Consideration of Toxicological Aspects in the Development of Lubricants Based on Synthetic Esters

Bibiane Erlenkaemper, Esm-CS, EvonikDegussa GmbH, Rodenbacher Chaussee 4, D-63457 Hanau, Germany, Wolfgang Dott, Institute for Hygiene and Environmental Medicine, RWTH Aachen, Pauwelsstr. 30, D-52074 Aachen, Germany, Marcel A. Liauw, Itmc, RWTH Aachen University, Worringerweg 1, Aachen, 52074, Germany, Sven Eichholz, RWTH Aachen, Institute of Technical and Macromolecular Chemistry, Worringerweg 1, Aachen, 52074, Germany, and Adolf Eisentraeger, Federal Environment Agency Germany, Woerlitzer Platz 1, D-06844 Dessau, Germany.

Up to now the development of new lubricants mainly aimed at an optimal technical performance. The consideration of toxicological characteristics only became relevant when the product was brought to market.

This study contributes to the equal implementation of toxicological and performance characteristics in the early stages of development of lubricants. In terms of sustainable development the application of environmentally acceptable lubricants in different technical applications is promoted. To enhance their technical performance and avoid the use of additives, bio-based lubricants are often chemically modified. These processes do not only influence their technical characteristics, but also their ecotoxicological behaviour. By the combined application of chemical analyses and standardised bioassays relevant compounds causing toxic effects were identified and an optimization of the synthesis was achieved. The applied analytical methods include the determination of acid number, saponification number, iodine number, peroxide number, epoxide number and viscosity, as well as gas chromatography, 1H-NMR, 13C-NMR, ATR-IR and reaction calorimetry. For the determination of ecotoxicological effects, aqueous extracts of the lubricants were prepared and applied to bioassays with algae and daphnids.

One example for the integrated approach is the detection of highly acidic compounds leached from the solid acid catalyst. These toxicologically detrimental substances were removed by steam treatment in the 20L technical setup.

The authors thank the DFG for financial support (SFB 442).