Corrosion inhibition of carbon steel in open recirculating cooling water system of petroleum refinery by a multi-component blend containing zinc (II) diethyldithiocarbamate

291-295A multi-component blend of inhibitors containing sodium salt of diethyldithiocarbamate (DEDTC) (50 to 100 ppm), Zn2+as ZnSO4.7H2O (50 to 70 ppm) and 1-hydroxy ethyledene-1,1-diphosphonic acid (HEDP) (50 to 150 ppm) was formulated as corrosion and fouling inhibitor for carbon steel in open recirculating cooling water system of Numaligarh Refinery Limited (NRL), Golaghat, Assam and evaluated by weight loss and potentiodynamic polarization methods. The results showed that each of NaDEDTC, HEDP and ZnSO4.7H2O in 1.0:1.4:1.0 ratios can significantly decrease corrosion, scale build-up and microbial growth under the test condition. Potentiodynamic polarization curves indicate both cathodic and anodic corrosion inhibition. SEM and EDS studies indicate the formation of an adsorbed protective film containing of Fe2+-HEDP, Zn2+-HEDP, Zn2+-DEDTC complexes on the metal surface

Study of filamentary behaviour in coaxial dielectric barrier discharge lamp

889-892In this study, filamentary discharges have been investigated at 1.5 mm dielectric-dielectric electrode gap of a coaxial dielectric barrier discharge (DBD) quartz tube filled with nitrogen gas. Different types of discharge patterns have been established in the tube using alternating field (35-45 kHz). Electrical characteristics of the discharge have been investigated, which mainly depend on gas pressure, applied frequency and voltage amplitude. The on set of the discharge current occurs earlier at higher operating voltage due to the increased value of E/n, where E is the electric field and n is the neutral gas density. The observed phenomenon occurs due to increase in rate of voltage rise time. At higher voltage, increase in net current increases the chances of electron impact. Analysis of the voltage versus charge plot (lissajous figure) supports the theory of capacitances of a double barrier discharge. The energy consumed per cycle of the DBD source measured using lissajous figure is few milli joules. Energy consumption per cycle is the key parameter for evaluating the efficiency of the device

Structural investigation and improvement of photoluminescence properties in Ba(ZrxTi1 x)O3 powders synthesized by the solid state reaction method

In this paper, Ba(ZrxTi1-x)O3 powders with different (x) compositions were synthesized by the solid state reaction method and their structure and improvement of photoluminescence (PL) properties with the Ti substitution by Zrwere discussed. The structural investigation of these powderswas performed by means of X-ray diffraction (XRD) and Fourier transformRaman (FT-Raman) spectroscopy. Their optical propertieswere monitored by ultravioletevisible (UVevis) absorption spectroscopy and PL measurements. XRD patterns indicated that the powders with x = 0 and 0.1 have a tetragonal structure while compositions with x 0.2 exhibit cubic structure. FT-Raman spectra revealed that the replacement of Ti by Zr significantly reduced the intensity of the Raman activemodes. This behavior is related to the increase of undistorted [ZrO6] clusters in the globalmatrix at short range and decrease in local concentration of distorted octahedral [TiO6] clusters. UV evis absorption spectra shownthe presence of intermediaryenergy levels between the valence band(VB) and the conduction band (BC). These intermediary electronic levels aremainly related to 2p orbitals ofOatoms, 4d orbitals of Zr atoms and 3d orbitals of Ti atoms between the VB and CB. A significant improvement in PL properties of Ba(ZrxTi1-x)O3 powders was observed with an increase of undistorted [ZrO6] clusters in the lattice. Finally,we propose possible wideband models based on intermediary energy deep and shallowlevels to explain the PL behavior at room temperature.DST - Science and Engineering Research Council (SERC) (SR/S2/\ud CMP-37/2007)FAPESP (09/50303-4)CNPq (159710/2011-1)CNPq - GERATEC (555684/2009-1)CAPE