The renewed Chemistry exam program is based on the Context ? Concept - approach. Using meaningful and appealing contexts students learn collaboratively concepts from the field of chemistry, which they relate and integrate with each other. The educational field of chemistry feels a need to seek new and fresh ways of teaching, which will stimulate learning processes. This research checks to which degree the Eduscrum®-didactics are suitable for this purpose. Eduscrum® is an adaption of successful scrum methods from the ICT world. Characteristics are: energetic application of personal qualities, ownership, clear targeting, moments of retrospectives and comprehensive timing, in which students realize which results will be produced. The hypothesis is that Eduscrum®-didactics stimulate critical thinking and reasoning, so concepts are going to be more effectively transferred to new contexts.

There is growing awareness and concern about the presence of so called micro-pollutants (MP’s) in our surface water and drinking water. MP’s, very small organic molecules (100-1000 dalton) stem from industrial, medicinal and agricultural waste. They have the potential to cause long-term harm to humans and the environment, something especially true for MP’s classified as Endocrine Disrupting Chemicals for which it is known that even at very low concentrations they can have a significant negative effect on health and environment. Techniques to remove these MP’s from surface and drinking water are available but are currently too costly and/or inconvenient for the treatment of large streams of water. An example of this is the current state of art Reverse Osmosis (RO) treatment. RO membranes represent the densest membranes used in water treatment and have been found to successfully remove many MP’s. However, these membranes were designed with a very different application in mind (desalination) and have significant drawbacks. For proper operation at the high pressures needed for desalination, RO membranes have a thick active separation layer (> 100 nm) resulting in low permeabilities and thus a high energy demand for non-desalination applications. Furthermore, current RO membranes are very susceptible to fouling and to make matters worse, they have a low chemical stability against common cleaning methods employed in drinking water industry, e.g. chlorine treatment. This means that currently RO membranes can only be effectively used with an expensive pre-treatment to prevent membrane fouling. In this project we propose the development of a novel RO membrane specifically designed for the removal of MP’s. For this we turn to a very different chemistry: the self-assembly of oppositely charged polyelectrolytes at the interface of a porous support membrane. In this so-called Layer-by-Layer assembly, the support membrane is alternatively exposed to polycations and polyanions, to build polyelectrolyte multilayer’s (PEMs) of controllable thickness. A large advantage of this approach is that the properties of the PEM layer, responsible for the separation properties of the membrane, can be tuned by choice of polymer and by the employed coating conditions such as pH and ionic strength. This method thus allows the design of a membrane with optimal MP removal, by careful choice of the density, charge density and hydrophilicity of the PEM layer. Furthermore, we propose to coat these PEM membranes in a novel asymmetric fashion, where coating at a high ionic strength leads to the formation of a very open layer, 20-40 nm in thickness that prevents defect formation, after which coating at low ionic strength leads to an additional very thin (5-10 nm) and dense layer that performs the actual separation. This asymmetric approach to PEM multilayers is expected to provide very high selectivity (a very dense and defect free membrane) with very high water permeability due to the ultra-thin selective layer. Furthermore, PEM membranes are known to be much more resistant to chemical cleaning than current RO membranes. The versatility of this approach allows the PEMs to be grown on a multitude of substrates, thus allowing its use for the development of hollow fiber RO. In this membrane geometry the membrane is much less susceptible to fouling. In combination with its increased resistance to chemical cleaning these novel asymmetric PEM based RO membranes would allow for RO treatment without expensive pre-treatment.

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