Qualifications

BACHELOR-, MASTER THESES AND PRACTICAL COURSES

• Highly porous magnesium silicates for dye adsorption based on plant residues and a sustainable process

Topics Bachelor, Advanced and Master Theses / Supervised by Dr. Susan Wassersleben

Dyes, which are widely used in the textile, food and pharmaceutical industries, among others, pose a risk to plants, animals and humans as well as to the environment as a whole. Billions of tonnes of wastewater containing dyes enter our water systems every year. New sustainable technologies are needed to tackle this challenge.
In the removal of dyes from wastewater, adsorption is one of the most environmentally friendly technologies with the greatest economic interest, in addition to its efficiency, low cost of use and ease of handling.
When selecting adsorbents, cost-effective, stable and highly efficient adsorbents have attracted a great deal of attention in the industry in recent decades. Silicates, also known as the "green materials of the 21st century", are often used as adsorbents due to their stable physicochemical properties.
For many years, synthetic silicates in particular were used as adsorbents in industry. However, the production of these is usually associated with high time and energy expenditure and low efficiency. Recently, sustainable silicates have increasingly come into focus, as they are cheaper, more environmentally friendly and more readily available. Higher adsorption rates are possible with metal silicates (e.g. Mg-Silicate) due to their ability to bind complexes.

Magnesium silicates are used particularly in the field of dye adsorption. In addition to their polar properties, this is also due to their fast adsorption rate and good adsorption capacity at comparatively low production costs and the readily available starting materials.
The sustainable development and production of magnesium silicate adsorbents based on agricultural residues for the efficient removal of environmentally hazardous azo dyes from wastewater and industrial waste streams from the textile industry is to be investigated.
For the first time, Mg-silicate adsorbents are to be produced under completely sustainable conditions in comparison with products already available on the market. The process chain includes the use of agricultural residues instead of technical silicates, from which biogenic water glass is obtained under mild reaction conditions. By using alternative, environmentally friendly magnesium salts that do not represent an additional burden for groundwater and drinking water, the adsorbents are also to be precipitated under mild reaction conditions. With the support of an industrial partner, moulded bodies are developed and produced from the Mg silicate powders. In the spirit of the circular economy, the material cycle is closed by regenerating the adsorbents and reusing them.

 

• Synthesis of highly porous silica xerogels as thermal insulation material

Topics Advanced and Master Theses | Supervised by M.Sc. Kai Müller

In order to reduce energy consumption in Germany and worldwide, effective materials for thermal insulation must be developed. With their help, the required heating energy can be significantly reduced.

One of the most promising materials is silica aerogels, which are produced based on the sol-gel process. These highly porous gels have extremely low thermal conductivities, but are only used to a limited extent due to the currently still high production costs and low stability. Silica xerogels, on the other hand, show improved stability and significantly lower manufacturing costs, although the thermal conductivity of the material increases.

Within the framework of a master's thesis, the properties of the xerogels are to be optimised in the direction of lower thermal conductivities with the same stability.

• Synthesis of sustainable carbon-silica composites for wastewater treatment

Topics Bachelor, Advanced and Master Theses / Supervised by M.Sc. Bettina Lilli

The discharge of contaminated wastewater into natural resources can cause harm to humans and the environment. The removal of pollutants such as persistent pharmaceuticals or pesticides from water is therefore crucial for the protection of the environment. Since the early 2000s, a large number of scientific studies have shown that conventional wastewater treatment plants do not remove pharmaceuticals adequately, if at all. One possible solution is to introduce a fourth adsorptive treatment stage in wastewater treatment plants. In addition to activated carbons, which are already known for their high adsorption capacity, carbon-silica composites, which contain both porous carbon and silica, are available as possible adsorption materials.

In the context of green chemistry, the sustainable synthesis of such adsorbents for the removal of pollutants from water is becoming increasingly important. Agricultural residues in particular are playing an increasingly important role. In this theme, carbon-silica composites will be prepared from the agricultural residue rice husks via various synthesis steps. The variation of different parameters will be investigated.

• Synthesis of sustainable foam glass panels for exhaust gas purification

 Topics Bachelor, Advanced and Master Theses / Supervised by M.Sc. Tobias Günther

In Germany there are approx. 11 million wood-burning stoves, which have to fulfil limit values for emissions and dust according to BImSchV. To achieve these limits, catalytically active porous Al2O3 ceramics are currently used, but these are produced in energy-intensive, unsustainable processes. A cost-effective and sustainable alternative is the synthesis of catalytically active, flowable glasses from waste glass. The working group is currently trialling a new foaming process that can be used to produce open-cell glass plates. By using waste glass, otherwise hazardous residual materials can be further utilised at much lower process temperatures than Al2O3.

As part of qualification work, "glass sponges" that can flow through are to be produced. The process is to be improved in terms of feasibility, reproducibility and suitability for application. The variation of the synthesis parameters should lead to an enlargement of the pores and an improvement of the flowability. In addition, various active catalysts are to be integrated into the material. The samples are primarily analysed using density measurements, pressure loss measurements, SEM-EDX, XRD and optical microscopy.

• Production and functionalisation of porous glass granulate as a concrete additive

 Topics Bachelor, Advanced and Master Theses / Supervised by M.Sc. Tobias Günther

The current problems of the construction industry include a shortage of skilled labour, scarcity of resources and a poor CO2 balance. An innovative method for 3D printing prefabricated concrete components with a high proportion of porous waste glass is intended to counteract these problems. As part of this project, the working group aims to develop a highly porous foam glass granulate that can be added to the cement in large quantities. In this way, waste glass that would otherwise be unusable could be recycled and also have an insulating effect on the components.

As part of qualification work, foam glass with a high proportion of pores is to be produced from soda lime glass. These glasses are then hydrophobised in the form of granules in a subsequent step. The manufacturing processes must also be optimised for subsequent industrial application in terms of cost-effectiveness and feasibility. The characterisation of the results is primarily carried out using TG-DTA, contact angle determination, microscopy and density measurements.

• Porous Glasses as Transdermal Drug Delivery Systems (TDDS)

Topics Bachelor, Advanced and Master Theses / Supervised by M.Sc. Theresa Paul

Porous glass is to be studied as a potential transdermal delivery systems for various drugs. Due to their tunable pore size and volume as well as their large surface area, porous glasses present advantageous and novel properties for these applications.
Student works are possible in our research group, where material science aspects are studied. Possible student works include functionalization of the glass surface, modification of the pore structure and the development as well as improvement of methods to obtain ultra-thin and flexible glass membranes. (BA, MA, Vertiefer possible)
Students interested in the construction and automation of a model plant-system to stretch form porous glasses are also welcome to apply. Basic knowledge or interest in LabView, coding and engineering are preferred. (MA, Vertiefer students only)
It is further possible to do student works with our research partners in the pharmacological department of the University of Leipzig (Rudolf-Boehm-Institute for pharmacology and toxicology). Thereby drug loading and release kinetics are investigated via HPLC mass spectrometry. Furthermore, biocompatibility, adhesion to skin and toxic effects of the innovative drug carrier are examined. (Vertiefer, MA or teaching students)
Student works are possible in English and German.

• Development of porous, high-temperature stable CeO₂ supports for sustainable CH₄ production from greenhouse gases

Topics regarding Bachelor, Advanced and Master Thesis / Supervised by M.Sc. Tim Jähnichen

Due to depleting oil and natural gas reserves sustainable production of valuable fuels such as synthetic natural gas from CO and CO₂ (SEG) or bioethanol from sugar- or starch-containing plants is becoming increasingly important. If CO/CO₂ from the atmosphere or renewable resources is used for sustainable SEG synthesis, greenhouse gases are reduced and global warming is counteracted. Low-cost supported nickel-based catalysts possess high selectivity and activity in this hydrogenation reaction. For these catalysts, it has been shown that the support (Al₂O₃, CeO₂, ZrO₂, etc.) not only determines the textural properties and dispersion of the active phase, but also plays a key role in CO₂ activation. Ceria has excellent redox properties (Ce³⁺/Ce⁴⁺ redox couple) and also exhibits high oxygen storage capacity. Accordingly, ceria supports possess a large amount of oxygen vacancies with intermediate basicity compared to other support materials, which promote CO₂ activation dissociation and metal-support interaction.

The following tasks will be pursued in the context of preparing an open-pore ceria support material from phase-separated glasses for SEG synthesis from atmospheres CO/CO₂:

• Preparation and characterization of homogeneous Na₂O-B₂O₃-CeO₂ glasses.
• Generation of uniform phase separation to adjust porosity.
• Obtaining a comprehensive understanding of phase transformation during heat treatment and extraction
• CO/CO₂ adsorption studies concerning the influence of pore texture as well as phase composition