نتایج جستجو برای: cr(vi)

تعداد نتایج: 60  

2014
B. Dari V Nair Rao Mylavarapu Wendy A. Mussoline Ann C. Wilkie

We investigated the effects of chromate (CrVI) and phosphate (P) on their uptake and translocation in As-hyperaccumulator Pteris vittata (PV). Plants were exposed to 1) 0.05 mM CrVI and 0, 0.05, 0.25 or 1.25 mM P or 2) 0.25 mM P and 0, 0.05, 0.25 or 1.25 mM CrVI for 24 h in hydroponics. PV accumulated 2,919 mg/kg Cr in the roots at CrVI0.05, and 5,100 and 3,500 mg/kg P in the fronds and roots a...

Journal: :Environmental pollution 2015
Letúzia M de Oliveira Jason T Lessl Julia Gress Rujira Tisarum Luiz R G Guilherme Lena Q Ma

We investigated the effects of chromate (CrVI) and phosphate (P) on their uptake and translocation in As-hyperaccumulator Pteris vittata (PV). Plants were exposed to 1) 0.10 mM CrVI and 0, 0.25, 1.25, or 2.50 mM P or 2) 0.25 mM P and 0, 0.50, 2.5 or 5.0 mM CrVI for 24 h in hydroponics. PV accumulated 2919 mg/kg Cr in the roots at CrVI₀.₁₀, and 5100 and 3500 mg/kg P in the fronds and roots at P₀...

Journal: :Journal of occupational and environmental hygiene 2004
Kyle J Hazelwood Pamela L Drake Kevin Ashley Dale Marcy

National Institute for Occupational Safety and Health method 7703 is a portable field procedure for the analysis of workplace air filter samples for hexavalent chromium (CrVI) content immediately after the samples are collected. The field method prescribes CrVI extraction from air filter samples with an ammonium sulfate/ammonium hydroxide extraction buffer using ultrasonic extraction (UE). Stro...

1999
Verónica Daier Sandra Signorella Marcela Rizzotto María Inés Frascaroli Claudia Palopoli Carlos Brondino Juan Manuel Salas-Peregrin Luis F. Sala

The oxidation of D-ribose and 2-deoxy-D-ribose by CrVI yields the aldonic acid and Cr3+ as final products when an excess of sugar over CrVI is used. The redox reaction occurs through CrVI→CrIII and CrVI→CrV→CrIII paths. The complete rate laws for the CrVI oxidation reactions are expressed by –d[CrVI]/dt = kH[H +]2 [ribose][CrVI], where kH = (5.9 ± 0.1) × 10–2 mol–3 dm9 s–1, and –d[CrVI]/dt = (k...

Journal: :Environmental Health Perspectives 1991
R J Bartlett

The major links in the cycling of chromium in soils and in natural waters are between chromium(III) and chromium (VI). Between the larger links are lesser links involving processes of mobilization and oxidation of CrIII and reduction of CrVI. The gaps are mainly in our understanding of the factors that control these processes. If soluble CrIII is added to an "average" soil, a portion of it will...

Journal: :Environmental science & technology 2005
Yeqing Lan Baolin Deng Chulsung Kim Edward C Thornton Huifang Xu

Chromate (CrVI) reduction by sulfide was conducted in anaerobic batch experimental systems. The molar ratio of the reduced CrVI to the oxidized S(-II) was 1:1.5 during the reaction, suggesting that the product of sulfide oxidation was elemental sulfur. Under the anaerobic condition, the reaction was pseudo first order initially with respect to CrVI, but the rate was dramatically accelerated at ...

Journal: :Environmental pollution 2014
Letúzia Maria de Oliveira Lena Q Ma Jorge A G Santos Luiz R G Guilherme Jason T Lessl

We investigated effects of arsenate (AsV), chromate (CrVI) and sulfate on As and Cr uptake and translocation by arsenic hyperaccumulator Pteris vittata (PV), which was exposed to AsV, CrVI and sulfate at 0, 0.05, 0.25 or 1.25 mM for 2-wk in hydroponic system. PV was effective in accumulating large amounts of As (4598 and 1160 mg/kg in the fronds and roots at 0.05 mM AsV) and Cr (234 and 12,630 ...

Journal: :Analytical sciences : the international journal of the Japan Society for Analytical Chemistry 2003
M Noroozifar M Khorasani-Motlagh

A very specific, selective, simple, and inexpensive procedure was developed for the speciation of CrVI and CrIII. This method is based on the quantitative extraction of chromate and CrIII (previously oxidized to CrVI) as a tetrabutylammonium-chromate ion-pair in methyl isobutyl ketone (MIBK), and then back extraction and preconcentration with an acidic diphenylcarbazide (DPC) solution. Back ext...

Journal: :Environment international 2015
J Gress L M de Oliveira E B da Silva J M Lessl P C Wilson T Townsend L Q Ma

Concern about children's exposure to arsenic (As) from wood treated with chromated-copper-arsenate (CCA) led to its withdrawal from residential use in 2004. However, due to its effectiveness, millions of American homes still have CCA-wood decks on which children play. This study evaluated the effects of three deck-cleaning methods on formation of dislodgeable As and hexavalent chromium (CrVI) o...

2018
An Manh Cuong Nguyen Thi Le Na Pham Nhat Thang Trinh Ngoc Diep Ly Bich Thuy Nguyen Lai Thanh Nguyen Dinh Thang

BACKGROUND Currently, it is recognized that water polluted with toxic heavy metal ions may cause serious effects on human health. Therefore, the development of new materials for effective removal of heavy metal ions from water is still a widely important area. Melanin is being considered as a potential material for removal of heavy metal from water. METHODS In this study, we synthesized two m...

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