News

Presentation at our Workgroup Seminar: Water-in-Water Emulsions

On wednesday July 18th, Dr. Jordi Esquena from the Institute of Advanced Chemistry of Catalonia (IQAC), part of the Consejo Superior de Investigaciones Científicas (CSIC), delivered a fascinating lecture on the topic of water-in-water emulsions during our weekly workgroup seminar. His research focuses on the complex mechanisms of liquid-liquid phase separations in aqueous systems and provides new insights into the potential applications of such systems.

Liquid/Liquid Phase Separations in Aqueous Environments

Dr. Esquena explained the fundamentals of phase separations in aqueous environments, which can be induced by various mechanisms. He particularly highlighted the role of salts and their ability to cause phase separations through the so-called "salting-out" effect. These phenomena occur when the ions of the salts alter the water structure, displacing certain macromolecules from the solution and causing them to form a separate phase.

Another focus of the presentation was the interactions between polyelectrolytes and polymers. These interactions can also induce phase separations, with the specific combination of polyelectrolytes and polymers being crucial for the stability and properties of the resulting emulsion. These systems offer unique opportunities to stabilize sensitive biomolecules, such as enzymes, in aqueous environments.

Stabilization of Enzymes and Controlled Release Systems

One particularly interesting application of these phase separations is the stabilization of enzymes, such as lactase. Dr. Esquena demonstrated how selecting appropriate polymers and their interactions with water can achieve controlled and retarded release of these enzymes. Such systems are particularly valuable as they protect the enzyme from the harsh conditions of digestive fluids, thereby increasing the effectiveness and longevity of enzyme preparations.

These advanced approaches offer promising prospects for developing new delivery systems that are not only more efficient but also ensure better bioavailability and stability of active ingredients. The research conducted by Dr. Esquena and his team thus makes a significant contribution to the advancement of water-based emulsion systems, which are of great interest in numerous biotechnological and pharmaceutical applications."

Our Group Outing to the geodetic fundamental station Wettzell

On August 1, 2024, we, the solution chemistry group, took a group outing to Bad Kötzting. In beautiful weather, we began our ascent on the Planetenweg, which features informational pillars about the solar system leading up to Wettzell. Upon arrival, we visited the geodetic fundamental station and received an interesting and informative tour from Dr. Thomas Klügel. After descending via a shaded hiking trail, we returned to Bad Kötzting, where we ended the day with a relaxing visit to a beer garden.

Prof. Michael Sternad Presents on Electrochemical Energy Storage

Prof. Michael Sternad of TH-Deggendorf recently delivered an insightful lecture on electrochemical energy storage as part of the Chair Seminar series. The presentation highlighted the work being done by his research group at the Technology Campus Plattling, providing a comprehensive overview of current technologies and future advancements in the field.

The lecture began with a brief introduction to the research group led by Prof. Sternad at the Technology Campus in Plattling. This team is at the forefront of innovation, dedicated to advancing the science of electrochemical energy storage through rigorous research and development.

Prof. Sternad then provided an overview of the fundamental components and functions of batteries and fuel cells. These energy storage devices consist of electrodes, separator, electrolyte and various -but important- electrolyte additives. The lecture emphasized the critical role of electrolytes and additives in enhancing the performance and longevity of these systems.

Delving deeper, Prof. Sternad explained the specific functions and requirements of electrolytes and their additives. The right combination of electrolytes and additives is essential for optimizing the efficiency and durability of electrochemical cells.

The discussion then shifted to secondary lithium-ion batteries, highlighting their advantages and unique features. 

Concluding the lecture, Prof. Sternad provided a glimpse into future technologies currently under development. His team is exploring novel concepts of Li-metal batteries (“anode-free” design) and advanced active materials for electrodes, innovative coatings for traditional electrodes, and new electrolytes capable of supporting higher cell voltages. These advancements aim to further enhance the performance and safety of electrochemical energy storage systems.

Prof. Sternad's lecture underscored the significant progress being made in the field of electrochemical energy storage and the exciting potential of future innovations. The work being done at the Plattling Technology Campus promises to contribute substantially to the advancement of energy storage technologies.

In Folge 10 des UR-Podcasts Gasthörer: Nachhaltige Chemie mit Professor Dr. Werner Kunz

Chemie ist nicht immer böse! Diese Botschaft ist das Anliegen von Professor Dr. Werner Kunz, Lehrstuhl für Physikalische Chemie an der Universität Regensburg. Der Wissenschaftler und sein Team forschen seit Jahrzehnten an umweltfreundlichen Lösungen für bestehende Produkte: Ob Körperpflege oder Haushaltsreiniger, Medikamente oder Düngemittel – für all diese Produkte gibt es Varianten, die genauso gut funktionieren, aber gleichzeitig nachhaltig und nicht giftig sind.

Prof. Dr. Werner Kunz. Fotos und Podcast: Katharina Herkommer / UR

Kunz und sein Team haben in den vergangenen Jahren unter anderem einen wirksamen Graffiti-Entferner entwickelt, den man sogar trinken könnte, oder auch ein umweltfreundliches Shampoo, das die Haare auf ganz besondere Weise pflegt. Wie sich diese Forschung auf dem Gebiet der Lösungsmittelchemie gestaltet und was es mit Erfindungen und Patenten auf sich hat, erklärt er in  Folge 10 des UR-Podcasts Gasthörer.

Chemielaborantin Theresa Ferstl, Mitarbeiterin am Lehrstuhl Kunz, im Labor an der Putzmaschine.

Nachruf Prof. Dr. Heiner Jakob Gores †

Viele von uns älteren erinnern sich noch gerne an unseren „letzten“ Elektrochemiker, seine Dynamik, wenn er wieder mal durch die Gänge stürmte, seine Vorlesungen und Praktikumsbetreuungen und seine unbedingte Hingabe an die Forschung, vor allem auf dem Gebiet der Lithiumbatterien, die er zusammen mit seiner beindruckenden Arbeitsgruppe (zeitweise über zehn Doktoranden und Diplomanden) noch viele Jahre nach der Emeritierung von Josef Barthel weiter trieb.

Seinen ehemaligen Chef folgte er 1971 von der Universität Saarbrücken, an der er studierte, mit nach Regensburg und arbeitete hier erst als Doktorand und ab 1975 als Akademischer Rat. 1989 wurde er zum Akademischen Direktor ernannt, 1997 folgte die Habilitation zum Thema „Transportkoeffizienten nichtwäßriger Elektrolytlösungen für technische Anwendungen – Ihre Interpretation auf der Grundlage chemischer Modelle und Beiträge zu Ihrer Optimierung“. Unter dem neuen Lehrstuhlinhaber Prof. Kunz leitete er danach eine eigene Arbeitsgruppe, ab 2006 als außerplanmäßiger Professor, bis zu seiner Pensionierung im Jahr 2011 und dann als Seniorprofessor an der Universität Münster. In seiner aktiven Zeit hat er zwanzig Doktoranden eigenständig zur Promotion geführt, davon viele, die heute in leitender Stellung in der Industrie oder auch selbst als Professor tätig sind.

Heiner Gores war ein Forscher und Lehrer mit Leib und Seele. Halbe Sachen waren nie seine Sache. Am liebsten gab er zweihundert Prozent. Die Zahl der Fachbücher, die er sich in seiner Karriere angeschafft hatte, überstieg sicherlich die Zehntausend. Wobei seine Interessen sich keineswegs auf die Chemie und Physik beschränkten. Gerade in seinen letzten Lebensjahren hat ihn noch die Geologie gepackt.

Unvergessen wird uns allen auch sein Humor bleiben. Um einen spöttisch-freundlichen Kommentar war er nie verlegen. Ein Gläschen französischen Weins musste auch sein.

Heiner wird für immer eine prägende Gestalt des Instituts für Physikalische und Theoretische Chemie bleiben. In der Hoffnung, dass er auch bei zukünftigen Generationen nicht vergessen wird. Aber dafür werden schon seine ehemaligen Schüler sorgen.  

In der Nacht zum 21. November ist sein Herz stehen geblieben und er ist friedlich eingeschlafen.

The best surfactant ... is no surfactant

Today, industrial chemical reactions are usually made in organic solvents. Due to environmental concerns and the search for new, sustainable processes, there is intense research for reactions that can be made in aqueous solutions. Of course, the lack of solubility of hydrophobic reactants is the major obstacle. To overcome this problem, usually surfactants are added to water. The result is called “micellar catalysis”. In a series of publications in high-impact journals, an American colleague has convinced the community and also industrial companies that micelles are mandatory for optimised reactivity in aqueous systems. Even more, the reactions work best with the very specific surfactants developed in his group. Since we had some doubts, we repeated some of the reactions published with micellar catalysis, but this time without any surfactant, just by performing the chemical transfer in simple mixtures of water and a simple alcohol. And it turned out, the yield was even better, and the conditions were milder! The crucial parameter is not the confinement in micelles, it is simply a sufficient and proper solubility of the reactants. Having proven this, we can now proceed to significantly simplify chemical reactions of industrial relevance. The results are published in the high-impact journal (IF = 16,74) Chemical Engineering Journal (https://doi.org/10.1016/j.cej.2023.144599).

Preis für nachhaltige Produkte und Verfahren

Auf der diesjährigen internationalen Konferenz Formula XI in Lille, Frankreich, wurde Prof. Kunz von der französischen chemischen Gesellschaft für seine jahrzehntelangen Beiträge zur Herstellung nachhaltigerer Produkte, besonders im Bereich Kosmetik und Reinigungsmittel und zur umweltfreundlicheren Produktion von Chemikalien mit dem Pierre-Fillet-Preis geehrt. Die Auszeichnung wird alle drei Jahre für Persönlichkeiten vergeben, die sich besonders um die verbesserte Formulierung von gebrauchsfertigen Produkten verdient gemacht haben. Nach dem Steinkopff-Preis 2019 der deutschen Kolloidgesellschaft ist dies bereits der zweite Preis für nachhaltige Chemie, den Prof. Kunz erhalten hat. Neben dieser Auszeichnung durfte Prof. Kunz im Rahmen eines 60-minütigen Hauptvortrages die wesentlichen Ergebnisse seiner Arbeitsgruppe in den letzten Jahren einem internationalen Publikum vorstellen. Dabei legte er besonderen Wert auf den Aspekt der Nachhaltigkeit der entwickelten Produkte und Verfahren, wobei nicht nur wissenschaftliche Aspekte (Umwelt, Energie, Toxizität) angesprochen wurden, sondern auch Performance, Preis, Kundenakzeptanz und die soziale Komponente. Gerade dieser ganzheitliche Ansatz bei der Umsetzung von nachhaltigen Ideen liegt Prof. Kunz besonders am Herzen.

A new strategy to dissolve long-chain surfactants in water at low temperatures

Surfactants find widespread use in daily life for cleaning purposes and form a vital part of many industrial formulations. So far, their application has been limited to amphiphilic structures with relatively short alkyl chains (typically up to C14 or C16) due to the poor solubility of longer-chain homologues under relevant conditions. Here we introduce a concept that eventually allows octadecyl sulfates and carboxylates to be effectively solubilised in water at room temperature. Through synthesis of alkoxylated derivatives of choline – an abundant molecule of natural origin – we have designed a new class of counterions preventing the precipitation of long-chain surfactants, as commonly observed with alkali ions or unmodified choline. The resulting amphiphilic systems show superior properties with respect to surface activity, which directly translates into enhanced cleaning performance in lab-based washing tests. Studies on the cytotoxicity and biodegradability of the alkoxylated choline derivatives highlight their potential for sustainable surfactant development. In the end, our approach could pave the way towards the use of hitherto unleveraged raw material resources in tailoured surfactant formulations for cleaning applications and beyond.

doi.org/10.1039/D2GC02460H

Physical-chemical and toxicological properties of osmolyte-based cationic surfactants and spontaneously formed low-toxic catanionic vesicles out of them

In the context of efficient drug delivery systems, catanionic vesicles offer several advantages, such as spontaneous formation and long-term stability. However, especially the cationic component of such vesicles is often toxic. Thus, the search for less toxic, biocompatible amphiphiles, while maintaining the desirable aggregation properties is crucial. In this work, we present cytotoxicity towards the human cell line Hela as well as biodegradability data of some cationic surfactants based on the natural osmolytes choline and ectoine. The synthesis, aggregation and solubility behaviour as well as the stability in water of these compounds is discussed. In order to induce the spontaneous formation of vesicles, several of these cationic surfactants are combined with choline carboxylates with varying chain length in different mixing ratios and characterised with cryo-TEM. Further, the cytotoxic effect of such novel catanionics is evaluated as a function of the cationic-anionic ratio and compared to that of classical combinations of sodium dodecylsulfate and dodecyltrimethylammonium bromide.

doi.org/10.1016/j.molliq.2022.119549

Nanoscopic microheterogeneities or pseudo-phase separations in non-conventional liquids

This article discusses new concepts in macroscopically monophasic colloidal systems, where entropy is a major driving force for very subtle interactions and structuring. First, we show how microemulsion-similar structures can be achieved with hydrotropes. These aggregates are less defined in structure and of shorter lifetime than classical micelles but still potentially useful microheterogeneities with internal interfaces. The other extreme case of strong interactions is given when cationic and anionic surfactants are mixed in equimolar ratios. It is well known that surfactants can be made more soluble when ethylene oxide groups are incorporated. This strategy is applied for such ‘catanionics’ to avoid surfactant precipitation. Finally, we consider the fact that ethylene oxide groups increase the size of the hydrophilic headgroups of carboxylates so that the geometrical constraints compel a direct spherical shape even in the absence of water. As a result, ‘water-free direct microemulsions’ with only charged surfactants and oil are conceivable.

https://doi.org/10.1016/j.cocis.2021.101535

Development of a Fully Water-Dilutable Mint Concentrate Based on a Food-Approved Microemulsion

Mentha spicata L. disappears in winter. The lack of fresh mint during the cold season can be a limiting factor for the preparation of mint tea. A fresh taste source that can be kept during winter is mint essential oil. As the oil is not soluble in water, a food-approved, water-soluble essential oil microemulsion was studied, investigating different surfactants, in particular Tween® 60. The challenge was to dissolve an extremely hydrophobic essential oil in a homogeneous, stable, transparent, and spontaneously forming solution of exclusively edible additives without adulterating the original fresh taste of the mint. Making use of the microemulsions’ water and oil pseudo-phases, hydrophilic sweeteners and hydrophobic dyes could be incorporated to imitate mint leaf infusions aromatically and visually. The resulting formulation was a concentrate, consisting of ~90% green components, which could be diluted with water or tea to obtain a beverage with a pleasant minty taste. https://doi.org/10.1016/j.foodchem.2021.131230

Ionic Liquids Based on the Concept of Melting Point Lowering Due to Ethoxylation

Most of the commonly used Ionic Liquids (ILs) contain bulky organic cations with suitable anions. With our COMPLET (Concept of Melting Point Lowering due to Ethoxylation), we follow a different approach. We use simple, low-toxic, cheap, and commercially available anions of thex type C_x(EO)_yCH₂COO^– to liquefy presumably any simple metal ion, independently of its charge. In the simplest case, the cation can be sodium or lithium, but synthesis of Ionic Liquids is also possible with cations of higher valences such as transition or rare earth metals. Anions with longer alkyl chains are surface active and form surface active ionic liquids (SAILs), which combine properties of ionic and nonionic surfactants at room temperature. They show significant structuring even in their pure state, i.e., in the absence of water or any other added solvent. This approach offers new application domains that go far beyond the common real or hypothetical use of classical Ionic Liquids. Possible applications include the separation of rare earth metals, the use as interesting media for metal catalysis, or the synthesis of completely new materials (for example, in analogy to metal organic frameworks). https://doi.org/10.3390/molecules26134034

Promising “green” solvent obtainable from woods & grasses

The molecule “γ-valerolactone“ (GVL)” can be readily synthesized from cellulosic biomass and could be used in a variety of commercial products, whilst having the potential to be even utilized in large-scale chemical processes. Additionally, it exhibits a very low toxicity towards aquatic environment and is readily biodegradable. These results were recently published in the leading journal for sustainable sciences “Green Chemistry” by the chair of Prof. Kunz in cooperation with researchers from TU Dresden. The article appeared on the cover of the respective issue and was featured for both the collection “2021 Hot Green Chemistry Articles” as well as the “Green Chemistry Editor’s Choice”. For the press release (in German), cf.: Link to press release.

In the article, the ecotoxicity of GVL towards aquatic plants, bacteria, invertebrates, and a vertebrate cell line was concluded to be very low. The lactone was also shown to be completely biodegradable within a month. Further, the solvent properties of GVL were modelled based on Hansen Solubility Parameters, COSMO-RS calculations and existing literature about GVL to evaluate potential applications of this “green solvent”. As a result, GVL could be shown to represent a promising substitute for several highly polar, aprotic solvents, such as the reprotoxic compounds N-methyl-2-pyrrolidone (NMP) and dimethylformamide (DMF). It was concluded to be of interest as a sustainable and less toxic solvent in the manufacture of certain polymers or pharmaceuticals, as a cleaning agent in various paint and coating formulations, as well as a solubilizer in cosmetics, pharmaceuticals, or agrochemicals.

Based on the promising results, the chair of Prof. Kunz is currently working together with an industrial company to build a pilot plant with a capacity of 2000 tons/year. In case of a higher demand, the production could then be boosted up to several thousand tons per year.

Link to the original article:
The green platform molecule gamma-valerolactone – ecotoxicity, biodegradability, solvent properties, and potential applications”, Green Chemistry (2021)

Protokoll zur jährlichen Unterweisung 2020 :>hier

Hinweise und Informationen für Prüfer und Aufsichten zum Ablauf von schriftlichen Prüfungen im Sommersemester 2020

Klick >Here

SHK-Job zu vergeben (September bis November 2020):638 Euro pro Monat für 3 Monate

Im Rahmen eines vom bayerischen Umweltministeriums geförderten Projektes zur Wiederaufarbeitung von PVC und des damit verbundenen Recyclings wertvoller Metalle ist ab 1. September eine SHK-Stelle am Lehrstuhl von Prof. Kunz zu vergeben.

Die studentische Hilfskraft soll im Rahmen des Projektes „Chlor-Plattform“ folgende Tätigkeiten an der Universität Regensburg durchführen.

·         Fällungsreaktionen und Filtrationen

• Zur Entfernung der kohlenstoffhaltigen Schlacke oder sonstigen Verunreinigungen aus den Metallkonzentraten sollen verschiedene Fällungsreagenzien verwendet werden.

·         Flüssig-Flüssig-/Fest-Flüssig-Extraktionen

• Die Metalle sollen durch Extraktionen von Verunreinigungen befreit werden. Hierzu werden verschiedenste klassische Lösungsmittel verwendet. Ebenfalls soll untersucht werden, ob weitere Metalle z.B. Pb aus den PVC-Koksen aufgrund der Schadstoffproblematik zurückgewonnen werden kann.

·         Fraktionierende Destillation

• Störstoffe in den Metallkonzentraten sollen vor oder nach der Extraktion entfernt werden.

Die Versuche sollten eigenständig nach Anleitung durchgeführt werden. Ebenfalls ist eine gute Dokumentation der Versuchsdurchführung sowie Ergebnisbericht wichtig.

Computational Fluid Phase Thermodynamics (53185)

ab 5. Okt. 2020

Professor Dr. Andreas Klamt
(2 SWS, Anrechnung für Aufbaumodul II in
Kombination mit anderer Vorlesung möglich)

Seminarvorträge SS2021

des Institutes für Physikalische und Theoretische Chemie für wissenschaftliche Mitarbeiter und Studenten nach der Bachelorarbeit Wintersemester 2020/21

Meeting schedule for regular seminar on Wednesday at 17:00 p.m.:

Schedule

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