DECHEMA

About: DECHEMA is a nonprofit organization based out in Frankfurt am Main, Germany. It is known for research contribution in the topics: Corrosion & Oxide. The organization has 756 authors who have published 1307 publications receiving 25693 citations.

Characterization of a membrane-separated and a membrane-less electrobioreactor for bioelectrochemical syntheses.

Abstract: Bioelectrochemical systems (BESs) have the potential to contribute to the energy revolution driven by the new bio-economy. Until recently, simple reactor designs with minimal process analytics have been used. In recent years, assemblies to host electrodes in bioreactors have been developed resulting in so-called "electrobioreactors." Bioreactors are scalable, well-mixed, controlled, and therefore widely used in biotechnology and adding an electrode extends the possibilities to investigate bioelectrochemical production processes in a standard system. In this work, two assemblies enabling a separated and non-separated electrochemical operation, respectively, are designed and extensively characterized. Electrochemical losses over the electrolyte and the membrane were comparable to H-cells, the bioelectrochemical standard reaction system. An effect of the electrochemical measurements on pH measurements was observed if the potential is outside the range of -1,000 to +600 mV versus Ag/AgCl. Electrobiotechnological characterization of the two assemblies was done using Shewanella oneidensis as an electroactive model organism. Current production over time was improved by a separation of anodic and cathodic chamber by a Nafion® membrane. The developed electrobioreactor was used for a scale-up of the anaerobic bioelectrochemical production of organic acids and lysine from glucose using an engineered Corynebacterium glutamicum. Comparison to a small-scale custom-made electrobioreactor indicates that anodic electro-fermentation of lysine and organic acids might not be limited by the BES setup but by the biocatalysis of the cells.

Novel protective coatings for steel based on a combination of self‐assembled monolayers and conducting polymers

Abstract: Investigations for a new primer system for iron or low alloyed steel have led to first results. Several special phosphonic acids with thiophene derivatives as head groups have been synthesized. They form stable self-assembled monolayers ( SAMs ) on passivated iron by dipping the substrates into aqueous phosphonic acid solutions. SAM formation was validated by current potential curves and also by contact angle measurements, which showed an intensive hydrophobisation of the iron surface after the dipping process. Finally cyclovoltammetric ( CV ) experiments after SAM formation indicated the successful polymerisation of the immobilised thiophene derivatives.

Bio-electro-remediation: electrokinetic transport of nitrate in a flow-through system for enhanced toluene biodegradation

Abstract: The availability of electron acceptors and nutrients is often limiting the microbiological clean-up of polluted groundwater at contaminated sites. In this study, the feasibility of electrokinetic processes to improve mass transfer was demonstrated in a model system simulating laminar groundwater flow conditions. Electrokinetic nitrate transport and enhanced biodegradation of toluene under denitrifying conditions was studied as function of voltage gradient in a new flow-through system. The study was done in a three-dimensional anaerobic model aquifer system filled with coarse sand. The influent area was divided into seven chambers thus enabling a separate addition of toluene and nitrate. Mesh electrodes were inserted laterally in order to form an electric field perpendicular to the flow direction with voltage gradients of 0, 0.125 and 0.25 V cm−1, respectively. Biodegradation was studied after inoculation with a denitrifying microbial mixed culture. Application of the electric field resulted in nitrate migration into areas containing toluene. In the presence of denitrifying bacteria, the availability of nitrate in toluene polluted areas resulted in toluene biodegradation, demonstrated by nitrite formation and decreased toluene concentration.

Pt-containing zeolites for enantioselective catalytic hydrogenation of ethylpyruvate – effects of zeolite structures, solvent and modifier concentration

Abstract: Platinum-containing zeolites of the types Y, ZSM-5, ZSM-35 and β demonstrate their suitability as catalysts for enantioselective hydrogenation of ethyl pyruvate to ethyl lactate. The catalyst on the basis of a ZSM-35 shows the best enantioselectivity with conversions of more than 99% and it permits high reaction rates. Enantiomeric excess is strongly influenced by the type of solvent selected. Best results in selectivity are attainable by using solvents with dielectric constants of less than 10. An increase in chiral modifier concentration leads to a decrease in reaction rate of the hydrogenation of ethyl pyruvate. In this case the enantiomeric excess remains almost constant.