Concerning the goal of the work chose the particles.

- In case you are seeking for an anti fouling enhancement in the membrane, consider the fouling substance if it is hydrophobic, chose an hydrophilic nanoparticle or vise versa.

- If you are looking for enhanced flux of an aqueous solution, add hydrophilic nanoparticles to improve the hydrophilicity.

- If you would like to increase the porosity or the flux, after solidification of the membrane remove the added nanoparticles.

- If you want to increase the Rejection % of an analyte by the membrane, add nanoparticles with the same charge of the analyte.

- If you want to increase the Adsorption % of an analyte into the membrane, add nanoparticles with the opposite charge to the analyte.

For details please see the following papers:

Article Enhanced water flux through ultrafiltration polysulfone memb...

Article Nano-scale modification of polysulfone membrane matrix and t...

Different nano-particles can be used to enhance the membrane properties like Flux , Anti-fouling property , Thermal and Mechanical strength, Pore Size etc. Some nano-particles improves the more than one property of the membrane. In your case (for desalination) you have to select such a nano-particle which enhance either the flux or rejection or Anti-fouling property or membrane life(Strength). The particle size and wt.% of loading of the nano-particles in the membrane is also very important in the improvement of the membrane property so you have to optimized the wt.% loading of nano-particles. Researcher have been tested various type of nano-particles i.e. Silica ,Titanium Oxide ,Zeolite ,Carbon nano tubes, Graphene ,Metal-organic frame work (MOF) etc.

Concerning the goal of the work chose the particles.

- In case you are seeking for an anti fouling enhancement in the membrane, consider the fouling substance if it is hydrophobic, chose an hydrophilic nanoparticle or vise versa.

- If you are looking for enhanced flux of an aqueous solution, add hydrophilic nanoparticles to improve the hydrophilicity.

- If you would like to increase the porosity or the flux, after solidification of the membrane remove the added nanoparticles.

- If you want to increase the Rejection % of an analyte by the membrane, add nanoparticles with the same charge of the analyte.

- If you want to increase the Adsorption % of an analyte into the membrane, add nanoparticles with the opposite charge to the analyte.

For details please see the following papers:

Article Enhanced water flux through ultrafiltration polysulfone memb...

Article Nano-scale modification of polysulfone membrane matrix and t...

ZnO nanoparticles can be used as addition into different polymers. Experimentally, you can change there properties by changing the size of nanoparticles and the wt%.