Researchers from Iran University of Science and Technology used nanotechnology to produce ceramic nanomembrane that is able to eliminate and degrade different types of pollutants in industrial wastewater.
The membrane carries out physical separation and photocatalytic degradation of the pollutants at the same time and it has very high efficiency.
According to Dr. Vahideh Tajer, one of the researchers, the presence of silica in titania network reduces the size of membrane porosity. As a result, the membrane becomes able to eliminate the pollutants based on separation mechanism. In addition, the presence of five molar percent of silica in the membrane increases the ability of the membrane to degrade pollutants by improving its photocatalytic properties. Therefore, the both factors of physical separation and photocatalytic degradation decrease the presence of pollutants in the system. On the other hand, since silica is cheaper than titania, the photocatalytic membrane will be cheaper when titania is replaced by silica in the membrane structure.
According to the results obtained by the researchers, the average size of pores in the membrane is about 4 nm. The ability of the membrane was investigated by studying the separation of methyl orange as the pollutant sample from water through physical separation and photocatalytic degradation methods both individually and simultaneously. Studies show that when UV waves are used, the elimination of methyl orange pollutant is about 63% by titania-silica composite membrane. However, when the two processes of physical separation and photocatalytic degradation are used at the same time, the separation value reaches 94%.
Results of the research have been published in Ceramics International, vol. 40, issue 1, January 2014, pp. 1747-1757.