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Studies on the Removal of Arsenate by Electrochemical Coagulation Using Aluminum Alloy Anode
No full textThe removal of arsenate from aqueous solution was carried out by electrochemical
coagulation using aluminum alloy as anode and stainless steel as cathode. Various
operating parameters on the removal efficiency of arsenate were investigated, such as
initial arsenate ion concentration, initial pH, current density, and temperature.
Effect of coexisting anions such as silicate, fluoride, phosphate, and carbonate were
studied on the removal efficiency of arsenate. The optimum removal efficiency of
98.4% was achieved at a current density of 0.2 A/dm2 at a pH of 7.0. The experimental
data were tested against different adsorption isotherm models for describing the
electrochemical coagulation process. The adsorption of arsenate preferably fitting
the Langmuir adsorption isotherm suggests monolayer coverage of adsorbed molecules.
First and second order rate equations were applied to study adsorption kinetics.
The adsorption process follows second order kinetics model with good correlation.
Temperature studies showed that adsorption was endothermic and spontaneous in
nature
Influence of Surface Pre-treatment of MWNTs Support on PEFC Performance
No full textThe influence of surface characteristics of multi-walled carbon
nanotubes (MWNTs) support on the catalytic performance of
PEFC electrodes is investigated by using oxidized and nonoxidized
MWNTs as the supports for platinum. The defect-free
morphology, high electrical conductivity and favorable pore-size
distribution of non-oxidized MWNTs ameliorate catalytic activity
and electrochemical stability of platinum. Physico-chemical
properties of oxidized and non-oxidized MWNTs and the
respective catalysts are studied by BET surface-area, XRD, XPS
and TEM measurements. Electrochemical stability of MWNTssupported
platinum as PEFC electrodes is assessed using potential
cycling and potentiostatic techniques. Owing to the higher
corrosion-resistance, platinum on non-oxidized MWNTs show
lower loss in electrochemical surface area (ESA) and also exhibit
22% lower corrosion current than oxidized MWNTs
Artemisia pallens as corrosion inhibitor for mild steel in HCl medium
No full textMethanolic extract of Artemisia pallens was tested as corrosion inhibitor for mild steel in 4N HCl and
conc. HCl. Weight loss and polarization techniques were used for evaluating corrosion inhibition in 4N
HCl, whilst weight loss, SEM and FT-IR studies were carried out in conc. HCl. The inhibition efficiency
was found to increase with increase of the inhibitor concentrations due to the adsorption of the inhibitor
molecules on the metal surface and the adsorption follows Langmuir’s adsorption isotherm. The inhibition
efficiency was found to be 93% at 1.5 g l−1 in 4N HCl and 96.5% at 40 g l−1 in conc. HCl
Effect of electron correlations on structural phase stability, magnetism, and spin-dependent transport in CeMnNi4
No full textFirst-principles calculations are carried out to study the effect of electron correlations on relative structural
stability, magnetism, and spin-dependent transport in CeMnNi4 intermetallic compound. The correct description
of Coulomb repulsion of Mn 3d electrons is shown to play a crucial role in reproducing the experimentally
observed cubic phase of CeMnNi4 as well as its relatively high degree of transport spin polarization
��66%�. These are the two fundamental properties of this compound which conventional density-functional
theory approaches fail to predict correctly. The reason for this failure is attributed to an extreme overdelocalization
of Mn 3d charges causing a strong d-d hybridization between Mn and Ni atoms in the orthorhombic
phase. Such an artificial hybridization, in turn, lowers the relative total energy of the orthorhombic phase with
respect to the cubic one. It also leads to an incorrect carrier concentration and mobility at the Fermi level and,
consequently, yields much lower degree of transport spin polarization for this nearly half-metallic compound
Nickel ferrite (NiFe2O4): A possible candidate material as reference electrode for corrosion monitoring of steel in concrete environments
No full textNickel ferrite (NiFe2O4) was tried first time as a possible candidate material as embeddable reference
sensor in concrete environments. NiFe2O4 was synthesized in the laboratory and assembled reference cell
which consists of three compartments. The sensor performance was evaluated in concrete environments
such as saturated calcium hydroxide solution, synthetic concrete pore solution and ordinary Portland
cement (OPC) extract. The consistency test and electrochemical stability test of the sensor were studied
in the said concrete environments and the half cell potential was found to be −300mV vs. SCE. The
reversibility of sensor in the three alkaline solutions was found to be within ±5 mV, which was very well
within the limit as sensor material for concrete. The polarization and impedance tests of NiFe2O4 sensor
in concrete environments showed the stability of the sensor material in the highly alkaline concrete
environments
Removal of Fatty Acids from Palm Oil Effluent by Combined Electro-Fenton and Biological Oxidation Process
No full textThe main objective of this study was to
find out a cost-effective treatment methodology for
the treatment of palm oil effluent (POE) obtained
from a food processing industry. An electro-Fenton
pretreatment and biological oxidation has been suggested
for the removal of recalcitrant contaminants
present in POE. An initial COD of about 6,700 mg/L
of POE was subjected to electrolytic degradation for
2 h and subsequently by biological oxidation. The
biological oxidation was carried out using Aspergillus
niger and Pseudomonas putida in anaerobic condition.
Electro-Fenton process removed 48.35% of the
COD. Biological oxidation subsequently decreased
the COD to 86.12% and BOD to 85.23%. In the
combined process, a high reduction in TOC and TN
were achieved. Experimental conditions have been
optimized and performances of these techniques have
been discussed. The treated water can be reused for
general and agricultural purposes
Role of substrate temperature on the structural, optoelectronic and morphological properties of (400) oriented indium tin oxide thin films deposited using RF sputtering technique
No full textRF sputtering process has been used to deposit
highly transparent and conducting films of tin-doped
indium oxide onto quartz substrates keeping the RF power
constant at 250 W. The electrical, optical and structural
properties have been investigated as a function of substrate
temperature. XRD has shown that deposited films are
polycrystalline and have (400) preferred orientation.
Indium tin oxide layers with low resistivity values and high
transmittance in the visible region have been deposited.
Detailed Analyses based on X-ray diffraction, optical and
electrical results are attempted to gain more insight into the
factors that are governed by the influence of varying substrate
temperature in this investigation. AFM pictures
showed uniform surface morphology with very low surface
roughness values. It has been observed that ITO films
deposited in this study, keeping the substrate temperature at
150 degree C, can provide the required optimum electrical and
optical properties rendering them useful for developing
many optoelectronic devices at a moderate temperature
High current density, low threshold field emission from functionalized carbon nanotube bucky paper
No full textField emission studies of bucky paper of multiwalled carbon nanotubes (MWNTs), prepared after microwave (MW) assisted acid functionalization are reported along with a comparison with that of “as-grown” sample. MW treated bucky papers reveal an interesting linear field emission behavior in
Fowler–Nordheim plot. The field emission currents at preset value are found to be remarkably stable over a period of more than 3 h sustaining current densities of 4.9 mA/cm2 and 8.5 mA/cm2 for “as-grown” and functionalized sample, respectively. The enhancement in the field emission due to
functionalization has been discussed in terms of tip opening and defect induced charge transport caused by intershell and intertubular interaction
High aspect ratio nanoscale multifunctional materials derived from hollow carbon nanofiber by polymer insertion and metal decoration
No full textA novel high aspect ratio material which can simultaneously
display multiple functions such as proton and electron
conductivity and electrocatalytic activity has been developed by incorporating both platinum nanoparticles and phosphoric acid doped polybenzimidazole along the inner and outer surfaces of a hollow carbon nanofibe
On the study of pH effects in the microwave enhanced rapid synthesis of nano-ZnO
No full textThe rapid synthesis of ZnO nanostructures by
microwave treatment of aqueous solutions of different pH
values is reported for the first time. Microwave in various
wattages was used as the source of heating or energy feeding
the aqueous precursors. The pH of the zinc metal source
was altered by a suitable amount of mineralisers. The considered
pH values are 8, 10, 12 and 13.5. Microwave dielectric
heating is dependent on the ability of the material to
absorb microwave. This is responsible for molecular friction
and dielectric loss, which as a result produce internal heating
of the dielectric medium, in this case the solution. In typical
microwave assisted synthesis, the total exposure to the
microwave treatment was near about 25 to 35 minutes. The
ZnO nanostructures obtained were studied by XRD, SEM
and TEM characterisations. From the XRD pattern and the
full width half maximum of the dominant reflections, microstructural
parameters of the nanostructures are calculated
and compared for the different pH values. Flower petal like
flakes and hexagonal nanorods are formed for the lower and
higher pH solutions, respectively. From the SEM images, the
size distributions for the pH 12 and 13.5 cases are compared
by drawing a histogram