Two-dimensional unsteady mixed convection in a porous cavity with heated bottom wall is numerically studied in the present paper. The forced flow conditions are imposed by providing a hydrostatic pressure head at the inlet port that is located at the bottom of one of the vertical side walls and an open vent at the top of the other vertical side wall. The Darcy model is adopted to model the fluid flow in the porous medium and the combination effects of hydrostatic pressure head and the heat flux quantity parameters are carefully investigated. These governing parameters are varied over wide ranges and their effect on the heat transfer characteristics is studied in detail. It is found that the time required to reach a desired temperature at the bottom wall decreases with heat flux and pressure head increase. The higher heat flux quantities leaves wider regions near the top wall at lower temperatures which is important in most engineering applications like drying.
Mixed Convection in a Square Cavity Filled with Porous
Medium with Heated Bottom Wall
Porous Medium
Mixed Convection
Square Cavity
Uniform
Heating
Finite Volume Method
Publication Date
Sat Oct 01 2022
Journal Name
Environmental Advances
Stability and performance studies of emulsion liquid membrane on pesticides removal using mixture of Fe3O4Â nanoparticles and span80
The current study investigated the impact of nonionic surfactant span 80 in the existence of Fe3O4 magnetic nanoparticles on the emulsification of mixture of kerosene as petroleum based organic solvents and corn oil as a green diluent in the ratio 1:1
HCl was used as internal phase and the stability of the emulsion was carried out. The proposed Pickering emulsion liquid membrane has been exploited to investigate it is ability in the extraction of Abamectin pesticides from aqueous solution without utilizing carrier agent. Further
the effects of experimental parameters on extraction efficiency and emulsion stability such as
homogenizer speed
emulsification speed
contact time
Fe3O4-Span 80 ratios
HCL concentration
internal to membrane volume ratio (I/O) and pH of the external feed solution were carried out. The results showed that more than 99% of Abamectin could be extracted at 10 min contact time with a minimum breakage percent of 0.52% at the optimal conditions. The kinetic of the extraction were studied and the mass transfer coefficient was found to be for external phase () of 1.2
interfacial reaction rate constant () of 5.83 and the overall mass transfer coefficient () of 3.91 . The results of recyclability of the PELM revealed that the emulsion stability and extraction efficiency was nearly unchanged after three cycles.
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Publication Date
Wed Jan 01 2020
Journal Name
Technologies And Materials For Renewable Energy, Environment And Sustainability: Tmrees20
Change detection of the land cover for three decades using remote sensing data and geographic information system
The changes in the land cover using geographical information systems and remote sensing techniques for the period (1990 - 2019) for part of the Baghdad governorate in central Iraq are detected and monitored. In this research
four satellite scenes with different sensors were used the TM
ETM+
and OLI
which were obtained by Landsat-5
Landsat-7 and Landsat-8 satellites
respectively. Maximum likelihood method supervised classification is adopted as the main classifier to distinguish different land cover types in the study region. The results showed that there are ten different classes in the values of their reflectance. This study proved that any landcover of the earth’s surface can be studied and determined by its spectral characteristics. The change for each class of the land cover for the study area was determined within the study period. The results of the study confirmed the possibility of identifying the types of land cover and finding the percentage of changes that occur in it and detecting it with high efficiency using the remote sensing technique.
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Publication Date
Sat Sep 01 2018
Journal Name
Polyhedron
Novel dichloro (bis {2-[1-(4-methylphenyl)-1H-1, 2, 3-triazol-4-yl-κN3] pyridine-κN}) metal (II) coordination compounds of seven transition metals (Mn, Fe, Co, Ni, Cu, Zn and Cd)
The 1
3-dipolar cycloaddition “click” reaction between an azide and an alkyne to give a 1
2
3-triazole was reported by Huisgen in 1961 [1]. In 2002 the Copper(I)-catalyzed Azide-Alkyne Cycloaddition (CuAAC) to prepare a 1
2
3-triazole was reported [2]
[3]. The existence of relatively basic nitrogen atoms in the 1
2
3-triazole rings
and the possibility of introducing additional donor groups in the substituents (Fig. 1)
made the CuAAC “click” reaction an attractive method to prepare differently substituted 1
2
3-triazoles. These compounds have been used as ligands to coordinate to various metal ions that display a range of applications such as in electrochemical and photochemical studies
in supramolecular chemistry
magnetism
metal-ion sensing and catalysis [4]. The reasons for the success of the “click” reaction
is that it is easy to carry out and is widely applicable. It is not affected by a variety of functional groups
and can be carried out with a variety of Cu(I) catalysts and solvents
including aqueous conditions. The Cu(I) catalysts overcome the high activation energy barrier of the non-catalyzed Huisgen reaction by changing the mechanism of the reaction. A large variety of copper catalysts can be used for the CuAAC reaction
on condition that the maximum concentration of Cu(I) species is generated during the reaction. The pre-catalyst can be a Cu(II) salt (usually CuSO4) together with a reducing agent (often sodium ascorbate) or a Cu(I) compound in the presence of a base or amine ligand and a reducing agent to prevent oxidation to Cu(II). Some strong oxidising cupric salts or complexes such as Cu(OAc)2 also work. The solvent is very flexible from organic to aqueous
with the most commonly used combination water + an alcohol (t-BuOH
MeOH or EtOH). The key role of the solvent or solvent mixture is to solubilize the substrates and Cu(I) catalyst in order to ensure rapid reactions. Such aqueous conditions are very useful for biochemical conjugations
as well as for organic syntheses.
We recently reported on the synthesis of a series of differently substituted 1
2
3-triazole chromophores
the substituted 2-(1-phenyl-1H-1
2
3-triazol-4-yl)pyridine ligands [5]
see Fig. 2 middle
with substituents R = H (L1)
CH3 (L2)
OCH3 (L3)
COOH
F
Cl
CN
CF3
O(CH2)3CH3 and N(CH3)2. These versatile ligands were found to coordinate to various first row transition metals
such as manganese
cobalt and nickel [6]. Here we extend the series to include more first row transition metal(II) coordination compounds
iron
copper and zinc
as well as a second row transition metal(II) coordination compound
cadmium
containing the 2-(1-(4-methyl-phenyl)-1H-1
2
3-triazol-1-yl)pyridine chromophore (Fig. 2 right with R = CH3). This series of seven novel coordination compounds is the first series of pyridyl-triazole based transition metal coordination compounds where seven different transition metals are coordinated to the same 1
2
3-triazole chromophore
namely 2-(1-(4-methyl-phenyl)-1H-1
2
3-triazol-1-yl)pyridine.