Catalytic Oxidation Degradation Research Articles

Study on the treatment of 2- sec-butyl-4,6-dinitrophenol (DNBP) wastewater by ClO 2 in the presence of aluminum oxide as catalyst

The chlorine dioxide (ClO 2) oxidative degradation of 2- sec-butyl-4,6-dinitrophenol (DNBP) in aqueous solution was studied in detail using Al 2O 3 as a heterogeneous catalyst. The operating parameters such as the ClO 2 concentration, catalyst dosage, initial DNBP concentration, reaction time and pH were evaluated. Compared with the conventional ClO 2 oxidation process without the catalyst, the ClO 2 catalytic oxidation system could significantly enhance the degradation efficiency. Under the optimal condition (DNBP concentration 39 mg L −1, ClO 2 concentration 0.355 g L −1, reaction time 60 min, catalyst dosage 10.7 g L −1 and pH 4.66), degradation efficiency approached 99.1%. The catalyst was used at least 8 cycles without any appreciable loss of activity. The kinetic studies revealed that the ClO 2 catalytic oxidation degradation of DNBP followed pseudo-first-order kinetics with respect to DNBP concentration. The ClO 2 catalytic oxidation process was found to be very effective in the decolorization and COD Cr reduction of real wastewater from DNBP manufacturing. Thus, this study showed potential application of ClO 2 catalytic oxidation process in degradation of organic contaminants and industrial effluents.

A study on rapid acid chrome black (MB 7) spectrophotometric determination of ClO2 and catalytic degradation of 2,6-dinitro-p-cresol (DNPC) by ClO2

Experiments were conducted to investigate the degradation of 2,6-dinitro-p-cresol (DNPC) in the chlorine dioxide (ClO2) catalytic oxidation process. Pure aluminum oxide was used as the catalyst in this process. The degradation of DNPC by ClO2 using aluminum oxide as catalyst was systematically studied by varying the experimental parameters, such as pH values, catalyst dosage, the initial concentration of DNPC and ClO2, reaction time, etc. Under optimal condition (DNPC concentration 39mg·L−1, ClO2 concentration 0.234 g·L−1, reaction time 15 min, catalyst dosage 4.7 g·L−1 and pH 4.32), almost complete degradation of DNPC can be achieved. The kinetic studies revealed that the ClO2 catalytic oxidation degradation of DNPC followed pseudo-first-order kinetics with respect to both ClO2 and DNPC concentration. The repetitive use of the catalyst was investigated along sequential feed-batch trials. The catalyst performed efficiently after five runs. In addition, a simple and convenient method for the determination of ClO2 in water was developed by using acid chrome black 7 (MB 7) spectrophotometry in this paper.

Synthesis, Characterization and Application οf Al,Fe-Pillared Clays

Al,Fe-pillared clay was synthesized from domestic clay from Bogovina according to a common procedure: grinding, sieving, Na exchange, pillaring, drying and calcination. Two synthesized samples differing only in calcining conditions were prepared. Phase composition and textural properties of the starting clay and synthesized pillared clays were characterized using X-ray diffraction and physisorption of nitrogen. Catalytic tests were performed using sample with better textural properties being the one submitted to milder calcining conditions. Catalytic wet peroxide oxidative degradation of aromatic compounds phenol and tartrazine on the synthesized catalyst was confirmed showing better efficiency in the case of tartrazine.

Structural and textural properties of Al,Fe-pillared clay catalysts

Metal oxide pillared interlayered clays (PILCs) represent a new class of materials that have found a wide range of potential applications including catalytic oxidative degradation of organic pollutants in water. Al,Fe-pillared smectite clays with different Fe content were synthesized for possible catalytic application. Starting clay and the obtained PILCs were characterized. Phase composition, textural and morphological properties of the starting clay and synthesized PILCs were determined using X-ray diffraction, physisorption of nitrogen and scanning electron microscopy. Chemical composition of the PILCs was determined using EDX. It was found that the synthesized PILCs have similar phasal composition, textural and morphological properties differing only in Fe content in accordance with the amount of Fe introduced to clay during the pillaring process.

Catalytic Oxidative Domino Degradation of Alkyl Phenols Towards 2- and 3-Substituted Muconolactones

The catalytic oxidative domino degradation of phenols was investigated. Hydrogen peroxide (30% aq.) was used as an oxidant and 2,2′-dinitro-4,4′-ditrifluoromethyldiphenyl diselenide 4e as a catalyst. The products were muconic acid 5, and muconolactones muconolactones—5-carboxymethylfuran-2(5H)-ones 7 and 9. Phenols with alkyl groups at 2 or 4 positions of the benzene ring were converted regioselectively to corresponding muconolactones substituted at alkenylene ring carbon atoms. The reaction mechanism is proposed.

Catalytic oxidative degradation of s-triazine and phenoxyalkanoic acid based herbicides with metalloporphyrins and hydrogen peroxide: Identification of two distinct reaction schemes

Oxidative degradation of the herbicides atrazine ( 1), atraton ( 2), ametryn ( 3) and mecoprop ( 4), was carried out with hydrogen peroxide and metalloporphyrins as catalysts. Two different reaction conditions were studied, the first involving Mn(TDCPP)Cl in an aprotic solvent with buffer ( S-I), and the second using Fe(TPFPP)Cl in a protic solvent ( S-II). Reaction products were characterized, and based on these it is shown that there are two distinct reaction schemes. In the case of the S-I conditions, it is suggested that the s-triazines were oxidized through hydroxylation of the alkyl side chains followed by dealkylation, while S-II was ineffective for these reactions. In contrast, mecoprop, was oxidized with high efficiency by S-II, leading to decarboxylation and further oxidation, while in the presence of S-I, low substrate conversion was observed, and reaction resulted mainly from oxidation at the benzyl position. Sulfoxidation of ametryn was observed with both systems. The different reactivity shown by the two systems supports the involvement of different reactive species, which we assign to the oxo and hydroperoxy complexes. These routes show similarities with metabolic pathways, with the reactivity pattern of S-I analogous to the reported metabolism of these pollutants with cytochrome P450 enzymes, while S-II catalyses mecoprop decarboxylation via a similar pathway to that seen with peroxidase catalysed reactions.

ChemInform Abstract: Iron Porphyrin Models of Peroxidase Enzymes: Catalytic Activity, Regeneration, and Oxidative Degradation of Mesoferriheme.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Iron porphyrin models of peroxidase enzymes: catalytic activity, regeneration, and oxidative degradation of mesoferriheme

The reaction of the iron(III) complex of mesoporphyrin IX, mesoferriheme, with two-electron oxidants, such as sodium hypochlorite and m-chloroperoxobenzoic acid, produces a spectroscopically distinct oxidized heme species viewed as a functional analogue of the reaction intermediate obtained by oxidation of hemoprotein peroxidase enzymes

Catalytic oxidative degradation of polyethylene crystals

Linear polyethylene crystals have been degraded with oxygen in the presence of a catalyst composed of cobaltous and bromide ions at temperatures between 60 and 130°. The number of carbonyl groups introduced into polyethylene increases as the oxidation temperature is raised. Infra-red spectroscopy and molecular weight evidence suggests that ketone groups are formed by a non-chain scission reaction, whereas aldehyde and carboxylic acid groups result from chain scission reactions. Molecular weight distributions of the degradation products show that reactions occur selectively in the amorphous regions at the crystal surfaces, when oxidations are performed below 110°. At higher temperatures, the chains are degraded randomly. The carbonyl groups introduced into polyethylene were oxidized to carboxylic acid groups with concentrated (∼ 70 per cent) nitric acid. The results demonstrate that this two-stage process yields a polydisperse long-chain linear paraffin with carboxylic acid end-groups, when the catalytic oxidations are performed between 115 and 130°.