Past exam of the MPhil in micro- and nanotechnology enterprise course of the University of Cambridge / 2023 / Paper 1 / Section B / 10 / i / c

Centrifuge the dispersion, separate the particle-rich sediment from the supernatant, wash the particles with a compatible solvent and repeat separation as necessary to remove soluble reagents and byproducts. Use conditions appropriate to the actual particle size and colloidal stability; the aim is particle separation rather than chemical decomposition.

A suitable membrane filtration process is another possibility if its pore size retains the particles. Simple solvent evaporation alone would leave soluble impurities together with the product, so it is not a selective isolation method.