hexavalent chromium Articles

  • Adsorption of hexavalent chromium on dunite

    The paper presents and discusses the effect of various physicochemical parameters (e.g. pH, ionic strength, Cr(VI) initial concentration, amount of the adsorbent, temperature and contact time between metal ion and adsorbent) on the adsorption efficiency of Cr(VI) on dunite in aqueous solutions under atmospheric conditions. Evaluation of the experimental data shows that dunite presents increased ...


    By IWA Publishing

  • Deadly Hexavalent Chromium in Soil

    Merging technologies will change over Hexavalent Chromium in soil to Trivalent Chromium, effectively stopping Hexavalent Chromium from becoming dangerously airborne or becoming even more deadly by migrating into the water table. There are three valences of Chromium: 1) Chromium—safe to humans, 2) Trivalent Chromium—safe and an essential element in humans and 3) Hexavalent ...


    By ABCOV Companies , LLC

  • Removal of hexavalent chromium using coffee husk

    The potential to remove chromium(VI) from aqueous solutions through biosorption using coffee husk was investigated. The effects of pH, contact time, initial concentration and adsorbent dosage on the adsorption of Cr(VI) were studied. The data obeyed Langmuir and Freundlich adsorption isotherms. The Langmuir adsorption capacity was found to be 44.95 mg/g. The Freundlich constants Kf and n were ...


    By Inderscience Publishers

  • Osha issues final standard on hexavalent Chromium

    After years of trying to craft an exposure standard for hexavelant chromium that would stand up under expected court challenges, the Occupational Safety and Health Administration (OSHA) issued a final standard on February 28, 2006 which became effective on May 29, 2006. Under the standard, the Permissible Exposure Limit (PEL) for exposure to hexavalent chromium will be lowered from 52 to 5 ...


    By Atlantic Environmental, Inc.

  • Biological Treatment of Hexavalent Chromium Treatability Study Report

    A former XXXX was found to be impacted by hexavalent chromium [Cr(VI)]. The site Cr(VI) plume has groundwater concentrations as high as 1,150,000 μg/L in the hot spot(s). Treatability studies were conducted at Shaw Environmental & Infrastructure, Inc.’s Technology Development Laboratory (TDL) in Knoxville, Tennessee, to evaluate treatment technologies to decrease the concentration of Cr(VI) ...


  • Is Hexavalent Chromium (Hex Chrome; Chrome VI) a carcinogen?

    In 1990, the International Agency for Research on Cancer (IARC), an agency of the World Health Organization (WHO), published their findings on chromium and chromium compounds as carcinogens.  Chromium may be isolated in any of three volume states: Chrome 0 or metallic chromium; Chrome III called “Chrome 3” or Chrome VI called “Chrome 6,” also called hexavalent ...


    By Atlantic Environmental, Inc.

  • Immobilised microbial reactor for the biotransformation of hexavalent chromium

    Out of an array of bacterial strains isolated from soil contaminated with effluents from electroplating wastewater, Bacillus coagulans exhibited the maximum Cr(VI) reduction potential. The feasibility of an immobilized B. coagulans bioreactor for hexavalent chromium reduction was investigated. Experimental results demonstrated that near complete removal of Cr(VI) was achieved in the reactor with ...


    By Inderscience Publishers

  • Adsorption of hexavalent chromium from aqueous solutions by wheat bran

    In this research, adsorption of chromium (VI) ions on wheat bran has been studied through using batch adsorption techniques. The main objectives of this study are to 1) investigate the chromium adsorption from aqueous solution by wheat bran, 2) study the influence of contact time, pH, adsorbent dose and initial chromium concentration on adsorption process performance and 3) determine appropriate ...

  • Removal of hexavalent chromium from aqueous solution by calcined Zn/Al-LDHs

    In this study, Zn/Al-layered double hydroxides (Zn/Al-LDHs) were synthesized by a co-precipitation method and characterized with X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. Then the hexavalent chromium Cr(VI) adsorption experiments on calcined Zn/Al-LDHs were carried out to analyze the effects of pH, temperature, adsorption time, initial Cr(VI) ...


    By IWA Publishing

  • Characteristics and kinetics of hexavalent chromium reduction by gallic acid in aqueous solutions

    Gallic acid (GA) is a naturally occurring plant polyphenol compound. Experiments were conducted to study the kinetics and effects of pH, temperature, irradiation, and initial hexavalent chromium (Cr(VI)) concentration on Cr(VI) reduction by GA. Results indicated that Cr(VI) could be reduced to chromium oxide (Cr(III)) with GA in a wide range of pH values from 2.0 to 8.5. The reaction followed a ...


    By IWA Publishing

  • Nitrite interference and elimination in diphenylcarbazide (DPCI) spectrophotometric determination of hexavalent chromium

    Cr(VI) is highly noted as a carcinogenic, mutagenic, and teratogenic pollutant. However, accurate determination of Cr(VI) in aqueous samples is difficult using the conventional diphenylcarbazide (DPCI) spectrophotometric method upon being interfered by co-existed nitrite. This paper illustrates how to eliminate the nitrite influence in a simple but efficient method based on a detailed analysis ...


    By IWA Publishing

  • Reduction remediation of hexavalent chromium by bacterial flora in Cr(VI) aqueous solution

    Chromium(VI) is a priority pollutant in soils and wastewaters and reduction of Cr(VI) to Cr(III) is a solution to this problem. In this study a low-cost method was proposed to adapt indigenous bacteria and use them to reduce Cr(VI) in solutions. The experiment results show that Cr(VI) could be efficiently reduced by indigenous bacteria under anaerobic and pH-unadjusted conditions. After about ...


    By IWA Publishing

  • Reduction of hexavalent chromium: photocatalysis and photochemistry and their application in wastewater remediation

    Hexavalent chromium present in wastewater discharge of galvanic industries is toxic to most microorganisms and potentially harmful to human health. This work examines the photochemical reduction of Cr(VI) with ethanol under ultraviolet (UV) and visible radiation, and photocatalytic reduction of Cr(VI) with TiO2 in the presence of ethanol under UV radiation. By means of different experimental ...


    By IWA Publishing

  • Hexavalent chromium removal in a tannery industry wastewater using rice husk silica

    Present study dealt the removal of Cr(VI) in a tannery industry wastewater using rice husk silica powder as an adsorbent.The experimental investigations have been carried out by using rice husk silica powder for different adsorption dosage, different contact time and different pH against the initial Cr(VI) concentration of 292 mg/L. The maximum percentage removal of Cr(VI) in the tannery ...


    By GJESM Journal

  • Hexavalent chromium removal by using synthesis of polyaniline and polyvinyl alcohol

    Over the past few years, heavy metals have been proved to be one of the most important contaminants in industrial wastewater. Chromium is one of these heavy metals, which is being utilized in several industries such as textile, finishing and leather industries. Since hexavalent chromium is highly toxic to human health, removal of it from the wastewater is essential for human safety. One of the ...


    By IWA Publishing

  • Treatment of hexavalent chromium by using a combined Fenton and chemical precipitation process

    This work aimed to remove hexavalent chromium and three treatment schemes were examined based on a laboratory scale design: (a) Fenton process, (b) precipitation process, and (c) Fenton process followed by precipitation process. Variations of this study including pH, Fenton and precipitation reagents (molar ratio of Fe2+/H2O2 and FeCl3), contact time, and ...


    By IWA Publishing

  • Influence of pH on hexavalent chromium reduction by Fe(II) and sulfide compounds

    Batch experiments were conducted to investigate the influence of pH on Cr(VI) reduction with Fe(II), sulfide and mixtures of Fe(II) and sulfide at pH 3.0–12.0. The results showed that Fe(II) could reduce Cr(VI) with a high removal of nearly 100% in the pH range of 3.0–9.0, while the reduction of Cr(VI) decreased to approximately 60% considering the oxygenation of ...


    By IWA Publishing

  • Differential Uptake and Transport of Trivalent and Hexavalent Chromium by Tumbleweed (Salsola kali)

    Experiments were conducted to determine the differential absorption of Cr species by tumbleweed (Salsola kali) as well as the effect of this heavy metal on plant growth and nutrient uptake. Tumbleweed seeds were grown in an agar-based media containing different concentrations of either Cr(III) or Cr(VI). The results demonstrated that the uptake of Cr was influenced by the Cr concentration in the ...


    By Springer

  • New OSHA program in 2010 targets hexavalent chromium (Hex Chrome)

    OSHA has launched a new National Emphasis Program (NEP) in 2010, designed to target workplaces with exposures to hexavalent chromium and certain other metals such as antimony, arsenic, cadmium, lead and iron oxide. Targeted industries include electroplating, aircraft manufacturing, welding, shipbuilding, iron and steel mills, ferrous foundries, chrome color manufacturing and other pigment ...

  • Assessment of the removal mechanism of hexavalent chromium from aqueous solutions by olive stone

    The objectives of this study were to study the removal mechanism of Cr(VI) by natural olive stone (OS) and to present a sequential-batch process for the removal of total chromium (original Cr(VI) and Cr(III) derived from reduction of Cr(VI) during biosorption at acidic conditions). First, experiments were conducted varying pH from 1 to 4, and showed that a combined effect of biosorption and ...


    By IWA Publishing

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