نتایج جستجو برای: chromium sampling method
تعداد نتایج: 1795033 فیلتر نتایج به سال:
BACKGROUND Chromium is an essential element in human nutrition. Serum concentrations of chromium are not well characterized during pregnancy or in gestational diabetes mellitus. OBJECTIVE The objective of this study was to determine whether low plasma chromium concentrations (< or =3 nmol/L) are associated with altered glucose, insulin, or lipid concentrations during pregnancy. DESIGN The s...
Reduction of chromium(VI) to chromium(Ill) by thiourea between pH 3.0 and 5.5 is a key aspect of the chrominm(VI)/thiourea/polyacrylamide gel polymer system used in enhanced oil recovery processes. A method has been developed to determine chromium(Vl) concentration during the reduction of chromium(VI) to chromium(III) in this pH range. The reduction reaction is run in the presence of an acetic ...
hazards of soluable hexa and trivalent chromium have been documented by many investigators. but there was no information regarding safety of about 5000 workers at exposure risk to chromium in 600 primitive electroplating work shops of tehran. during this study more than 70% of work shops were inactive due to some of their own problems. out of active plants those that were relatively more cooper...
Estimation of water soluble hexavalent chromium and total chromium has been devised. For the complete extraction of water soluble hexavalent chromium, leaching period of five days is done. It was ascertained that complete extraction was achieved in five days; the total chromium determination in these samples was done by fusing sample with sodium carbonate up to 1050 C in muffle furnace. Chromiu...
Chromium in fumes generated in work environments including sites of welding work appears in various and complex states. Determination of chromium speciation in samples is useful for estimating the toxicity of such fumes. In the present study, determination of chromium speciation in chromium fumes prepared using a plasma metal sprayer, which are regarded as a model of actual fumes, was carried o...
A flow injection preconcentration system for the flame atomic absorption spectrometric determination of hexavalent chromium has been developed. The method employs on-line preconcentration of Cr(VI) on a minicolumn packed with Cr(VI)-imprinted poly(4-vinyl pyridine-co-2-hydroxyethyl methacrylate) placed into a flow injection system. Hexavalent chromium was eluted with a small volume of diluted h...
Background and purpose: Heavy metals such as chromium, nickel, and zinc are the most common contaminants found in the plating wastewater that cause environmental pollution due to non-biodegradability. This study investigated the removal of chromium, nickel, zinc and turbidity from wastewater of plating and galvanized industries by electrocoagulation technology. Material and methods: This study...
in recent decades, enormous use of chromium in different industries as well as water and soil pollution by those industries caused serious concern. toxic impact of chromium on the growth of plants includes changes in the process of germination and root, stem and leaves’ growth. chromium also has harmful impact on the plants’ physiological processes such as photosynthesis. on the other hand, iro...
efficiency of removing chromium from plating industry wastewater using the electrocoagulation method
aims: chromium is one of the most important metallic pollutants in plating industry wastewater. this toxic metal is a serious threat to human health and to the environment due to its cumulative effects and non-degradability. this research intended to study the effects of ph, contact time, and voltage on the degree of chromium removal from wastewater of plating industry by using the electrocoagu...
a new kinetic spectrophotometic method for the determination of trace amount chromium (iii) in teareal samples has been described based on it s the catalytic effect on the oxidations of 1 - ( 2 –pyridylazo ) - 2 - naphthol, (pan), by potassium bromated in sulfuric acid. the reaction is followedspec- trophotometrically by measuring the decrease in the absorbance at 469 nm. under the optimumcondi...
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