نتایج جستجو برای: such as initial concentration
تعداد نتایج: 6272104 فیلتر نتایج به سال:
two groups of students were assigned as experimental and control ones, and were given instruction on directed reading-thinking activities and after some treatment, they were post-tested. although the initial pre-test did not show any significant differences, the final post-test result revealed that the cooperative reading comprehension helped the experimental group. the cooperative students’...
Synthesis of zinc oxide nanoparticle by zinc acetate precursor and study on its catalytic properties
ZnO nanoparticles have been prepared by a simple method in a short period of time. In this synthetic method, the sample was obtained using Zn(CH3COO)2·2H2O and a new template of hexamine salt. Their crystalline structure and morphology were studied by XRD and SEM. The optical properties of the sample were studied by UV–visible spectroscopy. The absorption spectr...
This work describes the photocatalytic removal of methylene blue from aqueous solution by titanium dioxide nanoparticles under ultraviolet irradiation in a batch system. The effect of operational parameters such as irradiation time, nano titanium dioxide dosage, pH and initial methylene blue concentration were analyzed and optimized by response surface methodology in the nano titanium dioxide/u...
Abstract Introduction: Chromium is an extremely important heavy metal which is used in different industries. It can be found in water resources due to insufficient treatment of industrial wastewater. The goal of this study was to survey the feasibility of application of hexavalent chromium reduction using granular magnesium as reducing agent and to investigate the affects of various operationa...
In the present study, the removal of lead (II) ions from aqueous solutions was investigated by powdered Henna. Henna is a herbal material that can dramatically adsorb metal ions. Adsorption experiments were carried out in a batch system at room temperature. Then, the equilibrium concentration of each sample was analyzed by atomic adsorption device. The effects of various parameters such as ...
Synthesis of zinc oxide nanoparticle by zinc acetate precursor and study on its catalytic properties
ZnO nanoparticles have been prepared by a simple method in a short period of time. In this synthetic method, the sample was obtained using Zn(CH3COO)2·2H2O and a new template of hexamine salt. Their crystalline structure and morphology were studied by XRD and SEM. The optical properties of the sample were studied by UV–visible spectroscopy. The absorption spectr...
The formal expression of pro positional attitudes, especially when nested (iterated), is an important problem for A I . An interesting first-order extensional logical system for such expression has been proposed by Creary. In this system concepts (and concepts of concepts, etc.) are made explicit. The system includes "concept functions", which are special functions which act on and deliver conc...
Background : 2-chlorophenol is one of the aromatic organic compounds found in large amounts in oil and petrochemical waste waters and chemical methods such as advanced oxidation, etc are used for removal there. Among various AOPs the method derived from sulfate radicals (SO4● -) and per sulfate (S2O82-) activating with heat, UV radiation and transition metals (such as iron ions) is of interest....
Background and Aim: Common sources of chromium in wastewater are electroplating and leather industries. Thus, the present study aimed at investigating and comparing between chemical (H2O2) method and nano-photocatalytical(UV/ZnO) method in removing of Cr(VI) from polluted water. Materials and Methods: In this experimental-analytical study, effective factors on reduction process such as ZnO (0.0...
Background and Objective: Electrochemical methods as one of the advanced oxidation processes (AOPs), have been applied effectively to degrade recalcitrant organics in aqueous solutions. In the present work, the performance of electro-Fenton (EF) method using iron electrodes on the degradation of phenol was studied. Materials and Methods: In this study, a lab-scale EF batch reactor equipped with...
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