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Electrochemical degradation of specialty chemical industry effluent
No full textConventional wastewater treatment techniques are inefficient to manage large quantities of refractory
organics discharged by specialty chemical industries. It is aimed in the present investigation to compare
overall performance of the basic electrochemical reactor configurations such as batch, batch recirculation
and continuous recycle reactors, in removing the organic part of wastewater from a medium-scale,
specialty chemical industry. The effects of current density, supporting electrolyte concentration, electrolysis
duration and fluid flow rate on the pollutant removal and energy consumption performances
were critically evaluated. Continuous recycle reactor is found to be the better configuration, because of
its flexibility of operation. Circulation flow rate and withdrawal flow rate enable control on transfer coefficients
and treatment duration respectively. The ability of artificial neural network (ANN) in predicting
the performance of the batch electrochemical treatment has also been demonstrated
Electrolytic recovery of dilute copper from a mixed industrial effluent of high strength COD
No full textIn this study, the electrochemical treatment has been investigated in the real acidic effluent of copper phthalocyanine dye manufacturing plant. Galvanostatic batch electrolyses have been carried out in an
undivided cell using stainless steel as cathode, dimensionally stable anode (DSA) and graphite as anodes
at different current densities and temperatures. The influence of these variables on current efficiency,
cell voltage, energy consumption and deposit quality was reported. Under optimized conditions, the
maximum copper recovery of 98% and COD removal efficiency of 87.3% with the energy consumption
of about 11.23 kWh/kg of Cu and 6.08 kWh/kg of COD, respectively at 30 ◦C were achieved in the acidic
raw effluent using 2D parallel-plate cathode. While in 3D stainless steel turning cathode reactor, 99.5%
of copper can efficiently be recovered from dilute solution with an acceptable current efficiency of about
56.8% with minimum energy consumption of 2.37 kWh/kg of Cu. The experimental results suggested that
the efficiency of copper removal is hindered by the presence of organic species in the mixed industrial
effluent
Development of electrochemical process for the production of Tetra Propyl Ammonium Hydroxide (TPAH) from Tetra Propyl Ammonium Bromide (TPAB)
No full textStructural and electrical studies of nano structured Sn12x SbxO2(x 5 0.0, 1, 2.5, 4.5 and 7 at%) prepared by co-precipitation method
No full textSnO2 semiconducting nanopowders doped with
antimony Sn1-x SbxO2 (x = 0.0, 1, 2.5, 4.5 and 7 at%) was
achieved by co-precipitation method. TG/DTA and FT-IR
studies revealed the removal of organic residuals in the
precursor leading to the formation of oxides during calcinations
process. A change in color from white to bluish
occurred on calcinations of the powder at 500 degree C in air.
The distortion ratio, strain and particle size were measured
from X-ray diffraction (XRD) spectra and their changes
with dopants concentration were determined. Transmission
electron microscopy (TEM) images support to conform the
particle size. The electrical resistivity and activation energy of the ATO particles decreases as compared with pure
SnO2, due to the incorporation of on Sn4? ions by as Sb5?
ion in the host SnO2 matrix. Incorporation of Sb5? was
evidenced through the XPS spectrum
Thermal and optical properties of Cd2SnO4 thin films using photoacoustic spectroscopy
No full textCadmium stannate (Cd2SnO4) thin films were
prepared by the RF magnetron sputtering technique on glass
substrates with substrate temperatures of room temperature
(RT), 100°C, 200°C and 300°C. Photoacoustic analyses
were made to obtain the thermal diffusivity and the
optical bandgap values of the Cd2SnO4 thin films. The
change in thermal diffusivity of the films with the substrate
temperature was analyzed. The optical bandgap values
obtained from the photoacoustic spectroscopy were
compared with the values obtained from the optical transmittance
spectra. X-ray photoelectron spectroscopic (XPS)
studies confirm the formation of stoichiometric films. Surface
morphological studies by atomic force microscopy
(AFM) revealed the crystalline nature of the films deposited
at 100°C
Relationship between Alumina and Chloride content on their physical and corrosion resistance properties of concrete
No full textThe relationship between alumina and chloride content on the physical and corrosion resistance properties of
OPC concrete was studied. Friedel’s salt was formed in situ in OPC concrete by the addition of various percentages
of alumina (1% to 15%) along with 1% CaCl2. The compressive strength data revealed that the addition of Al2O3
increased the early strength of concrete. The Friedel’s salt formation up to 5% Al2O3 showed maximum compressive
strength. The Rapid Chloride Ion Permeability Test (RCPT) revealed that the quantity of electrical charge passed for
OPC concrete at 5% Al2O3 showed a 50% reduction in coulombs. The 12V impressed voltage test indicated a
gradual increase in anodic current flow and delayed time taken for initial crack up to 5% Al2O3 addition. Potential vs
time data from macrocell corrosion studies maintained the passivity of steel embedded in OPC concrete up to 5%
Al2O3 throughout the exposure period of 12 months. Correspondingly, the macrocell current was also considerably
reduced (50%) in OPC concrete at the 5% Al2O3 level. Scanning electron micrographs revealed a denser formation of
Friedel’s salt at the 5% Al2O3 level. The XRD pattern at the 5% Al2O3 level also confirmed the existence of a greater
amount of Friedel’s salt. The optimum percentage of alumina for the formation of Friedel’s salt in OPC concrete
with improved properties was found to be 5%
Electrolytic recovery of dilute copper from a mixed industrial effluent of high strength COD
No full textIn this study, the electrochemical treatment has been investigated in the real acidic effluent of copperphthalocyanine
dye manufacturing plant. Galvanostatic batch electrolyses have been carried out in an
undivided cell using stainless steel as cathode, dimensionally stable anode (DSA) and graphite as anodes
at different current densities and temperatures. The influence of these variables on current efficiency,
cell voltage, energy consumption and deposit quality was reported. Under optimized conditions, the
maximum copper recovery of 98% and COD removal efficiency of 87.3% with the energy consumption
of about 11.23 kWh/kg of Cu and 6.08 kWh/kg of COD, respectively at 30 ◦C were achieved in the acidic
raw effluent using 2D parallel-plate cathode. While in 3D stainless steel turning cathode reactor, 99.5%
of copper can efficiently be recovered from dilute solution with an acceptable current efficiency of about
56.8% with minimum energy consumption of 2.37 kWh/kg of Cu. The experimental results suggested that
the efficiency of copper removal is hindered by the presence of organic species in the mixed industrial
effluent
High Pt Utilization Electrodes for Polymer Electrolyte Membrane Fuel Cells by Dispersing Pt Particles Formed by a Preprecipitation Method on carbon “Polished” with Polypyrrole
No full textPt utilization on carbon black (CB) has been significantly improved by initially utilizing polypyrrole (PPy)
as a moiety to “polish” the carbon surface and subsequently by dispersing Pt particles formed by a
preprecipitation process to minimize their migration into the geometrically restricted areas of the carbon
surface. This process strategy has helped to significantly extend the triple-phase boundary as a greater number
of Pt particles comes in direct contact with Nafion, leading to a substantial improvement in the overall catalyst
utilization. Preliminary analyses such as IR, thermogravimetric analysis, and N2 sorption confirmed the presence
of PPy on the surface. Approximately 50% reduction in the surface area of CB after the controlled in situ
polymerization of pyrrole monomer on the carbon surface indicated preferential filling and coverage of pores
and other geometrically restricted pockets of carbon surface. On the other hand, by converting Pt into colloids
in the preprecipitation method prior to their reduction, the platinum particles are forced to stay on the hybrid
support; a major part of which otherwise would have been migrated into the surface pores and defect sites.
Platinum particle size on these hybrid supports is 2 times higher than the catalyst prepared by polyol process.
However, the electroactive surface area and mass activity are 2 times higher than that of the Pt particles
prepared by polyol on hybrid material and are also significantly higher than that of the conventional
electrocatalysts prepared by the polyol method. At 0.8 V, the kinetic current density (jk) of Pt/C-PPy-Pre
obtained from the Koutecky-Levich plot is 1.5 and 2.5 times higher than that of catalysts prepared by the
polyol method on PPy-coated carbon and Vulcan XC-72 carbon, respectively. Almost 210 and 160 mW
cm-2 improvement for the maximum power density, respectively with oxygen and air, was obtained with the
modified system in comparison to the conventional system when the single cell evaluations were carried out at 60 °C with a Pt loading of 0.5 mg cm-2 in the anode and cathode sides. This enhancement in the cell performance under the two different oxygen partial pressure conditions clearly emphasizes the improved oxygen reduction reaction (ORR) and mass-transfer characteristics of the hybrid electrode material compared to the other catalysts
Influence of substrate temperature on the properties of electron beam evaporated ZnSe films
No full textZnSe films were deposited on glass substrates keeping the substrate temperatures, at room temperature (RT),
75, 150 and 250 °C. The films have exhibited cubic structure oriented along the (111) direction. Both the
crystallinity and the grain size increased with increasing deposition temperature. A very high value of
absorption co-efficient (104 cm-1) is observed. The band gap values decrease from a value of 2.94 eV to
2.69 eV with increasing substrate temperature. The average refractive index value is in the range of 2.39 –
2.41 for the films deposited at different substrate temperatures. The conductivity values increases
continuously with temperature. Laser Raman spectra showed peaks at 140.8 cm-1, 246.7 cm-1 and 204.5 cm-1
which are attributable to 2TA LO phonon and TO phonon respectively
Voltammetric Determination of l-Dopa on Poly(3,4-ethylenedioxythiophene)-Single-Walled Carbon Nanotube Composite Modified Microelectrodes
No full textIn the present communication, it is shown that platinum microelectrodes electrochemically coated with a composite of
poly(3,4-)ethylenedioxythiophene and single-walled carbon nanotubes (PEDOT/SWNT) enable determinations of
3,4-dihydroxy-l-phenylalaines (l-dopa) in neutral phosphate buffer solutions containing an excess of ascorbic acid.
The interpenetrated networked nanostructure of the composite was characterized by scanning electron microscope
(SEM) and Raman spectroscopy. It is shown that the presence of the composite gives rise to an increase in the
electroactive area of an order of magnitude in compared to the area for the bare microelectrodes. The composite filmcoated
microelectrode, which yielded reversible cyclic voltammograms for the ferro/ferricyanide redox couple for
scan rates between 0.01 and 0.10 V s�1, also gave rise to two well-resolved oxidation peaks for l-dopa and ascorbic
acid (AA). The latter effect, which was not seen in the absence of the composite, enabled differential pulse
voltammetric determinations of l-dopa in the concentration range between 0.1 to 20 mM with a detection limit of
100 nM