Behaviour of anionic arsenic compounds in microwave system with nitric acid and hydrogen peroxide — preliminary laboratory study

The complexometric method is usually applied to quantitative calcium determination in different materials; however the application of this method to calcium determination in molluscs shells infers significant interferences to the results. The snail Bradybaena similaris, a terrestrial gastropod, was used as experimental model to the improvement of this method. The shells were calcinated and dissolved in nitric acid, the hydrogen peroxide was also used to clarify the medium after the acid addition. The calcination procedure and the use of nitric acid reduced the significantly the interferences, allowing a major degree of destruction of the organic substances of the shell. The improvement of the calcium determination technique usually employed showed calcium content of 874.24 ± 56.617 mg of CaCO3/g of ash in comparison to the conventional technique that allowed the determination of 607.79 ± 67.751 mg of CaCO3/g of shell, wet weight.

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Effect of Modification with Nitric Acid and Hydrogen Peroxide on Chromium (VI) Adsorption by Activated Carbon Fiber

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.518-523.2099 ◽

2012 ◽

Vol 518-523 ◽

pp. 2099-2103

Author(s):

Guang Zhou Qu ◽

Hai Bing Ji ◽

Ran Xiao ◽

Dong Li Liang

Keyword(s):

Hydrogen Peroxide ◽

Activated Carbon ◽

Nitric Acid ◽

Carbon Fiber ◽

Adsorption Capacity ◽

Adsorption Kinetics ◽

Ph Value ◽

Activated Carbon Fiber ◽

Order Kinetic ◽

Adsorption Amount

The activated carbon fiber (ACF) was treated by different concentration nitric acid (HNO3) and hydrogen peroxide (H2O2) oxidization to enhance its adsorption capacity to hexavalent chromium (Cr6+) ion. The adsorption amount and adsorption kinetics of Cr6+ion on ACFs, and the surface chemical groups were investigated. The results showed that the modified ACFs with 1% HNO3and 10% H2O2had a better adsorption capacity, respectively. The adsorption amount of ACFs was affected strongly solution pH value, and decreased significantly with increasing of the pH value. The adsorption kinetics indicated that the adsorption rates of Cr6+ ion on different modified ACFs were well fitted with the pseudo-second-order kinetic model. After 1% HNO3and 10% H2O2modification, respectively, the total acidic oxygen-containing groups on ACFs surface had an increase obviously, which might be enhance the adsorption amount of Cr6+ion on ACFs.

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The association of trace elements with manganese minerals in Australian soils

Soil Research ◽

10.1071/sr9660029 ◽

1966 ◽

Vol 4 (1) ◽

pp. 29 ◽

Cited By ~ 136

Author(s):

RM Taylor ◽

RM McKenzie

Keyword(s):

Hydrogen Peroxide ◽

Trace Elements ◽

Nitric Acid ◽

Different Types ◽

The Common ◽

Manganese Minerals

In widely different types of Australian soils birnessite and lithiophorite appear to be the common forms of occurrence of mineralized manganese. These mineral forms were dissolved out of the soil by hydrogen peroxide acidified to pH 3 with nitric acid and analyses of the extracts were made. It was found that the concentration of trace elements is generally quite high in these minerals. In particular, most of the soil cobalt (average 79%) was contained in or associated with these minerals where they were present.

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