Water is of fundamental importance for life on earth. The synthesis and structure of cell constituents and transport of nutrients into the cells as well as body metabolism depend on water. The contaminations present in water disturb the spontaneity of the mechanism and result in long/short-term diseases. The probable contaminations and their possible routes are discussed in the present review. Continued research efforts result in some processes/technologies to remove the contaminations from water. The review includes concepts and potentialities of the technologies in a comprehensible form. It also includes some meaningful hybrid technologies and promising awaited technologies in coming years.

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Drinking water contamination and treatment techniques

Transport studies of NH4NO3 doped methyl cellulose electrolyte

Intrinsically conducting polymers have been studied extensively due to their intriguing electronic and redox properties and numerous potential applications. To improve and extend their functions, the fabrication of multifunctional conducting polymer nanocomposites has attracted a great deal of attention with the advent of nanoscale dimension. In this paper we report the comparative study of nanocomposite synthesized by an in-situ oxidative polymerization of aniline monomer in the presence of functionalized multiwall carbon nanotubes (MWCNT) with that of pure polyaniline (PANI). Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and x-ray diffraction (XRD) are employed to characterize the pure PANI and the PANI-CNT nanocomposite. XRD and SEM reveal the homogeneous coating of PANI onto the CNT indicating that carbon nanotubes were well dispersed in polymer matrix. The interaction between the quinoid ring of PANI and the MWCNT causes PANI chains to be adsorbed at the surface of MWCNT, thus forming a tubular core surrounding the MWCNT was confirmed from FTIR. Nanocomposite shows high electrical conductivity compared to pure PANI. The enhancement in conductivity of the nanocomposite is due to the charge transfer effect from the quinoid rings of the PANI to the MWCNT. The effect of MWCNT on the transport properties of PANI in the form of the transport parameters such as charge localization length, most probable hopping distance and charge hopping energy in the temperature range 300-430 K was also studied.

http://www.sapub.org/global/showpaperpdf.aspx?doi=10.5923/j.cmaterials.20120203.03

Transport Properties of Conductive Polyaniline Nanocomposites Based on Carbon Nanotubes

Catalytic steam reforming of ethanol has been regarded as a promising way to produce hydrogen. However, catalytic deactivation is a key problem in the process. In this paper, a novel nano-Ni/SiO2 catalyst was prepared by a simple sol−gel method and compared to catalysts prepared by an impregnation method in relation to the steam reforming ethanol process. Good Ni dispersion and high BET surface areas (>700 m2 g−1) were obtained for sol−gel catalysts, whereas only 1 m2 g−1 surface area was obtained for the Ni/SiO2 impregnation catalyst. The results of catalytic steam reforming of ethanol showed that about twice of the hydrogen production was produced with the Ni/SiO2 catalyst prepared by sol−gel (around 0.2 g h−1) compared with that prepared by impregnation (around 0.1 g h−1). The analysis of the used catalysts showed that 10Ni/SiO2-B and 20Ni/SiO2-B presented the highest stability, while other catalysts were fragmented into small pieces after the reforming process, especially the catalysts prepared by imp...

A novel nano-Ni/SiO2 catalyst for hydrogen production from steam reforming of ethanol.

Asymmetric supercapacitor based on vanadium disulfide nanosheets as a cathode and carbonized iron cations adsorbed onto polyaniline as an anode

Occurrence of fluoride in water, its metabol~sm, excretion. effect o ingestion in human and cattle systcm .,nd methods of fluoridation and defluorida- tion have been discussed. The presence of fluoride rn waters occurring in India, with special reference to Raj~sthan desert has been reviewed. Based on the survey and physico-chemical analyses of about 2,700 water samples of Rajasthan, distribution of fluoride in this area has been d~scussed wrth reference to drinking water standards. A water resources map showing concentrations of fluoride in four arid districts of Rajasthan is also presented.

http://publications.drdo.gov.in/ojs/index.php/dsj/article/download/6002/3127

Fluoride in Drinking Water .Its Effects and Removal

The electrical conductivity, both dc and ac, of conducting polyanilline dispersed with poly vinyl alcohol and blended with methyl cellulose has been investigated in the temperature range of 77⩽T⩽300K and in the frequency range 20 Hz to 1 MHz. The dc conductivity does not obey the standard variable range hopping model, but it satisfies hopping transport between the superlocalized states of polymer. The frequency dependence of conductivity has been described by the power law, σ(ω)αωs. The variation of “s” with temperature suggests that the ac conduction is due to the correlated barrier hopping. Temperature and frequency dependent dielectric constant indicates the Debye-type dispersion.

Alternate and direct current conductivity of conducting polyaniline dispersed with poly vinyl alcohol and blended with methyl cellulose

An all optical method of implementing a wavelength encoded simultaneous binary full adder–full subtractor unit exploiting nonlinear polarization rotation in semiconductor optical amplifier

A novel frequency encoded all optical CNOT gate exploiting difference frequency generation and implementation of fast binary adders using frequency encoding and nonlinear dielectric films

A novel frequency encoded all optical logic gates are proposed exploiting multiphoton processes in non linear optical medium. In the frequency encoding of the information the ‘0’ is represented by a frequency ω and ‘1’ is represented by another frequency 2ω. The gates proposed are NOT, OR, AND, NAND and NOR among which NAND and NOR are universal. Using these gates one can generate other important gates and logical function generating all optical devices. Two main three-photon processes, second harmonic generation (SHG) and parametric light generation (PLG) are used to implement the gates and the corresponding appropriate non linear material is LiB3O5 (LBO) which has wide operating and transparency range in the wavelength 350–3,200 nm. The source of optical frequency encoded signal may be derived from an external cavity diode laser generating a wavelength 1,560 nm for ω (‘0’ state of information) and its second harmonic 780 nm for 2ω (‘1’ state of information).

Parimal Ghosh

Papers

Fluoride in Drinking Water .Its Effects and Removal

Alternate and direct current conductivity of conducting polyaniline dispersed with poly vinyl alcohol and blended with methyl cellulose

An all optical method of implementing a wavelength encoded simultaneous binary full adder–full subtractor unit exploiting nonlinear polarization rotation in semiconductor optical amplifier

A novel frequency encoded all optical CNOT gate exploiting difference frequency generation and implementation of fast binary adders using frequency encoding and nonlinear dielectric films

A method of optical implementation of frequency encoded all optical logic gates based on multiphoton processes in non linear material