Abstract:Nanoporous and planar gold electrodes were utilised as supports for the redox enzymes Aspergillus niger glucose oxidase (GOx) and Corynascus thermophilus cellobiose dehydrogenase (CtCDH). Electrodes modified with hydrogels containing enzyme, Os-redox polymers and the cross-linking agent poly(ethylene glycol)diglycidyl ether (PEGDGE) were used as biosensors for the determination of glucose and lactose. Limits of detection of 6.0 (± 0.4), 16.0 (± 0.1) and 2.0 (± 0.1) µM were obtained for CtCDH modified lactose and glucose biosensors and GOx modified glucose biosensors, respectively, at nanoporous gold electrodes. Biofuel cells comprised of GOx and CtCDH modified gold electrodes were utilised as anodes, together with Myrothecium verrucaria bilirubin oxidase (MvBOD) or Melanocarpus albomyces laccase (rMaLc) as cathodes, in biofuel cells. A maximum power density of 41 µW/cm 2 was obtained for a CtCDH/MvBOD biofuel cell in 5 mM lactose and O 2 saturated buffer (pH 7.4, 0.1 M phosphate, 150 mM NaCl).2

The synthesis of hydroperoxymethyl oxazoles by oxidation of alkylideneoxazoles with molecular oxygen was implemented in a microstructured reactor for increased safety and larger-scale applications. Elaborate studies on the influence of pressure and temperature were performed, and the apparent activation energy for the oxidation reaction was determined.Elevated temperatures up to 100 °C and pressures up to 18 bar(a) led to a conversion rate of approximately 90 % within 4 h of the reaction time, thus displaying the high potential and beneficial effect of using a microreactor setup with liquid recycle loop for this oxidation. The in situ reduction of the generated hydroperoxide functionality shows the capability of this setup for follow-up transformations.

Microstructured reactors are the ideal device for highly exothermic reactions. In this work, the highly exothermic two-phase reaction of valeraldehyde with oxygen to valeric acid was carried out in a microreactor. The used device from one-A Engineering Austria GmbH is designed for process development and intensification and can be applied in the scale-up process to small-scale commercial production. The atom economic oxidation of valeraldehyde is performed at 0 to 40 °C with a catalytic amount of manganese­(II) acetate. A continuous flow oxidation of aldehydes in such reactors can be a safe and beneficial alternative to commercial batch processes.

We investigate the interaction of two immiscible fluids in a head-on device geometry, where both fluids are streaming opposite to each other. The simulations are based on the two-dimensional (2D) lattice Boltzmann method (LBM) using the Rothman and Keller (RK) model. We validate the LBM code with several benchmarks such as the bubble test, static contact angle, and layered flow. For the first time, we simulate a head-on device by forcing periodicity and a volume force to induce the flow. From low to high flow rates, three main flow patterns are observed in the head-on device, which are dripping-squeezing, jetting-shearing, and threading. In the squeezing regime, the flow is steady and the droplets are equal. The jetting-shearing flow is not as stable as dripping-squeezing. Moreover, the formation of droplets is shifted downstream into the main channel. The last flow form is threading, in which the immiscible fluids flow parallel downstream to the outlet. In contrast to other studies, we select larger microfluidic channels with 1-mm channel width to achieve relatively high volumetric fluxes as used in chemical synthesis reactors. Consequently, the capillary number of the flow regimes is smaller than 10−5. In conclusion, the simulation compares well to experimental data.

An efficient, safe and scalable continuous flow process for the synthesis of amine oxides with hydrogen peroxide is described.