Fakultät 09 / Institut Anlagen und Verfahrenstechnik
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Water serves for the production of pharmaceutical ingredients, intermediates and final products. Accordingly, the quality requirements are particularly high. Next to quality, sustainability of the production and climate change mitigation will play an increasingly important role. For instance, in 2015, the total global emissions of the pharma sector was significantly higher than the CO<sub>2</sub> emissions generated by the automotive sector. Thus, efforts must be made at all stages of production of pharmaceuticals to reduce the environmental impact.
The importance of lithium as a raw material is steadily increasing, especially in the growing markets of grid energy and e-mobility. Today, brines are the most important lithium sources. The rising lithium demand raises concerns over the expandability and the environmental impact of common mining techniques, which are mainly based on the evaporation of brine solutions (Salars) in arid and semiarid areas. In this case, much of the water contained in the brine is lost. Purification processes lead to further water losses of the ecosystems. This calls for new and improved processes for lithium production; one of them is electrodialysis (ED). Electrodialysis offers great potential in accessing lithium from brines in a more environmentally friendly way; furthermore, for the recovery of lithium from spent lithium-ion batteries (LIB), electrodialysis may become a vital technology. The following study focused on investigating the effect of varying brine compositions, different ED operation modes, and limiting factors on the use of ED for concentrating lithium-containing brine solutions. Synthetic lithium salt solutions (LiCl, LiOH) were concentrated using conventional ED in batch-wise operation. While the diluate solution was exchanged once a defined minimum concentration was reached, the concentrate solution was concentrated to the respective maximum. The experiments were conducted using a lab-scale ED-plant (BED1-3 from PCCell GmbH, Germany). The ion-exchange membranes used were PCSK and PCSA. The treated solutions varied in concentration and composition. Parameters such as current density, current efficiency, and energy requirements were evaluated. ED proved highly effective in the concentration of lithium salt solutions. Lithium chloride solutions were concentrated up to approximately 18-fold of the initial concentration. Current efficiencies and current densities depended on voltage, concentration, and the composition of the brine. Overall, the current efficiencies reached maximum values of around 70%. Furthermore, the experiments revealed a water transport of about 0.05 to 0.075% per gram of LiCl transferred from the diluate solution to the concentrate solution.
In this work, supported cellulose acetate (CA) mixed matrix membranes (MMMs) were prepared and studied concerning their gas separation behaviors. The dispersion of carbon nanotube fillers were studied as a factor of polymer and filler concentrations using the mixing methods of the rotor–stator system (RS) and the three-roll-mill system (TRM). Compared to the dispersion quality achieved by RS, samples prepared using the TRM seem to have slightly bigger, but fewer and more homogenously distributed, agglomerates. The green γ-butyrolactone (GBL) was chosen as a polyimide (PI) polymer-solvent, whereas diacetone alcohol (DAA) was used for preparing the CA solutions. The coating of the thin CA separation layer was applied using a spin coater. For coating on the PP carriers, a short parameter study was conducted regarding the plasma treatment to affect the wettability, the coating speed, and the volume of dispersion that was applied to the carrier. As predicted by the parameter study, the amount of dispersion that remained on the carriers decreased with an increasing rotational speed during the spin coating process. The dry separation layer thickness was varied between about 1.4 and 4.7 μm. Electrically conductive additives in a non-conductive matrix showed a steeply increasing electrical conductivity after passing the so-called percolation threshold. This was used to evaluate the agglomeration behavior in suspension and in the applied layer. Gas permeation tests were performed using a constant volume apparatus at feed pressures of 5, 10, and 15 bar. The highest calculated CO2/N2 selectivity (ideal), 21, was achieved for the CA membrane and corresponded to a CO2 permeability of 49.6 Barrer.
Abstract
In the chemical industry large amounts of saline wastewater occur. Its disposal into rivers is a considerable burden to the ecosystem. To strive for a circular economy and enable a viable raw material recycling, energy‐efficient concentration processes are requisite. High‐pressure reverse osmosis meets this criterion, but its industrial application demands suitable membrane elements that withstand the exceptional operation conditions and provide sufficient performance. Hence, new requirements regarding the design of spiral‐wound elements arise. To identify those, specific performance‐limiting effects need a better understanding.
The production of pharmaceutical ingredients, intermediates and final products strongly depends on the utilization of water. Water is also required for the purification and preparation of reagents. Each specific application determines the respective water quality. In the European Union, the European Pharmacopeia (Ph. Eur.) contains the official standards that assure quality control of pharmaceutical products during their life cycle. According to this, the production of water for pharmaceutical use is mainly based on multi-stage distillation and membrane processes, especially, reverse osmosis. Membrane distillation (MD) could be an alternative process to these classical methods. It offers advantages in terms of energy demand and a compact apparatus design. In the following study, the preparation of pharmaceutical-grade water from tap water in a one-step process using MD is presented. Special emphasis is placed on the performance of two different module designs and on the selection of optimum process parameters.
The main scope of this work is to develop nano-carbon-based mixed matrix celluloseacetate membranes (MMMs) for the potential use in both gas and liquid separation processes. Forthis purpose, a variety of mixed matrix membranes, consisting of cellulose acetate (CA) polymerand carbon nanotubes as additive material were prepared, characterized, and tested. Multi-walledcarbon nanotubes (MWCNTs) were used as filler material and diacetone alcohol (DAA) as solvent.The first main objective towards highly efficient composite membranes was the proper preparationof agglomerate-free MWCNTs dispersions. Rotor-stator system (RS) and ultrasonic sonotrode (USS)were used to achieve the nanofillers’ dispersion. In addition, the first results of the application of thethree-roll mill (TRM) technology in the filler dispersion achieved were promising. The filler material,MWCNTs, was characterized by scanning electron microscopy (SEM) and liquid nitrogen (LN2)adsorption-desorption isotherms at 77 K. The derivatives CA-based mixed matrix membranes werecharacterized by tensile strength and water contact angle measurements, impedance spectroscopy,gas permeability/selectivity measurements, and water permeability tests. The studied membranesprovide remarkable water permeation properties, 12–109 L/m2/h/bar, and also good separationfactors of carbon dioxide and helium separations. Specifically, a separation factor of 87 for 10%He/N2feed concentration and a selectivity value of 55.4 for 10% CO2/CH4feed concentrationwere achieved.
Water shortage and a rising water demand are prevalent issues on the political agenda worldwide. Available water resources must not only be provided to ensure a domestic and drinking water supply for a steadily increasing population but also for the growing industrial and agricultural sectors. This work outlines how the use of the innovative vacuum multi‐effect membrane distillation contributes to improve the water management efficiency in the following key industry sectors: desalination, drinking water and beverage industry, pharmaceutical, agro and chemical as well as oil and gas industry.
Pelleted biomass has a low, uniform moisture content and can be handled and stored cheaply and safely. Pellets can be made of industrial waste, food waste, agricultural residues, energy crops, and virgin lumber. Despite their many desirable attributes, they cannot compete with fossil fuel sources because the process of densifying the biomass and the price of the raw materials make pellet production costly.
Leaves collected from street sweeping are generally discarded in landfills, but they can potentially be valorized as a biofuel if they are pelleted. However, the lignin content in leaves is not high enough to ensure the physical stability of the pellets, so they break easily during storage and transportation. In this study, the use of eucalyptus kraft lignin as an additive in tree-leaf pellet production was studied. Results showed that when 2% lignin is added the abrasion resistance can be increased to an acceptable value. Pellets with added lignin fulfilled all requirements of European standards for certification except for ash content. However, as the raw material has no cost, this method can add value or contribute to financing continued sweeping and is an example of a circular economy scenario.
Durch das permanente Wachstum der Weltbevölkerung wird der Bedarf von Textilien stetig steigen. Die Produktvielfalt sowie der Konsum der Textilien werden immer größer. Die aktuellen Recyclingtechniken ermöglichen es nicht, den Rohstoffkreislauf für Textilien zu schließen. Dies liegt auch darin begründet, dass derzeit große Mengen der Textilien aus Mischgeweben zwischen Baumwolle und PET bestehen. Die Trennung dieser Komponenten ist jedoch eine Grundvoraussetzung für die Entwicklung eines geschlossenen Rohstoffkreislaufs und stellt gleichzeitig eine große Herausforderung für das Recycling dar. Durch chemische Recyclingverfahren können die Rohstoffe getrennt, aufbereitet und in die Textilproduktion zurückgeführt werden. In dieser Arbeit wird aufgezeigt, wie ein chemischer Recyclingprozess, der einen geschlossenen Rohstoffkreislauf erlaubt, technisch realisiert werden kann. Der Prozess erzeugt eine PET-Fraktion und eine Celluloselösung, die in weiteren Verarbeitungsschritten zu einer Regeneratfaser versponnen wird. In dieser frühen Projektphase werden in dieser Arbeit ebenfalls die Investitionsausgaben und die Herstellungskosten für das Verfahren abgeschätzt.
In dieser Arbeit wurde eine Machbarkeitsstudie zur Speicherung von Wasserstoff in Liquid organic hydrogen carriers (LOHCs) anhand eines gewählten Stoffsystems, Dibenzyltoluen, durchgeführt. Die Arbeit umfasst Bilanzierungen und Auslegungen für eine reversible Hydrierung und Dehydrierung in zwei getrennten Anlagen. Eine class 4-Kostenschätzung bildet die Grundlage für eine Wirtschaftlichkeitsberechnung. So konnten die Technologieziele hinsichtlich der Speicherfähigkeiten nicht realisiert werden. Dennoch zeigen die ermittelten Produktionskosten die Wettbewerbsfähigkeit dieses Ansatzes.
Kontakt: Fabian.Piehl@outlook.com