Continuous chromatography is essential for product purification in chemical, pharmaceutical and food industry. The goal of the method is to efficiently separate concentrated mixtures with a high throughput. Efficient separation means that a large difference is present in the retention time of the desired product and the undesired impurities. High throughput implies that the column used in the separation can handle a large amount of material, and this can be achieved by having a large surface per volume of column. Usually this is achieved by packing a column with porous particles. The drawback of this is that the closely packed particles create a large resistance for flow of the solvent (the mobile phase), while the pores introduce a high mass transfer resistance. Furthermore, the pores and spaces between particles are random, which leads to a large residence time distribution for individual molecules through the column, and therewith to lower separation resolution.
Our hypothesis that better chromatographic separation performance can be achieved with an open 3-dimensional column structure with high symmetry. We will use novel 3D printing techniques to create such a column. Because of the reduced residence time distribution, such a column, if it is modified with a catalyst, could also become very important in the area of heterogeneous catalysis.
Some pre-work has been done by a student who used two-photon stereolithography to manufacture 3D column structures (see figure). Modeling work on the optimal column design has been performed by the group of Gert Desmet at VU Brussels, with whom we collaborate. The first goal of the assignment is to learn the software and equipment for stereolithography. Next, potentially interesting symmetrical 3D patterns for chromatography and/or catalysis will be designed and fabricated. Of particular interest is the liquid flow resistance of the structure, as a function of the dimensions (which will be in the 0.5 - 50 µm range). It will be investigated if, simultaneously with the 3D metamaterial, also an injector, the walls of the device, and a suitable outlet can be printed. The column will be chemically treated to make it suitable for reversed-phase chromatography. Finally, the printed column will be tested for the separation of a number of components, and this will be done as a function of liquid velocity.
The technical skills that the student will learn include stereolithography (incl. NanoLab training), surface modification, advanced chromatography, material analysis, scanning electron microscopy.
The interested candidate is expected to have a background in Chemical Engineering or Nanotechnology.
First results of 3D printing of a mesoscale column
Han Gardeniers; Email: email@example.com