88 research outputs found
Survey efficiency of ultraviolet and zinc oxide process (UV/ZnO) for removal of diazinon pesticide from aqueous solution
The presence of persistent organic pollutants and toxics (e.g., pesticides) in ground, surface, and drinking water
resources combined with the inability of conventional treatment methods to remove these pollutants have led to
the development of advanced oxidation processes. Nowadays, nanophotocatalyst processes are considered as
clean and environmentally-friendly treatment methods that can be extensively used for removing contaminants.
The objective of the present study was to determine the efficiency of the ultraviolet and zinc oxide (UV/ZnO)
process in the removal of diazinon pesticide from aqueous solutions. For the purposes of this study, samples
were adjusted in a batch reactor at five different detention times. The pH levels used were 3, 7, and 9. Irradiation
was performed using a 125 W medium-pressure mercury lamp. The diazinon concentrations of the samples were
100 and 500 Sg/L and the concentrations of zinc oxide nanoparticles were 50, 100, and 150 mg/L. The highest
degradation efficiency was observed at pH 7 (mean = 80.92 ± 30.3), while the lowest was observed for pH 3
(mean 67.11 ± 24.49). Results showed that the optimal concentration of nanoparticles (6-12 nm) was 100 mg L-1
Potoccatalytic oxidation of oganophosphorus pesticides using zinc oxide
Abstract
In recent years, the application of heteroge-neous
photocatalytic water treatment processses has gained
wide attention due to its effectiveness in degra-ding
and mineralizing the pesticides. These pesticides are
often found in many surface and groundwater sources
and their concentration levels often exceed the
drinking water permissible limits recommended by
Iran and European drinking water standards. The aim
of the present study was to investigate the influence of
various parameters such as initial malathion and diazinon
concentration catalyst amount, initial pH of the
reaction medium and pesticide types on the photocatalytic
decomposition of pesticides in the presence
of ZnO using an ultraviolet lamp as the light source.
The best conditions for the photocatalytic degradation
of pesticides were obtained. Results showed that the
optimal concentration of catalyst was found to be 100
mg. L
-1
. The photodegradation efficiency of pesticides
increases with the increase of the illumination time.
The photodegradation rate of pesticides was higher in
alkaline than in acidic conditions. The photocatalytic
degradation rate of the malathion was more than
diazinon. The photodegradation efficiency decreases
with the increase in the initial concentration of pesticides.
The photocatalytic system afforded the highest
removed percentage at initial concentration for diazinon
and malatlion were 100 and 200 mg.L-1
respectivel
Magnetic Branes in Gauss-Bonnet Gravity
We present two new classes of magnetic brane solutions in
Einstein-Maxwell-Gauss-Bonnet gravity with a negative cosmological constant.
The first class of solutions yields an -dimensional spacetime with a
longitudinal magnetic field generated by a static magnetic brane. We also
generalize this solution to the case of spinning magnetic branes with one or
more rotation parameters. We find that these solutions have no curvature
singularity and no horizons, but have a conic geometry. In these spacetimes,
when all the rotation parameters are zero, the electric field vanishes, and
therefore the brane has no net electric charge. For the spinning brane, when
one or more rotation parameters are non zero, the brane has a net electric
charge which is proportional to the magnitude of the rotation parameter. The
second class of solutions yields a spacetime with an angular magnetic field.
These solutions have no curvature singularity, no horizon, and no conical
singularity. Again we find that the net electric charge of the branes in these
spacetimes is proportional to the magnitude of the velocity of the brane.
Finally, we use the counterterm method in the Gauss-Bonnet gravity and compute
the conserved quantities of these spacetimes.Comment: 17 pages, No figure, The version to be published in Phys. Rev.
Slowly rotating charged black holes in anti-de Sitter third order Lovelock gravity
In this paper, we study slowly rotating black hole solutions in Lovelock
gravity (n=3). These exact slowly rotating black hole solutions are obtained in
uncharged and charged cases, respectively. Up to the linear order of the
rotating parameter a, the mass, Hawking temperature and entropy of the
uncharged black holes get no corrections from rotation. In charged case, we
compute magnetic dipole moment and gyromagnetic ratio of the black holes. It is
shown that the gyromagnetic ratio keeps invariant after introducing the
Gauss-Bonnet and third order Lovelock interactions.Comment: 14 pages, no figur
Horizonless Rotating Solutions in -dimensional Einstein-Maxwell Gravity
We introduce two classes of rotating solutions of Einstein-Maxwell gravity in
dimensions which are asymptotically anti-de Sitter type. They have no
curvature singularity and no horizons. The first class of solutions, which has
a conic singularity yields a spacetime with a longitudinal magnetic field and
rotation parameters. We show that when one or more of the rotation
parameters are non zero, the spinning brane has a net electric charge that is
proportional to the magnitude of the rotation parameters. The second class of
solutions yields a spacetime with an angular magnetic field and
boost parameters. We find that the net electric charge of these traveling
branes with one or more nonzero boost parameters is proportional to the
magnitude of the velocity of the brane. We also use the counterterm method
inspired by AdS/CFT correspondence and calculate the conserved quantities of
the solutions. We show that the logarithmic divergencies associated to the Weyl
anomalies and matter field are zero, and the divergence of the action can
be removed by the counterterm method.Comment: 14 pages, references added, Sec. II amended, an appendix added. The
version to appear in Phys. Rev.
Applying job hazard analysis and William Fine methods on risks identification and assessment of jobs in hot rolling steel, Iran
Background and purpose: Comprehensive evaluation of jobs in industries is a practical and effective method that could identify the jobs and industries with negative effects on the environment. This study identified environmental hazards of hot rolling process and assessing their risks. Materials and methods: An observational study was carried out in which identification of human activity and job’s risks in production hall of Kavir Steel Complex was done according to ISO 14001 approaches (pollutant emissions to air, discharges to water, energy consumption, energy released as heat, wastes, side products, etc) by Job Hazard Analysis method (JHA). Then the risks identified were prioritized and assessed using William Fine method. Results: We identified 205 environmental hazards (in 9 groups) associated with production personnel (n= 81), mechanics and maintenance personnel (n= 44), bed personnel (n= 9), personnel of cleaning services (n= 33), and water plant personnel (n= 38). The highest and lowest rate of risks were due to creation and distribution of wastes (n= 73) and corrosion and depreciation of equipment, (n= 1), respectively. Conclusion: The production personnel were mainly responsible for environmental emissions. The leading causes were stress and anxiety about stoppage of production, payment reduction, and lack of awareness and workers and supervisors on environmental issues. © 2017, Mazandaran University of Medical Sciences. All rights reserved
Removal of malathion insecticide from water by employing acoustical wave technology
Background: Organophosphorus pesticides are one of the most prevalent usages for pest control in the country. Such pesticides
enter into water sources by different routes. Since drinking of contaminated water at the higher doses than the standard
level, may causes undesirable effects to human health and ecosystem. The object of this research was to investigate the effect
of various parameters including time, power and concentration on sonodecomposition of malathion insecticide in the
water.
Methods: The sonochemical degradation of malathion was investigated using acoustic wave technology (AWT). AWT with
130 kHz was used to study the decomposition of insecticide solution. Samples were analyzed using HPLC at different intervals
times. Effectiveness of AWT at different times (20, 40, 60, 80, 100, and 120 minutes), concentrations of malathion at 2,
4 and 8 mg/L as well as powers of device (300W, 400W, 500W) are compared.
Results: These findings showed that the degradation of the malathion insecticide at lower concentrations was greater in
comparison to higher concentrations. Also, there was positive correlation between power increasing and the ability to malathion
degradation
Conclusion: The sonodegradation of malathion at different concentrations and powers was successfully achieved. It has
been shown that acoustical wave technology can be used to reduce the concentration of dissolved insecticide using high frequency
Ricci flat rotating black branes with a conformally invariant Maxwell source
We consider Einstein gravity coupled to an gauge field for which the
density is given by a power of the Maxwell Lagrangian. In -dimensions the
action of Maxwell field is shown to enjoy the conformal invariance if the power
is chosen as . We present a class of charge rotating solutions in
Einstein-conformally invariant Maxwell gravity in the presence of a
cosmological constant. These solutions may be interpreted as black brane
solutions with inner and outer event horizons or an extreme black brane
depending on the value of the mass parameter. Since we are considering power of
the Maxwell density, the black brane solutions exist only for dimensions which
are multiples of four. We compute conserved and thermodynamics quantities of
the black brane solutions and show that the expression of the electric field
does not depend on the dimension. Also, we obtain a Smarr-type formula and show
that these conserved and thermodynamic quantities of black branes satisfy the
first law of thermodynamics. Finally, we study the phase behavior of the
rotating black branes and show that there is no Hawking--Page phase transition
in spite of conformally invariant Maxwell field.Comment: 13 pages, one figur
Charged rotating dilaton black branes in AdS universe
We present the metric for the -dimensional charged rotating dilaton
black branes with cylindrical or toroidal horizons in the background of anti-de
Sitter spacetime. We find the suitable counterterm which removes the
divergences of the action in the presence of the dilaton potential in all
higher dimensions. We plot the Penrose diagrams of the spacetime and reveal
that the spacetime geometry crucially modifies in the presence of the dilaton
field. The conserved and thermodynamic quantities of the black branes are also
computed.Comment: 13 pages, 3 figures, to appear in Gen. Relat. Gravi
Abelian Higgs Hair for Rotating and Charged Black Holes
We study the problem of vortex solutions in the background of rotating black
holes in both asymptotically flat and asymptoticlly anti de Sitter spacetimes.
We demonstrate the Abelian Higgs field equations in the background of four
dimensional Kerr, Kerr-AdS and Reissner-Nordstrom-AdS black holes have vortex
line solutions. These solutions, which have axial symmetry, are generalization
of the Nielsen-Olesen string. By numerically solving the field equations in
each case, we find that these black holes can support an Abelian Higgs field as
hair. This situation holds even in the extremal case, and no flux-expulsion
occurs. We also compute the effect of the self gravity of the Abelian Higgs
field show that the the vortex induces a deficit angle in the corresponding
black hole metrics.Comment: 22 pages, 16 figures, a section about the vortex self gravity on Kerr
black hole added, extremal black holes considered, one figure changed, one
reference adde
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