Chromium (VI), also known as hexavalent chromium, is the second most stable oxidation state of chromium. Rarely occurring naturally, most chromium (VI) compounds are manufactured (products or by-products). Chromium (VI) can be reduced to the more stable chromium (III) in the presence of reducing agents (e.g. iron) or oxidizable organic matter (OSHA, 2006). Selected chemical and physical propert...

In this study, the adsorption of hexavalent chromium and zinc ions from the solution is investigated by raw red mud and mechanical-chemical activated red mud along with the possibility of selective reclamation of these ions from the solution. The mechanical-chemical activation of red mud was done by employing high-energy milling and subsequent acid treatment with HNO3. Raw red mud (RRM) and mec...

abstract background: heavy metals in industrial wastewater especially chromium (vi) are considered as the main environmental pollutants. methods: electrochemical cell made of plexiglass with a volume of 1.95 lit was used. iron and graphite electrodes, electricity conductor, each with dimensions of 0.1×3×10 cm (width×length×height) were designed and built. tests were carried out in various condi...

background: the presence of heavy metals in the environment especially in water supplies have caused many concerns because of their toxicity and non-degradability. hexavalent chromium (cr) is one of the most toxic metals which is used in many industries, so it is essential to remove it from industrial wastewater. in this study, we made a comparison between different adsorption isotherms in the ...

abstract aims: the application of photocatalytic processes to remove heavy metals in aqueous solutions and industrial wastewater are regarded as extremely effective, clean and without producing waste methods. the goal of the present study was to investigate the photocatalytic activity of zno based on h-zsm-5 zeolite support. materials & methods: zno/h-zsm-5 composite synthesized by impregnation...

Introduction: Chromium is among the important heavy metals which is found in most industrial wastes and is associated with both health and environmental risks. Therefore, this study tries to analyze the efficiency of lemna and azolla powders in removing hexavalent chromium from aqueous solutions. Methods: As an experimental trial, this study was conducted experimentally in the lab scale. Initia...

Tannery effluent is a major source of aquatic pollution in India. Hexavalent chromium compounds are being used in a wide variety of commercial processes and unregulated disposal of the chromium containing effluent has led to the contamination of soil, sediment, surface and ground waters. In trace amounts, chromium is considered an essential nutrient for numerous organisms, but at higher level, ...

Hexavalent chromium is a bio accumulative toxic metal in water and fish. It enters aquaculture ponds mainly through anthropogenic sources. Hexavalent chromium concentrations and its effects on the morphology and behavior of Clarias gariepinus were investigated from four aquaculture ponds for 12 weeks. Chromium was measured using diphenyl carbohdrazide method; alkalinity and hardness were measur...

A rapid, reliable and accurate method for the determination of hexavalent chromium in Portland cement is developed. The proposed method includes direct spectrophotometric determination of Cr (VI) in Portland cement with 1, 2, 5, 8 Tetrahydroxyanthraquinone, (Quinalizarin, QINZ) at pH 1.5. The European Directive (2003/53/EC) limits the use of cements so that it contains no more than 2 mg·Kg of w...

Various pollutants (e.g. boron and hexavalent chromium) are introduced into the aquatic environment from a variety of industrial operations causing damages to environment and affecting human health. Boron in irrigation water is of particular interest because it can have beneficial or toxic effect on plants, depending on its concentration. Pollution of the environment with hexavalent chromium (C...