See Soft matter, Fluidics and Interfaces (SFI)

Student assignments

  • Photocatalytic degradation of glycerol in a microchannel

    Microreactors are well known to intensify a process. Higher conversion can be achieved by changing the reactor from a slurry reactor to a microreactor. It’s easier to determine what is happening in the channel and taking it into account due to the laminar flow. Kinetics can be identified as what is happening at the surface instead of in the bulk. Therefore, microreactors are the ideal platform to study different parameters which influence the kinetics of organic oxidation reactions. Parameters which could influence the kinetics are pH, temperature, oxygen concentration, and others. The microchannel is schematically shown in the figure below, adjusted from [1].

    In this project, the focus is on the influence of the light source on a photocatalytic reaction, which is the oxidation of glycerol to more valuable products. In combination with some modelling you’ll try to figure out what is happening in the channel at the catalytic wall. The experimental part will consist of conversion experiments, to measure how much is converted and into what. A second experimental part consists of fluorescence lifetime imaging microscopy, where real-time profiles of oxygen, pH, carbon dioxide and temperature can be made over the length of the channel. 

    Please do not hesitate to contact Nicole Timmerhuis ( for more information. 

    [1]Rafieian, D., Driessen, R. T., Ogieglo, W., & Lammertink, R. G. (2015). Intrinsic photocatalytic assessment of reactively sputtered TiO2 films. ACS applied materials & interfaces7(16), 8727-8732.

  • Ion transport through graphene

    Graphene is increasingly studied as a potential material for membrane applications. It does not have any separation capability in its pristine state, however a perforated monolayer graphene membrane can selectively separate material due to steric or electrostatic exclusion [1, 2].  In our work, we use ion-bombarded perforated monolayer graphene membrane supported on a polymer foil to study diffusional ion transport properties through graphene [3]. This membrane allows positive ions to pass through and blocks negative ions, acting as a cation-exchange membrane (CEM). We have studied the selectivity of the membrane with varying concentrations from range where Donnan potential dominates to concentrations where the diffusion potential dominates and the membrane loses all its selectivity. We have also analyzed our experimental results with theory, based on Donnan equilibrium and the Teorell, Mayer and Sievers (TMS) theory. 


    So far, we have done our measurements without applying any electric field across the membrane and the observations are based on diffusional ion transport. Now, we need to explore how the ions transport through the membrane when an electric field is applied across the membrane. The aim of the current student’s project is to study the ion transport behaviour of the graphene membrane with the application of electric field. Also, in the later part of the project the ion transport will be studied with varying number of pores in the membrane. Visualization of the ion transport with dyes will be possible by FLIM (Fluorescence Lifetime Imaging Microscopy).  Finally, the experimental result will be validated with theoretical understanding in terms of Nernst Planck framework. 

    For more information, feel free to contact Madakranta (Dona) Ghosh:

    [1] O’Hern et al. “Selective Ionic Transport through Tunable Subnanometer Pores in Single-Layer Graphene Membranes.” Nano Lett. 2014, 1234-1241

    [2] Rollings et al. “Ion selectivity of graphene nanopores” Nature Comm., 2016, 7, 11408

    [3] Madauß et al. “Fabrication of nanoporous graphene/polymer composite membranes” Nanoscale, 2017, 9, 10487

  • Diffusio-osmosis, an engineering approach

    Many heterogeneous systems have mass transfer limitations near the solid-liquid interface. These limitations in the boundary layer are due to fast reaction at the wall, creating a concentration drop towards the solid. Or it could be from the velocity which is standing still near the wall due to a laminar, parabolic flow pattern in the microchannel. The main focus of this project is to overcome this mass transfer limitation by creating an osmotic flow near the solid-liquid interface in the boundary layer.

    An osmotic flow is created by a pressure gradient in the liquid, which is directly proportional to the concentration gradient for non-electrolytes and to the natural logarithm of the concentration gradient for electrolytes [1]. The concentration gradient is created by the interaction between the liquid particles and solid interface, which can be repulsive or attractive. If different solid interfaces are used, alternating each other, a continuous osmotic flow can be created in the boundary layer along the wall. This is schematically shown in the figure below.

    In this project you’ll research the broader impact of diffusio-osmosis. What would be the design parameters to utilize osmotic flow for higher conversion or lower pump intensities? This could be investigated numerically. An experimental approach is also possible, where you would first come up with a possible experimental design to measure the diffusio-osmotic velocity.

    Please do not hesitate to contact Nicole Timmerhuis ( for more information. 

    [1] D.C. Prieve, J.L. Anderson, J.P. Ebel, M.E. Lowell, J. Fluid. Mech., 148:247-269, 1984

  • Catalytically Induced Convective Flow

    The electrochemical decomposition of hydrogen peroxide  has been reported to generate interfacial fluid flow by micro-pumps, and interdigitated microelectrodes[1], as well as the motion of bimetallic platinum/gold nano-motors [2]. In principle, the immersion of platinum/gold nanorods in hydrogen peroxide, triggers a series of oxidation and reduction reactions, where  is oxidized at the platinum anode into protons, electrons, and oxygen molecules, while reduction takes place at the gold cathode. The resulting ionic flux generates an electric field that is coupled with the charge density, thereby inducing an electric body force that drives interfacial fluid motion.The heterogeneous rate constant which largely influences ionic flux by way of proton generation and consumption is an important parameter that needs to be understood under steady state and transient conditions.

    The kochi and Kolinger’s approach [3] will be used in determining the reaction rate constant. Several electrochemical experimental techniques such as chronoamperometry, chronopotentiometry and cyclic voltammetry, will be used in determining important parameters such as, diffusion coefficient, charge transfer, number of electrons, and peak potentials needed for evaluating the rate constant. The experimental heterogenous rate constant will be implemented in existing numerical models by way of the Damköhler’s number to ascertain its influence on the reaction flux, proton distribution, induced potential and convective flow.

    For more information, contact:

    Abimbola ASHAJU (, Soft Matter, Fluidics and Interfaces, Meander 317)

    [1]          T. R. Kline, W. F. Paxton, Y. Wang, D. Velegol, T. E. Mallouk, and A. Sen, “Catalytic micropumps: Microscopic convective fluid flow and pattern formation,” J. Am. Chem. Soc., vol. 127, no. 49, pp. 17150–17151, 2005.

    [2]          T. R. Kline, W. F. Paxton, T. E. Mallouk, and A. Sen, “Catalytic Nanomotors: Remote-Controlled Autonomous Movement of Striped Metallic Nanorods**,” pp. 744–746, 2005.

    [3]          R. J. Klingler and J. K. Kochi, “Electron-transfer kinetics from cyclic voltammetry. Quantitative description of electrochemical reversibility,” J. Phys. Chem., vol. 85, no. 12, pp. 1731–1741, 1981.

  • Multicomponent nanofiltration modeling

    Nanofiltration membranes are commonly employed in industrial practice for separations of molecular species while working at relative low operation pressures. The unique property of these membranes is that they allow passage of certain solutes, while they can retain others. This makes nanofiltration a cost-effective step in the separation or purification of several streams. This can for instance be drinking water production, or resource recovery from waste streams. For an effective process, it is essential to understand the transport of the different solutes to and through the membrane. 

    One observed non-ideality is the emergence of non-intuitive phenomena, such as negative retention of solutes (the permeate of a process is more concentrated than the retentate). This is, in particular, more common in mixture systems due to the fascinating non-ideal thermodynamics involved and has important consequences in the design and operation of membrane processes for separations. Building a model framework that can capture these effects and understand the role of mixture interactions in a simple manner is therefore of crucial importance.

    In this assignment, you will work to build and compare multicomponent mass transfer models and compare the role of choosing an effective mixture thermo-dynamics rule + model framework in describing experimental data for hollow fiber filtration. The aim is to be able to describe industrially relevant hollow fiber filtration data obtained from actual membrane filtration experiments. The assignment will be performed at the UT in close collaboration with an industrial partner (NX Filtration).

    For more information please contact Jeff Wood ( or Joris de Grooth (