Nanoparticle separation using direct contact membrane distillation and its fouling study

Direct contact membrane distillation (DCMD) which emerges as an alternative separation technology can effectively perform a colloidal separation process under thermal driven force. DCMD is capable of extracting pure water from aqueous solutions containing non-volatile nanoparticles through the hydrophobic microporous membrane when a vapour pressure difference was established across the membrane. This work aims to study the efficiency of the MD process in separating TiO2 nanoparticles. It was interesting to find out that below 1.0 g/L TiO2 concentration, no sign of flux reduction was noticed. It is indicated that the pore blocking phenomenon was not significant. However, as concentration exceeding 1.0 g/L, the flux started to decline due to the resistance of the gelation layer which impeded water from flowing through the membrane. The blocking law analysis showed that the cake layer was developed within 3 hours of operation. At higher feed velocity, the flux declination problem could be solved due to the surface scouring effect.