Flocculation
By changing the electrical forces in the system (adding salt for instance), a stable suspension becomes unstable and its colloidal particles flocculate.

From microscale to macroscale : toward geotechnical applications

For the building industry and risk management there is an increasing need in predictive models, which can help to design safe constructions, like earthen dikes or houses on sensitive clay grounds. Models have been developed by geotechnical engineers to represent the mechanical behaviour of clay. However, these continuum-based models are complex in formulation and require a large number of material parameters, and thus, have never been accepted and used by industry. The consequent uncertainties and limitations force the design engineers to act conservatively, leading in many cases to the over-design of geo-structures to ensure safety at environmental costs i.e. by a waste of energy and construction material, and higher CO2-emission. In order to deliver a reliable model, with a limited number of measurable and physically meaningful parameters to the construction industry, work has been initiated within the center to couple colloid and interface science to the field of geotechnics.

Lyngseidet (Norway)

Liquefaction of quick clays can lead to disastrous landslides

With permission of MIT we have digitized the first 3 of the video lectures of Overbeek

Lecture 1

Lecture 2

part 1 part 2 part 3

Lecture 3

part 1 part 2 part 3

part 1 part 2 part 3 part 4

part 1 part 2 part 3

Links

Overview of his career

Google scholar Theo Overbeek

Wikipedia

Fysisch-chemicus J.Th.G. Overbeeken een hervonden verleden: Het kruisen van disciplinaire tradities

Organization of Theo Overbeek Center

Daily managing directors

The Theo Overbeek Center (TOC) is a 4TU center was founded with the aim to bring together scientists of different fields of research who study colloids and interfaces. This research not only covers a wide range of disciplines, but also in modelling and experiments, which range from micro-scale to full in-situ. An important research topic within the center is the sendiment-to-soil transition, where the properties of clays at different scales play an important role. Clays can be found all around us and play an important role in many applications, ranging from agriculture to ceramics industry. This 4 TU center wishes to promote multidisciplinary collaboration not only between the 4TU alliance but also between European universities and international universities. This collaboration focuses both on research and teaching. To this end, the center acts as an information hub for scientists and students and a catalyst for research.

The MRI facilities at the Darcy Lab are specially equipped for examining the porosity and composition of materials.

An overview of the NMR scanners ranging from 0.7 to 4.7T can be found here

MUDNET (TU-Delft)

An overview of the instruments available within MUDNET can be found here

Publications

Here an overview is given of articles related to TOC-center.

Events

Here an overview is given of events related to TOC-center.

2021 : Overbeekcenter website was launched

2022 : March improved website

Jan Theodoor Gerard Overbeek

30 January 1911 - 19 February 2007.

Overbeek was born in Groningen. He studied chemistry at the Utrecht University from 1928-1933. After doing his military service and he worked for two years in Belgium. Initially he worked with Jacques Errera at the Université libre de Bruxelles, after that a year with Arend Joan Rutgers at Ghent University.
His doctorate thesis was entitled Theory of Electrophoresis, the Relaxation Effect for which he received a doctorate on May 19, 1941. In his thesis Overbeek's explored the role of the deformation of the electrical double layer surrounding a charged colloidal particle which was set in motion by an external electric field.
After his graduation Overbeek he joined the Philips company. In addition to work his on luminescent screens, he kept looking a the interaction between colloidal particles. This research resulted into the Theory of the Stability of Lyophobic Colloids. This work is still of great influence, and is still used by considerations about the stability of colloids, but also in various other fields where charged surfaces interact with each other. The whole of that theory is now known as DLVO (Derjaguin, Landau, Verwey, Overbeek) theory.

Overbeek became a professor of physical chemistry at the Utrecht University in 1946. During this time he worked on polyelectrolytes, irreversible thermodynamics, wetting, thin films and biochemical problems. Confronted with a challenge, he was in the forefront of recognizing the essentials, defining the central problem and giving, or helping others to give, the essentials of the solution. He remained active after his retirement in 1981.

Overbeek received several prestigious awards:
- honorary degrees from Clarkson University and University of Bristol
- the Wolfgang Ostwald Prize.
- honorary membership of the Royal Netherlands Chemical Society
- elected as member of the Royal Netherlands Academy of Arts and Sciences

1911-2007

Research

Colloidal systems are systems that have one or more of their characteristic length in the range 10 1000 nm. Suspensions are colloidal when the suspended particles are in the colloidal range. These particles can be solid (like mineral particles) or soft (like polymers or droplets). The suspending medium is a solvent that in colloidal models is assumed to have bulk properties. Porous media can also be seen as colloidal systems when the size of the pores is within the colloidal range. In all cases, the macroscopic properties of the system is governed by its interfacial properties. The behaviour of ions close to charged interfaces drives the electrical properties of the double layer and the fluid transport that results from the forces applied to the system.

Two main research lines are set within the Overbeek center:

MODELS : (1) improvement of generic colloidal models (2) Linking colloidal models to macroscopic transport and consolidation models in the frame of clay and sediment applications

EXPERIMENTS: (1) Combining and developping measurements techniques so as to connect micro and macro properties of colloidal systems. (2) Using specific electrokinetic techniques such as to validate colloidal models or engineer colloidal systems.

Social relevance

Colloid and Interface science is an interdisciplinary research field, connecting disciplines that deal with colloids. Colloid and interface science has primarily applications in the food and chemical industry, pharmaceuticals, biotechnology, ceramics, minerals and nanotechnoly.

The microscale: from electrokinetics to flocculation
Electrokinetic phenomena, which are driven by electric forces on colloidal systems, are of key importance in the design of nanofluidic devices, which have a huge range of applications [1]. In the frame of clay and sediment research, electrokinetics enable to characterize particle-particle interactions, which in turn determine the stability of colloidal clayey materials. For instance, the DLVO theory, to which Overbeek contributed (The O in DLVO stands for Overbeek) enables to predicts whether a suspension will or will not flocculate. This feature is at the core of the dewatering principle used in sanitary engineering. It is also an important process in the dissemination of nutrients and pollutants in aquatic systems. The study of electrokinetics is therefore at the core of the Overbeek center.

[1] Sparreboom, Wouter, Albert van den Berg, and Jan CT Eijkel. "Principles and applications of nanofluidic transport." Nature nanotechnology 4.11 (2009): 713-720.
[2] Everett, Douglas H. Basic principles of colloid science. Royal society of chemistry, 2007.

Dr. Claire Chassagne

website TU-Delft

articles overview google-scholar

Dr.ir. Leo Pel

website TU-Eindhoven

personal website research

articles overview google-scholar

The four universities of technology in the Netherlands are jointly committed to strengthening and pooling technical knowledge

4TU contributes to the well-being of the Netherlands by strengthening and pooling knowledge and creativity in the technology sector, and by exploiting it to maximum effect. This is why the four universities of technology (TU Delft, Eindhoven University of Technology, University of Twente and University of Wageningen) are jointly committed to strengthening and pooling their technical knowledge with the aim of producing sufficient numbers of highly qualified engineers and technical designers, of conducting outstanding and socially relevant research of an international standard, and of promoting cooperation between research institutes and businesses

The Theo Overbeek Center is a cooperation between these 4 universities on colloid and interface research

The 4 universities which are :

An overview of the labs

Darcy lab (TU-Eindhoven)

Cooperations

As a Theo Overbeek Center we are actively seeking cooperation both national and international

Teaching

An important aspect of the Theo Overbeek Center is the support of teaching. Indeed, Prof Overbeek was one of the first to recognize the power of new multi media. In 1971 he started videotaping his course: a 55-lecture series about colloid and surface chemistry. There was already a publication in Chemical Engineering News in 1971 entitled 'MIT videotape series can replace textbooks' [1]. In a report in 1973 Overbeek himself refers to his videotaped lectures as made during his stay at MIT in the USA indicating that students so always would have access to his course. In the preface of his report of 1973 he writes: