Fouling has always been one of the obstacles to membrane technology. Materials such as lipids and proteins can cause blockage, technically referred to as fouling, to membrane filters used in food, water and purification industries.

Recently, researchers at Razi University in Iran, have reduced the amount of membrane fouling by coating titanium dioxide nanoparticles on membrane surface, and as a result, succeeded in enhancing membrane lifetime. The results of this research, published in Journal of Membrane Science, Vol. 313, pp. 158-169, 2008, reveal that the membranes whose surfaces have been coated by titanium dioxide nanoparticles are less fouled by lipids and proteins.

Ahmad Rahimpour, a member of the research team, declared: “In this research, we took advantage of photocatalytic and strong hydrophilic characteristics of titanium dioxide nanoparticles in order to modify the surface of polyethersulfone (PES) membranes and develop better foul-resistant membranes.Titanium dioxide nanoparticles show photocatalytic and strong hydrophilic effects at the same time. When exposed to UV irradiation, titanium dioxide nanoparticles are capable of decomposing many different organic compounds. On the other hand, due to increased hydrophilic characteristics of the new membranes, their surfaces are less blocked.”

About their techniques of depositing nanoparticles upon membrane surface, he added: ”We used two ways to modify membrane structure. In the first method, titanium dioxide nanoparticles are produced as solutions and then added to membranes. While in the second method, coated PES membranes, prepared by floatation technique, are exposed to UV irradiation for a specific time.”

“The new membranes not only show more antifouling properties but also they can kill bacteria and viruses living upon the surface.” he also pointed.