Christian Bradtmöller

Atomic force microscopy studies on the nanomechanical properties of Saccharomyces cerevisiae

In the past years atomic force microscopy (AFM) techniques have turned out to be a suitable and versatile tool for probing the physical properties of microbial cell surfaces. Besides interaction forces, nanomechanical properties can be obtained from force spectroscopic measurements. Analyzing the recorded force curves by applying appropriate models allows the extraction of cell mechanical parameters, e.g. the Youngs modulus or the cellular spring constant. In the present work the nanomechanical properties of the bakers yeast Saccharomyces cerevisiae are extensively studied by force spectroscopy using an AFM. Single cells deform purely elastically so that a cellular spring constant can reliably be determined. It is presented, how this spring constant depends on the probing position on the cell, and how it depends on the extracellular osmotic conditions. Investigations aiming a statistically firm description of the nanomechanical behavior of the yeast cell population are conducted. Finally, the informative value of the cellular spring constant as a cell mechanical parameter is critically discussed.

Separation of the Electrolyte—Thermal Drying

The recycled lithium-ion batteries are shredded to access value components for further processing. The material that has been shredded before must be dried. This is important not only because of the simplified separation of dry material, but also due to safety issues. A material loaded with electrolyte will be surrounded by a gaseous atmosphere loaded with electrolyte. Such a mixture of electrolyte and air has an environmental impact and can build an explosive atmosphere. Therefore, undried material requires gas tight as well as explosion protected equipment. Drying can be achieved by high temperature, low pressure and rinsing with inertization gas. To support process design and optimization, the influence of each parameter and advantageous parameter combinations can be determined with a flow sheet simulation. However, experimental investigations are required to verify simulation data and to identify critical aspects regarding handling of the material. This chapter discusses application and results of a flow sheet simulation as well as experimental investigations on drying.

Separation of the Electrolyte—Solvent Extraction

The extraction of electrolyte from lithium-ion batteries is a possibility to remove the high boiling organic components and the conducting salt from the battery material in the recycling of lithium-ion batteries. In these studies, dimethyl carbonate was employed as organic solvent. The influence of temperature and solvent to solid mass ratio have been tested with Panasonic CGR 18650 batteries in a stirred vessel. Although the conducting salt was successfully extracted with a crossflow extraction with four stages, the remaining fluoride loading of the battery material was too high for further processing. Therefore, a second series of extractions with water was used to remove fluoride. The combination of four extraction stages with dimethyl carbonate and six stages with water for the processing of hybrid electric vehicle batteries resulted in a fluoride loading of 173.3 mg per kg fine fraction of the raffinate. Suggestions for the design of an extraction apparatus based on the experiments were worked out.