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Studies on the Al–Zn–In-alloy as anode material for the removal of chromium from drinking water in electrocoagulation process
No full textThe present study provides the removal of chromium from water by an electrocoagulation process. The various operating parameters like effect of anode materials, effect of pH, concentration of chromium, current density and temperature have been studied. The effect of co-existing anions such as carbonate, boron, silicate and fluoride was studied on the removal efficiency of chromium. The results showed that the optimum removal efficiency of 98.2% was achieved using aluminum alloy anode at a current density of 0.2 A dm−2, at a pH of 7.0. First and second-order rate equations were applied to study the adsorption kinetics. The adsorption process follows first order kinetics model with good correlation. The Langmuir, Freundlich, D–R and Frumkin
adsorption models were applied to describe the equilibrium isotherms and the isotherm constants were determined. The experimental adsorption data were fitted to the Langmuir adsorption model. Temperature studies showed that the adsorption was endothermic and spontaneous in natur
Interaction between gold (III) chloride and potassium hexacyanoferrate (II/III)—Does it lead to gold analogue of prussian blue?
No full textPrussian blue analogues are a class of compounds formed by the reaction between metal salt and potassium
hexacyanoferrate (II/III). In our earlier report, the formation of Au@Prussian blue nano-composite was noticed on potential cycling the glassy carbon electrode in a medium containing gold (III) chloride and potassium hexacyanoferrate (III). Hence in this work, the formation of gold hexacyanoferrate was attempted by a simple chemical reaction. The reaction of gold (III) chloride with potassium hexacyanoferrate (II/III) was examined by UV–Vis spectroscopy and found that there is no redox reaction between gold (III) chloride and potassium hexacyanoferrate (III). However, the redox reaction occurs between gold (III) chloride and potassium hexacyanoferrate (II) leading to the formation of charge transfer band and the conversion of hexacyanoferrate (II) to hexacyanoferrate (III) was evidenced by the emergence of new absorption peaks in UV–Vis spectra. The oxidation state of gold in Au–Fe complex was found to be +1 from X-ray photoelectron spectroscopy. The stability of the Au–Fe complex was also studied by cyclic
voltammetry. Cyclic voltammetric results indicated the presence of high spin iron in Au–Fe complex. Hence ‘as formed’ Au complex may be KFex[Au(CN)2]y. The results revealed that the formation of gold hexacyanoferrate was not feasible by simple chemical or electrochemical reaction in contrast to other Prussian blue analogue
Nix–Fe(1-x)Fe(CN)6 hybrid thin films electrodeposited on glassy carbon: Effect of tuning of redox potentials on the electrocatalysis of hydrogen peroxide
No full textThe electrochemical deposition of mixed Nix–Fe(1-x)Fe(CN)6 thin films on a glassy carbon (GC) electrode surface were carried out by electro-deposition under continuous potential cycling condition for the first time. The redox potential of the low spin iron in the hybrid film was found to depend on the ratio of metal centres. The improvement in the electrocatalytic property of the nickel hexacyanoferrate film with incorporation of iron ions in the film towards the electrocatalysis of hydrogen peroxide was studied in electrolytes like KNO3 and NaNO3. The stability of hybrid film in Na+ containing supporting electrolytes was examined. Detection limit of H2O2 was about 1 lM as determined by amperometry with the sensitivity of 192 nA/lM. The chemically modified glassy carbon electrodes with NixFe(1-x)HCF hybrid films were characterized by cyclic voltammetry, impedance spectroscopy, energy dispersive X-ray analysis etc. These films may find extensive applications as redox mediators in biosensors which employ oxidase
enzyme
Experimental analysis of spatio-temporal behavior of anodic dead-end mode operated polymer electrolyte fuel cell
No full textDuring the anodic dead-end mode operation of fuel cells, the inert gases (nitrogen and water) present in the cathode side gas channel permeate to the anode side and accumulate in the anode gas channel. The inert gas accumulation in the anode decreases the fuel cell performance by impeding the access of hydrogen to the catalyst. The performance of fuel cell under potentiostatic dead-end mode operation is shown to have three distinct regions viz. time lag region, transient current region and a steady state current region. A current distribution measurement setup is used to capture the evolution of the current distribution as a function of time and space. Co- and counter-flow operations of dead-end mode confirm the propagation of inert gas from the dead-end of anode channel to the inlet of anode. Experiments with
different oxidants, oxygen and air, under dead-end mode confirm that nitrogen which permeates from cathode to anode causes the performance drop of the fuel cell. For different starting current densities of 0.15 A cm−2, 0.3 A cm−2 and 0.6 A cm−2 the inert gas occupies 35%, 45% and 57%, respectively of anode channel volume at the end of 60 min of dead-end mode operatio
Effects of alternating and direct current in electrocoagulation process on the removal of cadmium from water – a novel approach
No full textThe main objective of this study is to investigate the effects of AC and DC on the removal of cadmium from water using zinc as anode and as cathode. Various operating parameters on the removal efficiency of cadmium were investigated, such as initial cadmium ion concentration, initial pH, current density and temperature. The results showed that the removal efficiency of 97.8% and 96.9% with the energy consumption of 0.665 and 1.236 kWh/m3 was achieved at a current density of 0.2 A/dm2 and pH of 7.0 using zinc as electrodes using AC and DC, respectively. For both AC and DC, the adsorption of cadmium was preferably fitting Langmuir adsorption isotherm, the adsorption process follows second order kinetics and the temperature studies showed that adsorption was exothermic and spontaneous in natur
Use of open access journals by Indian researchers
No full textIndian researchers have published more than 43,400 papers in over 4,600 journals in 2009 as seen
from Science Citation Index (SCI) – Expanded. Of these, over 6,900 (or one in six) papers were
published in 445 open access (OA) journals. The proportion of papers published by Indian
researchers in OA journals is considerably higher than the world average, which is estimated to be
8.5–10.0%. Although India publishes well over a thousand journals, including about 360 OA journals,
SCI Expanded indexed in 2009 only 101 Indian S&T journals including 46 OA journals. It is
likely that the percentage of Indian papers in OA journals as seen from SCI will be higher if more
Indian journals are indexed in SCI Expanded
Development of electrochemical process for the production of Tetra Bytyl Ammonium Hydroxide (TBAH) from Tetra Butyl Ammonium Bromide (TBAB)
No full textSynthesis and photocatalytic properties of Ag[Li1/3Ru2/3]O2: A new delafossite oxide
No full textA new delafossite oxide, Ag[Li1/3Ru2/3]O2, synthesized by ion-exchanging interlayer-Li+ with Ag+ in layered
Li2RuO3, is reported. The transformation of layered Li2RuO3 (monoclinic, space group C2/c) to Ag[Li1/3Ru2/3]O2 possessing a delafossite structure (space group R¯3m) has been established with powder X-ray diffraction. The successful conversion of Li[Li1/3Ru2/3]O2 to Ag[Li1/3Ru2/3]O2 is further confirmed by EDAX analysis. The diffuse reflectance spectrum of Ag[Li1/3Ru2/3]O2 shows broad absorption in the UV–visible region suggesting its use as a photocatalyst. The photocatalytic activity of Ag[Li1/3Ru2/3]O2 has been investigated by degrading various dyes. It showed significant photocatalytic activity for dye
degradation both under UV and solar radiatio
Structural and tribological properties of DC reactive magnetron sputtered titanium/titanium nitride (Ti/TiN) multilayered coatings
No full textTi/TiN multilayered coatings of 200 layers with the thickness of 1.5 μm were deposited by a reactive DC
magnetron sputtering technique using a mixture of Ar and N2 gas. XRD technique was employed to elucidate the structural parameters. The presence of different phases like TiN, TiOxNy and TiO2 were confirmed by XPS analyses. The observation of longitudinal optic (LO) phonon modes in the Raman spectra confirmed the highly crystalline nature of the deposited films. A microhardness value of 25.5 GPa was observed for Ti/TiN multilayers. The observed lower friction coefficient value for the Ti/TiN multilayers on mild steel (MS) indicated that the stack layers have better wear resistance property. Results from the electrochemical
polarization and impedance studies showed the favorable behavior of the Ti/TiN multilayers, which have improved the corrosion resistance property of MS in 3.5% NaCl solution. The results of this study demonstrate that these multilayers can improve the corrosion resistance of mild steel substrate
A Comparative Study of Electrochemical Capacitive Behavior of NiFe2O4 Synthesized by Different Routes
No full textThe electrochemical capacitive behavior of NiFe2O4 ceramic powders prepared by
combustion synthesis, polyol-mediated and sol-gel methods was studied. The phase formation
and morphological characterizations of synthesized materials were carried out through thermal
analysis (TG-DTA), powder X-ray diffraction (XRD) and scanning electron microscopy (SEM).
Electrochemical performance of these electrode materials as capacitors were investigated in
aqueous NaCl electrolyte using cyclic voltammetry (CV) and the corresponding specific
capacitance (SC) values were determined. The observed electrochemical double layer capacitive
(EDLC) behavior in NiFe2O4 depends on the morphology which can be controlled by the
synthesis method adopted. NiFe2O4 synthesized by sol-gel method exhibited a specific
capacitance of 97.5F/g which is higher than the capacitance values of NiFe2O4 obtained through
other synthesis methods