Narendra Pal Singh Chauhan

Role of copper pyrovanadate as heterogeneous photo-Fenton like catalyst for the degradation of neutral red and azure-B: An eco-friendly approach

The heterogeneous photo-Fenton like process is a green chemical pathway. It has an edge over conventional Fenton and photo-Fenton processes as it does not require the removal of ferrous/ferric ions in the form of sludge. We prepeared copper pyrovanadate or Volborthite (Cu3V2(OH)2O7∙2H2O) composite photocatalyst by wet chemical method. The photocatalyst was characterized by SEM, XRD, IR, TGA/DSC, EDX and BET. Experiments demonstrated that catalyst could effectively catalyze degradation of neutral red and azure-B in presence of H2O2 in visible light. Moreover, the photo-Fenton-like catalytic activity of Cu3V2(OH)2O7∙2H2O was much higher than CuO and V2O5, when used alone as photocatalyst. The effect of variation of different parameters, i.e., pH, amount of photocatalyst, concentration of dye, amount of H2O2 and light intensity was also investigated. The degradation was well fitted under pseudo-first-order reaction with a rate constant of 2.081×10−4 sec−1 and 3.876×10−4 sec−1 for neutral red and azure-B, respectively. Quality parameters of dye solutions before and after photo-Fenton degradation were also determined. A tentative mechanism involving •OH radical as an oxidant has been proposed. The high catalytic activity may be due to the Cu3V2(OH)2O7∙2H2O shell, which not only increased the surface hydroxyl groups, but also enhanced the interfacial electron transfer. The catalyst has been found to possess good recyclability.

Synthesis and Characterization of Functionalized Polyaniline Having Methyl Violet as Pendant Groups

Methyl violet–substituted polyaniline is prepared by oxidative polymerization of aniline in an aqueous acidic media using tosic acid as dopant and ammonium persulphate as oxidant. Substitution of methyl violet (dye moieties) on polyaniline backbone takes place in the presence of butyl lithium. The structures of methyl violet–substituted polyanilinewas elucidated by Fourier transform infrared (FT-IR), fluorescence spectra, XRD and differential scanning calorimetery (DSC). Molecular weight is determined by gel permeation chromatography (GPC) and viscosity method. Conductivity and band gap of methyl violet–substituted polyaniline was computed by a two-probe conductometer.

Thermal curing and degradation kinetics of terpolymer resins derived from vanillin oxime, formaldehyde and p-chloro-/p-methylacetophenone

A novel class of linear terpolymer resins have been prepared from various macromers formed by vanillin oxime (VO), formaldehyde (F) and p-chloro/p-methylacetophenone in the presence of an acid as catalyst by convenient polycondensation process. The conversion of different macromers into respective terpolymeric resin was studied by DSC analysis from −50 °C to 250 °C. The first thermal transition endotherms ranging from 108–137 °C (VOFCA) and 125–150 °C (VOFMA) are due to expulsion of water molecules, and the second thermal transition exotherms 177–247 °C (VOFCA) and 183.9–249.8 °C (VOFMA) are attributed to the formation of methylene linkage between macromers moieties by utilizing methlol groups at terminals. The activation energy required for conversion of methylol into methylene groups for VOFCA and VOFMA was 3.4 and 3.9 kJ/mol, respectively. Structural confirmations were determined through IR, Uv-Vis, 1H NMR spectroscopy and GPC data. The activation energy (Ea) and thermodynamic parameters of the thermal decomposition process were investigated with thermogravimetric analysis (TGA) by isoconversional integral Kissinger-Akahira-Sunose (KAS) and differential Friedman methods. Empirical kinetic models, as well as generalized master plots, were applied to explain the degradation mechanisms of terpolymer resins. The degradation reaction follows Avrami-Erofeev (nucleation and growth) at initial stage to Jander (three-dimensional diffusion) model for PVOMAF and Jander (two-dimensional diffusion) for PVOFCA governed mechanisms. Among all the tested terpolymers, both resins revealed better activity compared to standard drugs as Gentamycin, Amphicilin, Chloramphenicol, Ciprofloxacin and Noorfloxacin.

Preparation and Characterization of Polyanilines Bearing Rhodamine 6-G and Azure B as Pendant Groups

Rhodamine 6G and Azure B substituted polyanilines are prepared by oxidative polymerization of aniline in an aqueous acidic media using hippuric acid and tosic acid as dopant and ammonium per sulphate as oxidant. Substitution of rhodamine 6G and azure B on polyaniline backbone takes place in presence of butyl lithium. The structures of rhodamine 6G and azure B substituted polyanilines was elucidated by UV–visible spectroscopy, IR spectroscopy,1H nuclear magnetic resonance (1H NMR), 13C nuclear magnetic resonance (13C NMR). Molecular weight and specific surface area were determined by gel permeation chromatography (GPC) and Brunauer–Emmett–Teller (BET) analysis. Conductivity of rhodamine 6G and azure B grafted polyanilines were computed by two probe conductometer.

Preparation and Applications of Non-Metal Doped Semiconductors as Photocatalysts

Water is one of the most essential commodity for mankind, but we know that only 1% of available water on earth may be used for human consumption. However, due to increasing anthropogenic activities the water is getting polluted. Scientists all over the world are looking for ecofriendly methods to treat polluted water for its reuse. One technique that has been gaining popularity in recent years and it is quite promising also for the treatment of resilient pollutants is the photocatalysis. Numerous studies have been reported in the last decade on the photocatalytic degradation of organic pollutants using semiconductor materials as photocatalysts, but the limited optical absorption due to the relatively wide band gap energies and recombination of photogenerated electron-hole pair results in low activity of photocatalysts. Therefore, improvement of charge separation as well as enhancement of visible light absorption is highly important for the efficient photocatalytic reactions. In this context, doping of semiconductor by non-metals seems a promising strategy to enhance the activity of a photocatalyst. In this chapter; preparation, characterization, mechanism and various applications of non-metal doped semiconductors has been reported and the applications of semiconductors have been focused on waste water treatment. Some other applications include generation of hydrogen by photocatalytic splitting of water, antimicrobial activity etc.

Nanobiomaterials set to revolutionize drug-delivery systems for the treatment of diabetes: State-of-the-art

Abstract Diabetes can result when the accurate control of insulin levels fails in the body. As a result, insulin has been conventionally administered for the treatment of diabetes mainly through subcutaneous injection. There have been several attempts to administer insulin orally. However, the oral bioavailability of insulin is strictly limited, mainly by low permeability across biological membranes. Advances in biotechnology and nanotechnology have recently led to the discovery of several new approaches for the delivery of drugs. In this concept, nanobiomaterials have been shown to be promising candidates for oral insulin delivery. This chapter describes the recent advances and future prospects of using nanobiomaterials for innovative drug-delivery systems.