Oxidation Of Butyric Acid Research Articles

Catalytic wet air oxidation of butyric acid and maleic acid solutions over noble metal catalysts prepared on TiO2

Abstract The catalytic wet air oxidation (CWAO) of butyric and maleic acids was carried out in a batch reactor operated at 333 K and at atmospheric pressure. Noble metals (platinum, palladium and ruthenium) supported on TiO2 were used as catalysts as well as commercial Pt/Al2O3. Maleic and butyric acids could be oxidized only into intermediates on the commercial Pt/Al2O3 catalysts with a conversion of 11% and 7.9%, respectively. Total oxidation to CO2 ranged from 0.0% to 0.35% for butyric acid (BA) and from 0.4% to 1.7% for maleic acid (MA). Intermediate products were oxalic and formic acids. In BA oxidation, acetic acid was also detected.

Kinetics and Mechanism of Wet Air Oxidation of Butyric Acid

Low molecular weight acids are common intermediate reaction compounds formed during the wet air oxidation (WAO) of aqueous waste streams, and frequently their oxidation is the rate-controlling step in the overall reaction. The WAO kinetics of aqueous solutions of butyric acid was studied in a stainless steel 316 autoclave over a temperature range of 200−320 °C with a total pressure of 15 MPa of synthetic air, which provides an excess of oxygen. Kinetic models were developed with respect to various concentrations of butyric acid and chemical oxygen demand (COD). Oxidation reactions always obeyed a pseudo-first-order kinetic, but two different activation energies were needed to represent the temperature dependence in two ranges, namely 200−275 and 275−320 °C. This finding can be explained by the competition between two main reaction pathways in the oxidation of the acid, since both pathways take place simultaneously. A mechanism in accordance with the results obtained is proposed.

Biofilm formation on polypropylene during start‐up of anaerobic fixed‐bed reactors

Initial biofilm formation was studied during start‐up of anaerobic fixed‐bed reactors with polypropylene as substratum. Five reactors were operated in parallel at 35°C with synthetic wastewater containing acetate, propionate and butyrate as substrates varying the mode of system operation. System variations included (a) operation with recirculation, (b) continuous and discontinuous (fed‐batch) feeding, and (c) different organic loading rates (OLR). An enrichment culture from sludge of a municipal sewage treatment plant, grown in a stirred tank reactor at an OLR of 2g.l−1d−1 for 72 d, was used as inoculum. Reactor performance and biofilm formation were followed over a period of 58 d. Highest biomass accumulation and maximal OLR of 23 kg CODm−3d−1 were obtained in the reactor with the highest space loading. The polypropylene support acted not only as a substratum for biofilm growth but also as a filter retaining biomass in flocs. Scanning electron microscopy (SEM), phase contrast microscopy and epifluorescence microscopy documented various bacteria in the biofilm community and the floc population. Propionic acid and butyric acid oxidation were carried out by Desulfobulbus sp., and by Syntrophomonas sp. and Syntrophospora sp. respectively. Methanothrix sp. was the main acetotrophic methanogen in both floes and biofilm. Morphologically distinct Methanosarcina sp. were only retained in a network of Methanothrix filaments within flocs. Irregular coccoid methanogens of the genera Methanogenium or Methanoculleus were the main hydrogenotrophic methanogens with cells of Methanospirillum sp., Methanocorpusculum sp. and Methanobrevibacter sp. occurring in lower numbers. Bacteria adhering during early phases of biofilm formation were detected as settlers responsible for primary colonisation and initiating development of a mature biofilm. Formation of microcolonies of trophic sub‐populations is demonstrated. Evidence for Desulfovibrio sp. responsible for glycocalyx secretion was provided.

Studies on degradation of fats by microorganisms. II. The mechanism of formation of ketones from fatty acids

Summary The experiments carried out on the oxidation of butyric acid by A. niger indicate that the butyric acid oxidation in vitro by molds can be believed to take place according to the beta -oxidation theory as well as according to the dehydrogenation mechanism, as the presence of acetoacetic acid in the oxidation products of butyric acid might be regarded as positive proof in support of the former hypothesis, and the development of slight unsaturation being indicative of the latter. The pH optimum for the oxidation of butyric, β -hydroxybutyric, and crotonic acids has also been determined. With these preliminary results in hand it has been possible to carry out a more detailed and quantitative study on the mechanism of butyric acid decomposition by the mold and this will form the subject of our next communication.

Oxidation of Butyric Acid by Streptococci

Oxidation of Butyric Acid by Streptococci

The Oxidation of Butyric Acid by means of Hydrogen Peroxide with Formation of Acetone, Aldehydes and other Products

The Oxidation of Butyric Acid by means of Hydrogen Peroxide with Formation of Acetone, Aldehydes and other Products