Wyniki wyszukiwania - BazTech

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Degradation of p-aminophenol by Fenton’s process. Influence of operational parameters

Ghosh P., Ghime D., Lunia D.

Environment Protection Engineering

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2017

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Vol. 43, nr 3

255--267

EN

Oxidative degradation of a model environmental pollutant, p-Aminophenol (PAP), in aqueous solution has been investigated in an environmentally friendly advanced oxidation Fenton process. Effects of various operating parameters such as pH of solutions, dosage of hydrogen peroxide and ferrous ions, initial PAP concentration and temperature on the degradation of PAP have been studied using a batch stirred ceil. Degradation kinetics for this pollutant was also investigated to determine the apparent rate constants (min-1)- The optimum conditions for the degradation of PAP solution (200-500 mg/dm3) were found to be pH = 3.0, 2400 mg H2O2dm, 300 mg Fe2+/dm3, 30°C. Under the optimum conditions, the degradation efficiency of PAP was 75% after 50 min of reaction. It was observed that process parameters play a major role in the overall degradation process.

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Metody określania struktury polisacharydów

Samaszko-Fiertek J., Kuźma M., Dmochowska B., Ślusarz R., Madaj J.

Wiadomości Chemiczne

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2016

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[Z] 70, 5-6

299--318

EN

Sequencing of polysaccharides is difficult to achieve because of the heterogeneous nature of the polysaccharide structure, high molecular weight (the size of a polysaccharide varies between approximately 16,000 and 16,000,000 daltons (Da)), and polydispersity of the polymer chains. The following information is essential to determine the primary structure of a polysaccharide: • monosaccharide composition: nature and molar ratios of the monosaccharide building blocks; • relative configuration of monosaccharides: d or l; • anomeric configuration: α- or β-configuration of the glycosidic linkage; • ring size: presence and distinction of furanosidic and pyranosidic rings; • linkage patterns: linkage positions between the monosugars and branches; • sequences of monosaccharide residues in the repeating units; • substitutions: position and nature of OH–modifications, such as O–phosphorylation, acetylation, O-sulfation, etc.; • molecular weight and molecular weight distribution. A polysaccharide extracted from plant materials or food products is usually purified before being subjected to structural analysis. The first step of characterizing a polysaccharide is the determination of its purity, which is reflected by its chemical composition, including total sugar content, level of uronic acids, proteins, ash, and moisture of the preparation. The second step is the determination of monosaccharide composition, which will unveil structural information such as the number of monosaccharides present in the polysaccharide and how many of each sugar unit. NMR spectroscopy has become the most powerful and noninvasive physicochemical technique for determining polysaccharide structures. It can provide detailed structural information of carbohydrates, including identification of monosaccharide composition, elucidation of α- or β-anomeric configurations, establishment of linkage patterns, and sequences of the sugar units in oligosaccharides and/or polysaccharides. Monosaccharide composition can be determined also by analysis of totally acid hydrolyzed polysacharide using high performance liquid chromatography (HPLC) or gas chromatography (GC). The ring size and glycosidic linkage positions of sugar units in a polysaccharide could be established by methylation analysis and/or cleavage reduction. The anomeric configuration is conventionally determined by oxidation, and this method can be combined with mass spectrometry to obtain more structural information.

3

Prognozowanie i diagnozowanie starzenia kabli w elektrowniach jądrowych

Boguski J., Przybytniak G.

Postępy Techniki Jądrowej

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2012

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z. 4

7--14