The outstanding chemical and thermal stability of native ceramic membranes make them excellent candidates to work in the more challenging liquid environments (organic solvents, high temperatures) encountered in chemical industry. However, the chemistry of the native liquid filtration ceramic membranes is limited to strong polarity. To create wide flexibility and tailor-made affinity, grafting of the pore surface is an efficient tool. In the last few years, we, at VITO, have developed and optimized several new technologies that allow the tuning of ceramic membranes for various filtration purposes.
The first method consists of modifying the membrane separation surface with simple alkyl groups, typically C1 - C8 chains. This produces a direct carbon metal covalent (Ti or Zr) bond. This modification of the membrane surface has been shown to have no effect upon molecular weight cut-off (MWCO) of the membrane, implying minimal or no pore shrinkage via this modification. However, significant influence over affinity-based separations have been demonstrated, improving noticeably upon the state of the art, especially in organic solvent nanofiltration (OSN), metal recovery applications and anti-fouling properties. This eventually led to the foundation of the spin-off company A-membranes.

To move further towards efficient solute affinity-based separations, the VITO grafting platform was recently extended to seriously increase the loading of functional groups (by grafting polymer brushes using SI-ATRP). The resulting hybrid membranes combine the best of two worlds: the superior overall properties of ceramics and the tunable surface properties offered by the organic/polymer layer. Our target is to combine chromatography-like selectivity with continuous and modular processing of membranes. With the rise of bio-based chemistry, ever more separations will profit from this development, and this is where we think tailor-made membranes can make a difference