A sensitive spectrophotometric method for the determination of trace amounts of chromium(VI) is described. Chromium(VI) forms chlorochromate anion in the presence of acid and chloride ion. The formed anion is extracted in toluene as ion-pair with a cationic dye rhodamine 6G. At 535 nlll absorption maximum molar absorptivity is 2x104 I mol-I em-I. The colour is stable for 4 h and the system obey...

Toxic heavy-metal pollution represents one of the most pressing environmental challenges that humankind faces today. The conventional approaches for removing highly toxic and carcinogenic heavy metals are currently unsuitable practical applications. reduction harmful metals, such as hexavalent chromium (Cr(VI)) into less trivalent Cr(III), has been gaining considerable interest. In response to ...

Hexavalent chromium (VI) compounds are widely used in industry, while trivalent chromium (III) is used as a nutritional supplement. CrVI is generally considered more toxic and carcinogenic than its trivalent form and the toxicity of this metal is associated with free radical processes generating reactive oxygen species (ROS). The detailed mechanism of ROS formation by chromium and its compounds...

Reactions of salicylaldehyde 4-methylthiosemicarbazone (H2L) and salicylaldehyde 4phenylthiosemicarbazone (H2L) with assorted chromium(III) precusors, [Cr(H2O)6]Cl3, [Cr(H2O)6](NO3)33H2O and [Cr(H2O)6](CH3COO)3, afforded new mononuclear chromium(III) complexes of the general formula [Cr(HL)2]X (X = Cl, NO3 and CH3COO). In all isolated compounds, Cr(III) ion is coordinated by the O,N,S atoms of...

A critical appraisal of single-step extraction procedures of chromium species from soil was done in terms of their selectivity towards Cr(III) and Cr(VI) species. Samples of natural mineral and organic soil and samples of soil enriched with different chromium compounds of various solubility (in liquid or solid form) were used to simulate contamination of soil by liquid and solid wastes. The eff...

Batch sorption experiments were performed for the removal of chromium(III) ions from aqueous solutions using Romanian Sphagnum moss peat (untreated and treated with NaCl solution) as sorbent. In order to establish the best conditions for the sorption of chromium(III), the influence of initial pH, contact time, peat dose and metal ion concentration was investigated. The Freundlich, Langmuir and ...

the use of an inorganic phase in water-in-oil (w/o) microemulsion   has   received considerable attention recently for preparing metal oxide   nanoparticles. this is a technique, which allows preparation of ultrafine   metal oxide nanoparticles within the size range 40 to 80 nm. preparation of   nano zno and cr 2 o 3 studied, investigated in the inverse   microemulsion system. therefore the nuc...

The evaluations of the potential carcinogenicity of metallic chromium and trivalent chromium by several international and national agencies [International Agency for Research on Cancer (IARC), 1990; Agency for Toxic Substances and Disease Registry (ATSDR), 1993; Canadian Environmental Protection Act (CEPA), 1994; United States Environmental Protection Agency (US EPA), 1998; United States Nation...

Single crystals of the title compound, Pb(2)CrF(7), were obtained by solid-state reaction. The monoclinic structure is isotypic with Pb(2)RhF(7) and is built up of CrF(6) (3-) octa-hedra isolated from each other, inserted in a fluorite-related matrix of PbF(6) distorted octa-hedra, and PbF(8) square anti-prisms sharing edges and corners. The seventh F atom is 'independent', connected only to th...

BACKGROUND In this study the removal of Chromium (III) and Chromium (VI) ions are investigated via polymer enhanced ultrafiltration under important process parameters. This study proposes the use of unmodified starch as a novel polymer in the ultrafiltration process and its performance on the removal of chromium ions was compared with a commonly used polymer, polyethylene glycol. METHODS The ...