Feasibility of w/o Pickering emulsion ultrafiltration

- Separation of w/o Pickering emulsions by ultrafiltration is possible.
- Pickering emulsions can be concentrated up to very high dispersed phase fractions.
- Results promise possibility of continuous (bio)catalysis in Pickering emulsions.
- Unexpected disproportionate permeability behaviour.

This study shows the possibility of separating w/o Pickering emulsions (PE) via ultrafiltration and consequently enables a continuous process concept for catalysed L/L reactions in Pickering emulsions which are currently receiving increased attention. In two types of filtration experiments, the stability of PE against coalescence caused by the applied filtration pressure and stirring was shown. The PE could be concentrated up to 80% water phase fraction. In pressure stepping experiments, permeabilities between 3 and 10 L/(m2 h bar) could be achieved depending on the drop size distribution of the PE. For the used 1 kDa PVDF membrane, an unexpected overproportional behaviour of the fluxes at higher pressures was observed. The presented results show that Pickering emulsions can be regarded as a promising alternative to conventional dispersions also in continuous L/L catalysis.