Desalination membranes
The increasing global concern over the limited supply of fresh water from conventional sources has led to great efforts towards the utilisation of alternative water sources.
Membrane desalination has been considered as one of the most promising techniques for saline water recovery. Two membrane methods of water desalination, reverse osmosis (RO) and electrodialysis (ED), compete for a dominating position in the water recovery systems. The ED method shows some advantages over RO in terms of the level of water pretreatment, membrane replacement frequency and energy cost, whereas one of the most challenging problems that hinder the development of ED technique are membrane materials.
To date it is generally only polymeric membranes with functional groups that have been used in the ED apparatus. However, the apparent disadvantages associated with polymer membranes, such as poor thermal and chemical stability, high sensitivity, and especially the fouling tendency toward organic contaminants, has resulted in limited applications for ED.
This project is a cluster project of the CSIRO Water Flagship program led by Prof Max Lu, Dr Lianzhou Wang and A/Prof Joe da Costa, aiming to prepare novel nanocomposite materials for ion-exchange membrane in electrodialysis (ED).
The key concept of the research is the incorporation of oxide nanoparticles into ionic conducting polymers to achieve homogeneously mixed nanocomposites with controllable porosity and tunable surface property. The outcomes will lead to possible breakthrough technologies in cost-effective and highly efficient water recovery systems.
Major achievements
- In the past one year, a bottom-up nanotechnology approach has been used to design polymer-inorganic nanocomposite membranes with tailored properties for electrodialysis water purification applications, and resultant composite membranes containing sulphonated SiO2 and sulphonated polyethersulfone exhibited excellent ion-exchange capability and good thermal stability, which are comparable to a commercial benchmark product.
- A robust electrodialysis cell has been designed and used to evaluate the electrodialysis performance of these novel membranes. This should lead not only to the generation of new and interesting membrane materials for water desalination by electrodialysis, but help to create and capture the knowledge and know-how to successfully apply these materials for the benefit of society.
One journal and one conference proceeding have been published, and two oral presentations were delivered at international conferences in 2008, with one of them winning first prize.
Future plans and directions
We expected that an extensive series of nanocomposite membranes will be synthesised and characterised in the coming year to enhance understanding of the relationship among structure, composition and ion-exchange efficiency of the membrane. Particularly, composite membranes with anti-fouling properties, by combining photocatalytic TiO2 nanoparticles with a polymer matrix will be one of the research focuses.
Collaborations
In this project, we are collaborating closely with Dr. B. P. Ladewig from Monash University, who has previously worked on the project as a research follow and then took a lectureship at Monash in 2008. Dr. Ladewig will continue to participate in the project, including experimental design, co-supervision of a PhD student/RA as well as in the preparation of manuscripts.
