In the first known kinetic application of the technique, synchrotron Fe-Mössbauer spectroscopy was used to follow the rate of heterogeneous electron transfer between aqueous reagents and a solid phase containing Fe. The solid, a synthetic Fe-enriched Fe(III)-bearing pyroaurite-like phase having terephthalate (TA) in the interlayer [Mg3Fe(OH)8(TA)0.5 2H2O], was reduced by Na2S2O4 and then reoxid...

The mineralization of [14C]acetate was studied in bottles with fresh soil and groundwater. Addition of toxicants inhibited the formation of 14CO2 and dose-effect curves were obtained. The acetate mineralization was not inhibited by zinc, cadmium, K2Cr2O7, chloropyrifos, and paraquat in an acid sandy soil at 1000 mg/kg dry soil. The IC10 is the toxicant concentration which inhibits 10% of the in...

Pseudokirchneriella subcapitata is a sickle-shaped freshwater green microalga that is normally found in unicellular form. Currently, it is the best known and most frequently used species of ecotoxicological bioindicator because of its high growth rate and sensitivity to toxicants. However, despite this organism's, our knowledge of its cell biology-for example, the patterns of nuclear and cytopl...

The quenching of quinine fluorescence intensity in the presence of some anions in aqueous solution at ambient temperature has been investigated. The quenching is found to be collisional or dynamical in nature. This study reveals the order of two groups of quencher: NaI > NaBr > NaCl > NaF and K2Cr2O7 > KMnO4 >Na2SO4 > NaClO3. Increasing anion size in the both groups leads to an  increase in the...

The objective of this study was to investigate the effect of chronic exposure to sublethal concentrations of hexavalent chromium (K2Cr2O7) on the immune response and disease resistance of Oreochromis mossambicus (Peters) to bacterial Aeromonas hydrophila infection. Fish (45 to 50 g) were exposed to 0.005, 0.05, 0.5, and 5 mg l(-1) [0.01, 0.1, 1, and 10% LC50, respectively] of hexavalent chromiu...

Hydrophilic treatment of bulk graphene-like carbon nitride (g-C3N4) for future applications has aroused extensive interest, due to its enhanced specific surface area and unusual electronic properties. Herein, water-dispersible g-C3N4 with a porous structure can be obtained by chemical oxidation of bulk g-C3N4 with K2Cr2O7-H2SO4. Acid oxidation results in the production of hydroxyl and carboxyl ...

The effect of chromium (VI) on the activity of dehydrogenases, urease, acid and alkaline phosphatases and the yield of lupine was assayed in a pot experiment. Chromium was applied as K2Cr2O7 in the amounts of 0, 10, 20, 30, 40, 50, 100 and 150 in mg · kg of soil. The tests were conducted on brown leached soil from slightly dusty clay sand of pH in 1 M KCl 5.80. Soil was inoculated with nitragin...

Characteristics of nanosized Pt electro-catalyst deposited on carbon nanotubes (CNTs) were studied with CO-stripping voltammogram and chronoamperometry measurements. The CNTs were pretreated by oxidation in HNO3, mixed HNO3 + H2SO4 and H2SO4 + K2Cr2O7 solution, respectively, to enable surface modification. Well-homogenized Pt particles (average size: 3 nm) were loaded onto the pretreated CNT sa...

The kinetics of reduction and oxidation of soluble chromium in various soils (peat, clay, sand, and luvi-chromic cambisols) were studied at constant soil moisture and constant temperature. A total of 1500 g of each soil was incubated with different concentrations of aqueous solutions of K2Cr2O7 or CrCl3 [1-1000 μg (g of dry soil)-1]. The total exchangeable chromium and Cr(VI) were analyzed in s...

Excessive agriculture, transport and mining often lead to the contamination of valuable water resources. Communities using this water for drinking, washing, bathing and the irrigation of crops are continuously being exposed to these heavy metals. The most vulnerable is the developing fetus. Cadmium (Cd) and chrome (Cr) were identified as two of the most prevalent heavy metal water contaminants ...