Vol. 8(4) December 2004
Microamperometric Method for Hydrogen Peroxide Determination
in Flow Injection Analysis
O. Largiuni*, R. Bocciolini, S. Becagli, R. Traversi and R. Udisti
A sensitive method for the hydrogen peroxide amperometeric
determination in aqueous samples by Flow Injection Analysis has been developed.
A thin layer microcell with a platinum working microelectrode has been used. The
developed method has a detection limit of 0.08 mg l-1 and a precision of 7% at 1
mg l-1 level (< 1% for concentration > 10 mg l-1). The calibration graph is linear
in over the range 1-34500 mg l-1. The sensitivity, rate of sample analysis, ease
of use and small volume of sample requested make this method ideal for hydrogen
peroxide determination in precipitation samples with concentration from very low
to very high by Flow Injection Analysis. The method has been applied to analysis
of 153 snowpit samples from Antarctica and the results have been compared with those
obtained with fluorimetric method.
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Settling in a Periodic Array of Eddies: A new procedure
of Separation and Classification of Heavy Particles Suspended in a Fluid
U.Sánchez* and M. J. Moreno-López
Disperse multiphase flows are very common in the environment
and in many industrial processes. Existing procedures of particle-fluid separation
do not sort particles with different characteristics. We propose a new procedure,
which differentiates small heavy particles suspended in a fluid depending on their
inertia values. For that purpose we simulate a velocity field generated by a 2D
array of vortices periodically repeated in space in two cases: firstly all the neighbouring
vortices swirling alternatively cyclonically and anticyclonically and secondly all
the neighbouring vortices swirling in the same sense (counterclockwise). In the
first case, for small particle inertia the particles follow the flow streamlines
surrounding the vortices, but for larger inertia values, every time the distance
between the particle and the vertical row of vortices is greater and at last all
the particles settle in the central region of low vorticity situated between two
vertical rows of vortices due to an inertial bias. In the second case, the behaviour
of the particles is the same as in the previous one for small or moderate particle
inertia values, but for sufficiently large particle inertia the particles do not
settle in the central region of low vorticity, they settle on some isolated curves
which limit some regions of low vorticity where particles can not enter. As larger
is the particle inertia, larger is the width of those regions. At the same time,
some empty regions situated under each vertical row of vortices appear. As larger
is particle inertia, smaller is the width of these empty regions because the influence
of the vorticity field is smaller. Therefore if we know the particle inertia we
will know the position in which it will settle and vice versa, so this fact suggests
to develop a mechanism to sort particles with different inertia values.
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Phase Behavior and Microscopy Propertiesof Batyl Alcohol
K.Anuar*, C. S. Lim, K. Dzulkefly and I.Zahariah
Batyl alcohol (BA) is widely used in cosmetic products,
little is known about its phase behaviour and its structure in ternary systems.
Phase diagram of BA/Isopropyl Myristate (IPM)/H2O were constructed at 80°C and the
phase changes were observed under a polarizing microscope. In the ternary systems,
lamellar and hexagonal areas were found in 90/10 and 100/0 mixtures of BA and IPM
respectively. They were identified by their patterns of Maltese crosses and fan
structures respectively. A focal conic fan-like and pseudo-isotropic texture was
also found in this system. This phase was observed before entering the liquid crystal
area. Further addition of either Medium Chain Triglyceride (MCT) or Propylene Glycol
(PG) to the system resulted in isotropic and two-phase areas being formed instead
of a liquid crystalline structure.
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The Preparation and Structural Studies of bis(aquachloro)chromium(III)
bis(m-hydroxy) hippuratohydroxyaquachromium(III) Complex
G. Kumar
The preparation and structural studies of bis(aquachloro)
chromium(III) bis(m-hydroxy) hippuratohy droxyaquachromium(III) complex have been
carried out by elemental analysis, IR, UV spectra and magnetic measurements. In
this complex, hippuric acid has been found to act as a bidentate ligand and the
coordination occurs both from carboxylate oxygen and nitrogen of the amido group.
The complex has been suggested to show octahedral structure.
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Tarnishing of Silver in Telephone Switching Centers
in Japan
Masamitsu Watanabe
The tarnishing of silver exposed in our nine telephone
switching centers has been studied. The silver tarnish rate was calculated from
the amount of sulfur detected on the silver surface determined by x-ray fluorescence
analysis on the assumption that the sulfur existed as silver sulfide (Ag2S). The
tarnish rates in the telephone switching centers obeyed a lognormal approximation
with a high correlation coefficient. The geometric means of the tarnish rates in
urban, rural, and hot spring areas were 3.23, 3.62, and 44.01 nm/30 days, respectively.
The tarnish rates obtained in our telephone switching centers in urban areas were
an order of magnitude lower than the rates reported for the US and Southeast Asia.
This was attributable to the lower hydrogen sulfide (H2S) concentration. The fast
tarnish rates at one rural site were considered and found to result from a high
concentration of carbonyl sulfide (COS). COS may account for the silver tarnishing
in our telephone switching centers.
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The contribution of Geophysical Methods in the determination
of Aquifer Parameters: the case of Mornos River Delta, Greece
Ioannis F. Louis*, George A. Karantonis, Nikolaos S. Voulgaris and Filippos I. Louis
Knowledge of hydraulic conductivity and transmissivity
is essential for the determination of natural water flow through an aquifer. Although
these characteristics are mainly deduced from pumping test analysis, attempts have
been made to employ geophysical methods in order to reduce the amount of hydrogeological
observations and the resulting cost. Use of layer thickness, as derived from the
interpretation of resistivity soundings data and hydraulic conductivity calculated
on the basis of both hydrogeological and geophysical data led to the calculation
of aquifer transmissivity. This technique was used for the determination of aquifer
parameters in Mornos River Valley at central Greece. Maps of the basement relief,
resistivity, transmissivity and Transverse Resistance provided the means to identify
areas where the aquiferous zone is prolific. The good agreement between aquifer
hydraulic conductivities obtained from the resistivity soundings interpretation
and those deduced from pumping test analysis emphasizes the potential of the methodology.
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A study of air pollution on Kharg Island in the South
Iran
S. Tasharrofi*, A. Dahaghin, H. Kazemi and M. Farhadynya
Nowadays the development of oil industry has severe effects
on environmental pollution. The problem begins from simple crude oil separation
units to large refineries. As a case study we chose Kharg Island where several production
units and oily pits are active. This paper is in connection with a research work
in two successive years 2000 and 2001, in which monthly concentrations of total
active sulfur compounds were measured in six stations in parallel. In this research
work, sources, effects and standards of pollutants are investigated and their relation
to emission sources have been evaluated. Then the results of measurements in different
stations are compared with each other and with standard limits.
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Study of Photogalvanic Effect in Azur C–Nals-ascorbic
Acid System
K.R. Genwa* and Anju Chouhan
The Photogalavanic effect was studied in a photogalvanic
cell containing NaLS–Ascorbic acid and Azur C as a surfactant, reductant and photosensitizer
respectively. The photopotential and photocurrent generated by this system were
623.0 mV and 145.0 mA respectively. The observed conversion efficiency was 0.4567%
and fill factor was determined as 0.30. The cell performance was 95.0 minutes in
dark. The effect of different parameters on the electrical output of the cell were
observed, current–voltage characteristics of the cell have also been studied and
mechanism has been proposed for the generation of photocurrent in photogalvanic
cell. Maximum power obtained from this cell was 47.50 mW.
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Use of 2, 4 –Dihydroxybenzophenone Oxime as a Reagent
for Extraction and Spectrophotometric Determination of Palladium (II)
R.S. Lokhande*, Ujwala Patil and Sheetal S. Dapale
2,4–Dihydroxybenzophenone Oxime(DHBPO) was synthesized
and its characterization study was carried out using elemental analysis, IR, NMR
techniques. The reagent was proposed as extractant for development of new extractive
spectrophotometric method for determination of Pd (II) metal. The reagent complexes
with metal to produce yellow coloured complex which was then extracted into Butan-1-ol
at pH 4.0. The complex is having absorption maxima at 410 nm. The molar absorptivity
of the extracted species is 0.672 x102 L mol-1 cm-1 and sensitivity is 0.06729 mg/ml.
The method permits separation and determination of Palladium catalyst and binary
mixture.
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Mass Spectrometric and I R spectroscopic study of
the destruction of environmentally hazardous Indanthrene Red FFB a textile pollutant
L. Gomathi Devi * and R.Geetha Balakrishna
Photocatalytic oxidation of organic pollutants over nano
particles of TiO2 prepared by gel to crystalline conversion was investigated as
a potential method for destroying textile pollutant Indanthrene Red FFB. Surface
morphology of synthesized anatase phase of TiO2 was studied using SEM analysis and
X-ray diffraction studies. Photodegradation path is followed by UV Visible spectroscopy,
Mass spectrometry and Infrared (FTIR) spectroscopy. There are significant quantities
of intermediates like phthalic acid, amino substituted phthalic acid, aniline, phenol
and benzene. These products have also been rationalized on the basis of chemical
reaction mechanism in which anthraquinone dye molecules are oxidized in a chain
reaction involving radicals. A kinetic model is thus formulated based on the results.
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Possibilities of using Red Mud as Raw Materials Mixture
Component for Production of Bricks
M.M. Krgovic*, N.Z. Blagojevic, Z. K. Jacimovic and R. Zejak
Red mud is a bye-product of Bayer process for obtaining
alumina (solid residue of dissolution of bauxite). In this paper possibility of
using red mud as a component of raw materials mixture for obtaining bricks has been
investigated. By using red mud cheap raw material for building construction and
ceramics would be obtained and, at the same time, the problems (air, underwater
and soil pollution) of environmental protection, which can be posed by frequent
disposal of red mud into the pools, would be solved. On the basis of all the results
of the investigations and their analysis, it can be concluded that red mud can be
used as a component of raw materials mixture for production of bricks satisfying
mechanical characteristics, shrinkage and porosity of sintering products.
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Removal of Zinc from Waste water
B. K. Bhattacharya*, S. K. Das and S. N. Mandal
Zinc is a very widely used metal. The main source of
aquatic contamination of zinc are the metal production units and the other industries
wastes like pharmaceuticals, electroplating, paints and pigments, which use metal
and its compounds. Zinc is present in the effluents from the electroplating, metal
processing, pigment manufacturing, textile and dye industries etc. which cause serious
problems to the environment. In an aquatic environment, high concentrations of heavy
metal through water and sediment phase tend to accumulate in different tissues of
the body of fishes and other aquatic lives and thus bio-accumulated and disturbing
the natural equilibrium of an aquatic environment. Symptoms of zinc toxicity include
irritability, loss of appetite, nausea. Increased concentration of zinc is dangerous
to human beings. In the presents study an attempt has been made to remove zinc from
aqueous medium by using fullers’ earth as an absorbent. The effects of pH, initial
concentration of zinc, contact time, adsorbent doses and isotherm models were studied
in batch processes
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