نتایج جستجو برای: chromium sampling method
تعداد نتایج: 1795033 فیلتر نتایج به سال:
background and aims: chromium is considered as one of the important environmental pollutants. there is high concentration of chromium in the wastewater of electroplating industries. magnetic iron nanoparticles are used to control and eliminate heavy metals from industrial effluents through the mechanisms of adsorption, ion exchange and electro-static forces. the aim of this study was to evaluat...
introduction: in electroplating processes, hexavalent chromium mist is emitted in air. hexavalent chromium mist can cause lung cancer and nasal septum in workers. as permissible exposure limit (pel) of hexavalent chromium is low (0.5 µg/m 3 ) and it is used in various industries, evaluation of workers exposure to hexavalent chromium is very important. however, hexavalent chromium is relatively ...
abstract objectives gradual increase length and complexity of utterance (gilcu) therapy method is a form of operant conditioning. this type of treatment is very precise and controlled that is done in 54 steps in 3 speech situations consisted of monologue, reading and conversation. this study aimed to examine the effects of gilcu treatment method on reduction of speech dysfluency of school-age...
abstract this study is an attempt to determine the effect of nano- technology education on science lesson for fifth grade in primary school in the city of kermanshah. this research is experimental and is conducted in the from of pre-test and post- test for the control group. an achievement test was administered to determine the rate of learning in the students. the research is an applied one. ...
A field study was conducted with the goal of comparing the performance of three recently developed or modified sampling and analytical methods for the determination of airborne hexavalent chromium (Cr(VI)). The study was carried out in a hard chrome electroplating facility and in a jet engine manufacturing facility where airborne Cr(VI) was expected to be present. The analytical methods evaluat...
The state of the art of analytical procedures based on solid-phase microextraction (SPME) and its applications to tin, mercury, arsenic, antimony, chromium, selenium, and lead determination in abiotic and biotic matrixes are critically reviewed from 1994 to present. First, sample pretreatment prior to SPME is evaluated, including a description of the most usual leaching procedures for sediment,...
The capabilities of a “universal platform” for the deployment of analytical sensors in the field for long-term monitoring of environmental contaminants were expanded in this investigation. The platform was previously used to monitor trichloroethene in monitoring wells and at groundwater treatment systems (1,2). The platform was interfaced with chromium (VI) and conductivity analytical systems t...
environmental pollution by various pollutants is one of the most important problems of this century. at least 20 elements, including chromium have been classified in toxic metals group, that half of them are released in the environment in excessive amounts of standards. chromium is a toxic pollutant that is widely spread in the environment and exists in cement and concrete. the aim of this stud...
Introduction: Since, rice is the main source of food for the majority of people in the world, including Iran, determine of concentration and distribution of heavy metals in rice plants is important. The aim of this study was to determine cadmium, chromium and zinc concentrations in rice produced of the Mobarakeh County. Material and Method: Sampling was conducted based on stratified random met...
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