxazine–ferrite nanocomposite has been reported. A simple aqueous solution based method was developed for preparation of several compositions of Ni1–xZnxFe2O4 (x=0.20–0.60) nanopowders using metal nitrates and EDTA. Benzoxazine monomer was prepared by employing a solvent less method using aniline, paraformaldehyde and bisphenol A as starting materials. Polybenzoxazine–ferrite nanocomposites were prepared by using a solvent casting method followed by thermal curing. The synthesised powders, monomer, polymer and the resultant composites were characterised by using thermogravimetric analysis and differential scanning calorimeter, surface area and pore size analyser, scanning electron microscope (SEM) and transmission electron microscope. X-ray diffraction spectra of the powders revealed the formation of single phase Ni–Zn ferrite, with average crystallite size of about 20–30 nm. Transmission electron microscopy micrographs confirmed the average ferrite particle size as ∼30 nm while SEM morphology showed a uniform dispersion of nanoferrite particles in the polybenzoxazine matrix. Room temperature magnetic properties of pure ferrite nanopowders as well as polybenzoxazine–ferrite nanocomposites were measured with a vibrating sample magnetometer.