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Effect of pulse parameter on pulsed electrodeposition of copper on stainless steel
No full textThe pulsed electrodeposition of copper on stainless steel has been studied in copper sulphate
bath and the effect of duty cycle and frequency on the thickness and current efficiencies were
compared at 50uC and at room temperature with average current density of 4 A dm22. A new
strike bath based on cupric chloride and hydrochloric acid was developed for the first time. The
Cu coatings were characterised by SEM, AFM and XRD. Crystallite sizes of Cu coatings were
calculated for various duty cycles from the Scherer’s equation. The deposits were smaller nodules
and fine grained
Electrochemical Method for the Preparation of Dibromomethyl, Bis(bromomethyl), and Bis(dibromomethyl) Arenes
No full textElectrochemical bromination of alkyl aromatic compounds by twophase
electrolysis yields the corresponding a,a-dibrominated products. The
reaction has been carried out in a single-compartment electrochemical cell using
aqueous sodium bromide (40–50%), containing a catalytic amount of HBr as electrolyte,
and chloroform, containing an alkyl aromatic compound, as the organic
phase with a Pt plate as anode at 10–15C. Two-phase electrolysis results in high
yields (70–90%) of dibromomethyl, bis(bromomethyl), and bis(dibromomethyl)
arenes, depending upon the charge passed
Materials properties of electrodeposited NiFe and NiCoFe coatings
No full textThe codeposition behaviour of the electrodeposited iron group alloy system, NiFe and NiCoFe,
was studied in acid sulphate electrolyte. X-ray diffraction measurements revealed the existence of
FCC phases. X-ray fluorescence analysis of the elemental composition in NiFe and NiCoFe
coatings electrodeposited over copper substrate was also carried out. The result suggested that
Ni is inhibited by the presence of Fe2z and Co2z ions. The properties of soft magnetic NiFe and
NiCoFe coatings electrodeposited in the presence of saccharin and sodium lauryl sulphate
additives were studied. Corrosion performance of these coatings in 3?5% NaCl solution was
evaluated using impedance electrochemical techniques. The superior coefficient of friction of
NiFeCo coatings was observed from block-on ring test
Improvement of cycle behaviour of SiO/C anode composite by thermochemically generated Li4SiO4 inert phase for lithium batteries
No full textA new anode composite material is prepared by thermal treatment of a blend made of silicon monoxide
(SiO) and lithium hydroxide (LiOH) at 550 ◦C followed by ball milling with graphite. X-ray diffraction
pattern confirms the presence of Li4SiO4 in the thermally treated (SiO + LiOH) material. The electrode
appears to be smooth and glassy as evident from observation with a scanning electron microscope (SEM),
possibly due to the presence of nano-silicon and Li4SiO4 particles, and exhibits superior performance
with a charge capacity of ∼333mAhg−1 at the 100th cycle with a low-capacity fade on cycling. Cyclic
voltammograms of the electrode predict high power capability. On the other hand, the electrode comprising
of only SiO and C prepared through ball milling, devoid of Li4SiO4, shows hard crust particulates
in the electrode exhibiting low charge–discharge capacities with cyclin
Electro-degradation and biological oxidation of non-biodegradable organic contaminants
No full textThe speciality chemical process requires large volumes of water of high purity and generates equally
large volumes of wastewater. The generated wastewater is complex and highly variable with respect to
its nature, containing high levels of chemical oxygen demand (COD), dissolved and suspended solids, a
medium to low level of biochemical oxygen demand, a considerable amount of total organic halogen and
an intense colour. In the present study the actual effluent was collected from the organic industry and
various experiments were conducted to reduce the pollution load and reuse treated wastewater.
The wastewater typically contains COD about 48,000mgL−1. When it was distilled, the COD of the
condensate reduces to 17,000mgL−1 which was subjected to electrolytic degradation and subsequently
biological oxidation. The operation was continued using various microorganisms such as Bacillus subtilis,
Pseudomonas aeruginosa and Proteus vulgaris in a batch reactor. Minimum of 80% reduction of COD was
obtained in the combined process
Polymer electrolyte fuel cells employing electrodes with gas-diffusion layers of mesoporous carbon derived from a sol–gel route
No full textSol–gel derived mesoporous carbon (MC) for the preparation of gas-diffusion layer (GDL)
and its ameliorating effect on the performance of polymer electrolyte fuel cells (PEFCs) is
reported. MC with a specific surface area of 370m2/g, pore diameter of 6.7 nm and pore volume
of 0.45 cm3/g has been synthesized by co-assembly of a tri-block copolymer, namely
pluronic-F127, as a structure directing agent, and a mixture of phloroglucinol and formaldehyde
as carbon precursor. X-ray diffraction and transmission electron microscopy have
been employed to examine the structural properties of the MC. Surface morphology of the
GDL comprising MC has been studied by scanning electron microscopy. A peak power density
of 0.53 W/cm2 at a load current-density of 1.1 A/cm2 is achieved for the PEFC employing
electrodes with GDL of MC compared to the peak power density of 0.47 W/cm2 at a load current-
density of 0.93 A/cm2 for the PEFC employing electrodes with GDL of commercial Vulcan
XC-72R carbon, while operating at 70 oC with H2 and air feeds at atmospheric pressur
Combustion synthesis of Ca1xCuxAl2O4 (x = 0.0, 0.4 and 0.8) copper doped calcium aluminate
No full textWe report the effect of Cu2+ ion on CaAl2O4 with different molar concentrations of 0.0, 0.4 and 0.8 M prepared by simple combustion method.
The materials have been characterized by X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR) and scanning electron microscopy
(SEM). DC electrical conductivity has also been measured to study the electrical behavior of the materials. The XRD patterns confirm the
formation of single-phase CaAl2O4 along with some impurity phases like CaAl4O7, CaAl12O19 and Ca12Al14O33. The FT-IR spectra show the
stretching and bending vibrations of the synthesized compounds. DC electrical conductivity of the Ca1xCuxAl2O4 is found to vary from
26.46 104 to 515.68 104 S cm1 for x = 0.0 to x = 0.8 at the measuring temperature of 1000 8C. SEM images show the morphological
features of the compounds
Ferric-oxalate-gluconate based redox mediated electrochemical system for vat dyeing
No full textThe voltammetric behaviour of the ferric-oxalategluconate
system is investigated along with some electrochemical
dyeing results. The results are compared with the
conventional ferric-triethanolamine-gluconate system on a
glassy carbon electrode. The ferric-triethanolamine redox
system is stable and exhibits quasi-reversible redox behaviour in alkaline medium. The ferric-oxalate system undergoes hydrolysis and precipitates above pH 8. Vat dyeing requires the stability of the redox system in alkaline solutions. The ferric-oxalate redox system alone cannot satisfy this requirement.
However, in the presence of excess gluconate, both
systems exhibit stability in alkaline media. Mechanistic
studies indicate the formation of ferrous-gluconate as the
reducing agent for vat dyeing from these mediator systems.
Electrochemical dyeing was also carried out in the mediator
system under investigation. Colour depth was characterized
by the Kubelka-Munk value (K/S) and CIE Lab-coordinates
for the dyed fabrics and was found to be comparable with
samples dyed using sodium dithionite as the reducing agent
Rapid charging characterization of MmNi3.03Si0.85Co0.60Mn0.31Al0.08 alloy used as anodes in Ni–MH batteries
No full textThe use of Nickel–Metal Hydride (Ni–MH) batteries for traction application in electric and
hybrid vehicles is on the rise. High-rate charge/discharge characteristics are important
parameters for electric vehicle applications. The ability to reduce charging time is essential
in these traction applications. In this paper, the performance of assembled Ni–MH batteries
(1.2 V, 0.5 Ah specimen cells) when subjected to different charging rates is described.
Changes in battery voltage during charging were monitored with a particular emphasis on
the quest for fast recharge characteristics. The charging curves reveal the formation of
different types of phases. Hydrogen evolution resulted in flat charge profile after certain
amount of overcharging. The changes in discharge level after different rates of charging are
insignificant. This paper describes the fast rechargeability of assembled Ni–MH cells under
various fast-charge regimes