Rashmi A. Agarwal

Ag/AgO Nanoparticles Grown via Time Dependent Double Mechanism in a 2D Layered Ni-PCP and Their Antibacterial Efficacy

A simple synthesis route for growth of Ag/AgO nanoparticles (NPs) in large quantitative yields with narrow size distribution from a functional, non-activated, Ni (II) based highly flexible porous coordination polymer (PCP) as a template has been demonstrated. This template is a stable storage media for the NPs larger than the pore diameters of the PCP. From EPR study it was concluded that NPs were synthesized via two mechanisms i.e. acid formation and the redox activity of the framework. Size range of Ag/AgO NPs is sensitive to choice of solvent and reaction time. Direct use of Ag/AgO@Ni-PCP shows influential growth inhibition towards Escherichia coli and the pathogen Salmonella typhimurium at extremely low concentrations. The pristine template shows no cytotoxic activity, even though it contains Ni nodes in the framework.

One Dimensional Coordination Polymer of Zn(II) for Developing Multifunctional Nanoparticles

A variety of nanoparticles (NPs) including Ag, Au, Pd, Cr and mixed Cu/Fe have been synthesized in a non-activated (without solvent removal) one dimensional coordination polymer (CP) of Zn(II) via two different mechanisms, acid formation and redox activity of the framework. Main driving force to grow these NPs within the cavities of CP is the presence of free oxygens of one of the monodentate carboxylate groups of BDC ligand. These free oxygens act as anchoring sites for the metal ions of the metal precursors. Chemical and physical characteristics of the NPs within the framework have been evaluated by the high resolution transmission electron microscopic (HRTEM) images. Excluding Ag(0) and Pd(0) other NPs are present as combinations of their elemental as well as oxide forms (Au/Au2O3, Cr/Cr2O3/CrO2 and Cu/Cu2O, Fe/FeO). Synthesized Ag NPs within the framework show remarkable antibacterial efficacy at extremely low concentrations. Ag, Au and Cu/Fe NPs show ferromagnetic properties within the framework at room temperature. This polymer has potential to sequester highly toxic Cr(VI) to non toxic Cr(0), Cr(III) and Cr(IV) species.

Toxicity and mutagenicity of exhaust from compressed natural gas: Could this be a clean solution for megacities with mixed-traffic conditions?

Despite intensive research carried out on particulates, correlation between engine-out particulate emissions and adverse health effects is not well understood yet. Particulate emissions hold enormous significance for mega-cities like Delhi that have immense traffic diversity. Entire public transportation system involving taxis, three-wheelers, and buses has been switched from conventional liquid fuels to compressed natural gas (CNG) in the Mega-city of Delhi. In this study, the particulate characterization was carried out on variety of engines including three diesel engines complying with Euro-II, Euro-III and Euro-IV emission norms, one Euro-II gasoline engine and one Euro-IV CNG engine. Physical, chemical and biological characterizations of particulates were performed to assess the particulate toxicity. The mutagenic potential of particulate samples was investigated at different concentrations using two different Salmonella strains, TA98 and TA100 in presence and absence of liver S9 metabolic enzyme fraction. Particulates emitted from diesel and gasoline engines showed higher mutagenicity, while those from CNG engine showed negligible mutagenicity compared to other test fuels and engine configurations. Polycyclic aromatic hydrocarbons (PAHs) adsorbed onto CNG engine particulates were also relatively fewer compared to those from equivalent diesel and gasoline engines. Taken together, our findings indicate that CNG is comparatively safer fuel compared to diesel and gasoline and can offer a cleaner transport energy solution for mega-cities with mixed-traffic conditions, especially in developing countries.

Integration of Ag/AgCl and Au nanoparticles into isostructural porous coordination polymers of Ni(II), Co(II) and Mn(II): magnetic studies

A systematic investigation of silver/silver chloride (Ag/AgCl) and gold (Au) nanoparticle (NP) formation within non-activated isostructural porous coordination polymers (PCPs) namely Ni-PCP, Co-PCP and Mn-PCP at room temperature is reported without the use of any reducing agent and deterioration of host frameworks. A supercharged environment due to the presence of free anions make these PCPs suitable templates for the growth of nanoparticles (NPs) in high yields. High resolution transmission electron microscopy (HRTEM) images provided insight into the size, shape and distribution of the NPs within the frameworks. Different shapes and sizes of the NPs are attributed to the differences in the levels of supramolecular interactions within these isostructural series and the ionic radii which is related to the charge density of metal nodes. From an electron paramagnetic resonance (EPR) study it is evidenced that synthesis of Au NPs in Ni-PCP is completely through redox reaction via strong charge transfer between coordinated metal and the metal precursor, and the others are via acid formation through anions present in the cavities of PCPs. Au NPs integrated frameworks display different soft ferromagnetic properties when placed in a magnetic field at room temperature.

Introduction of Alternative Fuels

Energy is a basic requirement for economic development. Growing energy consumption has resulted in world becoming increasingly dependent on fossil fuels such as coal, oil and gas; therefore, it becomes necessary to develop a sustainable path of energy. Gaseous fuels and biofuels seem to have the potential to contribute significantly to India’s energy security. This monograph shows the current status of different alternative fuels and describes some advanced techniques to improve the quality of alternative fuels. Utilization of these alternative fuels in existing vehicles is another important aspect, which has been covered in this monograph.

Introduction to Biofuels

Sustainable energy source and cleaner environment is the most important requirement for developing countries. In India, total primary energy consumption was ~0.5 BTOE in 2008, which is expected to rise up to ~1.2 BTOE by 2035. In such a scenario, biofuel utilization program seems to be a promising solution because biofuels are relatively cleaner and can be produced from indigenous resources available locally. However availability and continuous supply are the most challenging tasks for the countrywide implementation of biofuels program. In such a scenario, advanced techniques of biofuel production including bio-technology route seem to have significant potential for the energy security in future. This monograph covers practical aspects of biofuel production, utilisation, challenges and limitations and outlines the strengths and constraints of different biofuel production techniques.