Karl-Heinz Mohr

Chemiluminometric hydrogen peroxide sensor for flow injection analysis

SummaryA chemiluminometric hydrogen peroxide sensor was developed for fast flow injection analysis. Different peroxidases were covalently immobilized on affinity membranes and compared with respect to the catalytic luminol oxidation. A photomultiplier tube is connected with a fibre bundle to the flow cell. The small cell volume of 5–10 μl allows sampling rates between 90 and 200/h, depending on the flow rate. The highest sensitivity and the best long-term stability can be achieved with microbial peroxidase. Hydrogen peroxide can be determined in the range between 10−3 and 10−8 mol/l with a precision of <3% (n=6, α=0.05). The operational stability of the sensor is longer than 10 weeks.

The Rotary Trickle‐Bed Reactor – A New Reactor Concept for Biological Gas Purification

A new type of reactor employed to the biological gas purification is presented. The avoidance of clogging in the carrier packing is achieved by i) the use of a structured, rotating carrier packing, ii) a definite liquid irrigation regime during start‐up, operation and clean‐up time phases, iii) an on‐line determination and control of the fixed biofilm mass. A uniform biofilm thickness is generated by an optimized liquid irrigation of the carrier packing with spray nozzles. The detachment of the fixed biomass is accomplished by liquid shear forces generated with jet nozzles. The time‐scheduled operation regime of the reactor is founded on the on‐line quantification of the immobilized biomass, which results in a new quality of process governing of biotrickling reactors applied to gas purification. This is proved by the experimental results of pressure drop, dynamic liquid holdup as well as the volumetric degradation rates. The degradation of styrene was investigated in laboratory and field experiments showing a maximal volumetric degradation rate of 150 g m–3 h–1 at a pollutant load of 200 g m–3 h–1. The feasibility of this reactor prototype is demonstrated by employing it to the elimination of industrial waste gas.

Continuous Synthesis of (R)-(+)-Benzaldehydecyanohydrin Using (R)-Oxynitrilase in Lyotropic Liquid Crystals

The possibility of using the enzyme (R)-Oxynitrilase in a biphasic lyotropic liquid crystal/dibutylether system has been demonstrated. This reaction system is applicable for the continuous production of (R)-benzaldehydecyanohydrin in a fixed bed reactor. The optical purity was between 94 and 96% ee and independent of the flow rate. The space time yield was maximal (2650 g/(1*d)) at a flow rate of 1.6 ml/min.

Der Rotationstropfkörper — Ein neues Reaktorkonzept in der biologischen Gasreinigung

Ein neuer Reaktor zur Durchfuhrung des Biotropfkorperverfahrens in der biologischen Gasreinigung wird vorgestellt. Die dauerhafte Vermeidung der Tragerverblockung wird erreicht durch den Einsatz rotierender geordneter Tragerpackungselemente, ein definiertes Flussigkeitsregime in Anfahr-, Betriebs- und Reinigungsphase sowie die kontinuierliche Erfassung und Kontrolle der immobilisierten Biomasse. Ein gleichmasiger Biofilm auf der gesamten Trageroberflache wird durch eine optimierte Flussigkeitsverteilung mit Hilfe von Spruhdusen und unter Ausnutzung der Tragerkorperrotation erzeugt. Die Abreinigung erfolgt durch mit Strahldusen erzeugte Flussigkeitsscherkrafte. Die Durchfuhrung eines zeitablaufgesteuerten Betriebsregims basiert auf der On-line-Quantifizierung der immobilisierten Biomasse. Die daraus resultierende neue Qualitat der Prozesskontrolle in der biologischen Gasreinigung wird durch experimentelle Ergebnisse zum Gasdruckverlust, Flussigkeits-Hold-up und den Abbauraten dokumentiert. Die Praxisrelevanz dieses Reaktorprototypen wird durch den Einsatz im mobilen Pilotversuch mit Realgasemissionen demonstriert. The Rotating Trickle Bed — A New Reactor Concept for Biological Waste Gas Treatment This paper presents a new reactor for the biological trickle bed process in biological waste gas treatment. Clogging of the support is permanently avoided by 1. use of rotating support packing units; 2. a defined liquid regime in the start-up, operating, and cleaning phases, 3. continuous measurement and monitoring of the immobilised biomass. A uniform biofilm over the support surface is produced by optimised liquid distribution by spray jets and utilisation of support rotation. Cleaning is accomplished by liquid shear forces produced by jets. The time-controlled operating regime is accomplished with the aid of on-line quantification of the immobilised biomass. The resulting new quality of process control in biological gas treatment is demonstrated by experimental results on gas pressure drop, liquid hold-up, and degradation rates. The practical relevance of this reactor prototype has been demonstrated by its use in a mobile pilot experiment with real gas emissions.