Desalination of seawater is one of the methods used to produce fresh water. There are various methods for desalination of seawater. One of them, positive osmosis, which consumes less energy, has been attracting attention in recent years. When solutions with different osmotic pressures come into contact through a membrane, water molecules move from a solution with low osmotic pressure to a solution with high osmotic pressure. Forward osmosis is a method of concentrating and separating solutions using this osmosis phenomenon. Recently, in this process, it is the subject that create a driving solution of osmosis phenomena (Draw solution: DS) that have high osmotic pressure and can be easily separation. In this study, we attempted to develop a forward osmosis process using fine particles and a DC electric field to solve the above subject. It is well known that fine particles generate high osmotic pressure in water and can be used as a solute in a draw solution. We had also reported that the particles can be separated by sedimentation by applying a DC electric field to the slurry. Therefore, in this study, we combined these two elements to establish a positive osmosis process.

The slurry used as the draw solution was prepared using silica as the particle and ion-exchanged water as the solvent. The amount of water absorbed by the silica slurry was calculated from the volume change and its performance was evaluated. The volume change of the draw solution was recorded every 3 hours after the start of water absorption. The mass transfer flux density of water was calculated from this volume change. In the separation test, a DC electric field was applied using a carbon electrode to the draw solution after the volume change had stopped. The voltage of the DC electric field kept constant and the direction of DC electric field changed over a period of 30 seconds.

The average value of the mass transfer flux density of water in the test was 149.3 (g m^-2 h^-1). This value was larger than in our previous study. This is considered to be due to the use of smaller particles than in past studies, which resulted in