Enhanced photocatalytic performance of Hemin (chloro(protoporhyinato) iron(III)) anchored TiO2 photocatalyst for methyl orange degradation: A surface modification method

TiO2 was prepared by sol-gel method through the hydrolysis of TiCl4 and its surface derivatization was carried out with molecular catalyst like Hemin (chloro(protoporhyinato)iron(III)). Catalyst was characterized by various analytical techniques like UV-vis spectroscopy, FT-IR, FE-SEM and XRD. The anchoring of Hemin on titania surface is confirmed by FT-IR spectra through the linkage of OCOTi bond and also by TGA-DSC and elemental analysis. The photocatalytic activity of the surface modified catalyst is tested for the degradation of methyl orange (MO) as a model compound under UV light. The Hemin impregnated TiO2 (H-TiO2) in presence of H 2O2 shows an excellent photocatalytic activity compared to pristine TiO2, Hemin, H2O2, TiO 2/H2O2, and Hemin/H2O2 systems. The enhancement in the photocatalytic activity is attributed to the presence of iron (III) porphyrin ring on the TiO2 surface, which reduces the electron-hole recombination rate and also by acting as a mediator for continuous production of enriched concentration of hydroxyl radicals along with various other reactive free radicals. © 2013 Elsevier B.V. All rights reserved

Synergistic effect between orthorhombic α-Sulfur and TiO2 as co-photocatalysts for efficient degradation of methylene blue: A mechanistic approach

The synergistic effects between α-Sulfur (α-S) and TiO 2 photocatalysts is studied under UV/solar light. An enhancement in photocatalytic activity was observed under UV light, due to formation of sulfate anions in the reaction mixture and these ions get adsorbed on TiO2 surface by electrostatic force of attraction or it may react with holes/hydroxyl radicals to generate sulfate radical anion. An increase in quantum efficiency is observed with sulfated TiO2 due to reduction in electron-hole recombination rate. The extended response of α-S under visible region is due to non-vertical absorption process, which paved a new way for elemental photocatalysis. © 2014 Elsevier B.V

New Insights into the Origin of the Visible Light Photocatalytic Activity of Fe(iii) Porphyrin Surface Anchored TiO2

In order to utilize visible light more effectively in photocatalytic reactions, the surfaces of TiO2 nanoparticles are sensitized by Hemin molecules (H-TiO2) and the catalyst is characterized by various analytical techniques like powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), UV-Visible absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) with an energy-dispersive X-ray (EDX) technique, BET surface area measurements and thermogravimetric analysis (TGA). The results strongly confirm the chemisorption of Hemin molecules on the TiO2 surface through O&z.dbd;C-O-Ti bonds. The photocatalytic activity of H-TiO2 was investigated by the degradation of 4-nitrophenol as a model compound in an aqueous solution under solar light irradiation with the assistance of an appropriate amount of a sacrificial electron donor. The enhanced activity of H-TiO2 confirms the sensitization process. Intermediate products were identified by HPLC analysis and a possible degradation reaction mechanism was proposed. The development of this porphyrin-based photocatalyst provides an alternative approach in harnessing visible solar light and shows promise for waste water treatment in future industrial applications

Inkjet Printing of Polyacrylic Acid-Coated Silver Nanoparticle Ink onto Paper with Sub-100 Micron Pixel Size

Printed electronics (PE) technology shows huge promise for the realisation of low-cost and flexible electronics, with the ability to pattern heat- or pressure-sensitive materials. In future developments of the PE market, the ability to produce highly conductive, high-resolution patterns using low-cost and roll-to-roll processes, such as inkjet printing, is a critical technology component for the fabrication of printed electronics and displays. Here, we demonstrate inkjet printing of polyacrylic acid (PAA) capped silver nanoparticle dispersions onto paper for high-conductivity electronic interconnects. We characterise the resulting print quality, feature geometry and electrical performance of inkjet patterned features and demonstrate the high-resolution printing, sub-100 micron feature size, of silver nanoparticle materials onto flexible paper substrate. Printed onto photo-paper, these materials then undergo chemically triggered sintering on exposure to chloride contained in the paper. We investigated the effect of substrate temperature on the properties of printed silver material from room temperature to 50 °C. At room temperature, the resistivity of single layer printed features, of average thickness of 500 nm and width 85 μm, was found to be 2.17 × 10−7 Ω·m or 13 times resistivity of bulk silver (RBS). The resistivity initially decreased with an increase in material thickness, when achieved by overprinting successive layers or by decreasing print pitch, and a resistivity of around 10 times RBS was observed after overprinting two times at pitch 75 μm and with single pass print pitch of between 60 and 80 μm, resulting in line thickness up to 920 nm. On further increases in thickness the resistivity increased and reached 27 times RBS at print pitch of 15 μm. On moderate heating of the substrate to 50 °C, more compact silver nanoparticle films were formed, reducing thickness to 200 nm from a single pass print, and lower material resistivity approaching five times RBS was achieved

Heterogeneous advanced photo- Fenton process using peroxymonosulfate and peroxydisulfate in presence of zero valent metallic iron: A comparative study with hydrogen peroxide photo-Fenton process

The present research work has demonstrated the use of zero valent metallic iron (Fe0) in the photo-Fenton process under the UV illumination as a promising and novel technique. Oxidants like oxone a peroxymonosulfate (PMS) and ammonium persulfate a peroxydisulfate (PDS) were used in comparison with classical hydrogen peroxide (HP). PMS was found to be a better oxidant in comparison with HP and PDS at higher pH conditions especially in the pH range of 5–7. PMS acts as better oxidant with dipolar unsymmetrical structure, higher oxidation potential and its lower LUMO energy can easily accept electrons more readily compared to the other two oxidants. The degradation rate for various oxidation processes at pH 3 shows the following decreasing order: Fe0/PMS/UV ≈ Fe0/HP/UV > Fe0/PDS/UV > HP/UV > PDS/UV> PMS/UV > Fe0/PMS/dark > Fe0/HP/dark > Fe0/PDS/dark > Fe0/UV > Fe0/dark. At pH 5, PMS/UV and PDS/UV systems show similar efficiencies as Fe0/PMS/UV and Fe0/PDS/UV process, since most of the Fe0 surface is covered by the precipitates of hydroxide and oxyhydroxides. Though recycling capability of iron powder is almost comparable for first to fifth repetitions, Fe0 retains its recycling capability better in the presence of HP for the further runs rather than PDS and PMS

Satellite Image Fusion in Various Domains

In order to find out the fusion algorithm which is best suited for the panchromatic and multispectral images, fusion algorithms, such as PCA and wavelet algorithms have been employed and analyzed. In this paper, performance evaluation criteria are also used for quantitative assessment of the fusion performance. The spectral quality of fused images is evaluated by the ERGAS and Q4. The analysis indicates that the DWT fusion scheme has the best definition as well as spectral fidelity, and has better performance with regard to the high textural information absorption. Therefore, as the study area is concerned, it is most suited for the panchromatic and multispectral image fusion. an image fusion algorithm based on wavelet transform is proposed for Multispectral and panchromatic satellite image by using fusion in spatial and transform domains. In the proposed scheme, the images to be processed are decomposed into sub-images with the same resolution at same levels and different resolution at different levels and then the information fusion is performed using high-frequency sub-images under the Multi-resolution image fusion scheme based on wavelets produces better fused image than that by the MS or WA schemes

Monitoring Cryptographic Strength of Wireless Sensor Networks using ZKP 1

Abstract The security mechanisms used for wired networks cannot be directly used in sensor networks as there is no user-controlling of each individual node, wireless environment, and more importantly, scarce energy resources. In this paper, we address some of the special security threats and attacks in Wireless Sensor Networks offer a powerful methodology to monitor environments, and have a lot of interesting applications, We propose a scheme for detection of distributed sensor cloning attack and use of zero knowledge protocol for verifying the authenticity of the sender sensor nodes. The cloning attack is addressed by attaching a unique fingerprint to each node that depends on the set of neighboring nodes and itself. The fingerprint is attached with every message a sensor node sends. The Zero knowledge protocol is used to ensure non transmission of crucial cryptographic information in the wireless network in order to avoid man-in-the middle attack and replay attack. The paper presents a detailed analysis for various scenarios and also analyzes the performance and cryptographic strength. Keywords Wireless Sensor Networks, Zero Knowledge Protocol Cloning Attack, Man-in-the-Middle Attack. I. Introduction Wireless sensor networks consist of large numbers of sensors that act cooperatively to provide "usable chunks of predigested information rather than a confusing wash of number&quot