Membrane development for forward osmosis system

The demand for water and energy has increased dramatically in recent years as the world's population has expanded exponentially. These two crucial needs for humankind cannot be considered independently of each other since the production of freshwater needs energy, and typically large amounts of water are required for power generation. In particular in the Gulf region where seawater has a high salinity, thermal desalination requires a large amount of heating iterations, thus a large plant and high costs. Consequently, an efficient hybrid concentrated solar power system design that drives on this waste heat an innovative forward osmosis (FO)/membrane distillation (MD) system is suggested to produce drinking water at low costs.

FO employs the osmotic pressure difference between a diluted (feed) solution and a highly concentrated (draw) solution. The osmotic pressure and thus the chemical potential difference over the semipermeable membrane drives the water molecules towards the highly concentrated draw solution in order to nullify the chemical potential difference. The thermoresponsive draw solution is investigated for the separation process after MD where fresh drinking water recovers. The main drawback of FO is the occurrence of severe internal concentration polarization (ICP) induced by diluting and insufficient mixing of the draw solution within the membrane support. This decreases the effective osmotic pressure difference over the selective membrane and lowers the driving force for water transport (J_W).

In this project, wire electrospinning is used to produce highly open porous membrane supports to lower the ICP contribution. A Layer-by-Layer (LbL) coating aims to decrease reverse draw solute flux (J_S) while generating a high J_W and reducing the fouling sensitivity of the membrane.